EXHIBIT 4.1

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                     PLASMA & MATERIALS TECHNOLOGIES, INC.
                                  as Company



                           _________________________



                7 1/8% Convertible Subordinated Notes Due 2001



                           _________________________



                                   INDENTURE

                          Dated as of October 7, 1996


                           _________________________



                    U.S. Trust Company of California, N.A.,
                                  as Trustee



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                               TABLE OF CONTENTS
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                                                                                        PAGE
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ARTICLE 1  Definitions and Incorporation by Reference..................................   1
           SECTION 1.1     Definitions.................................................   1
           SECTION 1.2     Other Definitions...........................................   8
           SECTION 1.3     Incorporation by Reference of Trust Indenture Act...........   9
           SECTION 1.4     Rules of Construction.......................................  10

ARTICLE 2  The Notes...................................................................  10
           SECTION 2.1     Form and Dating.............................................  10
                   (a)     Global Notes................................................  10
                   (b)     Book-Entry Provisions.......................................  11
                   (c)     Certificated Notes..........................................  12
           SECTION 2.2     Execution and Authentication................................  12
           SECTION 2.3     Registrar, Paying Agent and Conversion Agent................  13
           SECTION 2.4     Paying Agent to Hold Money in Trust.........................  13
           SECTION 2.5     Noteholder Lists............................................  13
           SECTION 2.6     Transfer and Exchange.......................................  13
                   (a)     Transfer and Exchange of Global Notes.......................  14
                   (b)     Transfer and Exchange of Certificated Notes.................  16
                   (c)     Transfer of a Beneficial Interest in a Restricted
                           Global Note or Unrestricted Global Note for a
                           Certificated Note...........................................  17
                   (d)     Restrictions on Transfer and Exchange of Global
                           Notes.......................................................  18
                   (e)     Transfer and Exchange of a Certificated Note for a
                           Beneficial Interest in a Global Note........................  18
                   (f)     Authentication of Certificated Note in Absence of
                           Depositary..................................................  19
                   (g)     Legends.....................................................  19
                   (h)     Initial Purchasers..........................................  20
           SECTION 2.7     Replacement Notes...........................................  20
           SECTION 2.8     Outstanding Notes...........................................  21
           SECTION 2.9     Treasury Notes..............................................  21
           SECTION 2.10    Temporary Notes.............................................  21
           SECTION 2.11    Cancellation................................................  22
           SECTION 2.12    Defaulted Interest or Liquidated Damages....................  22

ARTICLE 3  Redemption..................................................................  23
           SECTION 3.1     Notices to Trustee..........................................  23
           SECTION 3.2     Selection of Notes to be Redeemed...........................  23
           SECTION 3.3     Notice of Redemption........................................  23
           SECTION 3.4     Effect of Notice of Redemption..............................  24
           SECTION 3.5     Deposit of Redemption Price.................................  24
           SECTION 3.6     Notes Redeemed in Part......................................  24
 

                                       i

 

                                                                                
           SECTION 3.7     Optional Redemption.........................................  25
           SECTION 3.8     Designated Event Offer......................................  25
           SECTION 3.9     Special Mandatory Redemption................................  27

ARTICLE 4  Covenants...................................................................  27
           SECTION 4.1     Payment of Notes............................................  27
           SECTION 4.2     SEC Reports.................................................  27
           SECTION 4.3     Compliance Certificate......................................  27
           SECTION 4.4     Stay, Extension and Usury Laws..............................  28
           SECTION 4.5     Corporate Existence.........................................  28
           SECTION 4.6     Taxes.......................................................  29
           SECTION 4.7     Designated Event............................................  29
           SECTION 4.8     Deposit of Proceeds with Trustee Pending
                           Consummation of Acquisition.................................  29

ARTICLE 5  Conversion..................................................................  30
           SECTION 5.1     Conversion Privilege........................................  30
           SECTION 5.2     Conversion Procedure........................................  31
           SECTION 5.3     Fractional Shares...........................................  32
           SECTION 5.4     Taxes on Conversion.........................................  32
           SECTION 5.5     Company to Provide Stock....................................  32
           SECTION 5.6     Adjustment of Conversion Price..............................  32
           SECTION 5.7     No Adjustment...............................................  36
           SECTION 5.8     Other Adjustments...........................................  36
           SECTION 5.9     Adjustments for Tax Purposes................................  36
           SECTION 5.10    Adjustments by the Company..................................  36
           SECTION 5.11    Notice of Adjustment........................................  37
           SECTION 5.12    Notice of Certain Transactions..............................  37
           SECTION 5.13    Effect of Reclassifications, Consolidations, Mergers
                           or Sales on Conversion Privilege............................  37
           SECTION 5.14    Trustee's Disclaimer........................................  38

ARTICLE 6  Subordination...............................................................  38
           SECTION 6.1     Agreement to Subordinate....................................  38
           SECTION 6.2     No Payment on Notes if Senior Debt in Default...............  38
           SECTION 6.3     Distribution on Acceleration of Notes; Dissolution
                           and Reorganization; Subrogation of Notes....................  40
           SECTION 6.4     Reliance by Senior Debt on Subordination
                           Provisions..................................................  43
           SECTION 6.5     No Waiver of Subordination Provisions.......................  43
           SECTION 6.6     Trustee's Relation to Senior Debt...........................  43
           SECTION 6.7     Other Provisions Subject Hereto.............................  44

ARTICLE 7  Successors..................................................................  44
           SECTION 7.1     Merger, Consolidation or Sale of Assets.....................  44
           SECTION 7.2     Successor Corporation Substituted...........................  45
 

                                      ii

 

                                                                                
ARTICLE 8  Defaults and Remedies.......................................................  45
           SECTION 8.1     Events of Default...........................................  45
           SECTION 8.2     Acceleration................................................  47
           SECTION 8.3     Other Remedies..............................................  47
           SECTION 8.4     Waiver of Past Defaults.....................................  47
           SECTION 8.5     Control by Majority.........................................  47
           SECTION 8.6     Limitation on Suits.........................................  48
           SECTION 8.7     Rights of Noteholders to Receive Payment....................  48
           SECTION 8.8     Collection Suit by Trustee..................................  48
           SECTION 8.9     Trustee May File Proofs of Claim............................  48
           SECTION 8.10    Priorities..................................................  49
           SECTION 8.11    Undertaking for Costs.......................................  49

ARTICLE 9  Trustee.....................................................................  49
           SECTION 9.1     Duties of Trustee...........................................  49
           SECTION 9.2     Rights of Trustee...........................................  50
           SECTION 9.3     Individual Rights of Trustee................................  51
           SECTION 9.4     Trustee's Disclaimer........................................  51
           SECTION 9.5     Notice of Defaults..........................................  51
           SECTION 9.6     Reports by Trustee to Noteholders...........................  51
           SECTION 9.7     Compensation and Indemnity..................................  51
           SECTION 9.8     Replacement of Trustee......................................  52
           SECTION 9.9     Successor Trustee by Merger, Etc............................  53
           SECTION 9.10    Eligibility; Disqualification...............................  53
           SECTION 9.11    Preferential Collection of Claims Against Company...........  53
           SECTION 9.12    Sections Applicable to Registrar, Paying Agent and
                           Conversion Agent............................................  53

ARTICLE 10 Discharge of Indenture......................................................  54
           SECTION 10.1    Termination of Company's Obligations........................  54
           SECTION 10.2    Repayment to Company........................................  54

ARTICLE 11 Amendments, Supplements and Waivers.........................................  54
           SECTION 11.1    Without Consent of Noteholders..............................  54
           SECTION 11.2    With Consent of Noteholders.................................  55
           SECTION 11.3    Compliance with Trust Indenture Act.........................  56
           SECTION 11.4    Revocation and Effect of Consents...........................  56
           SECTION 11.5    Notation on or Exchange of Notes............................  57
           SECTION 11.6    Trustee Protected...........................................  57

ARTICLE 12 Miscellaneous...............................................................  57
           SECTION 12.1    Trust Indenture Act Controls................................  57
           SECTION 12.2    Notices.....................................................  57
           SECTION 12.3    Communication by Noteholders with Other
                           Noteholders.................................................  58
           SECTION 12.4    Certificate and Opinion as to Conditions Precedent..........  58
           SECTION 12.5    Statements Required in Certificate or Opinion...............  58
 

                                      iii

 

                                                                                
           SECTION 12.6    Rules by Trustee and Agents.................................  58
           SECTION 12.7    Legal Holidays..............................................  58
           SECTION 12.8    No Recourse Against Others..................................  59
           SECTION 12.9    Counterparts................................................  59
           SECTION 12.10   Variable Provisions.........................................  59
           SECTION 12.11   Governing Law...............................................  59
           SECTION 12.12   No Adverse Interpretation of Other Agreements...............  60
           SECTION 12.13   Successors..................................................  60
           SECTION 12.14   Severability................................................  60
           SECTION 12.15   Table of Contents, Headings, Etc............................  60
           SECTION 12.16   Persons Deemed Owners.......................................  60

                                      iv

 
                             CROSS-REFERENCE TABLE*


 
Trust Indenture                                            Indenture       
Act Section                                                 Section        
                                                                     
                                                                           
310(a)(1)....................................................  7.10
   (a)(2)....................................................  7.10
   (a)(3)....................................................  N.A.
   (a)(4)....................................................  N.A.
   (b)..................................................  7.8; 7.10
   (c).......................................................  N.A.
311(a).......................................................  7.11
   (b).......................................................  7.11
   (c).......................................................  N.A.
312(a).......................................................   2.5
   (b).......................................................  10.3
   (c).......................................................  10.3
313(a).......................................................   7.6
   (b)(1)....................................................  N.A.
   (b)(2)....................................................   7.6
   (c).......................................................   7.6
   (d).......................................................   7.6
314(a)...................................................  4.2, 4.3
   (b).......................................................  N.A.
   (c)(1)....................................................  10.4
   (c)(2)....................................................  10.4
   (c)(3)....................................................  N.A.
   (d).......................................................  N.A.
   (e).......................................................  N.A.
   (f).......................................................  N.A.
315(a).......................................................7.1(b)
   (b).......................................................   7.5
   (c).......................................................7.1(a)
   (d).......................................................7.1(c)
   (e).......................................................  6.11
316(a) (last sentence).......................................   2.9
   (a)(1)(A).................................................   6.5
   (a)(1)(B).................................................   6.4
   (a)(2)....................................................  N.A.
   (b).......................................................   6.7
   (c).......................................................   9.4
317(a)(1)....................................................   6.8
   (a)(2)....................................................   6.9
   (b).......................................................   2.4
318(a).......................................................  N.A.

                           N.A. means not applicable.
__________
*This Cross-Reference Table is not part of the Indenture.

                                       v

 
     INDENTURE dated as of October 7, 1996 between Plasma & Materials
Technologies, Inc., a California corporation (the "Company"), and U.S. Trust
Company of California, N.A., a national banking association duly organized and
existing under the laws of the State of California, as trustee (the "Trustee").

     Each party agrees as follows for the benefit of the other party and for the
equal and ratable benefit of the Noteholders of the Company's 7 1/8% Convertible
Subordinated Notes due 2001 (the "Notes"):


                                   ARTICLE 1

                  Definitions and Incorporation by Reference
                  ------------------------------------------

     SECTION 1.1  Definitions.
                  ----------- 

     "Acquisition" means the acquisition by the Company of all of the
outstanding capital stock of Electrotech, and directly or indirectly, each
subsidiary thereof pursuant to the Share Purchase Agreement.

     "Affiliate" of any specified person means any other person directly or
indirectly controlling or controlled by or under direct or indirect common
control with such specified person.  For the purposes of this definition,
"control" (including, with correlative meanings, the terms "controlling",
"controlled by" and "under common control with"), as used with respect to any
person, shall mean the possession, directly or indirectly, of the power to
direct or cause the direction of the management or policies of such person,
whether through the ownership of voting securities or by agreement or otherwise;
provided, however, that beneficial ownership of 10% or more of the voting
- --------  -------                                                        
securities of a person shall be deemed to be control.

     "Agent" means any Security Registrar, Paying Agent, Conversion Agent or co-
registrar.

     "Board of Directors" means the Board of Directors of the Company or any
authorized committee of the Board.

     "Board Resolution" means a duly authorized resolution of the Board of
Directors.

     "Business Day" means any day that is not a Legal Holiday.

     "Capital Stock" means any and all shares, interests, participations, rights
or other equivalents (however designated) of equity interests in any entity,
including, without limitation, corporate stock, including any preferred stock,
and partnership interests, whether general or limited.

     "Cash Equivalents" means:  (a) securities with maturities of one year or
less from the date of acquisition issued or fully guaranteed or insured by the
United States Government or

                                       1

 
any agency thereof, (b) certificates of deposit and Eurodollar time deposits
with maturities of one year or less from the date of acquisition and overnight
bank deposits of any commercial bank having capital and surplus in excess of
$500,000,000, (c) repurchase obligations of any commercial bank satisfying the
requirements of clause (b) of this definition, having a term of not more than 30
days, with respect to securities issued or fully guaranteed or insured by the
United States Government or any agency thereof, (d) commercial paper of a
domestic issuer at the time of acquisition having a rating of at least A-1 by
Standard and Poor's Ratings Group ("S&P") or P-1 by Moody's Investors Service,
Inc. ("Moody's"), (e) securities with maturities of one year or less from the
date of acquisition issued or fully guaranteed by any state, commonwealth or
territory of the United States, or by any political subdivision or taxing
authority of any such state, commonwealth or territory, the securities of which
state, commonwealth, territory, political subdivision, taxing authority (as the
case may be) are rated at least A by S&P or A by Moody's, or (f) shares of money
market mutual or similar funds which invest exclusively in assets satisfying the
requirements of clauses (a) through (e) of this definition.

     "Change of Control" means any event where: (i) any "person" or "group" (as
such terms are used in Section 13(d) and 14(d) of the Exchange Act) is or
becomes the "beneficial owner" (as defined in Rules 13d-3 and 13d-5 under the
Exchange Act) of shares representing more than 50% of the combined voting power
of the then outstanding securities entitled to vote generally in elections of
directors of the Company ("Voting Stock"), (ii) the Company consolidates with or
merges into any other corporation, or any other corporation merges into the
Company, and, in the case of any such transaction, the outstanding Common Stock
of the Company is reclassified into or exchanged for any other property or
security, unless the shareholders of the Company immediately before such
transaction own, directly or indirectly immediately following such transaction,
at least a majority of the combined voting power of the outstanding voting
securities of the corporation resulting from such transaction in substantially
the same proportion as their ownership of the Voting Stock immediately before
such transaction, (iii) the Company conveys, transfers or leases all or
substantially all of its assets (other than to one or more wholly-owned
subsidiaries of the Company) or (iv) any time the Continuing Directors do not
constitute a majority of the Board of Directors of the Company (or, if
applicable, a successor corporation to the Company); provided, that a Change of
                                                     --------                  
Control shall not be deemed to have occurred if at least 90% of the
consideration (excluding cash payments for fractional shares) in the transaction
or transactions constituting the Change of Control consists of shares of common
stock that are, or upon issuance will be, traded on a United States national
securities exchange or approved for trading on an established automated over-
the-counter trading market in the United States and as a result of such
transaction or transactions the Notes become convertible solely into such common
stock or a combination of such common stock and cash.

     "Closing Date" means the date on which the Acquisition is consummated.

     "Collateral" means (i) the Collateral Account, (ii) the Special Redemption
Amount and all other cash deposited in the Collateral Account from time to time
and the Eligible Investments made pursuant to Section 4.8 hereof, (iii) all
rights and privileges of the Company with respect to the Collateral Account and
the Eligible Investments, (iv) all

                                       2

 
dividends, interest and other payments and distributions made on or with respect
to the Eligible Investments or the Collateral Account and (v) all Proceeds of
any of the foregoing.

     "Common Stock" means the common stock of the Company as the same exists at
the date of the execution of this Indenture or as such stock may be constituted
from time to time.

     "Company" means the party named as such above until a successor replaces it
in accordance with Article 7 and thereafter means the successor.

     "Continuing Directors" means, as of any date of determination, any member
of the Board of Directors of the Company who (i) was a member of such Board of
Directors on the date of this Indenture or (ii) was nominated for election or
elected to such Board of Directors with the approval of a majority of the
Continuing Directors who were members of such Board at the time of such
nomination or election.

     "Corporate Trust Office" shall be at the address of the Trustee specified
in Section 12.10 or such other address as the Trustee may give notice to the
Company.

     "Daily Market Price" means the price of a share of Common Stock on the
relevant date, determined (a) on the basis of the last reported sale price
regular way of the Common Stock as reported on the Nasdaq Stock Market's
National Market (the "NNM"), or if the Common Stock is not then listed on the
NNM, as reported on such national securities exchange upon which the Common
Stock is listed, or (b) if there is no such reported sale on the day in
question, on the basis of the average of the closing bid and asked quotations
regular way as so reported, or (c) if the Common Stock is not listed on the NNM
or on any national securities exchange, on the basis of the average of the high
bid and low asked quotations regular way on the day in question in the over-the-
counter market as reported by the National Association of Securities Dealers
Automated Quotation System, or if not so quoted, as reported by National
Quotation Bureau, Incorporated, or a similar organization.

     "Default" means any event that is, or with the passage of time or the
giving of notice or both, would be an Event of Default.

     "Depositary" means The Depository Trust Company, its nominees and their
respective successors.

     "Designated Event" means the occurrence of a Change of Control or a
Termination of Trading.

     "Designated Senior Debt" means (i) any Senior Debt which, as of the date of
the Indenture, has an aggregate principal amount outstanding of at least $20
million, (ii) any Senior Debt which, at the date of determination, has an
aggregate principal amount outstanding of, or commitments to lend up to, at
least $20 million, (iii) Senior Debt which, at the date of determination, has a
principal amount outstanding of at least $5 million and consists of one capital
leasing facility to which the Company is a party with respect to equipment used
in the operation of the Company, and (iv) any Senior Debt which, at the date of
determination, has an aggregate principal amount outstanding of, or commitments
to lend

                                       3

 
up to, at least $2.5 million and consists of obligations for borrowed money to a
bank, savings and loan association or foreign bank or savings and loan
association or equivalent institution as defined in Rule 144A(a)(1)(vi) pursuant
to the Securities Act; provided, further, that with respect to the Senior Debt
referenced in clauses (ii), (iii) and (iv) above, such Senior Debt is
specifically designated by the Company in the instrument evidencing or governing
such Senior Debt as "Designated Senior Debt" for purposes of this Indenture
(provided that such instrument may place limitations and conditions on the right
of such Senior Debt to exercise the rights of Designated Senior Debt).

     "Electrotech" means Electrotech Limited and Electrotech Equipments Limited,
and each of their successors.

     "Eligible Investments" means Cash Equivalents which, in order to provide
the Trustee with a perfected security interest therein, shall be either:  (i)
evidenced by negotiable certificates or instruments, or if non-negotiable then
issued in the name of the Trustee, which (together with any appropriate
instruments of transfer) are delivered to, and held by, the Trustee or an agent
thereof in the State of New York; or (ii) in book-entry form and issued by the
United States Government or agency thereof and backed by the full faith and
credit of the United States and subject to pledge under applicable state law and
Treasury regulations.

     "Excess Payment" means the excess of (i) the aggregate of the cash and fair
market value of other consideration paid by the Company or any of its
subsidiaries with respect to the shares acquired in a tender offer or other
negotiated transaction over (ii) the Daily Market Price on the Trading Day
immediately following the completion of such tender offer or other negotiated
transaction multiplied by the number of acquired shares.

     "Exchange Act" means the Securities Exchange Act of 1934, as amended.

     "GAAP" means generally accepted accounting principles set forth in the
opinions and pronouncements of the Accounting Principles Board of the American
Institute of Certified Public Accountants and statements and pronouncements of
the Financial Accounting Standards Board or in such other statements by such
other entity as may be approved by a significant segment of the accounting
profession of the United States, which are in effect from time to time.

     "Global Notes" means, individually and collectively, the Unrestricted
Global Notes and the Restricted Global Notes.

     "Guarantee" means a guarantee (other than by endorsement of negotiable
instruments for collection in the ordinary course of business), direct or
indirect, in any manner (including, without limitation, letters of credit and
reimbursement agreements in respect thereof), of all or any part of any
Indebtedness.

     "Indebtedness" means, with respect to any person, all obligations, whether
or not contingent, of such person (i) (a) for borrowed money (including, but not
limited to, any indebtedness secured by a security interest, mortgage or other
lien on the assets of such person which is (1) given to secure all or part of
the purchase price of property subject

                                       4

 
thereto, whether given to the vendor of such property or to another, or (2)
existing on property at the time of acquisition thereof), (b) evidenced by a
note, debenture, bond or other written instrument, (c) under a lease required to
be capitalized on the balance sheet of the lessee under GAAP or under any lease
or related document (including a purchase agreement) which provides that such
person is contractually obligated to purchase or to cause a third party to
purchase such leased property, (d) in respect of letters of credit, bank
guarantees or bankers' acceptances (including reimbursement obligations with
respect to any of the foregoing), (e) with respect to indebtedness secured by a
mortgage, pledge, lien, encumbrance, charge or adverse claim affecting title or
resulting in an encumbrance to which the property or assets of such person are
subject, whether or not the obligation secured thereby shall have been assumed
or Guaranteed by or shall otherwise be such person's legal liability, (f) in
respect of the balance of deferred and unpaid purchase price of any property or
assets and (g) under interest rate or currency swap agreements, cap, floor and
collar agreements, spot and forward contracts and similar agreements and
arrangements; (ii) with respect to any obligation of others of the type
described in the preceding clause (i) or under clause (iii) below, assumed by or
Guaranteed in any manner by such person or in effect Guaranteed by such person
through an agreement to purchase (including, without limitation, "take or pay"
and similar arrangements), contingent or otherwise (and the obligations of such
person under any such assumptions, Guarantees or other such arrangements); and
(iii) any and all deferrals, renewals, extensions, refinancings and refundings
of, or amendments, modifications or supplements to, any of the foregoing.

     "Indenture" means this Indenture, as amended or supplemented from time to
time, in accordance with the terms hereof.

     "Initial Purchasers" means Salomon Brothers Inc and Unterberg Harris.

     "Interest Payment Date" means the Stated Maturity of an installment of
interest on the Notes.

     "Issuance Date" means October 7, 1996.

     "Liquidated Damages" means any liquidated damages payable pursuant to the
Registration Agreement.

     "Material Subsidiary" means any Subsidiary of the Company which at the date
of determination is a "significant subsidiary" as defined in Rule 1-02(w) of
Regulation S-X under the Securities Act and the Exchange Act (as such Regulation
is in effect on the date hereof).

     "Noteholder" or "holder" means a person in whose name a Note is registered.

     "Notes" means the Notes described in the preamble above that are issued,
authenticated and delivered under this Indenture.

                                       5

 
     "Obligations" means any principal, interest, penalties, fees,
indemnifications, reimbursements, damages and other liabilities payable under
the documentation governing any Indebtedness.

     "Offering Memorandum" means the offering memorandum relating to the Notes
dated October 1, 1996.

     "Officers' Certificate" means a certificate signed by two Officers, one of
whom must be the Chairman of the Board, the President, the Treasurer or a Vice-
President of the Company.  See Sections 12.4 and 12.5 hereof.

     "Opinion of Counsel" means a written opinion from legal counsel who is
reasonably acceptable to the Trustee.  The counsel may be an employee of or
counsel to the Company or the Trustee.  See Sections 12.4 and 12.5 hereof.

     "person" means any individual, corporation, partnership, joint venture,
association, joint stock company, trust, unincorporated organization, limited
liability company or government or any agency or political subdivision thereof.

     "principal" of a debt security means the principal of the security plus the
premium, if any, on the security.

     "Proceeds" means all proceeds of, and all other profits, products, rents or
receipts, in whatever form arising from the collection, sale, lease, exchange,
assignment, licensing, or other disposition of, or other realization upon,
Collateral, whether now existing or hereafter arising.

     "Record Date" for the interest payable on any Interest Payment Date means
the 15th day (whether or not a Business Day) next preceding such Interest
Payment Date.

     "Registration Agreement" means the Registration Agreement relating to the
Notes dated October 7, 1996, between the Company and the Initial Purchasers, a
form of which is attached as Exhibit C hereto.

     "Regulation S" means Regulation S promulgated under the Securities Act.

     "Representative" means the trustee, agent or representative (if any) for an
issue of Senior Debt.

     "Restricted Global Note" means a permanent global note that contains the
paragraph referred to in footnote 1 and Schedule A to the form of Note attached
hereto as Exhibit A-1, and that is deposited with and registered in the name of
the Depositary, representing the Notes sold in reliance on Rule 144A.

     "Rule 144A" means Rule 144A promulgated under the Securities Act.

                                       6

 
     "SEC" means the Securities and Exchange Commission and any successor entity
thereto.

     "Securities Act" means the Securities Act of 1933, as amended.

     "Senior Debt" means the principal of, premium, if any, interest on and
other amounts due on Indebtedness of the Company, whether outstanding on the
date of the Indenture or thereafter created, incurred, assumed or Guaranteed by
the Company; unless, in the instrument creating or evidencing or pursuant to
which Indebtedness is outstanding, it is expressly provided that such
Indebtedness is not senior in right of payment to the Notes.  Senior Debt
includes, with respect to the obligations described above, interest accruing,
pursuant to the terms of such Senior Debt, on or after the filing of any
petition in bankruptcy or for reorganization relating to the Company, whether or
not post-filing interest is allowed in such proceeding, at the rate specified in
the instrument governing the relevant obligation.  Notwithstanding anything to
the contrary in the foregoing, Senior Debt shall not include: (a) Indebtedness
of or amounts owed by the Company for compensation to employees, or for goods,
services or materials purchased in the ordinary course of business; (b)
Indebtedness of the Company to a Subsidiary of the Company; or (c) any liability
for Federal, state, local, foreign or other taxes, owed or owing by the Company.

     "Share Purchase Agreement" means the Share Purchase Agreement, dated as of
July 17, 1996 entered into among the Company, Electrotech and the shareholders
of Electrotech, including all exhibits and schedules thereto and all related
agreements entered into on or prior to the Issuance Date, in each case as in
effect on the Issuance Date.

     "Shelf Registration Statement" shall have the meaning set forth in the
Registration Agreement.

     "Special Redemption Date" means January 16, 1997.

     "Special Redemption Notice Date" means December 31, 1996.

     "Stated Maturity" when used with respect to any Note or any installment of
interest thereon, means the date specified in such Note as the fixed date on
which the principal of such Note or such installment of interest is due and
payable.

     "Subsidiary" means any corporation, association or other business entity of
which more than 50% of the total voting power of shares of Capital Stock
entitled (without regard to the occurrence of any contingency) to vote in the
election of directors, managers or trustees thereof is at the time owned or
controlled, directly or indirectly, by any person or one or more of the other
Subsidiaries of that person or a combination thereof.

     "Termination of Trading" means an event where the Common Stock (or other
common stock into which the Notes are then convertible) is neither listed for
trading on a United States national securities exchange nor approved for trading
on an established automated over-the-counter trading market in the United
States.

                                       7

 
     "TIA" means the Trust Indenture Act of 1939 (15 U.S. Code (S)(S)77aaa-
77bbbb) as in effect on the date of execution of this Indenture and as it may be
amended from time to time.

     "Trading Day" shall mean (A) if the applicable security is listed or
admitted for trading on the New York Stock Exchange or another national
securities exchange, a day on which the New York Stock Exchange or another
national securities exchange is open for business, (B) if the applicable
security is quoted on The Nasdaq National Market, a day on which trades may be
made thereon or (C) if the applicable security is not so listed, admitted for
trading or quoted, any day other than a Saturday or Sunday or a day on which
banking institutions in the State of New York are authorized or obligated by law
or executive order to close.

     "Transfer Restricted Securities" means securities that bear or are required
to bear the legend set forth in Section 2.6.

     "Trustee" means U.S. Trust Company of California, N.A. and its successors
and any corporation resulting from or surviving any consolidation or merger to
which it or its successors may be a party and any successor trustee at the time
serving as successor trustee hereunder.

     "Trust Officer" means any officer within the corporate trust division (or
any successor group) of the Trustee or any other officer of the Trustee
customarily performing functions similar to those performed by the persons who
at that time shall be such officers, and also means, with respect to a
particular corporate trust matter, any other officer or the Trustee to whom such
trust matter is referred because of his knowledge of and familiarity with the
particular subject.

     "Unrestricted Global Note" means a permanent global note that contains the
paragraph referred to in footnote 1 and Schedule A to the form of Note attached
hereto as Exhibit A-1, and that is deposited with and registered in the name of
the Depositary, representing the Notes sold in reliance on Regulation S.

     SECTION 1.2  Other Definitions.
                  ----------------- 


 
                                            Defined in
Term                                         Section
- ----                                        ----------
                                          
"Acquisition Date"............................  4.8
"Agent Members"...............................  2.1
"Bankruptcy Law"..............................  8.1
"Cedel".......................................  2.1
"Collateral Account"..........................  4.8
"Commencement Date"...........................  3.8
"Conversion Agent"............................  2.3
"Conversion Date".............................  5.2
"Conversion Price"............................  5.1
"Conversion Shares"...........................  5.6
 


                                       8

 

                                         
"Custodian"...................................  8.1
"Designated Event Offer"......................  4.7
"Designated Event Payment"....................  4.7
"Designated Event Payment Date"...............  3.8
"Distribution Date"...........................  5.6
"Distribution Record Date"....................  5.6
"Euroclear"...................................  2.1
"Event of Default"............................  8.1
"Global Note".................................  2.1
"Institutional Accredited Investors...........  2.1(c)
"Legal Holiday"............................... 12.7
"Offer Amount"................................  3.8
"Offering Proceeds"...........................  4.8
"Officer".....................................12.10
"Paying Agent"................................  2.3
"Payment Blockage Notice".....................  6.2
"Payment Blockage Period".....................  6.2
"Payment Default".............................  8.1
"Purchase Agreement"..........................  2.1
"Purchase Date"...............................  5.6
"QIBs"........................................  2.1
"Registrar"...................................  2.3
"Regulation S"................................  2.1
"Restricted Notes"............................  2.1
"Rights"......................................  5.6
"Rule 144A"...................................  2.1
"Special Redemption"..........................  3.1
"Special Redemption Amount"...................  4.8
"Tender Period"...............................  3.8
 


     SECTION 1.3  Incorporation by Reference of Trust Indenture Act.  Whenever
                  -------------------------------------------------           
this Indenture refers to a provision of the TIA, from and after the date this
Indenture becomes subject to the TIA, the provision is incorporated by reference
in and made a part of this Indenture.

     The following TIA terms used in this Indenture have the following meanings:

     "indenture securities" means the Notes;

     "indenture security holder" means a Noteholder;

     "indenture to be qualified" means this Indenture;

     "indenture trustee" or "institutional trustee" means the Trustee; and

     "obligor" on the Notes means the Company or any other obligor on the Notes.

                                       9

 
     All other terms used in this Indenture that are defined by the TIA, defined
by TIA reference to another statute or defined by SEC rule under the TIA have
the meanings so assigned to them.

     SECTION 1.4  Rules of Construction.  Unless the context otherwise requires:
                  ---------------------                                         

          (a) a term has the meaning assigned to it;

          (b) an accounting term not otherwise defined has the meaning assigned
     to it in accordance with GAAP consistently applied;

          (c) "or" is not exclusive;

          (d) words in the singular include.the plural, and words in the plural
     include the singular; and

          (e) provisions apply to successive events and transactions.

                                   ARTICLE 2

                                   The Notes
                                   ---------

     SECTION 2.1  Form and Dating.  The Notes and the Trustee's certificate of
                  ---------------                                             
authentication shall be substantially in the form of Exhibit A which is hereby
incorporated in and expressly made a part of this Indenture.  The Notes may have
notations, legends or endorsements required by law, stock exchange rule,
agreements to which the Company is subject, if any, or usage (provided that any
such notation, legend or endorsement is in a form acceptable to the Company).
The Company shall furnish any such legend not contained in Exhibit A to the
Trustee in writing.  Each Note shall be dated the date of its authentication.
The terms and provisions of the Notes set forth in Exhibit A are part of the
terms of this Indenture and to the extent applicable, the Company and the
Trustee, by their execution and delivery of this Indenture, expressly agree to
such terms and provisions and to be bound thereby.  The Notes shall be issued
only in registered form and in denominations of $1,000 and integral multiples of
$1,000.

          (a) Global Notes.  The Notes are being offered and sold by the Company
              ------------                                                      
     pursuant to a purchase agreement relating to the Notes, dated October 1,
     1996, between the Company and the Initial Purchasers (the "Purchase
     Agreement").

          Notes offered and sold to Qualified Institutional Buyers as defined in
     Rule 144A ("QIBs") in reliance on Rule 144A shall be issued initially in
     the form of one or more Restricted Global Notes in definitive, fully
     registered form without interest coupons, which shall be deposited on
     behalf of the purchasers of the Notes represented thereby with the Trustee,
     at its Corporate Trust Office, as custodian for the Depositary, and
     registered in the name of the Depositary or a nominee of the Depositary,
     duly executed by the Company and authenticated by the Trustee as
     hereinafter provided.  The aggregate principal amount of the Restricted
     Global Note

                                       10

 
     may from time to time be increased or decreased by adjustments made on the
     records of the Trustee and the Depositary or its nominee as hereinafter
     provided.

          Notes offered and sold in reliance on Regulation S shall be issued
     initially in the form of one or more Unrestricted Global Notes in
     definitive, fully registered form without interest coupons, which shall be
     deposited on behalf of the purchasers of the Notes represented thereby with
     the Trustee, at its Corporate Trust Office, as custodian for the
     Depositary, and registered in the name of the Depositary or a nominee of
     the Depositary for the accounts of designated agents holding on behalf of
     the Euroclear System ("Euroclear") or Cedel Bank Societe Anonyme ("Cedel")
     duly executed by the Company and authenticated by the Trustee as
     hereinafter provided.  The aggregate principal amount of the Unrestricted
     Global Note may from time to time be increased or decreased by adjustments
     made on the records of the Trustee and the Depositary or its nominee as
     hereinafter provided.

          Each Global Note shall represent such of the outstanding Notes as
     shall be specified therein and each shall provide that it shall represent
     the aggregate amount of outstanding Notes from time to time endorsed
     thereon and that the aggregate amount of outstanding Notes represented
     thereby may from time to time be reduced or increased, as appropriate, to
     reflect exchanges and redemptions.  Any endorsement of a Global Note to
     reflect the amount of any increase or decrease in the amount of outstanding
     Notes represented thereby shall be made by the Trustee or the custodian, at
     the direction of the Trustee, in accordance with instructions given by the
     holder thereof as required by Section 2.6 hereof.

          The provisions of the "Operating Procedures of the Euroclear System"
     and "Terms and Conditions Governing Use of Euroclear" and the "Management
     Regulations" and "Instructions to Participants" of Cedel shall be
     applicable to interests in the Unrestricted Global Note that are held by
     the Agent Member through Euroclear or Cedel.

          Except as set forth in Section 2.6 hereof, the Global Notes may be
     transferred, in whole and not in part, only to another nominee of the
     Depositary or to a successor of the Depositary or its nominee.

          (b) Book-Entry Provisions.  This Section 2.1(b) shall apply only to a
              ---------------------                                            
     Global Note deposited with or on behalf of the Depositary.

          The Company shall execute and the Trustee shall, in accordance with
     this Section 2.1(b), authenticate and deliver initially one or more Global
     Notes that (a) shall be registered in the name of the Depositary or nominee
     of the Depositary and (b) shall be delivered by the Trustee to such
     Depositary or pursuant to such Depositary's instructions or held by the
     Trustee as custodian for the Depositary pursuant to a FAST Balance
     Certificate Agreement between the Depositary and the Trustee.

                                       11

 
          Members of, or participants in, the Depositary ("Agent Members") shall
     have no rights under this Indenture with respect to any Global Note held on
     their behalf by the Depositary or by the Trustee as the custodian of the
     Depositary or under such Global Note, and the Depositary may be treated by
     the Company, the Trustee and any agent of the Company or the Trustee as the
     absolute owner of such Global Note for all purposes whatsoever.
     Notwithstanding the foregoing, nothing herein shall prevent the Company,
     the Trustee or any agent of the Company or the Trustee from giving effect
     to any written certification, proxy or other authorization furnished by the
     Depositary or impair, as between the Depositary and its Agent Members, the
     operation of customary practices of such Depositary governing the exercise
     of the rights of a holder of a beneficial interest in any Global Note.

          (c) Certificated Notes.  Except as provided in Sections 2.6(f) and
              ------------------                                            
     2.10, owners of beneficial interests in Global Notes will not be entitled
     to receive physical delivery of certificated Notes.  Purchasers of Notes
     who are institutional "accredited investors" (as defined in Rule 501(a)(1),
     (2), (3) or (7) under the Securities Act and are referred to as
     "Institutional Accredited Investors") who are not QIBs will receive
     certificated Notes bearing the Restricted Notes Legend set forth in Exhibit
     A hereto.

          After a transfer of any Notes during the period of the effectiveness
     of a Shelf Registration Statement with respect to the Notes, all
     requirements pertaining to legends on such Note will cease to apply, the
     requirements requiring any such Note issued to certain holders be issued in
     global form will cease to apply, and a certificated Note without legends
     will be available to the holder of such Note.

     SECTION 2.2  Execution and Authentication.  Two Officers shall sign the
                  ----------------------------                              
Notes for the Company by manual or facsimile signature.  The Company's seal
shall be reproduced on the Notes.

     If an Officer whose signature is on a Note no longer holds that office at
the time the Note is authenticated, the Note shall nevertheless be valid.

     A Note shall not be valid until authenticated by the manual signature of an
authorized officer of the Trustee.  The signature shall be conclusive evidence
that the Note has been authenticated under this Indenture.

     Upon a written order of the Company signed by two Officers, the Trustee
shall authenticate the Notes for original issue up to an aggregate principal
amount of $75,000,000 (plus up to $11,250,000 aggregate principal amount of
Notes that may be sold by the Company pursuant to the overallotment option
granted pursuant to the Purchase Agreement).  The aggregate principal amount of
Notes outstanding at any time shall not exceed such amount except as provided in
Section 2.7.

     The Trustee may appoint an authenticating agent acceptable to the Company
to authenticate Notes.  An authenticating agent may authenticate Notes whenever
the Trustee may do so.  Each reference in this Indenture to authentication by
the Trustee includes

                                       12

 
authentication by such agent.  An authenticating agent has the same rights as an
Agent to deal with the Company or an Affiliate.

     SECTION 2.3  Registrar, Paying Agent and Conversion Agent.  The Company
                  --------------------------------------------              
shall maintain in the Borough of Manhattan, City of New York, State of New York
(i) an office or agency where Notes may be presented for registration of
transfer or for exchange ("Registrar"), (ii) an office or agency where Notes may
be presented for payment ("Paying Agent") and (iii) an office or agency where
Notes may be presented for conversion ("Conversion Agent").  The Registrar shall
keep a register of the Notes and of their transfer and exchange.  The Company
may appoint the Registrar, the Paying Agent and the Conversion Agent and may
appoint one or more co-registrars, one or more additional paying agents and one
or more additional conversion agents in such other locations as it shall
determine.  The term "Paying Agent" includes any additional paying agent and the
term "Conversion Agent" includes any additional conversion agent.  The Company
may change any Paying Agent, Registrar, co-registrar or Conversion Agent without
prior notice to any Noteholder.  The Company shall notify the Trustee of the
name and address of any Agent not a party to this Indenture.  If the Company
fails to appoint or maintain another entity as Registrar, Paying Agent or
Conversion Agent, the Trustee shall act as such. The Company or any of its
Affiliates may act as Paying Agent, Registrar, co-registrar or Conversion Agent.
The Company initially appoints the Trustee as Paying Agent, Registrar,
Conversion Agent and authenticating agent and the Trustee hereby accepts such
appointments.


     SECTION 2.4  Paying Agent to Hold Money in Trust. The Company shall require
                  -----------------------------------                           
each Paying Agent other than the Trustee to agree in writing that the Paying
Agent will hold in trust for the benefit of Noteholders or the Trustee all money
held by the Paying Agent for the payment of principal of, premium, if any, or
interest on, the Notes, and will notify the Trustee of any default by the
Company in making any such payment.  While any such default continues, the
Trustee may require a Paying Agent to pay all money held by it to the Trustee.
The Company at any time may require a Paying Agent to pay all money held by it
to the Trustee and to account for any money disbursed by it.  Upon payment over
to the Trustee, the Paying Agent (if other than the Company or an Affiliate of
the Company) shall have no further liability for the money.  If the Company or
an Affiliate of the Company acts as Paying Agent, it shall segregate and hold in
a separate trust fund for the benefit of the Noteholders all money held by it as
Paying Agent.

     SECTION 2.5  Noteholder Lists.  The Trustee shall preserve in as current a
                  ----------------                                             
form as is reasonably practicable the most recent list available to it of the
names and addresses of Noteholders.  If the Trustee is not the Registrar, the
Company shall furnish to the Trustee on or before each interest payment date and
at such other times as the Trustee may request in writing a list in such form
and as of such date as the Trustee may reasonably require of the names and
addresses of Noteholders.

     SECTION 2.6  Transfer and Exchange.  Where Notes are presented to the
                  ---------------------                                   
Registrar or a co-registrar with a request to register the transfer or to
exchange them for an equal principal amount of Notes of other denominations, the
Registrar shall register the transfer or make the exchange if its requirements
for such transactions are met.  To permit registrations

                                       13

 
of transfers and exchanges, the Company shall issue and the Trustee shall
authenticate Notes at the Registrar's request.  No service charge shall be made
for any registration of transfer or exchange (except as otherwise expressly
permitted herein), but the Company may require payment of a sum sufficient to
cover any transfer tax or similar governmental charge payable in connection
therewith (other than any such transfer tax or similar governmental charge
payable upon exchanges pursuant to Sections 2.10, 3.6 or 11.5 hereof).

     The Company and the Registrar shall not be required (i) to issue, register
the transfer of, or exchange Notes during a period beginning at the opening of
business 30 days before the day of any selection of Notes for redemption under
Section 3.2 hereof and ending at the close of business on the day of selection,
or (ii) to exchange or register the transfer of any Note so selected for
redemption in whole or in part, except the unredeemed portion of any Note being
redeemed in part.

          (a) Transfer and Exchange of Global Notes.  The transfer and exchange
              -------------------------------------                            
     of Global Notes or beneficial interests therein shall be effected through
     the Depositary, in accordance with this Indenture and the procedures of the
     Depositary therefor, which shall include restrictions on transfer
     comparable to those set forth herein to the extent required by the
     Securities Act.  Beneficial interests in a Global Note may be transferred
     to persons who take delivery thereof in the form of a beneficial interest
     in the same Global Note in accordance with the transfer restrictions set
     forth in the legend in subsection (g) of this Section 2.6.  Transfers of
     beneficial interests in the Global Notes to persons required to take
     delivery thereof in the form of an interest in another Global Note shall be
     permitted as follows:

               (i) Restricted Global Note to Unrestricted Global Note.  If, at
                   --------------------------------------------------         
          any time, an owner of a beneficial interest in a Restricted Global
          Note deposited with the Depositary (or the Trustee as custodian for
          the Depositary) wishes to transfer its interest in such Restricted
          Global Note to a person who is required or permitted to take delivery
          thereof in the form of an interest in an Unrestricted Global Note,
          such owner shall, subject to compliance with the applicable procedures
          described herein (the "Applicable Procedures"), exchange or cause the
          exchange of such interest for an equivalent beneficial interest in an
          Unrestricted Global Note as provided in this Section 2.6(a)(i).  Upon
          receipt by the Trustee of (1) instructions given in accordance with
          the Applicable Procedures from an Agent Member directing the Trustee
          to credit or cause to be credited a beneficial interest in the
          Unrestricted Global Note in an amount equal to the beneficial interest
          in the Restricted Global Note to be exchanged, (2) a written order
          given in accordance with the Applicable Procedures containing
          information regarding the participant account of the Depositary and
          the Euroclear or Cedel account to be credited with such increase, and
          (3) a certificate in the form of Exhibit B-1 hereto given by the owner
          of such beneficial interest stating that the transfer of such interest
          has been made in compliance with the transfer restrictions applicable
          to the Global Notes and pursuant to and in accordance with Rule 903 or
          Rule 904 of Regulation S, then the Trustee, as Registrar, shall
          instruct the Depositary to reduce or cause to be reduced the aggregate
          principal amount at maturity of

                                       14

 
          the applicable Restricted Global Note and to increase or cause to be
          increased the aggregate principal amount at maturity of the applicable
          Unrestricted Global Note by the principal amount at maturity of the
          beneficial interest in the Restricted Global Note to be exchanged, to
          credit or cause to be credited to the account of the person specified
          in such instructions a beneficial interest in the Unrestricted Global
          Note equal to the reduction in the aggregate principal amount at
          maturity of the Restricted Global Note, and to debit, or cause to be
          debited, from the account of the person making such exchange or
          transfer the beneficial interest in the Restricted Global Note that is
          being exchanged or transferred.

               (ii) Unrestricted Global Note to Restricted Global Note.  If, at
                    --------------------------------------------------         
          any time, an owner of a beneficial interest in an Unrestricted Global
          Note deposited with the Depositary or with the Trustee as custodian
          for the Depositary wishes to transfer its interest in such
          Unrestricted Global Note to a person who is required or permitted to
          take delivery thereof in the form of an interest in a Restricted
          Global Note, such owner shall, subject to the Applicable Procedures,
          exchange or cause the exchange of such interest for an equivalent
          beneficial interest in a Restricted Global Note as provided in this
          Section 2.6(a)(ii).  Upon receipt by the Trustee of (1) instructions
          from Euroclear or Cedel, if applicable, and the Depositary, directing
          the Trustee, as Registrar, to credit or cause to be credited a
          beneficial interest in the Restricted Global Note equal to the
          beneficial interest in the Unrestricted Global Note to be exchanged,
          such instructions to contain information regarding the participant
          account with the Depositary to be credited with such increase, (2) a
          written order given in accordance with the Applicable Procedures
          containing information regarding the participant account of the
          Depositary and (3) if such transfer is being effected prior to the
          expiration of the "40 day restricted period" (as defined by Regulation
          S under the Securities Act), a certificate in the form of Exhibit B-2
          attached hereto given by the owner of such beneficial interest stating
          (A) if the transfer is pursuant to Rule 144A, that the person
          transferring such interest in an Unrestricted Global Note reasonably
          believes that the person acquiring such interest in a Restricted
          Global Note is a QIB and is obtaining such beneficial interest in a
          transaction meeting the requirements of Rule 144A and any applicable
          blue sky or securities laws of any state of the United States, (B)
          that the transfer complies with the requirements of Rule 144A under
          the Securities Act and any applicable blue sky or securities laws of
          any state of the United States or (C) if the transfer is pursuant to
          any other exemption from the registration requirements of the
          Securities Act, that the transfer of such interest has been made in
          compliance with the transfer restrictions applicable to the Global
          Securities and pursuant to and in accordance with the requirements of
          the exemption claimed, such statement to be supported by an Opinion of
          Counsel from the transferee or the transferor in form reasonably
          acceptable to the Company and to the Registrar then the Trustee, as
          Registrar, shall instruct the Depositary to reduce or cause to be
          reduced the aggregate principal amount at maturity of such
          Unrestricted Global Note and to increase or cause to be

                                       15

 
          increased the aggregate principal amount at maturity of the applicable
          Restricted Global Note by the principal amount at maturity of the
          beneficial interest in the Unrestricted Global Note to be exchanged,
          and the Trustee, as Registrar, shall instruct the Depositary,
          concurrently with such reduction, to credit or cause to be credited to
          the account of the person specified in such instructions a beneficial
          interest in the applicable Restricted Global Note equal to the
          reduction in the aggregate principal amount at maturity of such
          Unrestricted Global Note and to debit or cause to be debited from the
          account of the person making such transfer the beneficial interest in
          the Unrestricted Global Note that is being transferred.

          (b) Transfer and Exchange of Certificated Notes.  When certificated
              -------------------------------------------                    
     Notes are presented by a holder to the Registrar with a request:

               (x) to register the transfer of the certificated Notes; or

               (y) to exchange such certificated Notes for an equal principal
          amount of certificated Notes of other authorized denominations,

     the Registrar shall register the transfer or make the exchange as
     requested; provided, however, that the certificated Notes presented or
     surrendered for register of transfer or exchange:

               (i) shall be duly endorsed or accompanied by a written
          instruction of transfer in form satisfactory to the Registrar duly
          executed by such holder or by his attorney, duly authorized in
          writing; and

               (ii) in the case of a certificated Note that is a Transfer
          Restricted Note, such request shall be accompanied by the following
          additional information and documents, as applicable:

                    (A) if such Transfer Restricted Note is being delivered to
               the Registrar by a holder for registration in the name of such
               holder, without transfer, or such Transfer Restricted Note is
               being transferred to the Company, no certification is required;

                    (B) if such Transfer Restricted Note is being transferred to
               a QIB in accordance with Rule 144A under the Securities Act or
               pursuant to an exemption from registration in accordance with
               Rule 144 or Rule 904 under the Securities Act or pursuant to an
               effective registration statement under the Securities Act, a
               certification to that effect from such holder (in substantially
               the form of Exhibit B-3 hereto); or

                    (C) if such Transfer Restricted Note is being transferred in
               reliance on any other exemption from the registration
               requirements of the Securities Act, a certification to that
               effect from such holder (in substantially the form of Exhibit B-3
               hereto) and an Opinion of Counsel

                                       16

 
               from such holder or the transferee reasonably acceptable to the
               Company and to the Registrar to the effect that such transfer is
               in compliance with the Securities Act.

          (c) Transfer of a Beneficial Interest in a Restricted Global Note or
              ----------------------------------------------------------------
     Unrestricted Global Note for a Certificated Note.
     ------------------------------------------------ 

               (i) Any person having a beneficial interest in a Restricted
          Global Note or Unrestricted Global Note may upon request, subject to
          the Applicable Procedures, exchange such beneficial interest for a
          certificated Note.  Upon receipt by the Trustee of written
          instructions or such other form of instructions as is customary for
          the Depositary (or Euroclear or Cedel, if applicable), from the
          Depositary or its nominee on behalf of any person having a beneficial
          interest in a Restricted Global Note or Unrestricted Global Note, and,
          in the case of a Transfer Restricted Note, the following additional
          information and documents (all of which may be submitted by
          facsimile):

                    (A) if such beneficial interest is being transferred to the
               person designated by the Depositary as being the beneficial
               owner, a certification to that effect from such person (in
               substantially the form of Exhibit B-4 hereto);

                    (B) if such beneficial interest is being transferred to a
               QIB in accordance with Rule 144A under the Securities Act or
               pursuant to an exemption from registration in accordance with
               Rule 144 under the Securities Act or pursuant to an effective
               registration statement under the Securities Act, a certification
               to that effect from the transferor (in substantially the form of
               Exhibit B-4 hereto); or

                    (C) if such beneficial interest is being transferred in
               reliance on any other exemption from the registration
               requirements of the Securities Act, a certification to that
               effect from the transferor (in substantially the form of Exhibit
               B-4 hereto) and an Opinion of Counsel from the transferee or the
               transferor reasonably acceptable to the Company and to the
               Registrar to the effect that such transfer is in compliance with
               the Securities Act,

          in which case the Trustee or the custodian, at the direction of the
          Trustee, shall, in accordance with the standing instructions and
          procedures existing between the Depositary and the custodian, cause
          the aggregate principal amount of Restricted Global Notes or
          Unrestricted Global Notes, as applicable, to be reduced accordingly
          and, following such reduction, the Company shall execute and, the
          Trustee shall authenticate and deliver to the transferee a
          certificated Note in the appropriate principal amount.

               (ii) Certificated Notes issued in exchange for a beneficial
          interest in a Restricted Global Note or Unrestricted Global Note, as
          applicable, pursuant

                                       17

 
          to this Section 2.6(c) shall be registered in such names and in such
          authorized denominations as the Depositary, pursuant to instructions
          from its direct or indirect participants or otherwise, shall instruct
          the Trustee.  The Trustee shall deliver such certificated Notes to the
          persons in whose names such Notes are so registered.  Following any
          such issuance of certificated Notes, the Trustee, as Registrar, shall
          instruct the Depositary to reduce or cause to be reduced the aggregate
          principal amount at maturity of the applicable Global Note to reflect
          the transfer.

          (d) Restrictions on Transfer and Exchange of Global Notes.
              -----------------------------------------------------  
     Notwithstanding any other provision of this Indenture (other than the
     provisions set forth in subsection (f) of this Section 2.6 or Section
     2.10), a Global Note may not be transferred as a whole except by the
     Depositary to a nominee of the Depositary or by a nominee of the Depositary
     to the Depositary or another nominee of the Depositary or by the Depositary
     or any such nominee to a successor Depositary or a nominee of such
     successor Depositary.

          (e) Transfer and Exchange of a Certificated Note for a Beneficial
              -------------------------------------------------------------
     Interest in a Global Note.  A certificated Note may not be transferred or
     -------------------------                                                
     exchanged for a beneficial interest in a Global Note except upon
     satisfaction of the following requirements.  Any holder having a
     certificated Note may upon request, subject to the Applicable Procedures,
     exchange such beneficial interest for a beneficial interest in a Global
     Note.  Upon receipt by the Registrar of a certificated Note, duly endorsed
     or accompanied by a written instruction of transfer in form satisfactory to
     the Registrar duly executed by such holder or his attorney, duly authorized
     in writing, and the following additional information and documents (all of
     which may be submitted by facsimile):

               (1)  If such certificated Note is a Transfer Restricted Note and
          is being transferred to a QIB in accordance with Rule 144A under the
          Securities Act, a certification to that effect from such holder (in
          substantially the form of Exhibit B-2 hereto); and

               (2)  Whether or not such certificated Note is a Transfer
          Restricted Note, written instructions of the holder directing the
          Trustee or the custodian, at the direction of the Trustee, to make an
          endorsement on the applicable Global Note to reflect an increase in
          the aggregate principal amount of the Notes represented by such Global
          Note,

     then the Registrar shall cancel such certificated Note and the Trustee or
     the custodian, at the direction of the Trustee, shall, in accordance with
     the standing instructions and procedures existing between the Depositary
     and the custodian, cause the aggregate principal amount of Restricted
     Global Notes or Unrestricted Global Notes, as applicable, to be increased
     accordingly.  If no Global Notes are then outstanding, the Company shall
     issue and the Trustee shall authenticate a new Global Note in the
     appropriate principal amount.

                                       18

 
          (f) Authentication of Certificated Note in Absence of Depositary.  If
              ------------------------------------------------------------     
     at any time:

               (i) the Depositary for the Notes notifies the Company that the
          Depositary is unwilling or unable to continue as Depositary for the
          Global Notes and a successor Depositary for the Global Notes is not
          appointed by the Company within 90 days after delivery of such notice;

               (ii) the Company, at its sole discretion, notifies the Trustee in
          writing that it elects to cause the issuance of certificated Notes
          under this Indenture; or

               (iii)  an Event of Default has occurred and is continuing.

     then the Company shall execute, and the Trustee shall, upon receipt of an
     authentication order in accordance with Section 2.2 hereof, authenticate
     and deliver, certificated Notes in an aggregate principal amount equal to
     the principal amount of the Global Notes in exchange for such Global Notes.

          (g)  Legends.
               ------- 

               (i) Except as permitted by the following paragraphs (ii) and
          (iii), each Note certificate evidencing the Global Notes and the
          certificated Notes (and all Notes issued in exchange therefor or
          substitution thereof) shall bear legends in substantially the form set
          forth in Exhibit A as the "Restricted Notes Legend".

               (ii) Upon any sale or transfer of a Transfer Restricted Note
          (including any Transfer Restricted Note represented by a Global Note)
          pursuant to Rule 144 under the Securities Act or pursuant to an
          effective registration statement under the Securities Act:

                    (A) in the case of any Transfer Restricted Note that is a
               certificated Note, the Registrar shall permit the holder thereof
               to exchange such Transfer Restricted Note for a certificated Note
               that does not bear the legend set forth in (i) above and rescind
               any restriction on the transfer of such Transfer Restricted Note
               upon receipt of a certification from the transferring holder
               substantially in the form of Exhibit B-4 hereto; and

                    (B) in the case of any Transfer Restricted Note represented
               by a Global Note, such Transfer Restricted Note shall not be
               required to bear the legend set forth in (i) above, but shall
               continue to be subject to the provisions of Section 2.6(a) and
               (b) hereof; provided, however, that with respect to any request
               for an exchange of a Transfer Restricted Note that is represented
               by a Global Note for a certificated Note that does not bear the
               legend set forth in (i) above, which request

                                       19

 
               is made in reliance upon Rule 144 under the Securities Act, the
               holder thereof shall certify in writing to the Registrar that
               such request is being made pursuant to Rule 144 under the
               Securities Act (such certification to be substantially in the
               form of Exhibit B-4 hereto).

               (iii)  Upon any sale or transfer of a Transfer Restricted Note
          (including any Transfer Restricted Note represented by a Global Note)
          in reliance on any exemption from the registration requirements of the
          Securities Act (other than exemptions pursuant to Rule 144A or Rule
          144 under the Securities Act) in which the holder or the transferee
          provides an Opinion of Counsel to the Company and the Registrar in
          form and substance reasonably acceptable to the Company and the
          Registrar (which Opinion of Counsel shall also state that the transfer
          restrictions contained in the legend are no longer applicable):

                    (A) in the case of any Transfer Restricted Note that is a
               certificated Note, the Registrar shall permit the holder thereof
               to exchange such Transfer Restricted Note for a certificated Note
               that does not bear the legend set forth in (i) above and rescind
               any restriction on the transfer of such Transfer Restricted Note;
               and

                    (B) in the case of any Transfer Restricted Note represented
               by a Global Note, such Transfer Restricted Note shall not be
               required to bear the legend set forth in (i) above, but shall
               continue to be subject to the provisions of Section 2.6(a) and
               (b) hereof.

          (h) Initial Purchasers.  The Initial Purchasers shall not be required
              ------------------                                               
     to deliver, and neither the Company nor the Trustee shall demand therefrom,
     any of the certifications or opinions described in this Section 2.6 in
     connection with the initial issuance and delivery by the Company of the
     Notes on the effective date hereof or on the date of any settlement in
     connection with the exercise of the overallotment option granted to the
     Initial Purchasers in the Purchase Agreement, including with respect to the
     issuance and delivery of Notes that are Transfer Restricted Notes.

     SECTION 2.7  Replacement Notes.  If the holder of a Note claims that the
                  -----------------                                          
Note has been lost, destroyed or wrongfully taken or if such Note is mutilated
and is surrendered to the Trustee, the Company shall issue and the Trustee shall
authenticate a replacement Note if the Trustee's and the Company's requirements
are met.  If required by the Trustee or the Company, such holder shall be
required to provide an indemnity bond sufficient in the judgment of both to
protect and hold harmless the Company, the Trustee, any Agent or any
authenticating agent from any loss, liability or expense which any of them may
suffer if a Note is replaced.  The Company may charge for its expenses in
replacing a Note.

     In case any such mutilated, destroyed, lost or stolen Note has become or is
about to become due and payable, or is about to be purchased by the Company
pursuant to Article 3 hereof, the Company in its discretion may, instead of
issuing a new Note, pay or purchase such Note, as the case may be.

                                       20

 
     Every replacement Note is an additional obligation of the Company and shall
be entitled to all the benefits provided under this Indenture equally and
proportionately with all other Notes duly issued hereunder.

     SECTION 2.8  Outstanding Notes.  The Notes outstanding at any time are all
                  -----------------                                            
the Notes authenticated by the Trustee except for those cancelled by it, those
delivered to it for cancellation, and those described in this Section as not
outstanding.

     If a Note is replaced, paid or purchased pursuant to Section 2.7 hereof, it
ceases to be outstanding unless the Trustee receives proof satisfactory to it
that the replaced, paid or purchased Note is held by a bona fide purchaser.

     If Notes are considered paid under Section 4.1 hereof, they cease to be
outstanding and interest on them ceases to accrue.

     A Note does not cease to be outstanding because the Company or an Affiliate
of the Company holds the Note.

     SECTION 2.9  Treasury Notes.  In determining whether the Noteholders of the
                  --------------                                                
required principal amount of Notes have concurred in any direction, waiver or
consent, Notes owned by the Company or an Affiliate of the Company shall be
considered as though they are not outstanding, except that for the purposes of
determining whether the Trustee shall be protected in relying on any such
direction, waiver or consent, only Notes which a Trust Officer of the Trustee
actually knows are so owned shall be so disregarded.  Notes that the Company or
any Affiliate of the Company offers to purchase or acquire pursuant to an
exchange offer, tender offer or otherwise shall not be deemed to be owned by the
Company or such Affiliate until legal title passes to the Company or such
Affiliate.

     SECTION 2.10  Temporary Notes.
                   --------------- 

          (a) Until definitive Notes are ready for delivery, the Company may
     prepare and the Trustee shall authenticate temporary Notes.  Temporary
     Notes shall be substantially in the form of definitive Notes but may have
     variations that the Company considers appropriate for temporary Notes.  As
     promptly as is reasonably practicable, the Company shall prepare and the
     Trustee shall authenticate definitive Notes in exchange for temporary
     Notes.

          (b) A Global Note deposited with the Depositary or with the Trustee as
     custodian for the Depositary pursuant to Section 2.1 shall be transferred
     to the beneficial owners thereof in the form of certificated Notes only if
     such transfer complies with Section 2.6 and (i) the Depositary notifies the
     Company that it is unwilling or unable to continue as Depositary for such
     Global Note or if at any time such Depositary ceases to be a "clearing
     agency" registered under the Exchange Act and a successor depositary is not
     appointed by the Company within 90 days of such notice, or (ii) an Event of
     Default has occurred and is continuing.

                                       21

 
          (c)  Any Global Note that is transferable to the beneficial owners
     thereof in the form of certificated Notes pursuant to this Section 2.10
     shall be surrendered by the Depositary to the Trustee located in The City
     of New York, to be so transferred, in whole or from time to time in part,
     without charge, and the Trustee shall authenticate and deliver, upon such
     transfer of each portion of such Global Note, an equal aggregate principal
     amount at maturity of Notes of authorized denominations in the form of
     certificated Notes.  Any portion of a Global Note transferred pursuant to
     this Section shall be executed, authenticated and delivered only in
     denominations of $1,000 and any integral multiple thereof and registered in
     such names as the Depositary shall direct.  Any Notes in the form of
     certificated Notes delivered in exchange for an interest in the Global Note
     shall, except as otherwise provided by Section 2.6(b) bear the Restricted
     Notes Legend set forth in Exhibit A hereto.

          (d) Subject to the provisions of Section 2.10(b), the registered
     holder of a Global Note may grant proxies and otherwise authorize any
     person, including Agent Members and persons that may hold interests through
     Agent Members, to take any action which a holder is entitled to take under
     this Indenture or the Notes.

          (e) In the event of the occurrence of either of the events specified
     in Section 2.10(b), the Company will promptly make available to the Trustee
     a reasonable supply of certificated Notes in definitive, fully registered
     form without interest coupons.

     SECTION 2.11  Cancellation.  The Company at any time may deliver Notes to
                   ------------                                               
the Trustee for cancellation.  The Registrar, Paying Agent and Conversion Agent
shall forward to the Trustee any Notes surrendered to them for registration of
transfer, redemption, conversion, exchange or payment.  The Trustee shall
promptly cancel all Notes surrendered for registration of transfer, redemption,
conversion, exchange, payment, replacement or cancellation and shall dispose of
cancelled Notes as the Company directs.  The Company may not issue new Notes to
replace Notes that it has paid or that have been delivered to the Trustee for
cancellation or that any holder has converted.

     SECTION 2.12  Defaulted Interest or Liquidated Damages.  If the Company
                   ----------------------------------------                 
fails to make a payment of interest or Liquidated Damages on the Notes, it shall
pay such defaulted interest or Liquidated Damages plus any interest payable on
the defaulted interest or Liquidated Damages, in any lawful manner.  It may pay
such defaulted interest, plus any such interest payable on them, to the persons
who are Noteholders on a subsequent special record date.  The Company shall fix
any such record date (which shall be at least 5 and not more than 30 days before
the payment date) and the payment date.  At least 15 days before any such record
date, the Company shall mail to Noteholders a notice that states the record
date, payment date, and amount of such interest or Liquidated Damages to be
paid.  Interest or Liquidated Damages to be paid prior to the expiration of the
30-day grace period specified in Section 8.1(a) of this Indenture shall be paid
to the holders on the regular record date for the interest payment that has not
been made.

                                       22

 
                                   ARTICLE 3

                                  Redemption
                                  ----------

          SECTION 3.1  Notices to Trustee.  If the Company elects to redeem
                       ------------------                                  
Notes pursuant to the Optional Redemption provision of Section 3.7 hereof, it
shall notify the Trustee of the redemption date and the principal amount of
Notes to be redeemed.  The Company shall give each notice provided for in this
Section 3.1 with respect to any Optional Redemption at least 20 days before the
redemption date (unless a shorter notice period shall be satisfactory to the
Trustee).  In the event the Company is required to redeem Notes pursuant to the
special redemption provision of Section 3.9 hereof (the "Special Redemption"),
it shall notify the Trustee ten Business Days before a redemption date (unless a
shorter notice period shall be satisfactory to the Trustee).  The Company will
also provide the Trustee with any additional information that the Trustee
reasonably requests in connection with any redemption.

          SECTION 3.2  Selection of Notes to be Redeemed.  If less than all the
                       ---------------------------------                       
Notes are to be redeemed, the Trustee shall select the Notes to be redeemed in
compliance with the requirements of the principal national securities exchange,
if any, on which the Notes are listed, or, if the Notes are not so listed, on a
pro rata basis, by lot or by such method as the Trustee shall deem fair and
appropriate.  The Trustee shall make the selection not more than 60 days and not
less than 15 days before the redemption date from Notes outstanding not
previously called for redemption.  The Trustee may select for redemption
portions of the principal of Notes that have denominations larger than $1,000.
Notes and portions of them it selects shall be in amounts of $1,000 or integral
multiples of $1,000.  Provisions of this Indenture that apply to Notes called
for redemption also apply to portions of Notes called for redemption.  The
Trustee shall notify the Company and each Registrar promptly of the Notes or
portions of Notes to be called for redemption.

          If any Note selected for partial redemption is converted in part after
such selection, the converted portion of such Note shall be deemed (so far as
may be) to be the portion to be selected for redemption.  The Notes (or portions
thereof) so selected shall be deemed duly selected for redemption for all
purposes hereof, notwithstanding that any such Note is converted in whole or in
part before the mailing of the notice of redemption.  Upon any redemption of
less than all the Notes, the Company and the Trustee may treat as outstanding
any Notes surrendered for conversion during the period 15 days next preceding
the mailing of a notice of redemption and need not treat as outstanding any Note
authenticated and delivered during such period in exchange for the unconverted
portion of any Note converted in part during such period.

          SECTION 3.3  Notice of Redemption.  At least 15 days but not more than
                       --------------------                                     
60 days before a redemption date (other than with respect to a Special
Redemption), the Company shall mail a notice of redemption to each holder whose
Notes are to be redeemed at such holder's registered address.  In the event of a
Special Redemption, the Company shall mail a notice of redemption to each holder
at such holder's registered address at least ten Business Days before a
redemption date.

                                       23

 
     The notice shall identify the Notes to be redeemed and shall state:

          (a)  the redemption date;

          (b)  the redemption price;

          (c) if any Note is being redeemed in part, the portion of the
     principal amount of such Note to be redeemed and that, after the redemption
     date, upon cancellation of such Note, a new Note or Notes in principal
     amount equal to the unredeemed portion will be issued in the name of the
     holder thereof;

          (d)  the name and address of the Paying Agent;

          (e) that Notes called for redemption must be surrendered to the Paying
     Agent to collect the redemption price plus accrued interest and Liquidated
     Damages, if any;

          (f) that, unless the Company defaults in making such redemption
     payment or the Paying Agent is prohibited from making such payment pursuant
     to the terms of this Indenture, interest on Notes or portions thereof
     called for redemption ceases to accrue on and after the redemption date;
     and

          (g) the paragraph of the Notes pursuant to which the Notes called for
     redemption are being redeemed.

     Such notice shall also state the current Conversion Price, if any, and the
date on which the right to convert such Notes or portions thereof into Common
Stock of the Company will expire.

     At the Company's request, the Trustee shall give notice of redemption in
the Company's name and at its expense.

     SECTION 3.4  Effect of Notice of Redemption. Once notice of redemption is
                  ------------------------------                              
mailed, Notes called for redemption become due and payable on the redemption
date at the price set forth in the Note.

     SECTION 3.5  Deposit of Redemption Price.  On or before the redemption date
                  ---------------------------                                   
(other than for a Special Redemption), the Company shall deposit with the
Trustee or with the Paying Agent money sufficient to pay the redemption price of
and accrued interest and Liquidated Damages, if any, if up to but not including
the redemption date on all Notes to be redeemed on that date (subject to the
right of holders of record on the relevant record date to receive interest and
Liquidated Damages, if any, due on an interest payment date) unless theretofore
converted into Common Stock pursuant to the provisions hereof.  The Trustee or
the Paying Agent shall return to the Company any money not required for that
purpose.

     SECTION 3.6  Notes Redeemed in Part.  Upon cancellation of a Note that is
                  ----------------------                                      
redeemed in part, the Company shall issue and the Trustee shall authenticate for
the holder at

                                       24

 
the expense of the Company a new Note equal in principal amount to the 
unredeemed portion of the Note surrendered.

     SECTION 3.7  Optional Redemption.  The Company may redeem all or any
                  -------------------                                    
portion of the Notes, upon the terms and at the redemption prices set forth in
each of the Notes.  Any redemption pursuant to this Section 3.7 shall be made
pursuant to the provisions of Section 3.1 through 3.6 hereof.

     SECTION 3.8  Designated Event Offer.
                  ---------------------- 

          (a) In the event that, pursuant to Section 4.7 hereof, the Company
     shall commence a Designated Event Offer, the Company shall follow the
     procedures in this Section 3.8.

          (b) The Designated Event Offer shall remain open for a period
     specified by the Company which shall be no less than 30 calendar days and
     no more than 40 calendar days following its commencement on the date of the
     mailing of notice in accordance with Section 4.7(b) hereof (the
     "Commencement Date"), except to the extent that a longer period is required
     by applicable law (the "Tender Period").  Upon the expiration of the Tender
     Period (the "Designated Event Payment Date"), the Company shall purchase
     the principal amount of Notes required to be purchased pursuant to Section
     4.7 hereof (the "Offer Amount").

          (c) If the Designated Event Payment Date is on or after an interest
     payment record date and on or before the related interest payment date, any
     accrued interest or Liquidated Damages, if any, to the related interest
     payment date will be paid to the person in whose name a Note is registered
     at the close of business on such record date, and no additional interest or
     Liquidated Damages, if any, will be payable to Noteholders who tender Notes
     pursuant to the Designated Event Offer.

          (d) The Company shall provide the Trustee with notice of the
     Designated Event Offer at least 5 Business Days before the Commencement
     Date.

          (e) On or before the Commencement Date, the Company or the Trustee (at
     the request and expense of the Company) shall send, by first class mail, a
     notice to each of the Noteholders, which shall govern the terms of the
     Designated Event Offer and shall state:

               (i) that the Designated Event Offer is being made pursuant to
          this Section 3.8 and Section 4.7 hereof and that all Notes tendered
          will be accepted for payment;

               (ii) the purchase price (as determined in accordance with Section
          4.7 hereof), the length of time the Designated Event Offer will remain
          open and the Designated Event Payment Date;

                                       25

 
               (iii)  that any Note or portion thereof not tendered or accepted
          for payment will continue to accrue interest and, if applicable,
          Liquidated Damages, if any;

               (iv) that, unless the Company defaults in the payment of the
          Designated Event Payment, any Note or portion thereof accepted for
          payment pursuant to the Designated Event Offer shall cease to accrue
          interest or Liquidated Damages, if any, on and after the Designated
          Event Payment Date;

               (v) that Noteholders electing to have a Note or portion thereof
          purchased pursuant to any Designated Event Offer will be required to
          surrender the Note, with the form entitled "Option of Noteholder To
          Elect Purchase" on the reverse of the Note completed, to the Paying
          Agent at the address specified in the notice prior to the close of
          business on the third Business Day preceding the Designated Event
          Payment Date;

               (vi) that Noteholders will be entitled to withdraw their election
          if the Paying Agent receives, not later than the close of business on
          the second Business Day preceding the Designated Event Payment Date,
          or such longer period as may be required by law, a letter or a
          telegram, telex or facsimile transmission (receipt of which is
          confirmed and promptly followed by a letter) setting forth the name of
          the Noteholder, the principal amount of the Note or portion thereof
          the Noteholder delivered for purchase and a statement that such
          Noteholder is withdrawing his election to have the Note or portion
          thereof purchased; and

               (vii)  that Noteholders whose Notes are being purchased only in
          part will be issued new Notes equal in principal amount to the
          unpurchased portion of the Notes surrendered, which unpurchased
          portion must be equal to $1,000 in principal amount or an integral
          multiple thereof.

          In addition, the notice shall contain all instructions and materials
     that the Company shall reasonably deem necessary to enable such Noteholders
     to tender Notes pursuant to the Designated Event Offer.

          (f)  On or prior to the Designated Event Payment Date, the Company
     shall irrevocably deposit with the Trustee or a Paying Agent in immediately
     available funds an amount equal to the Offer Amount to be held for payment
     in accordance with the terms of this Section 3.8. On the Designated Event
     Payment Date, the Company shall, to the extent lawful, (i) accept for
     payment the Notes or portions thereof tendered pursuant to the Designated
     Event Offer, (ii) deliver or cause to be delivered to the Trustee Notes so
     accepted and (iii) deliver to the Trustee an Officers' Certificate stating
     such Notes or portions thereof have been accepted for payment by the
     Company in accordance with the terms of this Section 3.8.  The Paying Agent
     shall promptly (but in any case not later than ten (10) calendar days after
     the Designated Event Payment Date) mail or deliver to each tendering
     Noteholder an amount equal to the purchase price of the Notes tendered by
     such Noteholder, and the

                                       26

 
     Trustee shall promptly authenticate and mail or deliver to such Noteholders
     a new Note equal in principal amount to any unpurchased portion of the Note
     surrendered, if any; provided, that each new Note shall be in a principal
                          --------                                            
     amount of $1,000 or an integral multiple thereof.  Any Notes not so
     accepted shall be promptly mailed or delivered by or on behalf of the
     Company to the holder thereof.  The Company will publicly announce the
     results of the Designated Event Offer on, or as soon as practicable after,
     the Designated Event Payment Date.

          (g) The Designated Event Offer shall be made by the Company in
     compliance with all applicable provisions of all applicable securities
     laws, including the Exchange Act, and all applicable tender offer rules
     promulgated thereunder, and shall include all instructions and materials
     that the Company shall reasonably deem necessary to enable such Noteholders
     to tender their Notes.

     SECTION  3.9  Special Mandatory Redemption.  The Company will be required
                   ----------------------------                               
to redeem all Notes on or prior to the Special Redemption Date, upon the terms
and at the redemption prices set forth in paragraph 5(b) of the Notes and in
Section 4.8 hereof.

                                   ARTICLE 4

                                   Covenants
                                   ---------

     SECTION  4.1  Payment of Notes.  The Company shall pay the principal of,
                   ----------------                                          
premium, if any, Liquidated Damages, if any, and interest on, the Notes on the
dates and in the manner provided in the Notes.  Principal, premium, if any,
Liquidated Damages, if any, and interest shall be considered paid on the date
due if the Paying Agent (other than the Company or an Affiliate of the Company)
holds on that date money designated for and sufficient to pay all principal,
premium, if any, Liquidated Damages, if any, and interest then due and such
Paying Agent is not prohibited from paying such money to the Noteholders on that
date pursuant to the terms of this Indenture.  To the extent lawful, the Company
shall pay interest and Liquidated Damages, if any (including post-petition
interest in any proceeding under any Bankruptcy Law) on overdue installments of
interest (without regard to any applicable grace period) at the rate borne by
the Notes, compounded semiannually.  The Company shall also pay all Liquidated
Damages, if any, in the manner, on the dates and in the amounts set forth in the
Registration Agreement.

     SECTION 4.2  SEC Reports.  Whether or not required by the rules and
                  -----------                                           
regulations of the SEC, so long as any Notes are outstanding, the Company will,
to the extent permitted by the SEC, file with the SEC and, if requested, furnish
to the Trustee and to the holders of Notes all quarterly and annual financial
information required to be contained in a filing with the SEC on Forms 10-Q and
10-K, including a "Management's Discussion and Analysis of Financial Condition
and Results of Operations" and, with respect to annual information only, a
report thereon by the Company's certified independent accountants.

     SECTION 4.3  Compliance Certificate.  The Company shall deliver to the
                  ----------------------                                   
Trustee, within 120 days after the end of each fiscal year of the Company, an
Officers' Certificate stating that a review of the activities of the Company and
its subsidiaries during the

                                       27

 
preceding fiscal year has been made under the supervision of the signing
officers with a view to determining whether the Company has kept, observed,
performed and fulfilled its obligations under, and complied with the covenants
and conditions contained in, this Indenture, and further stating, as to each
such Officer signing such certificate, that to the best of his knowledge, the
Company has kept, observed, performed and fulfilled each and every covenant, and
complied with the covenants and conditions contained in this Indenture and is
not in default in the performance or observance of any of the terms, provisions
and conditions hereof (or, if a Default or Event of Default shall have occurred,
describing all such Defaults or Events of Default of which he may have
knowledge) and that to the best of his knowledge no event has occurred and
remains in existence by reason of which payments on account of the principal or
of interest, if any, on the Notes are prohibited.

     One of the Officers signing such Officers' Certificate shall be either the
Company's principal executive officer, principal financial officer or principal
accounting officer.

     The Company will, so long as any of the Notes are outstanding, deliver to
the Trustee, forthwith upon becoming aware of:

          (a) any Default or Event of Default arising under this Indenture; or

          (b) any event of default under any other mortgage, indenture or
     instrument as that term is used in Section 8.1(e),

an Officers' Certificate specifying such Default, Event of Default or default.

     Immediately upon the occurrence of any event giving rise to Liquidated
Damages in respect of the Notes in accordance with Section 11 of the form
thereof or the termination of any such Liquidated Damages, the Company shall
give the Trustee notice of such Liquidated Damages or termination, of the
interest rate borne by the Notes after giving effect to such Liquidated Damages
or termination and of the event giving rise to such Liquidated Damages or
termination thereof (such notice to be contained in an Officers' Certificate),
and prior to receipt of such Officers' Certificate the Trustee shall be entitled
to assume that no such Liquidated Damages are owing or termination has occurred,
as the case may be.

     SECTION 4.4  Stay, Extension and Usury Laws.  The Company covenants (to the
                  ------------------------------                                
extent that it may lawfully do so) that it will not at any time insist upon,
plead, or in any manner whatsoever claim or take the benefit or advantage of,
any stay, extension or usury law wherever enacted, now or at any time hereafter
in force, which may affect the covenants or the performance of this Indenture;
and the Company (to the extent it may lawfully do so) hereby expressly waives
all benefit or advantage of any such law, and covenants that it will not, by
resort to any such law, hinder, delay or impede the execution of any power
herein granted to the Trustee, but will suffer and permit the execution of every
such power as though no such law has been enacted.

     SECTION 4.5  Corporate Existence.  Subject to Article 7 hereof, the Company
                  -------------------                                           
will do or cause to be done all things necessary to preserve and keep in full
force and effect its corporate existence and the corporate, partnership or other
existence of each subsidiary of the

                                       28

 
Company in accordance with the respective organizational documents of each
subsidiary and all material rights (charter and statutory), licenses and
franchises of the Company and its subsidiaries; provided, however, that the
                                                --------  -------          
Company shall not be required to preserve any such right, license or franchise,
or the corporate, partnership or other existence of any subsidiary, if the Board
of Directors shall determine that the preservation thereof is no longer
desirable in the conduct of the business of the Company and its subsidiaries
taken as a whole and that the loss thereof is not adverse in any material
respect to the Noteholders.  Notwithstanding the foregoing, the corporate
existence of any Subsidiary may be terminated in connection with any Board
approved corporate restructuring or reorganization.

     SECTION 4.6  Taxes.  The Company shall, and shall cause each of its
                  -----                                                 
subsidiaries to, pay prior to delinquency all taxes, assessments and
governmental levies, except as contested in good faith and by appropriate
proceedings.

     SECTION 4.7  Designated Event.
                  ---------------- 

          (a) Upon the occurrence of a Designated Event, each holder of Notes
     shall have the right, in accordance with this Section 4.7 and Section 3.8
     hereof, to require the Company to repurchase all or any part (equal to
     $1,000 or an integral multiple thereof) of such holder's Notes pursuant to
     the terms of Section 3.8 (the "Designated Event Offer") at a purchase price
     equal to 101% of the principal amount thereof, together with accrued and
     unpaid interest and Liquidated Damages, if any, thereon to the Designated
     Event Payment Date (the "Designated Event Payment").

          (b) Within 30 days following any Designated Event, the Company shall
     mail to each holder the notice provided by Section 3.8(e) of this
     Indenture, and shall comply with the provisions of Section 3.8 in regard to
     the related Designated Event Offer.

     SECTION 4.8  Deposit of Proceeds with Trustee Pending Consummation of
                  --------------------------------------------------------
Acquisition.
- ----------- 

          (a) On the Issuance Date, the Company shall deposit with the Trustee
     as hereinafter provided the proceeds from the issuance of the Notes (the
     "Offering Proceeds") and such other amount as, when added to the Offering
     Proceeds, equals $75,000,000 plus an amount equal to the interest that
     would accrue on $75,000,000 from the Issuance Date to the Special
     Redemption Date at an interest rate of 7 1/8% per annum plus $1,500,000
     (the "Special Redemption Amount").  In the event that the overallotment
     option granted in the Purchase Agreement is exercised, the Company shall
     also deposit with the Trustee the proceeds from the issuance of Notes
     pursuant to such option (the "Overallotment Proceeds") and such other
     amount as, when added to the Overallotment Proceeds, equals the total
     principal amount of Notes issued upon the exercise of such overallotment
     (the "Overallotment Amount"), plus an amount equal to the interest that
     would accrue on the Overallotment Amount from the Issuance Date to the
     Special Redemption Date at an interest rate of 7 1/8% per annum, plus 2% of
     the Overallotment Amount.  Such additional amounts shall be deemed part of
     the "Special Redemption Amount" upon deposit with the Trustee.

                                       29

 
          (b) In order to secure the full and punctual payment and performance
     of the Company's obligation to redeem the Notes upon a Special Redemption,
     the Company hereby grants to the Trustee, for the benefit of the holders, a
     continuing security interest in and to the Collateral, whether now owned or
     existing or hereafter acquired or arising.

          (c) At all times until the earlier to occur of (i) receipt by the
     Trustee of (x) an Officers' Certificate stating that the Acquisition is to
     be consummated concurrently with the release of the funds on the terms and
     conditions described in the Offering Memorandum in all material respects
     and requesting the Trustee to release the Collateral to the order of the
     Company for application in connection with the Acquisition and to the order
     of the Initial Purchasers for payment of amounts due to the Initial
     Purchasers pursuant to the Purchase Agreement and (y) an Opinion of Counsel
     to the effect that all conditions precedent described in the preceding
     clause (x) have been satisfied in all material respects and (ii) the date
     that the Notes are to be specially redeemed, there shall be maintained with
     the Trustee an account (the "Collateral Account") designated "Plasma &
     Materials Technologies, Inc. Account Pledged to U.S. Trust Company of
     California, N.A., as Trustee."  On the Issuance Date, the Company shall
     cause the Special Redemption Amount to be deposited in the Collateral
     Account.  Amounts on deposit in the Collateral Account shall be invested
     and reinvested from time to time in such Eligible Investments as the
     Company shall direct and, if no direction is made, then in the Federated
     Government Obligation Fund.  Any income received with respect to the
     balance from time to time standing to the credit of the Collateral Account,
     including any interest or capital gains on Eligible Investments, shall
     remain, or be deposited, in the Collateral Account; provided, that the
                                                         --------          
     Trustee shall release any amounts in the Collateral Account in excess of
     the Special Redemption Amount upon request from the Company from time to
     time as specified in an Officers' Certificate to the Trustee.

          (d) Upon notice from the Company to the Trustee pursuant to subsection
     (c)(i) above, the security interests in the Collateral shall terminate as
     of the Acquisition Date and all funds in the Collateral Account shall be
     released as of the Acquisition Date to the order of the Company and to the
     Initial Purchasers; and on the date for redemption of the Notes pursuant to
     subsection (c)(ii) above, the Trustee shall apply funds in the Collateral
     Account to fund the Special Redemption and the Trustee shall pay any amount
     in the Collateral Account in excess of the amount needed to fund the
     Special Redemption to the Company.

                                   ARTICLE 5

                                  Conversion
                                  ----------

     SECTION 5.1  Conversion Privilege.  A holder of a Note may convert the
                  --------------------                                     
principal amount thereof (or any portion thereof that is an integral multiple of
$1,000) into fully paid and nonassessable shares of Common Stock of the Company
at any time after the later to occur of (a) 90 days following the Issuance Date
or (b) the consummation of the Acquisition, and prior to the close of business
(New York time) on the Business Day immediately

                                       30

 
preceding the maturity date of the Notes at the Conversion Price then in effect,
except that, with respect to any Note called for redemption, such conversion
right shall terminate at the close of business on the Business Day immediately
preceding the redemption date (unless the Company shall default in making the
redemption payment when it becomes due, in which case the conversion right shall
terminate on the date such default is cured).  The number of shares of Common
Stock issuable upon conversion of a Note is determined by dividing the principal
amount of the Note converted by the conversion price in effect on the Conversion
Date (the "Conversion Price").

     The initial Conversion Price is stated in paragraph 10 of the Notes and is
subject to adjustment as provided in this Article 5.

     Provisions of this Indenture that apply to conversion of all of a security
also apply to conversion of a portion of it.  A holder of Notes is not entitled
to any rights of a holder of Common Stock until such holder of Notes has
converted such Notes into Common stock, and only to the extent that such Notes
are deemed to have been converted into Common Stock under this Article 5.

     SECTION 5.2  Conversion Procedure.  To convert a Note, a holder must
                  --------------------                                   
satisfy the requirements in paragraph 10 of the Notes.  The date on which the
holder satisfies all of those requirements is the conversion date (the
"Conversion Date").  As soon as practicable after the Conversion Date, the
Company shall deliver to the holder through the Conversion Agent a certificate
for the number of whole shares of Common Stock issuable upon the conversion and
a check for any fractional share determined pursuant to Section 5.3. The person
in whose name the certificate is registered shall become the stockholder of
record on the Conversion Date and, as of such date, such person's rights as a
Noteholder shall cease; provided, however, that no surrender of a Note on any
                        --------  -------                                    
date when the stock transfer books of the Company shall be closed shall be
effective to constitute the person entitled to receive the shares of Common
Stock upon such conversion as the stockholder of record of such shares of Common
Stock on such date, but such surrender shall be effective to constitute the
person entitled to receive such shares of Common Stock as the stockholder of
record thereof for all purposes at the close of business on the next succeeding
day on which such stock transfer books are open; provided further, however, that
                                                 ----------------  -------      
such conversion shall be at the Conversion Price in effect on the date that such
Note shall have been surrendered for conversion, as if the stock transfer books
of the Company had not been closed.

     No adjustment or payment will be made for accrued and unpaid interest on a
converted Note or for dividends or distributions on shares of Common Stock
issued upon conversion of a Note, but if any holder surrenders a Note for
conversion after the close of business on the record date for the payment of an
installment of interest and Liquidated Damages, if any, and prior to the opening
of business on the next succeeding interest payment date, then, notwithstanding
such conversion, the interest and Liquidated Damages, if any, payable on such
interest payment date shall be paid to the registered holder of such Note on
such record date.  In such event, such Note, when surrendered for conversion
after October 15, 1999, must be accompanied by payment in funds acceptable to
the Company of an amount equal to the interest payable and Liquidated Damages,
if any, on such interest

                                       31

 
payment date on the portion so converted and, when surrendered for conversion on
or prior to October 15, 1999, need not be accompanied by such payment.

     If a holder converts more than one Note at the same time, the number of
whole shares of Common Stock issuable upon the conversion shall be based on the
total principal amount of Notes converted.

     Upon surrender of a Note that is converted in part, the Trustee shall
authenticate for the holder a new Note equal in principal amount to the
unconverted portion of the Note surrendered.

     SECTION 5.3  Fractional Shares.  The Company will not issue fractional
                  -----------------                                        
shares of Common Stock upon conversion of a Note.  In lieu thereof, the Company
will pay an amount in cash based upon the Daily Market Price of the Common Stock
on the trading day prior to the date of conversion.

     SECTION 5.4  Taxes on Conversion.  The issuance of certificates for shares
                  -------------------                                          
of Common Stock upon the conversion of any Note shall be made without charge to
the converting Noteholder for such certificates or for any tax in respect of the
issuance of such certificates, and such certificates shall be issued in the
respective names of, or in such names as may be directed by, the holder or
holders of the converted Note; provided, however, that in the event that
                               --------  -------                        
certificates for shares of Common Stock are to be issued in a name other than
the name of the holder of the Note converted, such Note, when surrendered for
conversion, shall be accompanied by an instrument of transfer, in form
satisfactory to the Company, duly executed by the registered holder thereof or
his duly authorized attorney; and provided further, however, that the Company
                                  ----------------  -------                  
shall not be required to pay any tax which may be payable in respect of any
transfer involved in the issuance and delivery of any such certificates in a
name other than that of the holder of the converted Note,and the Company shall
not be required to issue or deliver such certificates unless or until the person
or persons requesting the issuance thereof shall have paid to the Company the
amount of such tax or shall have established to the satisfaction of the Company
that such tax has been paid or is not applicable.

     SECTION 5.5  Company to Provide Stock.  The Company shall at all times
                  ------------------------                                 
reserve and keep available, free from preemptive rights, out of its authorized
but unissued Common Stock, solely for the purpose of issuance upon conversion of
Notes as herein provided, a sufficient number of shares of Common Stock to
permit the conversion of all outstanding Notes for shares of Common Stock.

     All shares of Common Stock which may be issued upon conversion of the Notes
shall be duly authorized, validly issued, fully paid and nonassessable when so
issued.

     SECTION 5.6  Adjustment of Conversion Price.  The Conversion Price shall be
                  ------------------------------                                
subject to adjustment from time to time as follows:

          (a) In case the Company shall (1) pay a dividend in shares of Common
     Stock to holders of Common Stock, (2) make a distribution in shares of
     Common

                                       32

 
     Stock to holders of Common Stock, (3) subdivide its outstanding shares of
     Common Stock into a greater number of shares of Common Stock or (4) combine
     its outstanding shares of Common Stock into a smaller number of shares of
     Common Stock, the Conversion Price in effect immediately prior to such
     action shall be adjusted so that the holder of any Note thereafter
     surrendered for conversion shall be entitled to receive the number of
     shares of Common Stock which he would have owned immediately following such
     action had such Notes been converted immediately prior thereto.  Any
     adjustment made pursuant to this subsection (a) shall become effective
     immediately after the record date in the case of a dividend or distribution
     and shall become effective immediately after the effective date in the case
     of a subdivision or combination.

          (b) In case the Company shall issue rights or warrants to
     substantially all holders of Common Stock entitling them (for a period
     commencing no earlier than the record date for the determination of holders
     of Common Stock entitled to receive such rights or warrants and expiring
     not more than 45 days after such record date) to subscribe for or purchase
     shares of Common Stock (or securities convertible into Common Stock) at a
     price per share less than the Current Market Price (as determined pursuant
     to subsection (f) below) of the Common Stock on such record date, the
     Conversion Price shall be adjusted so that the same shall equal the price
     determined by multiplying the Conversion Price in effect immediately prior
     to such record date by a fraction of which the numerator shall be the
     number of shares of Common Stock outstanding on such record date, plus the
     number of shares of Common Stock which the aggregate offering price of the
     offered shares of Common Stock (or the aggregate conversion price of the
     convertible securities so offered) would purchase at such Current Market
     Price, and of which the denominator shall be the number of shares of Common
     Stock outstanding on such record date plus the number of additional shares
     of Common Stock offered (or into which the convertible securities so
     offered are convertible).  Such adjustments shall become effective
     immediately after such record date.

          (c) In case the Company shall distribute to all holders of Common
     Stock shares of any class of Capital Stock of the Company other than Common
     Stock, evidences of indebtedness or other assets (other than cash dividends
     out of current or retained earnings), or shall distribute to substantially
     all holders of Common Stock rights or warrants to subscribe for securities
     (other than those securities referred to in subsection (b) above), then in
     each such case the Conversion Price shall be adjusted so that the same
     shall equal the price determined by multiplying the Conversion Price in
     effect immediately prior to the date of such distribution by a fraction of
     which the numerator shall be the Current Market Price (determined as
     provided in subsection (f) below) of the Common Stock on the record date
     mentioned below less the then fair market value (as determined by the Board
     of Directors, whose determination shall be conclusive evidence of such fair
     market value and described in a Board Resolution) of the portion of the
     assets so distributed or of such subscription rights or warrants applicable
     to one share of Common Stock, and of which the denominator shall be such
     Current Market Price of the Common Stock.  Such adjustment shall become
     effective immediately after the record date for the determination of the
     holders of

                                       33

 
     Common Stock entitled to receive such distribution.  Notwithstanding the
     foregoing, in the event that the Company shall distribute rights or
     warrants to subscribe for additional shares of the Company's Capital Stock
     (other than the Common Stock referred to in subsection (b) above)
     ("Rights") to substantially all holders of Common Stock, the Company may,
     in lieu of making any adjustment pursuant to this Section 5.6, make proper
     provision so that each holder of a Note who converts such Note (or any
     portion thereof) after the record date for such distribution and prior to
     the expiration or redemption of the Rights shall be entitled to receive
     upon such conversion, in addition to the shares of Common Stock issuable
     upon such conversion (the "Conversion Shares"), a number of Rights to be
     determined as follows: (i) if such conversion occurs on or prior to the
     date for the distribution to the holders of Rights of separate certificates
     evidencing such Rights (the "Distribution Date"), the same number of Rights
     to which a holder of a number of shares of Common Stock equal to the number
     of Conversion Shares is entitled at the time of such conversion in
     accordance with the terms and provisions of and applicable to the Rights;
     and (ii) if such conversion occurs after the Distribution Date, the same
     number of Rights to which a holder of the number of shares of Common Stock
     into which the principal amount of the Note so converted was convertible
     immediately prior to the Distribution Date would have been entitled on the
     Distribution Date in accordance with the terms and provisions of and
     applicable to the Rights.

          (d) In case the Company shall, by dividend or otherwise, at any time
     distribute to all holders of its Common Stock cash (including any
     distributions of cash out of current or retained earnings of the Company
     but excluding any cash that is distributed as part of a distribution
     requiring a Conversion Price adjustment pursuant to paragraph (c) of this
     Section) in an aggregate amount that, together with the sum of (x) the
     aggregate amount of any other distributions to all holders of its Common
     Stock made in cash plus (y) all Excess Payments, in each case made within
     the 12 months preceding the date fixed for determining the shareholders
     entitled to such distribution (the "Distribution Record Date") and in
     respect of which no Conversion Price adjustment pursuant to paragraphs (c)
     or (e) of this Section or this paragraph (d) has been made, exceeds 15% of
     the product of the Current Market Price per share (determined as provided
     in paragraph (f) of this Section) of the Common Stock on the Distribution
     Record Date times the number of shares of Common Stock outstanding on the
     Distribution Record Date (excluding shares held in the treasury of the
     Company), the Conversion Price shall be reduced so that the same shall
     equal the price determined by multiplying such Conversion Price in effect
     immediately prior to the effectiveness of the Conversion Price reduction
     contemplated by this paragraph (d) by a fraction of which the numerator
     shall be the Current Market Price per share (determined as provided in
     paragraph (f) of this Section) of the Common Stock on the Distribution
     Record Date less the amount of such cash and other consideration (including
     any Excess Payments) so distributed applicable to one share (based on the
     pro-rata portion of the aggregate amount of such cash and other
     consideration (including any Excess on the Distribution Record Date)) of
     Common Stock and the denominator shall be such Current Market Price per
     share (determined as provided in paragraph (f) of this Section) of the
     Common Stock on the Distribution Record Date,

                                       34

 
     such reduction to become effective immediately prior to the opening of
     business on the day following the Distribution Record Date.

          (e) In case a tender offer or other negotiated transaction made by the
     Company or any Subsidiary of the Company for all or any portion of the
     Common Stock shall be consummated, if an Excess Payment is made in respect
     of such tender offer or other negotiated transaction and the amount of such
     Excess Payment, together with the sum of (x) the aggregate amount of all
     Excess Payments plus (y) the aggregate amount of all distributions to all
     holders of the Common Stock made in cash (specifically including
     distributions of cash out of retained earnings), in each case made within
     the 12 months preceding the date of payment of such current negotiated
     transaction consideration or expiration of such current tender offer, as
     the case may be (the "Purchase Date"), and as to which no adjustment
     pursuant to paragraph (c) or paragraph (d) of this Section or this
     paragraph (e) has been made, exceeds 15% of the product of the Current
     Market Price per share (determined as provided in paragraph (f) of this
     Section) of the Common Stock on the Purchase Date times the number of
     shares of Common Stock outstanding (including any tendered shares but
     excluding any shares held in the treasury of the Company) on the Purchase
     Date, the Conversion Price shall be reduced so that the same shall equal
     the price determined by multiplying such Conversion Price in effect
     immediately prior to the effectiveness of the Conversion Price reduction
     contemplated by this paragraph (e) by a fraction of which the numerator
     shall be the Current Market Price per share (determined as provided in
     paragraph (f) of this Section) of the Common Stock on the Purchase Date
     less the amount of such Excess Payments and such cash distributions, if
     any, applicable to one share of Common Stock equal to the aggregate amount
     of such Excess Payments and such cash distributions, divided by number of
     the shares of Common Stock outstanding on the Purchase Date) and the
     denominator shall be such Current Market Price per share (determined as
     provided in paragraph (f) of this Section) of the Common Stock on the
     Purchase Date, such reduction to become effective immediately prior to the
     opening of business on the day following the Purchase Date.

          (f) The "Current Market Price" per share of Common Stock on any date
     shall be deemed to be the average of the Daily Market Prices for the
     shorter of (i) 30 consecutive Business Days ending on the last full Trading
     Day on the exchange or market referred to in determining such Daily Market
     Prices prior to the time of determination or (ii) the period commencing on
     the date next succeeding the first public announcement of the issuance of
     such rights or such warrants or such other distribution or such negotiated
     transaction through such last full trading day on the exchange or market
     referred to in determining such Daily Market Prices prior to the time of
     determination.

          (g) In any case in which this Section 5.6 shall require that an
     adjustment be made immediately following a record date for an event, the
     Company may elect to defer, until such event, issuing to the holder of any
     Note converted after such record date the shares of Common Stock and other
     Capital Stock of the Company issuable upon such conversion over and above
     the shares of Common Stock and other Capital

                                       35

 
     Stock of the Company issuable upon such conversion only on the basis of the
     Conversion Price prior to adjustment; and, in lieu of the shares the
     issuance of which is so deferred, the Company shall issue or cause its
     transfer agents to issue due bills or other appropriate evidence of the
     right to receive such shares.

     SECTION 5.7  No Adjustment.  No adjustment in the Conversion Price shall be
                  -------------                                                 
required until cumulative adjustments amount to 1% or more of the Conversion
Price as last adjusted; provided, however, that any adjustments which by reason
                        --------  -------                                      
of this Section 5.7 are not required to be made shall be carried forward and
taken into account in any subsequent adjustment.  All calculations under this
Article 5 shall be made to the nearest cent or to the nearest one-hundredth of a
share, as the case may be.  No adjustment need be made for rights to purchase
Common Stock pursuant to a Company plan for reinvestment of dividends or
interest.  No adjustment need be made for a change in the par value or no par
value of the Common Stock.

     SECTION 5.8  Other Adjustments.
                  ----------------- 

          (a) In the event that, as a result of an adjustment made pursuant to
     Section 5.6 above, the holder of any Note thereafter surrendered for
     conversion shall become entitled to receive any shares of Capital Stock of
     the Company other than shares of its Common Stock, thereafter the
     Conversion Price of such other shares so receivable upon conversion of any
     Notes shall be subject to adjustment from time to time in a manner and on
     terms as nearly equivalent as practicable to the provisions with respect to
     Common Stock contained in this Article 5.

          (b) In the event that shares of Common Stock are not delivered after
     the expiration of any of the rights or warrants referred to in Section
     5.6(b) and Section 5.6(c) hereof, the Conversion Price shall be readjusted
     to the Conversion Price which would otherwise be in effect had the
     adjustment made upon the issuance of such rights or warrants been made on
     the basis of delivery of only the number of shares of Common Stock actually
     delivered.

     SECTION 5.9  Adjustments for Tax Purposes.  The Company may, at its option,
                  ----------------------------                                  
make such reductions in the Conversion Price, in addition to those required by
Section 5.6 above, as it determines to be advisable in order that any stock
dividend, subdivision of shares, distribution of rights to purchase stock or
securities or distribution of securities convertible into or exchangeable for
stock made by the Company to its stockholders will not be taxable to the
recipients thereof.

     SECTION 5.10  Adjustments by the Company.  The Company from time to time
                   --------------------------                                
may, to the extent permitted by law, reduce the Conversion Price by any amount
for any period of at least 20 days, in which case the Company shall give at
least 15 days' notice of such reduction in accordance with Section 5.11, if the
Board of Directors has made a determination that such reduction would be in the
best interests of the Company, which determination shall be conclusive.

                                       36

 
     SECTION 5.11  Notice of Adjustment.  Whenever the Conversion Price is
                   --------------------                                   
adjusted, the Company shall promptly mail to Noteholders at the addresses
appearing on the Registrar's books a notice of the adjustment and file with the
Trustee an Officers' Certificate briefly stating the facts requiring the
adjustment and the manner of computing it. The certificate shall be conclusive
evidence of the correctness of such adjustment.

     SECTION 5.12  Notice of Certain Transactions.  In the event that:
                   ------------------------------                     

          (a) the Company takes any action which would require an adjustment in
     the Conversion Price;

          (b) the Company takes any action that would require a supplemental
     indenture pursuant to Section 5.13; or

          (c) there is a dissolution or liquidation of the Company;

a holder of a Note may wish to convert such Note into shares of Common Stock
prior to the record date for or the effective date of the transaction so that he
may receive the rights, warrants, securities or assets which a holder of shares
of Common Stock on that date may receive.  Therefore, the Company shall mail to
Noteholders at the addresses appearing on the Registrar's books and the Trustee
a notice stating the proposed record or effective date, as the case may be.  The
Company shall mail the notice at least 15 days before such date; however,
failure to mail such notice or any defect therein shall not affect the validity
of any transaction referred to in clause (a), (b) or (c) of this Section 5.12.

     SECTION 5.13  Effect of Reclassifications, Consolidations, Mergers or Sales
                   -------------------------------------------------------------
on Conversion Privilege.  If any of the following shall occur, namely:  (i) any
- -----------------------                                                        
reclassification or change of outstanding shares of Common Stock issuable upon
conversion of Notes (other than a change in par value, or from par value to no
par value, or from no par value to par value, or as a result of a subdivision or
combination), (ii) any consolidation or merger to which the Company is a party
other than a merger in which the Company is the continuing corporation and which
does not result in any reclassification of, or change (other than a change in
name, or par value, or from par value to no par value, or from no par value to
par value or as a result of a subdivision or combination) in, outstanding shares
of Common Stock or (iii) any sale or conveyance of all or substantially all of
the property or business of the Company as an entirety, then the Company, or
such successor or purchasing corporation, as the case may be, shall, as a
condition precedent to such reclassification, change, consolidation, merger,
sale or conveyance, execute and deliver to the Trustee a supplemental indenture
in form satisfactory to the Trustee providing that the holder of each Note then
outstanding shall have the right to convert such Note into the kind and amount
of shares of stock and other securities and property (including cash) receivable
upon such reclassification, change, consolidation, merger, sale or conveyance by
a holder of the number of shares of Common Stock deliverable upon conversion of
such Note immediately prior to such reclassification, change, consolidation,
merger, sale or conveyance.  Such supplemental indenture shall provide for
adjustments of the Conversion Price which shall be as nearly equivalent as may
be practicable to the adjustments of the Conversion Price provided for in this
Article 5.  The foregoing, however, shall not in any way affect the right a
holder of a

                                       37

 
Note may otherwise have, pursuant to clause (ii) of the last sentence of
subsection (c) of Section 5.6, to receive Rights upon conversion of a Note.  If,
in the case of any such consolidation, merger, sale or conveyance, the stock or
other securities and property (including cash) receivable thereupon by a holder
of Common Stock includes shares of stock or other securities and property of a
corporation other than the successor or purchasing corporation, as the case may
be, in such consolidation, merger, sale or conveyance, then such supplemental
indenture shall also be executed by such other corporation and shall contain
such additional provisions to protect the interests of the holders of the Notes
as the Board of Directors of the Company shall reasonably consider necessary by
reason of the foregoing.  The provision of this Section 5.13 shall similarly
apply to successive consolidations, mergers, sales or conveyances.

     In the event the Company shall execute a supplemental indenture pursuant to
this Section 5.13, the Company shall promptly file with the Trustee an Officers'
Certificate briefly stating the reasons therefor, the kind or amount of shares
of stock or securities or property (including cash) receivable by holders of the
Notes upon the conversion of their Notes after any such reclassification,
change, consolidation, merger, sale or conveyance and any adjustment to be made
with respect thereto.

     SECTION 5.14  Trustee's Disclaimer.  The Trustee has no duty to determine
                   --------------------                                       
when an adjustment under this Article 5 should be made, how it should be made or
what such adjustment should be, but may accept as conclusive evidence of the
correctness of any such adjustment, and shall be protected in relying upon the
Officers' Certificate with respect thereto which the Company is obligated to
file with the Trustee pursuant to Section 5.11. The Trustee makes no
representation as to the validity or value of any securities or assets issued
upon conversion of Notes, and the Trustee shall not be responsible for the
Company's failure to comply with any provisions of this Article 5.

     The Trustee shall not be under any responsibility to determine the
correctness of any provisions contained in any supplemental indenture executed
pursuant to Section 5.13, but may accept as conclusive evidence of the
correctness thereof, and shall be protected in relying upon, the Officers'
Certificate with respect thereto which the Company is obligated to file with the
Trustee pursuant to Section 5.13.

                                   ARTICLE 6

                                 Subordination
                                 -------------

     SECTION 6.1  Agreement to Subordinate.  The Company, for itself and its
                  ------------------------                                  
successors, and each Noteholder, by his acceptance of Notes, agree that the
payment of the principal of or interest or Liquidated Damages, if any, on or any
other amounts due on the Notes is subordinated in right of payment, to the
extent and in the manner stated in this Article 6, to the prior payment in full
of all existing and future Senior Debt.

     SECTION 6.2  No Payment on Notes if Senior Debt in Default.  Anything in
                  ---------------------------------------------              
this Indenture to the contrary notwithstanding, no payment on account of
principal of or

                                       38

 
redemption of, interest on or other amounts due on the Notes (including the
making of a deposit pursuant to Section 8.1), and no redemption, purchase, or
other acquisition of the Notes, shall be made by or on behalf of the Company (i)
unless full payment of amounts then due for principal, premium, if any, and
interest and of all other amounts then due on all Designated Senior Debt has
been made or duly provided for pursuant to the terms of the instrument governing
such Designated Senior Debt, (ii) if, at the time of such payment, redemption,
purchase or other acquisition, or immediately after giving effect thereto, there
shall exist under any Senior Debt, or any agreement pursuant to which any Senior
Debt is issued, any default, which default shall not have been cured or waived
and which default shall have resulted in the full amount of such Senior Debt
being declared due and payable and (iii) if, at the time of such payment,
redemption, purchase or other acquisition, the Trustee shall have received
written notice from the Representative of the holders of Designated Senior Debt
(a "Payment Blockage Notice") that there exists under such Designated Senior
Debt, or any agreement pursuant to which such Designated Senior Debt is issued,
any default, which default shall not have been cured or waived, permitting the
holders thereof to declare any amounts of such Designated Senior Debt due and
payable, but only for the period (the "Payment Blockage Period") commencing on
the date of receipt of the Payment Blockage Notice and ending (unless earlier
terminated by notice given to the Trustee by the Representative of the holders
of such Designated Senior Debt) on the earlier of (a) the date on which such
event of default shall have been cured or waived or (b) 180 days from the
receipt of the Payment Blockage Notice.  Notwithstanding the provisions
described in the immediately preceding sentence (other than in clauses (i) and
(ii)), unless the holders of such Designated Senior Debt or the Representative
of such holders shall have accelerated the maturity of such Designated Senior
Debt, the Company may resume payments on the Notes after the end of such Payment
Blockage Period.  Not more than one Payment Blockage Notice may be given in any
consecutive 365-day period, irrespective of the number of defaults with respect
to Senior Debt during such period.

     In the event that, notwithstanding the provisions of this Section 6.2,
payments are made by or on behalf of the Company in contravention of the
provisions of this Section 6.2, such payments shall be held by the Trustee, any
Paying Agent or the holders, as applicable, in trust for the benefit of, and
shall be paid over to and delivered to, the Representative of the holders of
Senior Debt or the trustee under the indenture or other agreement (if any),
pursuant to which any instruments evidencing any Senior Debt may have been
issued for application to the payment of all Senior Debt ratably according to
the aggregate amounts remaining unpaid to the extent necessary to pay all Senior
Debt in full in accordance with the terms of such Senior Debt, after giving
effect to any concurrent payment or distribution to or for the holders of Senior
Debt.

     The Company shall give prompt written notice to the Trustee and any Paying
Agent of any default or event of default under any Senior Debt or under any
agreement pursuant to which any Senior Debt may have been issued.

                                       39

 
     SECTION 6.3  Distribution on Acceleration of Notes; Dissolution and
                  ------------------------------------------------------
Reorganization; Subrogation of Notes.
- ------------------------------------ 

          (a) If the Notes are declared due and payable because of the
     occurrence of an Event of Default, the Company shall give prompt written
     notice to the holders of all Senior Debt or to the trustee(s) for such
     Senior Debt of such acceleration.  The Company may not pay the principal of
     or interest on or any other amounts due on the Notes until five days after
     such holders or trustee(s) of Senior Debt receive such notice and,
     thereafter, the Company may pay the principal of or interest on or any
     other amounts due on the Notes only if the provisions of this Article 6
     permit such payment.

          (b) Upon (i) any acceleration of the principal amount due on the Notes
     because of an Event of Default or (ii) any distribution of assets of the
     Company upon any dissolution, winding up, liquidation or reorganization of
     the Company (whether in bankruptcy, insolvency or receivership or upon an
     assignment for the benefit of creditors or any other dissolution, winding
     up, liquidation or reorganization of the Company):

               (i) the holders of all Senior Debt shall first be entitled to
          receive payment in full of the principal thereof, the interest thereon
          and any other amounts due thereon before the holders are entitled to
          receive payment on account of the principal of or interest on or any
          other amounts due on the Notes;

               (ii) any payment or distribution of assets of the Company of any
          kind or character, whether in cash, property or securities (other than
          securities of the Company as reorganized or readjusted or securities
          of the Company or any other corporation provided for by a plan of
          reorganization or readjustment the payment of which is subordinate, at
          least to the extent provided in this Article 6 with respect to the
          Notes, to the payment in full without diminution or modification by
          such plan of all Senior Debt), to which the holders or the Trustee
          would be entitled except for the provisions of this Article 6, shall
          be paid by the liquidating trustee or agent or other person making
          such a payment or distribution, directly to the holders of Senior Debt
          (or their representatives(s) or trustee(s) acting on their behalf),
          ratably according to the aggregate amounts remaining unpaid on account
          of the principal of or interest on and other amounts due on the Senior
          Debt held or represented by each, to the extent necessary to make
          payment in full of all Senior Debt remaining unpaid, after giving
          effect to any concurrent payment or distribution to the holders of
          such Senior Debt; and

               (iii)  in the event that, notwithstanding the foregoing, any
          payment or distribution of assets of the Company of any kind or
          character, whether in cash, property or securities (other than
          securities of the Company as reorganized or readjusted, or securities
          of the Company or any other corporation provided for by a plan of
          reorganization or readjustment the

                                       40

 
          payment of which is subordinate, at least to the extent provided in
          this Article 6 with respect to the Notes, to the payment in full
          without diminution or modification by such plan of Senior Debt), shall
          be received by the Trustee or the holders before all Senior Debt is
          paid in full, such payment or distribution shall be held in trust for
          the benefit of, and be paid over to upon request by a holder of the
          Senior Debt, the holders of the Senior Debt remaining unpaid (or their
          representatives) or trustee(s) acting on their behalf, ratably as
          aforesaid, for application to the payment of such Senior Debt until
          all such Senior Debt shall have been paid in full, after giving effect
          to any concurrent payment or distribution to the holders of such
          Senior Debt.

          Subject to the payment in full of all Senior Debt, the holders shall
     be subrogated to the rights of the holders of Senior Debt to receive
     payments or distributions of cash, property or securities of the Company
     applicable to the Senior Debt until the principal of and interest on the
     Notes shall be paid in full and, for purposes of such subrogation, no such
     payments or distributions to the holders of Senior Debt of cash, property
     or securities which otherwise would have been payable or distributable to
     holders shall, as between the Company, its creditors other than the holders
     of Senior Debt, and the holders, be deemed to be a payment by the Company
     to or on account of the Senior Debt, it being understood that the
     provisions of this Article 6 are and are intended solely for the purpose of
     defining the relative rights of the holders, on the one hand, and the
     holders of Senior Debt, on the other hand.

          Nothing contained in this Article 6 or elsewhere in this Indenture or
     in the Notes is intended to or shall (i) impair, as between the Company and
     its creditors other than the holders of Senior Debt, the obligation of the
     Company, which is absolute and unconditional, to pay to the holders the
     principal of and interest on the Notes as and when the same shall become
     due and payable in accordance with the terms of the Notes, (ii) affect the
     relative rights of the holders and creditors of the Company other than
     holders of Senior Debt or, as between the Company and the Trustee, the
     obligations of the Company to the Trustee, or (iii) prevent the Trustee or
     the holders from exercising all remedies otherwise permitted by applicable
     law upon default under this Indenture, subject to the rights, if any, under
     this Article 6 of the holders of Senior Debt in respect of cash, property
     and securities of the Company received upon the exercise of any such
     remedy.

          Upon distribution of assets of the Company referred to in this Article
     6, the Trustee, subject to the provisions of Section 9.1 hereof, and the
     holders shall be entitled to rely upon a certificate of the liquidating
     trustee or agent or other person making any distribution to the Trustee or
     to the holders for the purpose of ascertaining the persons entitled to
     participate in such distribution, the holders of the Senior Debt and other
     indebtedness of the Company, the amount thereof or payable thereon, the
     amount or amounts paid or distributed thereon and all other facts pertinent
     thereto or to this Article 6.  The Trustee, however, shall not be deemed to
     owe any fiduciary duty to the holders of Senior Debt.  Nothing contained in
     this Article 6 or elsewhere in this indenture, or in any of the Notes,
     shall prevent the good faith application by the Trustee of any moneys which
     were deposited with it

                                       41

 
     hereunder, prior to its receipt of written notice of facts which would
     prohibit such application, for the purpose of the payment of or on account
     of the principal of or interest on the Notes unless, prior to the date on
     which such application is made by the Trustee, the Trustee shall be charged
     with actual notice under Section 6.3(d) hereof of the facts which would
     prohibit the making of such application.

          (c) The provisions of this Article 6 shall not be applicable to any
     cash, properties or securities received by the Trustee or by any holder
     when received as a holder of Senior Debt and nothing in Section 9.11 hereof
     or elsewhere in this Indenture shall deprive the Trustee or such holder of
     any of its rights as such holder.

          (d) The Company shall give prompt written notice to the Trustee of any
     fact known to the Company which would prohibit the making of any payment of
     money to or by the Trustee in respect of the Notes pursuant to the
     provisions of this Article 6.  The Trustee, subject to the provisions of
     Section 9.1 hereof, shall be entitled to assume that no such fact exists
     unless the Company or any holder of Senior Debt or any trustee therefor has
     given notice thereof to the Trustee.  Notwithstanding the provisions of
     this Article 6 or any other provisions of this Indenture, the Trustee shall
     not be charged with knowledge of the existence of any fact which would
     prohibit the making of any payment of moneys to or by the Trustee in
     respect of the Notes pursuant to the provisions in this Article 6, unless
     the Trustee shall have received written notice thereof from the Company or
     any holder or holders of the Senior Debt or from any trustee therefor; and,
     prior to the receipt of any such written notice, the Trustee, subject to
     the provisions of Section 9.1 hereof, shall be entitled in all respects
     conclusively to assume that no such facts exist.

          The Trustee shall be entitled to conclusively rely on the delivery to
     it of a written notice by a person representing himself to be a holder of
     Senior Debt (or a trustee on behalf of such holder) to establish that such
     notice has been given by a holder of Senior Debt (or a trustee on behalf of
     any such holder or holders).  In the event that the Trustee determines in
     good faith that further evidence is required with respect to the right of
     any person as a holder of Senior Debt to participate in any payment or
     distribution pursuant to this Article 6, the Trustee may request such
     person to furnish evidence to the reasonable satisfaction of the Trustee as
     to the amount of Senior Debt held by such person, the extent to which such
     person is entitled to participate in such payment or distribution and any
     other facts pertinent to the rights of such person under this Article 6,
     and, if such evidence is not furnished, the Trustee may defer any payment
     to such person pending judicial determination as to the right of such
     person to receive such payment; nor shall the Trustee be charged with
     knowledge of the curing or waiving of any default of the character
     specified in Section 6.2 hereof or that any event or any condition
     preventing any payment in respect of the Notes shall have ceased to exist,
     unless and until the Trustee shall have received written notice to such
     effect.

          (e) The provisions of this Section 6.3 applicable to the Trustee shall
     (unless the context requires otherwise) also apply to any Paying Agent for
     the Company.

                                       42

 
     SECTION 6.4  Reliance by Senior Debt on Subordination Provisions.  Each
                  ---------------------------------------------------       
holder of any Note by his acceptance thereof acknowledges and agrees that the
foregoing subordination provisions are, and are intended to be, an inducement
and a consideration for each holder of any Senior Debt, whether such Senior Debt
was created or acquired before or after the issuance of the Notes, to acquire
and continue to hold, or to continue to hold, such Senior Debt, and such holder
of Senior Debt shall be deemed conclusively to have relied on such subordination
provisions in acquiring and continuing to hold, or in continuing to hold, such
Senior Debt.  Notice of any default in the payment of any Senior Debt, except as
expressly stated in this Article 6, and notice of acceptance of the provisions
hereof are hereby expressly waived.  Except as otherwise expressly provided
herein, no waiver, forbearance or release by any holder of Senior Debt under
such Senior Debt or under this Article 6 shall constitute a release of any of
the obligations or liabilities of the Trustee or holders of the Notes provided
in this Article 6.

     SECTION 6.5  No Waiver of Subordination Provisions.  Except as otherwise
                  -------------------------------------                      
expressly provided herein, no right of any present or future holder of any
Senior Debt to enforce subordination as herein provided shall at any time in any
way be prejudiced or impaired by any act or failure to act on the part of the
Company or by any act or failure to act, in good faith, by any such holder, or
by any noncompliance by the Company with the terms, provisions and covenants of
this Indenture, regardless of any knowledge thereof any such holder may have or
be otherwise charged with.

     Without in any way limiting the generality of the foregoing paragraph, the
holders of Senior Debt may, at any time and from time to time, without the
consent of, or notice to, the Trustee or the holders of the Notes, without
incurring responsibility to the holders of the Notes and without impairing or
releasing the subordination provided in this Article 6 or the obligations
hereunder of the holders of the Notes to the holders of Senior Debt, do any one
or more of the following:  (i) change the manner, place or terms of payment of,
or renew or alter, Senior Debt, or otherwise amend or supplement in any manner
Senior Debt or any instrument evidencing the same or any agreement under which
Senior Debt is outstanding; (ii) sell, exchange, release or otherwise dispose of
any property pledged, mortgaged or otherwise securing Senior Debt; (iii) release
any person liable in any manner for the collection of Senior Debt; and (iv)
exercise or refrain from exercising any rights against the Company or any other
person.

     SECTION 6.6  Trustee's Relation to Senior Debt.  The Trustee in its
                  ---------------------------------                     
individual capacity shall be entitled to all the rights set forth in this
Article 6 in respect of any Senior Debt at any time held by it, to the same
extent as any holder of Senior Debt, and nothing in Section 9.11 hereof or
elsewhere in this Indenture shall deprive the Trustee of any of its rights as
such holder.

     With respect to the holders of Senior Debt, the Trustee undertakes to
perform or to observe only such of its covenants and obligations, as are
specifically set forth in this Article 6, and no implied covenants or
obligations with respect to the holders of Senior Debt shall be read into this
Indenture against the Trustee.  The Trustee shall not owe any fiduciary duty to
the holders of Senior Debt but shall have only such obligations to such holders
as are expressly set forth in this Article 6.

                                       43

 
     Each holder of a Note by his acceptance thereof authorizes and directs the
Trustee on his behalf to take such action as may be necessary or appropriate to
effectuate the subordination provided in this Article 6 and appoints the Trustee
his attorney-in-fact for any and all such purposes, including, in the event of
any dissolution, winding up or liquidation or reorganization under any
applicable bankruptcy law of the Company (whether in bankruptcy, insolvency or
receivership proceedings or otherwise), the timely filing of a claim for the
unpaid balance of such holder's Notes in the form required in such proceedings
and the causing of such claim to be approved.  If the Trustee does not file a
claim or proof of debt in the form required in such proceedings prior to 30 days
before the expiration of the time to file such claims or proofs, then any holder
or holders of Senior Debt or their representative or representatives shall have
the right to demand, sue for, collect, receive and receipt for the payments and
distributions in respect of the Notes which are required to be paid or delivered
to the holders of Senior Debt as provided in this Article 6 and to file and
prove all claims therefor and to take all such other action in the name of the
holders or otherwise, as such holders of Senior Debt or representative thereof
may determine to be necessary or appropriate for the enforcement of the
provisions of this Article 6.

     SECTION 6.7  Other Provisions Subject Hereto.  Expect as expressly stated
                  -------------------------------                             
in this Article 6, notwithstanding anything contained in this Indenture to the
contrary, all the provisions of this Indenture and the Notes are subject to the
provisions of this Article 6.  However, nothing in this Article 6 shall apply to
or adversely affect the claims of, or payment to, the Trustee pursuant to
Section 9.7. Notwithstanding the foregoing, the failure to make a payment on
account of principal of or interest on the Notes by reason of any provision of
this Article 6 shall not be construed as preventing the occurrence of an Event
of Default under Section 8.1.

                                   ARTICLE 7

                                  Successors
                                  ----------

     SECTION 7.1  Merger, Consolidation or Sale of Assets.  The Company may not
                  ---------------------------------------                      
consolidate or merge with or into any person (whether or not the Company is the
surviving corporation), or sell, assign, transfer, lease, convey or otherwise
dispose of all or substantially all of its properties or assets unless:

          (a) the Company is the surviving corporation or the entity or the
     person formed by or surviving any such consolidation or merger (if other
     than the Company) or to which such sale, assignment, transfer, lease,
     conveyance or other disposition shall have been made is a corporation
     organized or existing under the laws of the United States, any state
     thereof or the District of Columbia;

          (b) the entity or person formed by or surviving any such consolidation
     or merger (if other than the Company) or the person to which such sale,
     assignment, transfer, lease conveyance or other disposition will have been
     made assumes all the Obligations of the Company, pursuant to a supplemental
     indenture in a form reasonably satisfactory to the Trustee, under the Notes
     and the Indenture;

                                       44

 
          (c) such sale, assignment, transfer, lease, conveyance or other
     disposition of all or substantially all of the Company's properties or
     assets shall be as an entirety or virtually as an entirety to one person
     and such person shall have assumed all the Obligations of the Company,
     pursuant to a supplemental indenture in a form reasonably satisfactory to
     the Trustee, under the Notes and the Indenture;

          (d) immediately after such transaction no Default or Event of Default
     exists; and

          (e) the Company or such person shall have delivered to the Trustee an
     Officers' Certificate and an Opinion of Counsel, each stating that such
     transaction and the supplemental indenture comply with the Indenture and
     that all conditions precedent in the Indenture relating to such transaction
     have been satisfied.

     SECTION 7.2  Successor Corporation Substituted.  Upon any consolidation or
                  ---------------------------------                            
merger, or any sale, assignment, transfer, lease, conveyance or other
disposition of all or substantially all of the assets of the Company in
accordance with Section 7.1 hereof, the successor corporation formed by such
consolidation or into or with which the Company is merged or to which such sale,
assignment, transfer, lease, conveyance or other disposition is made shall
succeed to, and be substituted for and may exercise every right and power of,
the Company under this Indenture with the same effect as if such successor
person has been named as the Company herein; provided, however, that the
                                             --------  -------          
predecessor Company in the case of a sale, assignment, transfer, lease,
conveyance or other disposition shall not be released from the obligation to pay
the principal of and interest on the Notes.

                                   ARTICLE 8

                             Defaults and Remedies
                             ---------------------

     SECTION 8.1  Events of Default.  An "Event of Default" occurs if:
                  -----------------                                   

          (a) the Company defaults in the payment of interest on any Note when
     the same becomes due and payable,whether or not such payments shall be
     prohibited by Article 6, and the Default continues for a period of 30 days
     after the date due and payable;

          (b) the Company defaults in the payment of the principal of any Note
     when the same becomes due and payable at maturity, upon redemption or
     otherwise, whether or not such payment shall be prohibited by Article 6;

          (c) the Company fails to observe or perform any covenant or agreement
     contained in Section 4.7 or 4.8 hereof, whether or not such purchase shall
     be prohibited by Article 6;

          (d) the Company fails to observe or perform any other covenant or
     agreement contained in this Indenture or the Notes, required by it to be
     performed and the Default continues for a period of 60 days after the
     receipt of written notice

                                       45

 
     from the Trustee to the Company or from the holders of 25% in aggregate
     principal amount of the then outstanding Notes to the Company and the
     Trustee stating that such notice is a "Notice of Default";

          (e) there is a default under any mortgage, indenture or instrument
     under which there may be issued or by which there may be secured or
     evidenced any Indebtedness for money borrowed by the Company or any
     Subsidiary of the Company (or the payment of which is guaranteed by the
     Company or any Subsidiary of the Company), whether such Indebtedness or
     guarantee now exists or is created after the Issuance Date, which default
     (i) is caused by a failure to pay when due principal of or interest on such
     Indebtedness within the grace period provided for in such Indebtedness
     (which failure continues beyond any applicable grace period) (a "Payment
     Default") or (ii) results in the acceleration of such Indebtedness prior to
     its express maturity without such acceleration being rescinded or annulled
     and, in each case, the principal amount of any such Indebtedness, together
     with the principal amount of any other such Indebtedness under which there
     is a Payment Default or the maturity of which has been so accelerated,
     aggregates $10 million or more;

          (f) a final, nonappealable judgment or final, nonappealable judgments
     (other than any judgment as to which a reputable insurance company has
     accepted full liability except for customary deductibles or co-insurance
     retentions) for the payment of money are entered by a court or courts of
     competent jurisdiction against the Company or any Subsidiary of the Company
     and remain undischarged, unstayed or unbonded for a period (during which
     execution shall not be effectively stayed) of 60 days, provided that the
     aggregate of all such judgments exceeds $10 million;

          (g) the Company or any Material Subsidiary pursuant to or within the
     meaning of any Bankruptcy Law:  (i) commences a voluntary case, (ii)
     consents to the entry of an order for relief against it in an involuntary
     case in which it is the debtor, (iii) consents to the appointment of a
     Custodian of it or for all or substantially all of its property, (iv) makes
     a general assignment for the benefit of its creditors, or (v) makes the
     admission in writing that it generally is unable to pay its debts as the
     same become due; or

          (h) a court of competent jurisdiction enters an order or decree under
     any Bankruptcy Law that: (i) is for relief against the Company or any
     Subsidiary of the Company in an involuntary case, (ii) appoints a Custodian
     of the Company or any Subsidiary of the Company or for all or substantially
     all of its property, and the order or decree remains unstayed and in effect
     for 60 days, or (iii) orders the liquidation of the Company or any
     Subsidiary of the Company, and the order or decree remains unstayed and in
     effect for 60 days.

     The term "Bankruptcy Law" means Title 11, U.S. Code or any similar Federal
or state law for the relief of debtors.  The term "Custodian" means any
receiver, trustee, assignee, liquidator or similar official under any Bankruptcy
Law.

                                       46

 
     SECTION 8.2  Acceleration.  If an Event of Default (other than an Event of
                  ------------                                                 
Default specified in clauses (g) and (h) of Section 8.1 hereof) occurs and is
continuing, the Trustee by notice to the Company, or the Noteholders of at least
25% in principal amount of the then outstanding Notes by notice to the Company
and the Trustee, may declare all the Notes to be due and payable.  Upon such
declaration, the principal of, premium, if any, and accrued and unpaid interest
on the Notes shall be due and payable immediately.  If an Event of Default
specified in clause (g) or (h) of Section 8.1 hereof occurs, such an amount
shall ipso facto become and be immediately due and payable without any
declaration or other act on the part of the Trustee or any Noteholder.  If there
has been a declaration of acceleration of the Notes because an Event of Default
under Section 8.1(e) has occurred, such declaration of acceleration shall be
automatically annulled if the holders of the Indebtedness described in Section
8.1(e) have rescinded the declaration of acceleration in respect of such
Indebtedness within 60 days of such declaration and if:  (1) the annulment of
the acceleration of the Notes would not conflict with any judgment or decree of
a court of competent jurisdiction, (2) all existing Events of Default, except
non-payment of principal of, or premium, if any, or interest on the Notes that
became due solely because of the acceleration of the Notes, have been cured or
waived, and (3) the Company has delivered an Officers' Certificate to the
Trustee to the effect of clauses (1) and (2) above.  The Noteholders of a
majority in aggregate principal amount of the then outstanding Notes by notice
to the Trustee may rescind an acceleration and its consequences if the
rescission would not conflict with any judgment or decree and if all existing
Events of Default have been cured or waived except nonpayment of principal or
interest that has become due solely because of the acceleration.

     SECTION 8.3  Other Remedies.  If an Event of Default occurs and is
                  --------------                                       
continuing, the Trustee may pursue any available remedy to collect the payment
of principal of or interest on the Notes or to enforce the performance of any
provision of the Notes or this Indenture.

     The Trustee may maintain a proceeding even if it does not possess any of
the Notes or does not produce any of them in the proceeding.  A delay or
omission by the Trustee or any Noteholder in exercising any right or remedy
accruing upon an Event of Default shall not impair the right or remedy or
constitute a waiver of or acquiescence in the Event of Default.  All remedies
are cumulative to the extent permitted by law.

     SECTION 8.4.  Waiver of Past Defaults.  The Noteholders of a majority in
                   -----------------------                                   
aggregate principal amount of the then outstanding Notes by notice to the
Trustee may waive an existing Default or Event of Default and its consequences
except a continuing Default or Event of Default in the payment of the Designated
Event Payment or the principal of, or interest on, any Note.  When a Default or
Event of Default is waived, it is cured and ceases; but no such waiver shall
extend to any subsequent or other Default or impair any right consequent
thereon.

     SECTION 8.5  Control by Majority.  The Noteholders of a majority in
                  -------------------                                   
principal amount of the then outstanding Notes may direct the time, method and
place of conducting any proceeding for any remedy available to the Trustee or
exercising any trust or power conferred on it.  However, the Trustee may refuse
to follow any direction that conflicts with law or this Indenture, is unduly
prejudicial to the rights of other Noteholders, or would involve the Trustee in
personal liability.

                                       47

 
     SECTION 8.6  Limitation on Suits.  A Noteholder may pursue a remedy with
                  -------------------                                        
respect to this Indenture or the Notes only if:

          (a) the Noteholder gives to the Trustee notice of a continuing Event
     of Default;

          (b) the Noteholders of at least 25% in principal amount of the then
     outstanding Notes make a request to the Trustee to pursue the remedy;

          (c) such Noteholder or Noteholders offer to the Trustee indemnity
     satisfactory to the Trustee against any loss, liability or expense;

          (d) the Trustee does not comply with the request within 60 days after
     receipt of the request and the offer of indemnity; and

          (e) during such 60-day period the Noteholders of a majority in
     principal amount of the then outstanding Notes do not give the Trustee a
     direction inconsistent with the request.

     A Noteholder may not use this Indenture to prejudice the rights of another
Noteholder or to obtain a preference or priority over another Noteholder.

     SECTION 8.7  Rights of Noteholders to Receive Payment.  Notwithstanding any
                  ----------------------------------------                      
other provision of this Indenture, the right of any Noteholder of a Note to
receive payment of principal of and interest on the Note, on or after the
respective due dates expressed in the Note, or to bring suit for the enforcement
of any such payment on or after such respective dates, shall not be impaired or
affected without the consent of the Noteholder made pursuant to this Section.

     SECTION 8.8  Collection Suit by Trustee.  If an Event of Default specified
                  --------------------------                                   
in Section 8.1(a) or (b) occurs and is continuing, the Trustee may recover
judgment in its own name and as trustee of an express trust against the Company
for the whole amount of principal and interest remaining unpaid on the Notes and
interest on overdue principal and interest and such further amount as shall be
sufficient to cover the costs and, to the extent lawful, expenses of collection,
including the reasonable compensation, expenses, disbursements and advances of
the Trustee, its agents and counsel.

     SECTION 8.9  Trustee May File Proofs of Claim.  The Trustee may file such
                  --------------------------------                            
proofs of claim and other papers or documents as may be necessary or advisable
in order to have the claims of the Trustee and the Noteholders allowed in any
judicial proceedings relative to the Company, its creditors or its property.
Nothing contained herein shall be deemed to authorize the Trustee to authorize
or consent to or accept or adopt on behalf of any Noteholder any plan of
reorganization, arrangement, adjustment or composition affecting the Notes or
the rights of any Noteholder thereof, or to authorize the Trustee to vote in
respect of the claim of any Noteholder in any such proceeding.

                                       48

 
     SECTION 8.10  Priorities.  If the Trustee collects any money pursuant to
                   ----------                                                
this Article 8, it shall pay out the money in the following order:

          First:  to the Trustee for amounts due under Section 9.7 hereof;
          ------                                                          

          Second:  to the holders of Senior Debt to the extent required by
          -------                                                         
     Article 6;

          Third:  to Noteholders for amounts due and unpaid on the Notes for
          ------                                                            
     principal and interest, ratably, without preference or priority of any
     kind, according to the amounts due and payable on the Notes for principal
     and interest, respectively; and

          Fourth:  to the Company.
          -------                 

     Except as otherwise provided in Section 2.12 hereof, the Trustee may fix a
record date and payment date for any payment to Noteholders made pursuant to
this Section.

     SECTION 8.11  Undertaking for Costs.  In any suit for the enforcement of
                   ---------------------                                     
any right or remedy under this Indenture or in any suit against the Trustee for
any action taken or omitted by it as a Trustee, a court in its discretion may
require the filing by any party litigant in the suit of an undertaking to pay
the costs of the suit, and the court in its discretion may assess reasonable
costs, including reasonable attorneys' fees, against any party litigant in the
suit, having due regard to the merits and good faith of the claims or defenses
made by the party litigant.  This Section does not apply to a suit by the
Trustee, a suit by a holder pursuant to Section 8.7 hereof, or a suit by
Noteholders of more than 10% in principal amount of the then outstanding Notes.

                                   ARTICLE 9

                                    Trustee
                                    -------

     SECTION 9.1 Duties of Trustee.
                 ----------------- 

          (a) If an Event of Default has occurred and is continuing, the Trustee
     shall exercise such of the rights and powers vested in it by this
     Indenture, and use the same degree of care and skill in their exercise, as
     a prudent man would exercise or use under the circumstances in the conduct
     of his own affairs.

          (b) Except during the continuance of an Event of Default: (i) the
     Trustee need perform only those duties that are specifically set forth in
     this Indenture and no others and (ii) in the absence of bad faith on its
     part, the Trustee may conclusively rely, as to the truth of the statements
     and the correctness of the opinions expressed therein, upon certificates or
     opinions furnished to the Trustee and conforming to the requirements of
     this Indenture.  However, the Trustee shall examine the certificates and
     opinions to determine whether or not they conform to the requirements of
     this Indenture.

                                       49

 
          (c) The Trustee may not be relieved from liability for its own
     negligent action, its own negligent failure to act, or its own wilful
     misconduct, except that:  (i) this paragraph does not limit the effect of
     paragraph (b) of this Section 9.1; (ii) the Trustee shall not be liable for
     any error of judgment made in good faith by a Trust Officer, unless it is
     proved that the Trustee was negligent in ascertaining the pertinent facts
     and (iii) the Trustee shall not be liable with respect to any action it
     takes or omits to take in good faith and without negligence in accordance
     with a direction received by it pursuant to Section 8.5 hereof.

          (d) Every provision of this Indenture that in any way relates to the
     Trustee is subject to paragraphs (a), (b) and (c) of this Section 9.1. No
     provision of this Indenture shall require the Trustee to expend or risk its
     own funds or otherwise incur any financial liability in the performance of
     any of its duties hereunder, or in the exercise of any of its rights or
     powers, if it shall have reasonable grounds for believing that repayment of
     such funds or adequate indemnity against such risk or liability is not
     reasonably assured to it.

          (e) The Trustee may refuse to perform any duty or exercise any right
     or power unless it receives indemnity satisfactory to it against any loss,
     liability or expense.

          (f) Except as provided in this Indenture, the Trustee shall not be
     liable for interest on any money received by it except as the Trustee may
     agree in writing with the Company.  Money held in trust by the Trustee need
     not be segregated from other funds except to the extent required by law.

     SECTION 9.2  Rights of Trustee.
                  ----------------- 

          (a) The Trustee may rely on any document reasonably believed by it to
     be genuine and to have been signed or presented by the proper person.  The
     Trustee need not investigate any fact or matter stated in the document.

          (b) Before the Trustee acts or refrains from acting, it (unless other
     evidence be herein specifically prescribed) may require an Officers'
     Certificate or an Opinion of Counsel, or both.  The Trustee shall not be
     liable for any action it takes or omits to take in good faith in reliance
     on such Officers' Certificate or Opinion of Counsel.

          (c) The Trustee may act through agents and nominees and shall not be
     responsible for the misconduct or negligence of any agent (other than an
     agent who is an employee of the Trustee) appointed with due care.

          (d) The Trustee shall not be liable for any action that it takes or
     omits to take in good faith, without negligence or wilful misconduct, and
     that it reasonably believes to be authorized or within its rights or
     powers.

                                       50

 
          (e) The Trustee shall not be charged with knowledge of any Event of
     Default under subsection (c), (d), (e) or (f) of Section 8.1 or of the
     identity of any Material Subsidiary unless either (1) a Trust Officer
     assigned to its Institutional Trust Administration shall have actual
     knowledge thereof, or (2) the Trustee shall have received notice thereof in
     accordance with Section 12.2 hereof from the Company or any holder.

     SECTION 9.3  Individual Rights of Trustee.  The Trustee in its individual
                  ----------------------------                                
or any other capacity may become the owner or pledgee of Notes and may otherwise
deal with the Company or an Affiliate with the same rights it would have if it
were not Trustee.  Any Agent may do the same with like rights.  However, the
Trustee is subject to Sections 9.10 and 9.11 hereof.

     SECTION 9.4  Trustee's Disclaimer.  The Trustee makes no representation as
                  --------------------                                         
to the validity or adequacy of this Indenture or the Notes, it shall not be
accountable for the Company's use of the proceeds from any Notes authenticated
and delivered by the Trustee in conformity with the provisions of this
Indenture, and it shall not be responsible for any statement of the Company in
the Indenture or any statement in the Notes other than the Trustee's
authentication thereof.

          The Trustee in its capacity as Registrar hereunder, shall not be
charged with knowledge of the Applicable Procedures and may conclusively rely
that instructions and certificates presented to it are in accordance with such
Applicable Procedures in effecting transfers pursuant to Section 2.6 hereof.

     SECTION 9.5  Notice of Defaults.  If a Default or Event of Default occurs
                  ------------------                                          
and is continuing and if it is actually known to the Trustee, the Trustee shall
mail to Noteholders a notice of the Default or Event of Default within 90 days
after it occurs.  Except in the case of a Default or Event of Default in payment
on any Note, the Trustee may withhold the notice if and so long as a committee
of its Trust Officers in good faith determines that withholding the notice is in
the interests of Noteholders.

     SECTION 9.6  Reports by Trustee to Noteholders.  Within 60 days after the
                  ---------------------------------                           
reporting date stated in Section 12.10, the Trustee shall mail to Noteholders a
brief report dated as of such reporting date that complies with TIA (S) 313(a)
if and to the extent required by such (S) 313(a).  The Trustee also shall comply
with TIA (S) 313(b)(2).  The Trustee shall also transmit by mail all reports as
required by TIA (S) 313(c).

     A copy of each report at the time of its mailing to Noteholders shall be
filed with the SEC and each stock exchange on which the Notes are listed.  The
Company shall notify the Trustee when the Notes are listed on any stock
exchange.

     SECTION 9.7  Compensation and Indemnity.  The Company shall pay to the
                  --------------------------                               
Trustee from time to time reasonable compensation for its services hereunder.
The Trustee's compensation shall not be limited by any law on compensation of a
trustee of an express trust.  The Company shall reimburse the Trustee upon
request for all reasonable and duly documented disbursements, expenses and
advances incurred or made by it.  Such

                                       51

 
disbursements and expenses may include the reasonable and duly documented
disbursements, compensation and expenses of the Trustee's agents and counsel
(subject to the limitations set forth in this Section 9.7).

     The Company shall indemnify the Trustee and its officers, directors,
employees and all other agents against any loss or liability incurred by it
except as set forth in the next paragraph.  The Trustee shall notify the Company
promptly of any claim for which it may seek indemnity.  The Company shall defend
the claim and the Trustee shall cooperate in the defense.  If the Trustee is
advised by counsel in writing that it may have available to it defenses that are
in conflict with those available to the Company, the Trustee may have separate
counsel and the Company shall pay the reasonable and duly documented fees,
disbursements and expenses of such counsel.  The Company need not pay for any
settlement made without its consent, which consent shall not be unreasonably
withheld.

     The Company need not reimburse any expense or indemnify against any loss or
liability incurred by the Trustee through its negligence, bad faith or wilful
misconduct.

     To secure the Company's payment obligations in this Section, the Trustee
shall have a lien prior to the Notes on all money or property held or collected
by the Trustee, except money or property held in trust to pay principal of and
interest on particular Notes.

     When the Trustee incurs expenses or renders services after an Event of
Default specified in Section 8.1(g) or (h) occurs, the expenses and the
compensation for the services are intended to constitute expenses of
administration under any Bankruptcy Law.

     The provisions of this Section 9.7 shall survive the termination of this
Indenture, as provided by Section 10.1 hereof.

     SECTION 9.8  Replacement of Trustee.  A resignation or removal of the
                  ----------------------                                  
Trustee and appointment of a successor Trustee shall become effective only upon
the successor Trustee's acceptance of appointment as provided in this Section.

     The Trustee may resign by so notifying the Company.  The Noteholders of a
majority in aggregate principal amount of the then outstanding Notes may remove
the Trustee by so notifying the Trustee and the Company.  The Company may remove
the Trustee if:

          (a) the Trustee fails to comply with Section 9.10 hereof, unless the
     Trustee's duty to resign is stayed as provided in TIA (S) 310(b);

          (b) the Trustee is adjudged a bankrupt or an insolvent or an order for
     relief is entered with respect to the Trustee under any Bankruptcy Law;

          (c) a Custodian or public officer takes charge of the Trustee or its
     property; or

          (d) the Trustee becomes incapable of acting.

                                       52

 
     If the Trustee resigns, is removed or becomes incapable of acting, or if a
vacancy exists in the office of Trustee for any reason, the Company shall
promptly appoint a successor Trustee.  Within one year after the successor
Trustee takes office, the Noteholders of a majority in principal amount of the
then outstanding Notes may appoint a successor Trustee to replace the successor
Trustee appointed by the Company.

     If a successor Trustee does not take office within 60 days after the
retiring Trustee resigns or is removed, the retiring Trustee, the Company or the
Noteholders of at least 10% in principal amount of the then outstanding Notes
may petition any court of competent jurisdiction for the appointment of a
successor Trustee.

     If the Trustee fails to comply with Section 9.10 hereof, unless the
Trustee's duty to resign is stayed as provided in TIA (S) 310(b), any Noteholder
who has been a bona fide holder of a Note for at least six months may petition
any court of competent jurisdiction for the removal of the Trustee and the
appointment of a successor Trustee.

     A successor Trustee shall deliver a written acceptance of its appointment
to the retiring Trustee and to the Company.  Thereupon the resignation or
removal of the retiring Trustee shall become effective, the Company shall
promptly pay all amounts due and payable to the retiring Trustee pursuant to
Section 9.7 hereof and the successor Trustee shall have all the rights, powers
and duties of the Trustee under this Indenture.  The successor Trustee shall
mail a notice of its succession to Noteholders.  The retiring Trustee shall
promptly transfer all property and money held by it as Trustee to the successor
Trustee, subject to the lien provided for in Section 9.7 hereof.
Notwithstanding replacement of the Trustee pursuant to this Section 9.8, the
Company's obligations under Section 9.7 hereof shall continue for the benefit of
the retiring trustee with respect to expenses and liabilities incurred by it
prior to such replacement.

     SECTION 9.9  Successor Trustee by Merger, Etc.  If the Trustee
                  ---------------------------------                
consolidates, merges or converts into, or transfers all or substantially all of
its corporate trust business to, another corporation, the successor corporation
without any further act shall be the successor Trustee; provided that such
                                                        --------          
successor shall otherwise be qualified and eligible to act as a Trustee pursuant
to the provisions of this Article.

     SECTION 9.10  Eligibility; Disqualification.  This Indenture shall always
                   -----------------------------                              
have a Trustee who satisfies the requirements of TIA (S) 310(a)(1) and (5).  The
Trustee shall always have a combined capital and surplus as stated in Section
12.10 hereof.  The Trustee is subject to TIA (S) 310(b).

     SECTION 9.11  Preferential Collection of Claims Against Company.  The
                   -------------------------------------------------      
Trustee is subject to TIA (S) 311(a), excluding any creditor relationship listed
in TIA (S) 311(b).  A Trustee who has resigned or been removed shall be subject
to TIA (S) 311(a) to the extent indicated therein.

     SECTION 9.12  Sections Applicable to Registrar, Paying Agent and Conversion
                   -------------------------------------------------------------
Agent.  The term "Trustee" as used in Sections 9.1, 9.2, 9.3, 9.4 and 9.7 hereof
- ------                                                                          
shall

                                       53

 
(unless the context requires otherwise) be construed as extending to and
including the Trustee acting in its capacity, if any, as Registrar, Paying Agent
and Conversion Agent.

                                  ARTICLE 10

                            Discharge of Indenture
                            ----------------------

     SECTION 10.1  Termination of Company's Obligations.  This Indenture shall
                   ------------------------------------                       
cease to be of further effect (except that the Company's obligations under
Sections 9.7 and 10.2 hereof shall survive) when all outstanding Notes
theretofore authenticated and issued have been delivered to the Trustee for
cancellation and the Company has paid all sums payable hereunder.

     Thereupon, the Trustee upon request of the Company, shall acknowledge in
writing the discharge of the Company's obligations under this Indenture, except
for those surviving obligations specified above.

     SECTION 10.2  Repayment to Company.  The Trustee and the Paying Agent shall
                   --------------------                                         
promptly pay to the Company upon request any excess money or securities held by
them at any time.

     The Trustee and the Paying Agent shall pay to the Company upon request any
money held by them for the payment of principal or interest that remains
unclaimed for two years after the date upon which such payment shall have become
due; provided, however, that the Company shall have first caused notice of such
     --------  -------                                                         
payment to the Company to be mailed to each Noteholder entitled thereto no less
than 30 days prior to such payment.  After payment to the Company, the Trustee
and the Paying Agent shall have no further liability with respect to such money
and Noteholders entitled to the money must look to the Company for payment as
general creditors unless any applicable abandoned property law designates
another person.

                                  ARTICLE 11

                      Amendments, Supplements and Waivers
                      -----------------------------------

     SECTION 11.1  Without Consent of Noteholders.  The Company and the Trustee
                   ------------------------------                              
may amend or supplement this Indenture or the Notes without the consent of any
Noteholder:

          (a)  to cure any ambiguity, defect or inconsistency;

          (b)  to comply with Sections 5.13 and 7.1 hereof;

          (c) to provide for uncertificated Notes in addition to certificated
     Notes;

          (d) to make any change that does not adversely affect in any material
     respect the legal rights hereunder of any Noteholder;

                                       54

 
          (e)  to qualify this Indenture under the TIA or to comply with the
     requirements of the SEC in order to maintain the qualification of the
     Indenture under the TIA; or

          (f) to make any change that provides any additional rights or benefits
     to the holders of Notes.

     An amendment under this Section may not make any change that adversely
affects the rights under Article 6 of any holder of Senior Debt then outstanding
unless the holders of such Senior Debt (or any group or representative thereof
authorized to give a consent) consent to such change by the requisite percent
approval applicable to such consent under the instrument governing such Senior
Debt.

     SECTION 11.2  With Consent of Noteholders.  Subject to Section 8.7 hereof,
                   ---------------------------                                 
the Company and the Trustee may amend or supplement this Indenture or the Notes
with the written consent (including consents obtained in connection with any
tender offer or exchange offer for Notes) of the Noteholders of at least a
majority in aggregate principal amount of the then outstanding Notes.  Subject
to Sections 8.4 and 8.7 hereof, the Noteholders of a majority in aggregate
principal amount of the Notes then outstanding may also by their written consent
(including consents obtained in connection with any tender offer or exchange
offer for Notes) waive any existing Default as provided in Section 8.4 or waive
compliance in a particular instance by the Company with any provision of this
Indenture or the Notes.  However, without the consent of each Noteholder
affected, an amendment, supplement or waiver under this Section may not (with
respect to any Notes held by a nonconsenting Noteholder):

          (a) reduce the amount of Notes whose Noteholders must consent to an
     amendment, supplement or waiver;

          (b) reduce the rate of or change the time for payment of interest on
     any Note;

          (c) reduce the principal of or change the fixed maturity of any Note
     or alter the redemption provisions with respect thereto;

          (d) make any Note payable in money other than that stated in the Note;

          (e) make any change in Section 8.4, 8.7 or 11.2 hereof (this
     sentence);

          (f) waive a default in the payment of the Designated Event Payment or
     the principal of, or interest on, any Note (other than as provided in
     Section 8.4);

          (g) waive a redemption payment payable on any Note;

          (h) make any change that adversely affects the right of Noteholders to
     convert Notes into Common Stock of the Company; or

                                       55

 
          (i) make any change in Articles 5 or 6 hereof that adversely affects
     in any material respect the interests of the Noteholders.

     To secure a consent of the Noteholders under this Section 11.2, it shall
not be necessary for the Noteholders to approve the particular form of any
proposed amendment, supplement or waiver, but it shall be sufficient if such
consent approves the substance thereof.

     An amendment under this Section may not make any change that adversely
affects the rights under Article 6 of any holder of Senior Debt then outstanding
unless the holders of such Senior Debt (or any group or representative thereof
authorized to give a consent) consent to such change by the requisite percent
approval applicable to such consent under the instrument governing such Senior
Debt.

     Neither the Company nor any of its Subsidiaries shall, directly or
indirectly, pay or cause to be paid any consideration, whether by way of
interest, fee or otherwise, to any holder of Notes for or as an inducement to
any consent, waiver or amendment of any of the terms or provisions of this
Indenture or the Notes unless such consideration is offered to be paid or agreed
to be paid to all holders of the Notes that consent, waive or agree to amend in
the time frame set forth in the solicitation documents relating to such consent,
waiver or agreement.

     After an amendment, supplement or waiver under this Section becomes
effective, the Company shall mail to Noteholders a notice briefly describing the
amendment or waiver.

     SECTION 11.3  Compliance with Trust Indenture Act.  After this Indenture
                   -----------------------------------                       
becomes subject to the TIA, every amendment to this Indenture or the Notes shall
be set forth in a supplemental indenture that complies with the TIA as then in
effect.

     SECTION 11.4  Revocation and Effect of Consents.  Until an amendment,
                   ---------------------------------                      
supplement or waiver becomes effective, a consent to it by a Noteholder of a
Note is a continuing consent by the Noteholder and every subsequent Noteholder
of a Note or portion of a Note that evidences the same debt as the consenting
Noteholder's Note, even if notation of the consent is not made on any Note.
However, any such Noteholder or subsequent Noteholder may revoke the consent as
to such Noteholder's Note or portion of a Note if the Trustee receives the
notice of revocation before the date on which the Trustee receives an Officers'
Certificate certifying that the Noteholders of the requisite principal amount of
Notes have consented to the amendment, supplement or waiver.

     The Company may, but shall not be obligated to, fix a record date for the
purpose of determining the Noteholders entitled to consent to any amendment,
supplement or waiver.  If a record date is fixed, then notwithstanding the
provisions of the immediately preceding paragraph, those persons who were
Noteholders at such record date (or their duly designated proxies), and only
those persons, shall be entitled to consent to such amendment, supplement or
waiver or to revoke any consent previously given, whether or not such persons
continue to be Noteholders after such record date.  No consent shall be valid or
effective for more than 90 days after such record date unless consents from
Noteholders of the principal amount of

                                       56

 
Notes required hereunder for such amendment or waiver to be effective shall have
also been given and not revoked within such 90-day period.

     After an amendment, supplement or waiver becomes effective it shall bind
every Noteholder, unless it is of the type described in any of clauses (a)
through (i) of Section 11.2 hereof.  In such case, the amendment or waiver shall
bind each Noteholder who has consented to it and every subsequent Noteholder
that evidences the same debt as the consenting Noteholder's Note.

     SECTION 11.5  Notation on or Exchange of Notes.  The Trustee may place an
                   --------------------------------                           
appropriate notation about an amendment or waiver on any Note thereafter
authenticated.  The Company in exchange for all Notes may issue and the Trustee
shall authenticate new Notes that reflect the amendment or waiver.  However,
failure to make such notation in any Note shall not affect the validity and
effect of such amendment or waiver.

     SECTION 11.6  Trustee Protected.  The Trustee shall sign all supplemental
                   -----------------                                          
indentures, except that the Trustee may, but need not, sign any supplemental
indenture that adversely affects its rights.

                                  ARTICLE 12

                                 Miscellaneous
                                 -------------

     SECTION 12.1  Trust Indenture Act Controls.  If, at any time that the TIA
                   ----------------------------                               
is applicable to this Indenture, any provision of this Indenture limits,
qualifies, or conflicts with another provision which is automatically deemed to
be incorporated in this Indenture by the TIA, the incorporated provision shall
control.

     SECTION 12.2  Notices.  Any notice or communication by the Company or the
                   -------                                                    
Trustee to the other is duly given if in writing and delivered in person or
mailed by first-class mail to the other's address stated in Section 12.10
hereof.  The Company or the Trustee by notice to the other may designate
additional or different addresses for subsequent notices or communications.

     Any notice or communication to a Noteholder shall be mailed by first-class
mail to such Note holder's address shown on the register kept by the Registrar.
Failure to mail a notice or communication to a Noteholder or any defect in it
shall not affect its sufficiency with respect to other Noteholders.

     If a notice or communication is mailed in the manner provided above within
the time prescribed, it is duly given, whether or not the addressee receives it.

     If the Company mails a notice or communication to Noteholders, it shall
mail a copy to the Trustee and each Agent at the same time.

     All other notices or communications shall be in writing.

                                       57

 
     In case by reason of the suspension of regular mail service, or by reason
of any other cause, it shall be impossible to mail any notice as required by the
Indenture, then such method of notification as shall be made with the approval
of the Trustee shall constitute a sufficient mailing of such notice.

     SECTION 12.3  Communication by Noteholders with Other Noteholders.
                   ---------------------------------------------------  
Noteholders may communicate pursuant to TIA (S) 312(b) with other Noteholders
with respect to their rights under this Indenture or the Notes.  The Company,
the Trustee, the Registrar and anyone else shall have the protection of TIA (S)
312(c).

     SECTION 12.4  Certificate and Opinion as to Conditions Precedent.  Upon any
                   --------------------------------------------------           
request or application by the Company to the Trustee to take any action under
this Indenture, the Company shall furnish to the Trustee:

          (a) an Officers' Certificate stating that, in the opinion of the
     signers, all conditions precedent, if any, provided for in this Indenture
     relating to the proposed action have been complied with; and

          (b) an Opinion of Counsel stating that, in the opinion of such
     counsel, all such conditions precedent have been complied with.

     SECTION 12.5   Statements Required in Certificate or Opinion.  Each
                    ---------------------------------------------       
certificate or opinion with respect to compliance with a condition or covenant
provided for in this Indenture (other than pursuant to Section 4.3) shall
include:

          (a) a statement that the person signing such certificate or rendering
     such opinion has read such covenant or condition;

          (b) a brief statement as to the nature and scope of the examination or
     investigation upon which the statements or opinions contained in such
     certificate or opinion are based;

          (c) a statement that, in the opinion of such person, such person has
     made such examination or investigation as is necessary to enable such
     person to express an informed opinion as to whether or not such covenant or
     condition has been complied with; and

          (d) a statement as to whether or not, in the opinion of such person,
     such condition or covenant has been complied with.

     SECTION 12.6  Rules by Trustee and Agents.  The Trustee may make reasonable
                   ---------------------------                                  
rules for action by, or a meeting of, Noteholders.  The Registrar or Paying
Agent may make reasonable rules and set reasonable requirements for its
functions.

     SECTION 12.7  Legal Holidays.  A "Legal Holiday" is a Saturday, a Sunday or
                   --------------                                               
a day on which banking institutions in the State of New York or California are
not required to be open.  If a payment date is a Legal Holiday at a place of
payment, payment may be made

                                       58

 
at that place on the next succeeding day that is not a Legal Holiday, and no
interest shall accrue for the intervening period.  If any other operative date
for purposes of this Indenture shall occur on a Legal Holiday then for all
purposes the next succeeding day that is not a Legal Holiday shall be such
operative date.

     SECTION 12.8  No Recourse Against Others.  A director, officer, employee or
                   --------------------------                                   
stockholder, as such, of the Company shall not have any liability for any
obligations of the Company under the Notes or the Indenture or for any claim
based on, in respect of or by reason of such obligations or their creation.
Each Noteholder by accepting a Note waives and releases all such liability.  The
waiver and release are part of the consideration for the issue of the Notes.

     SECTION 12.9  Counterparts.  This Indenture may be executed in any number
                   ------------                                               
of counterparts and by the parties hereto in separate counterparts, each of
which when so executed shall be deemed to be an original and all of which taken
together shall constitute one and the same agreement.

     SECTION 12.10  Variable Provisions.  "Officer" means the Chairman of the
                    -------------------                                      
Board, the President, any Vice-President, the Treasurer, the Secretary, any
Assistant Treasurer or any Assistant Secretary of the Company.

     The first certificate pursuant to Section 4.3 hereof shall be for the
fiscal year ending on December 31, 1996.

     The reporting date for Section 9.6 hereof is March 15 of each year.  The
first reporting date is March 15, 1997.

     The Trustee shall always have a combined capital and surplus of at least
$100,000,000 as set forth in its most recent published annual report of
condition.

     The Company's address is:  Plasma & Materials  Technologies, Inc.
                                9255 Deering Avenue 
                                Chatsworth, California 91311
                                Telephone Number: (818) 886-8000 
                                Telefax Number: (818) 886-8756 
                                Attn: Chief Financial Officer

     The Trustee's address is:  U.S. Trust Company of California, N.A.
                                c/o U.S. Trust Company of New York, N.A.
                                770 Broadway, 13th Floor                
                                New York, New York  10003               
                                Telephone Number:  (212)                
                                Telefax Number:  (212)                   

     SECTION 12.11  Governing Law.  THE INTERNAL LAWS OF THE STATE OF NEW YORK
                    -------------                                             
SHALL GOVERN THIS INDENTURE AND THE Notes, WITHOUT REGARD TO THE CONFLICT OF
LAWS PROVISIONS THEREOF.

                                       59

 
     SECTION 12.12  No Adverse Interpretation of Other Agreements.  This
                    ---------------------------------------------       
Indenture may not be used to interpret another indenture, loan or debt agreement
of the Company or an Affiliate.  Any such indenture, loan or debt agreement may
not be used to interpret this Indenture.

     SECTION 12.13  Successors.  All agreements of the Company in this Indenture
                    ----------                                                  
and the Notes shall bind its successor.  All agreements of the Trustee in this
Indenture shall bind its successor.

     SECTION 12.14  Severability.  In case any provision in this Indenture or in
                    ------------                                                
the Notes shall be invalid, illegal or unenforceable, the validity, legality and
enforceability of the remaining provisions shall not in any way be affected or
impaired thereby.

     SECTION 12.15  Table of Contents, Headings, Etc.  The Table of Contents,
                    ---------------------------------                        
Cross-Reference Table, and headings of the Articles and Sections of this
Indenture have been inserted for convenience of reference only, are not to be
considered a part hereof, and shall in no way modify or restrict any of the
terms or provisions hereof.

     SECTION 12.16  Persons Deemed Owners.  Prior to the presentment, in proper
                    ---------------------                                      
form, of a Note for registration of transfer, the Trustee and the Company and
any agent of either may treat the Person in whose name such Note is then
registered as the absolute owner thereof for all purposes, and shall not be
affected by any notice to the contrary.

     IN WITNESS WHEREOF, the parties hereto have caused this Indenture to be
duly executed, all as of the date first written above.

                              Plasma & Materials Technologies, Inc.,
                              as Company,

                              By /s/ John W. LaValle
                                -----------------------------------
                                    Name: John W. LaValle
                                    Title: Secretary

                              U.S. Trust Company of California, N.A.,
                              as Trustee

                              By /s/ Sandee Parks
                                -----------------------------------
                                    Name: Sandee Parks
                                    Title: Vice President

                                       60

 
STATE OF CALIFORNIA      )
                         ) ss:
COUNTY OF LOS ANGELES    )


On             October 4, 1996                 before me, Bunnie Dees, Notary
   -------------------------------------------                               
Public, personally appeared    John W. LaValle
                           --------------------------------------------------
personally known to me (or proved to me on the basis of satisfactory evidence)
to be the person whose name is subscribed to the within instrument and
acknowledged to me that he executed the same in his authorized capacity, and
that by his signature on the instrument the person, or the entity upon behalf of
which the person acted, executed the instrument.

WITNESS my hand and official seal.

/s/ Bunnie Dees
- -------------------------------------



STATE OF CALIFORNIA      )
                         ) ss:
COUNTY OF LOS ANGELES    )


On             October 4, 1996                 before me, Bunnie Dees, Notary
   -------------------------------------------                               
Public, personally appeared          Sandee Parks
                           -----------------------------------------------------
personally known to me (or proved to me on the basis of satisfactory evidence)
to be the person whose name is subscribed to the within instrument and
acknowledged to me that she executed the same in her authorized capacity, and
that by her signature on the instrument the person, or the entity upon behalf of
which the person acted, executed the instrument.

WITNESS my hand and official seal.

/s/ Bunnie Dees
- -------------------------------------

                                       61

 
                                                                     EXHIBIT A-1



                             [FORM OF FACE OF NOTE]

                             [Global Notes Legend]

          UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE
OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), NEW YORK, NEW
YORK, TO THE COMPANY OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR
PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR
SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY
PAYMENT IS MADE TO CEDE & CO., OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN
AUTHORIZED REPRESENTATIVE OF DTC) ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR
VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED
OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

          TRANSFERS OF THIS GLOBAL NOTE SHALL BE LIMITED TO TRANSFERS IN WHOLE,
BUT NOT IN PART, TO NOMINEES OF DTC OR TO A SUCCESSOR THEREOF OR SUCH
SUCCESSOR'S NOMINEE AND TRANSFERS OF PORTIONS OF THIS GLOBAL NOTE SHALL BE
LIMITED TO TRANSFERS MADE IN ACCORDANCE WITH THE RESTRICTIONS SET FORTH IN THE
INDENTURE REFERRED TO ON THE REVERSE HEREOF.

                           [Restricted Notes Legend)

          "THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF
1933, AS AMENDED (THE "SECURITIES ACT").  THE HOLDER HEREOF, BY PURCHASING THIS
SECURITY, AGREES FOR THE BENEFIT OF THE COMPANY THAT THIS SECURITY MAY NOT BE
RESOLD, PLEDGED OR OTHERWISE TRANSFERRED (X) PRIOR TO THE THIRD ANNIVERSARY (OR
SUCH SHORTER PERIOD AS MAY THEN BE APPLICABLE UNDER THE SECURITIES ACT REGARDING
THE HOLDING PERIOD FOR NOTES UNDER RULE 144(k) OF THE SECURITIES ACT OR ANY
SUCCESSOR RULE) OF THE ISSUANCE HEREOF (OR ANY PREDECESSOR SECURITY HERETO) OR
(Y) BY ANY HOLDER THAT WAS AN AFFILIATE OF THE COMPANY AT ANY TIME DURING THE
THREE MONTHS PRECEDING THE DATE OF SUCH TRANSFER, IN EITHER CASE OTHER THAN (1)
TO THE COMPANY, (2) SO LONG AS THIS SECURITY IS ELIGIBLE FOR RESALE PURSUANT TO
RULE 144A UNDER THE SECURITIES ACT ("RULE 144A") TO A PERSON WHOM THE SELLER
REASONABLY BELIEVES IS A QUALIFIED INSTITUTIONAL BUYER WITHIN THE MEANING OF
RULE 144A PURCHASING FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF A QUALIFIED

 
                                                                               2

INSTITUTIONAL BUYER TO WHOM NOTICE IS GIVEN THAT THE RESALE, PLEDGE OR OTHER
TRANSFER IS BEING MADE IN RELIANCE ON RULE 144A (AS INDICATED BY THE BOX CHECKED
BY THE TRANSFEROR ON THE CERTIFICATE OF TRANSFER ON THE REVERSE SIDE OF THIS
SECURITY) AND A CERTIFICATE WHICH MAY BE OBTAINED FROM THE COMPANY OR THE
TRUSTEE IS DELIVERED BY THE TRANSFEREE TO THE COMPANY AND THE TRUSTEE, (3) IN AN
OFFSHORE TRANSACTION IN ACCORDANCE WITH REGULATION S UNDER THE SECURITIES ACT
(AS INDICATED BY THE BOX CHECKED BY THE TRANSFEROR ON THE CERTIFICATE OF
TRANSFER ON THE REVERSE OF THIS SECURITY), AND, IF SUCH TRANSFER IS BEING
EFFECTED BY CERTAIN TRANSFERORS SPECIFIED IN THE INDENTURE (AS DEFINED BELOW)
PRIOR TO THE EXPIRATION OF THE "40 DAY RESTRICTED PERIOD" (WITHIN THE MEANING OF
RULE 903(c)(3) OF REGULATION S UNDER THE SECURITIES ACT), A CERTIFICATE WHICH
MAY BE OBTAINED FROM THE COMPANY OR THE TRUSTEE IS DELIVERED BY THE TRANSFEREE
TO THE COMPANY AND THE TRUSTEE, (4) TO AN INSTITUTION THAT IS AN "ACCREDITED
INVESTOR" AS DEFINED IN RULE 501(a)(1), (2), (3) OR (7) UNDER THE SECURITIES ACT
(AS INDICATED BY THE BOX CHECKED BY THE TRANSFEROR ON THE CERTIFICATE OF
TRANSFER ON THE REVERSE OF THIS SECURITY) THAT IS ACQUIRING THIS SECURITY FOR
INVESTMENT PURPOSES AND NOT FOR DISTRIBUTION, AND A CERTIFICATE IN THE FORM
ATTACHED TO THIS SECURITY IS DELIVERED BY THE TRANSFEREE TO THE COMPANY AND THE
TRUSTEE (PROVIDED THAT CERTAIN HOLDERS SPECIFIED IN THE INDENTURE MAY NOT
TRANSFER THIS SECURITY PURSUANT TO THIS CLAUSE (4) PRIOR TO THE EXPIRATION OF
THE "40 DAY RESTRICTED PERIOD" (WITHIN THE MEANING OF RULE 903(c)(3) OF
REGULATION S UNDER THE SECURITIES ACT), (5) PURSUANT TO AN EXEMPTION FROM
REGISTRATION UNDER THE SECURITIES ACT PROVIDED BY RULE 144 (IF APPLICABLE) UNDER
THE SECURITIES ACT, AND A CERTIFICATE WHICH MAY BE OBTAINED FROM THE COMPANY OR
THE TRUSTEE IS DELIVERED BY THE TRANSFEREE TO THE COMPANY AND THE TRUSTEE, OR
(6) PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT,
AND A CERTIFICATE WHICH MAY BE OBTAINED FROM THE COMPANY OR THE TRUSTEE IS
DELIVERED BY THE TRANSFEREE TO THE COMPANY AND THE TRUSTEE IN EACH CASE IN
ACCORDANCE WITH ANY APPLICABLE SECURITIES LAWS OF ANY STATE OF THE UNITED STATES
OR OTHER JURISDICTION.  AN INSTITUTIONAL ACCREDITED INVESTOR HOLDING THIS
SECURITY AGREES THAT IT WILL FURNISH TO THE COMPANY AND THE TRUSTEE SUCH
CERTIFICATES AND OTHER INFORMATION AS THEY MAY REASONABLY REQUIRE TO CONFIRM
THAT ANY TRANSFER BY IT OF THIS SECURITY COMPLIES WITH THE FOREGOING
RESTRICTIONS.  THE HOLDER HEREOF, BY PURCHASING THIS SECURITY, REPRESENTS AND
AGREES FOR THE BENEFIT OF THE COMPANY THAT IT IS (1) A QUALIFIED INSTITUTIONAL
BUYER WITHIN THE MEANING OF RULE 144A OR (2) AN INSTITUTION THAT IS AN
"ACCREDITED INVESTOR" AS DEFINED IN RULE 501(a)(1), (2), (3) OR (7) UNDER

 
                                                                               3

THE SECURITIES ACT AND THAT IT IS HOLDING THIS SECURITY FOR INVESTMENT PURPOSES
AND NOT FOR DISTRIBUTION OR (3) A NON-U.S. PERSON OUTSIDE THE UNITED STATES
WITHIN THE MEANING OF (OR AN ACCOUNT SATISFYING THE REQUIREMENTS OF PARAGRAPH
(o)(2) OF RULE 902 UNDER) REGULATION S UNDER THE SECURITIES ACT."

 
                                                                               4

No. __________

                                                                       Cusip No.
                                                                  144A-72753MAA7
                                                                 Reg S-U72608AA7


                     PLASMA & MATERIALS TECHNOLOGIES, INC.
                       7 1/8% CONVERTIBLE SUBORDINATED NOTE
                                    DUE 2001



          Plasma & Materials Technologies, Inc., a California corporation (the
"Company") promises to pay to                               or registered
                              ------------------------------
assigns, the principal sum [indicated on Schedule A hereof] /1/ [of
              Dollars] /2/ on October 15, 2001, and to pay interest thereon
- ---------------------
beginning October 7, 1996 at the rate of 7 1/8% per annum.


Interest Payment Dates:    April 15 and October 15, commencing
                           April 15, 1997

Record Dates:              April 1 and October 1

          Reference is hereby made to the further provisions of this Convertible
Note set forth on the reverse hereof,

- ------------------

/1/  Applicable to Global Securities only.
/2/  Applicable to certificated Securities only.

 
                                                                               5

which further provisions shall for all purposes have the same effect as if set
forth at this place.


     IN WITNESS WHEREOF, Plasma & Materials Technologies, Inc. has caused this
Convertible Note to be signed manually or by facsimile by its duly authorized
officers and a facsimile of its corporate seal to be affixed hereto or imprinted
hereon.

Dated: October 7, 1996

                              PLASMA & MATERIALS TECHNOLOGIES, INC.


                                  By ______________________________


                                  By ______________________________


[Seal]

TRUSTEE'S CERTIFICATE OF
AUTHENTICATION


This is one of the 7 1/8%
Convertible Subordinated Notes
due 2001 described in the
within-mentioned Indenture.

U.S. Trust Company of California, N.A.,
as Trustee,


By ________________________________
          Authorized Officer

 
                                                                               6

                     PLASMA & MATERIALS TECHNOLOGIES, INC.


                   7 1/8% Convertible Subordinated Note Due 2001



          1.   Interest.  PLASMA & MATERIALS TECHNOLOGIES, INC., a California
               --------                                                      
corporation (the "Company"), is the issuer of this 7 1/8% Convertible
Subordinated Note due 2001 (the "Convertible Note"). The Company promises to pay
interest on the Convertible Notes in cash semiannually on each April 15 and
October 15, commencing on April 15, 1997, to holders of record on the
immediately preceding April 1 and October 1, respectively.

          Interest on the Convertible Notes will accrue from the most recent
date to which interest has been paid, or if no interest has been paid from
October 7, 1996.  Interest will be computed on the basis of a 360-day year
comprised of twelve 30-day months.  To the extent lawful, the Company shall pay
interest (including post-petition interest in any proceeding under any
Bankruptcy Law) on overdue installments of interest or Liquidated Damages, if
any (without regard to any applicable grace period) at the rate borne by the
Convertible Notes, compounded annually.

          2.   Method of Payment.  The Company will pay interest and Liquidated
               -----------------                                               
Damages, if any, on the Convertible Notes (except defaulted interest) to the
persons who are registered holders of the Convertible Notes at the close of
business on the Record Date for the next Interest Payment Date even though
Convertible Notes are cancelled after the Record Date and on or before the
Interest Payment Date.  The Noteholder hereof must surrender Convertible Notes
to a Paying Agent to collect principal payments.  The Company will pay principal
and interest and Liquidated Damages, if any, in money of the United States that
at the time of payment is legal tender for payment of public and private debts.
However, the Company may pay principal and interest and Liquidated Damages, if
any, by check payable in such money.  It may mail an interest check to a
holder's registered address.

          3.   Paying Agent and Registrar.  The Trustee will act as Paying
               --------------------------                                 
Agent, Registrar and Conversion Agent.  The Company may change any Paying Agent,
Registrar, co-registrar or Conversion Agent without prior notice.  The Company
or any of its Affiliates may act in any such capacity.

          4.   Indenture.  The Company issued the Convertible Notes under an
               ---------                                                    
indenture, dated as of October 7, 1996 (the "Indenture"), between the Company
and U.S. Trust Company of California, N.A., as Trustee.  The terms of the
Convertible Notes include those stated in the Indenture and those made part of
the Indenture by the Trust Indenture Act of 1939 (15 U.S. Code (S)(S) 77aaa-
77bbbb) as in effect on the date of the Indenture.  The Convertible Notes are
subject to, and qualified by, all such terms, certain of which are summarized
hereon, and Noteholders are referred to the Indenture and such Act for a

 
                                                                               7

statement of such terms. The Convertible Notes are general unsecured obligations
of the Company limited to (except as otherwise provided in the Indenture) an
aggregate principal amount of $75,000,000 (plus up to $11,250,000 aggregate
principal amount of Convertible Notes that may be sold by the Company pursuant
to the overallotment option granted pursuant to the Purchase Agreement), and are
subordinated in right of payment to all existing and future Senior Debt of the
Company as provided in the Indenture. The Indenture does not limit the ability
of the Company or any of its Subsidiaries to incur indebtedness or to grant
security interests or liens in respect of their assets. Any holder of this
Convertible Note shall be deemed to have agreed to and be bound by all the terms
and conditions contained in the Indenture applicable to a holder of a
Convertible Note.

          5.   Redemption.
               ---------- 

               (a)  Optional Redemption.
                    ------------------- 

          The Convertible Notes are not subject to redemption at the Company's
option prior to October 15, 1999.  On such date and thereafter, the Convertible
Notes will be subject to redemption at the option of the Company, in whole or in
part (in any integral multiple of $1,000), upon not less than 15 nor more than
60 days' prior notice by mail at the following redemption prices (expressed as
percentages of the principal amount set forth below), in each case together with
accrued and unpaid interest and Liquidated Damages, if any, up to but not
including the redemption date (subject to the right of holders of record on the
relevant Record Date to receive interest due on an Interest Payment Date).  If
redeemed during the 12-month period beginning October 15 of the years indicated
below, such redemption price shall be as indicated:
 
 
                                            Redemption
               Year                            Price
               ----                         -----------
                                           
               1999........................   102.85%
               2000........................   101.425%
 

On or after the redemption date, interest will cease to accrue on the
Convertible Notes, or portion thereof, called for redemption.

               (b)    Special Mandatory Redemption.
                      ----------------------------
 
          If the Acquisition is not consummated in all material respects on or
before the Special Redemption Notice Date, the Company will be required to
redeem the Convertible Notes, in whole and not in part, on January 16, 1997 at a
redemption price equal to 102% of the principal amount of the Convertible Notes,
plus accrued and unpaid interest up to but not including the redemption date.
On and after the Special Redemption Date, interest will cease to accrue on the
Convertible Notes, if the Acquisition is not consummated on or prior to the
Special Redemption Notice Date.  The Convertible Notes are also subject to
special mandatory redemption, in whole and not in part, at any time prior to the
Special

 
                                                                               8

Redemption Date, if it appears, in the sole judgment of the Company, that the
Acquisition cannot be consummated in all material respects on or prior to the
Special Redemption Notice Date, at a redemption price equal to 101% of the
principal amount thereof if notice is given prior to November 15, 1996 and at a
redemption price equal to 102% of the principal amount thereof if notice is
given on or after November 15, 1996, in each instance plus accrued and unpaid
interest to the date of redemption.

          6.  Notice of Redemption.  Notice of redemption will be mailed at
              --------------------                                         
least 15 days but not more than 60 days before the redemption date (other than a
Special Redemption Date) to each holder of the Convertible Notes to be redeemed
at his address of record.  The Convertible Notes in denominations larger than
$1,000 may be redeemed in part but only in integral multiples of $1,000.  In the
event of a redemption of less than all of the Convertible Notes, the Convertible
Notes will be chosen for redemption by the Trustee in accordance with the
Indenture.  In the event of a Special Redemption, the Company shall mail a
notice of redemption to each holder of the Convertible Notes at such holder's
address of record at least ten Business Days before a redemption date.  Unless
the Company defaults in making such redemption payment, or the Paying Agent is
prohibited from making such payment pursuant to the Indenture, interest and
Liquidated Damages cease to accrue on the Convertible Notes or portions of them
called for redemption on and after the redemption date.

          If this Convertible Note is redeemed subsequent to a Record Date with
respect to any Interest Payment Date specified above and on or prior to such
Interest Payment Date, then any accrued interest or Liquidated Damages, if any,
will be paid to the person in whose name this Convertible Note is registered at
the, close of business on such Record Date.

          7.  Mandatory Redemption.  Other than the Special Redemption, the
              --------------------                                         
Company will not be required to make mandatory redemption payments with respect
to the Convertible Notes.  There are no sinking fund payments with respect to
the Convertible Notes.

          8.  Repurchase at Option of Holder.  If there is a Designated Event,
              ------------------------------                                  
the Company shall be required to offer to purchase on the Designated Event
Payment Date all outstanding Convertible Notes at a purchase price equal to 101%
of the principal amount thereof on the date of purchase, plus accrued and unpaid
interest and Liquidated Damages, if any, to the Designated Event Payment Date.
Holders of Convertible Notes that are subject to an offer to purchase will
receive a Designated Event Offer from the Company prior to any related
Designated Event Payment Date and may elect to have such Convertible Notes or
portions thereof in authorized denominations purchased by completing the form
entitled "Option of Noteholder To Elect Purchase" appearing below.  Noteholders
have the right to withdraw their election by delivering a written notice of
withdrawal or the Paying Agent in accordance with the terms of the Indenture.

          9.  Subordination.  The payment of the principal of, premium, if any,
              -------------                                                    
and Liquidated Damages, if any, and interest on or any other amounts due on the
Convertible

 
                                                                               9

Notes is subordinated in right of payment to all existing and future Senior Debt
of the Company, as described in the Indenture.  Each Noteholder, by accepting a
Convertible Note, agrees to such subordination and authorizes and directs the
Trustee on its behalf to take such action as may be necessary or appropriate to
effectuate the subordination so provided and appoints the Trustee as its
attorney-in-fact for such purpose.

          10.  Conversion.  The holder of any Convertible Note has the right,
               ----------                                                    
exercisable at any time after the later to occur of (i) 90 days following the
Issuance Date or (ii) the consummation of the Acquisition, and prior to the
close of business (New York time)  on the Business Day immediately preceding the
maturity date of the Convertible Notes, to convert the principal amount thereof
(or any portion thereof that is an integral multiple of $1,000) into shares of
Common Stock at the initial Conversion Price of $15.635 per share, subject to
adjustment under certain circumstances, except that if a Convertible Note is
called for redemption, the conversion right will terminate at the close of
business on the Business Day immediately preceding the date fixed for
redemption.

          To convert a Convertible Note, a holder must (1) complete and sign a
notice of election to convert substantially in the form set forth below, (2)
surrender the Convertible Note to a Conversion Agent, (3) furnish appropriate
endorsements or transfer documents if required by the Registrar or Conversion
Agent and (4) pay any transfer or similar tax, if required.  Upon conversion, no
adjustment or payment will be made for accrued and unpaid interest on a
converted Convertible Note or for dividends or distributions on shares of Common
Stock issuable upon conversion of a Convertible Note, but if any Noteholder
surrenders a Convertible Note for conversion after the close of business on the
Record Date for the payment of an installment of interest and Liquidated
Damages, if any, prior to the opening of business on the next succeeding
Interest Payment Date, then, notwithstanding such conversion, the interest and
Liquidated Damages, if any, payable on such Interest Payment Date will be paid
to the registered holder of such Convertible Note on such Record Date.  In such
event, such Convertible Note, when surrendered for conversion after October 15,
1999, must be accompanied by payment in funds acceptable to the Company of an
amount equal to the interest payable and Liquidated Damages, if any, on such
Interest Payment Date on the portion so converted and, when surrendered for
conversion on or prior to October 15, 1999, need not be accompanied by such
payment.  The number of shares of Common Stock issuable upon conversion of a
Convertible Note is determined by dividing the principal amount of the
Convertible Note converted by the Conversion Price in effect on the Conversion
Date.  No fractional shares will be issued upon conversion but a cash adjustment
will be made for any fractional interest.

          A Convertible Note in respect of which a holder has delivered an
"Option of Noteholder to Elect Purchase" form appearing below exercising the
option of such holder to require the Company to purchase such Convertible Note
may be converted only if the notice of exercise is withdrawn as provided above
and in accordance with the terms of the Indenture.  The above description of
conversion of the Convertible Notes is qualified by reference to, and is subject
in its entirety by, the more complete description thereof contained in the
Indenture.

 
                                                                              10

          11.  Registration Rights.  The holder of this Convertible Note is
               -------------------                                         
entitled to the benefits of a Registration Agreement, dated October 7, 1996,
among the Company and the Initial Purchasers (the "Registration Agreement")
which agreement is attached to the Indenture as an Exhibit thereto.  Such
benefits include the right of the holder to receive Liquidated Damages in the
event of the failure on the part of the Company to comply with certain covenants
pertaining to registration and availability of a prospectus for resale, as
provided in the Registration Agreement.

          12.  Denominations, Transfer, Exchange.  The Convertible Notes are in
               ---------------------------------                               
registered form, without coupons, in denominations of $1,000 and integral
multiples of $1,000.  The transfer of Convertible Notes may be registered, and
Convertible Notes may be exchanged, as provided in the Indenture.  The Registrar
may require a Noteholder, among other things, to furnish appropriate
endorsements and transfer documents and to pay any taxes and fees required by
law or permitted by the Indenture.  The Registrar need not exchange or register
the transfer of any Convertible Note or portion of a Convertible Note selected
for redemption (except the unredeemed portion of any Convertible Note being
redeemed in part).  Also, it need not exchange or, register the transfer of any
Convertible Note for a period of 30 days before a selection of Convertible Notes
to be redeemed.

          13.  Persons Deemed Owners.  Except as provided in paragraph 2 of this
               ---------------------                                            
Convertible Note, the registered Noteholder of a Convertible Note shall be
treated as its owner for all purposes.

          14.  Unclaimed Money.  If money for the payment of principal,
               ---------------                                         
Liquidated Damages, if any, or interest remains unclaimed for two years, the
Trustee and the Paying Agent shall pay the money back to the Company at its
request.  After that, Noteholders of Convertible Notes entitled to the money
must look to the Company for payment unless an abandoned property law designates
another person and all liability of the Trustee and such Paying Agent with
respect to such money shall cease.

          15.  Defaults and Remedies.  The Convertible Notes shall have the
               ---------------------                                       
Events of Default so set forth in Section 8.1 of the Indenture.  Subject to
certain limitations in the Indenture, if an Event of Default occurs and is
continuing, the Trustee by notice to the Company or the Noteholders of at least
25% in aggregate principal amount of the then outstanding Convertible Notes by
notice to the Company and the Trustee may declare all the Convertible Notes to
be due and payable immediately, except that in the case of an Event of Default
arising from, certain events of bankruptcy or insolvency, all unpaid principal,
Liquidated Damages, if any, and interest accrued on the Convertible Notes shall
become due and payable immediately without further action or notice.  Upon
acceleration as described in either of the preceding sentences, the
subordination provisions of the Indenture preclude any payment being made to
Noteholders for at least 5 days except as otherwise provided in the Indenture.

          The Noteholders of a majority in principal amount of the Convertible
Notes then outstanding by written notice to the Trustee may rescind an
acceleration and its

 
                                                                              11

consequences if the rescission would not conflict with any judgment or decree
and if all existing Events of Default have been cured or waived except
nonpayment of principal or interest that has become due solely because of the
acceleration.  Noteholders may not enforce the Indenture or the Convertible
Notes except as provided in the Indenture.  Subject to certain limitations,
Noteholders of a majority in principal amount of the then outstanding
Convertible Notes issued under the Indenture may direct the Trustee in its
exercise of any trust or power.  The Company must furnish compliance
certificates to the Trustee annually.  The above description of Events of
Default and remedies is qualified by reference to, and subject in its entirety
by, the more complete description thereof contained in the Indenture.

          16.  Amendments, Supplements and Waivers.  Subject to certain
               -----------------------------------                     
exceptions, the Indenture or the Convertible Notes may be amended or
supplemented with the consent of the Noteholders of at least a majority in
principal amount of the then outstanding Convertible Notes (including consents
obtained in connection with a tender offer or exchange offer for Convertible
Notes), and any existing default may be waived with the consent of the
Noteholders of a majority in principal amount of the then outstanding
Convertible Notes including consents obtained in connection with a tender offer
or exchange offer for Convertible Notes.  Without the consent of any Noteholder,
the Indenture or the Convertible Notes may be amended, among other things, to
cure any ambiguity, defect or inconsistency, to provide for assumption of the
Company's obligations to Noteholders, to make any change that does not adversely
affect in any material respect the rights of any Noteholder, to qualify the
Indenture under the TIA, and to comply with the requirements of the SEC in order
to maintain the qualification of the Indenture under the TIA.

          17.  Trustee Dealings with the Company.  The Trustee, in its
               ---------------------------------                      
individual or any other capacity, may become the owner or pledgee of Convertible
Notes and may otherwise deal with the Company or an Affiliate with the same
rights it would have if it were not Trustee, subject to certain limitations
provided for in the Indenture and in the TIA.  Any Agent may do the same with
like rights.

          18.  No Recourse Against Others.  A director, officer, employee or
               --------------------------                                   
stockholder, as such, of the Company shall not have any liability for any
obligations of the Company under the Convertible Notes or the Indenture or for
any claim based on, in respect of or by reason of such obligations or their
creation.  Each Noteholder, by accepting a Convertible Note, waives and releases
all such liability.  The waiver and release are part of the consideration for
the issue of the Convertible Notes.

          19.  Governing Law.  THE INTERNAL LAWS OF THE STATE OF NEW YORK SHALL
               -------------                                                   
GOVERN THE INDENTURE AND THE CONVERTIBLE NOTES WITHOUT REGARD TO CONFLICT OF LAW
PROVISIONS THEREOF.

          20.  Authentication.  The Convertible Notes shall not be valid until
               --------------                                                 
authenticated by the manual signature of an authorized officer of the Trustee or
an authenticating agent.

 
                                                                              12

          21.  Abbreviations.  Customary abbreviations may be used in the name
               -------------                                                  
of a Noteholder or an assignee, such as:  TEN COM (for tenants in common, TENENT
(for tenants by the entireties), JT TEN (for joint tenants with right of
survivorship and not as tenants in common), CUST (for Custodian), and U/G/M/A
(for Uniform Gifts to Minors Act).

          22.  Definitions.  Capitalized terms not defined in this Convertible
               -----------                                                    
Note have the meaning given to them in the Indenture.

          The Company will furnish to any Noteholder of the Convertible Notes
upon written request and without charge a copy of the Indenture and the
Registration Agreement.  Request may be made to:

          Plasma & Materials Technologies, Inc.
          9255 Deering Avenue
          Chatsworth, California 91311
          Attention of:  Investor Relations Department

 
                                                                              13

                                ASSIGNMENT FORM


          To assign this Convertible Note, fill in the form below:

          (I) or (we) assign and transfer this Convertible Note to

- -------------------------------------------------------------------------------
              (Insert assignee's social security or tax I.D. no.)
                                        
- -------------------------------------------------------------------------------

- -------------------------------------------------------------------------------

- -------------------------------------------------------------------------------
             (Print or type assignee's name, address and zip code)

and irrevocably appoint                                 agent to transfer this
                        -------------------------------
Convertible Note on the books of the Company.  The agent may substitute another
to act for him.


     Your Signature:
                    ------------------------------------------------------------
                         (Sign exactly as your name appears on the other side of
                         this Convertible Note)


     Date:
          ------------------

     Signature Guarantee: *
                           ----------------------------------------------------

In connection with any transfer of any of the Convertible Notes evidenced by
this certificate occurring prior to the date that is three years (or such
shorter period as may then be applicable under the Securities Act) after the
later of the date of original issuance of such Convertible Notes and the last
date, if any, on which such Convertible Notes were owned by the Company or any
Affiliate of the Company, the undersigned confirms that such Convertible Notes
are being transferred:



- ------------------- 
*Signature must be guaranteed by a commercial bank, trust company or member firm
of the New York Stock Exchange.

 
                                                                              14

CHECK ONE BOX BELOW

     (1) [_]  to the Company; or

     (2) [_]  pursuant to and in compliance with Rule 144A under the Securities
              Act of 1933; or

     (3) [_]  pursuant to and in compliance with Regulation S under the
              Securities Act of 1933; or

     (4) [_]  to an institutional "accredited investor" (as defined in Rule
              501(a)(1),(2),(3) or (7) under the Securities Act of 1933 that has
              furnished to the Trustee a signed letter containing certain
              representations and agreements (the form of which letter can be
              obtained from the Trustee); or

     (5) [_]  pursuant to another available exemption from the registration
              requirements of the Securities Act of 1933.

Unless one of the boxes is checked, the Trustee will refuse to register any of
the Convertible Notes evidenced by this certificate in the name of any person
other than the registered holder thereof; provided, however, that if box (3),
                                          --------  -------                  
(4) or (5) is checked, the Trustee may require, prior to registering any such
transfer of the Convertible Notes such legal opinions, certifications and other
information as the Company has reasonably requested to confirm that such
transfer is being made pursuant to an exemption from, or in a transaction not
subject to, the registration requirements of the Securities Act of 1933, such as
the exemption provided by Rule 144 under such Act.

                                       ----------------------------------------
                                             Signature

Signature Guarantee:*

- ----------------------------           ----------------------------------------
Signature must be guaranteed                 Signature


- -------------------------------------------------------------------------------
             TO BE COMPLETED BY PURCHASER IF (2) ABOVE IS CHECKED.

     The undersigned represents and warrants that it is purchasing this
Convertible Note for its own account with respect to which it exercises sole
investment discretion that it

- ------------------------

     *    Signature must be guaranteed by a commercial bank, trust company or
member firm of the New York Stock Exchange.

 
                                                                              15

and any such account is a "qualified institutional buyer" within the meaning of
Rule 144A under the Securities Act of 1933, and is aware that the sale to it is
being made in reliance on Rule 144A and acknowledges that it has received such
information regarding the Company as the undersigned has requested pursuant to
Rule 144A or has determined not to request such information and that it is aware
that the transferor is relying upon the undersigned's foregoing representations
in order to claim the exemption from registration provided by Rule 144A.

Dated:  ________________      _______________________________________________
                              NOTICE:  To be executed by an executive officer

 
                                                                              16


                        [TO BE ATTACHED TO GLOBAL NOTES]

                                   SCHEDULE A

     The initial principal amount at maturity of this Global Note shall be
$_______.  The following increases or decreases in the principal amount of this
Global Note have been made:


====================================================================================================================== 
                Amount of increase
                in Principal Amount
                of this Global Note      Amount of decrease        Principal Amount of         Signature of
                including upon           in Principal Amount       this Global Note            authorized officer of
                exercise of the over-    of this Global Note       following such              Trustee or Notes
Date Made       allotment option                                   decrease or increase        Custodian
- ---------------------------------------------------------------------------------------------------------------------- 
                                                                                  
- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

- ---------------------------------------------------------------------------------------------------------------------- 

====================================================================================================================== 


 
                                                                              17

                     OPTION OF NOTEHOLDER TO ELECT PURCHASE
                     --------------------------------------

          If you want to elect to have this Convertible Note or a portion
thereof repurchased by the Company pursuant to Section 3.8 or 4.7 of the
Indenture, check the box: [ ]

          If the purchase is in part, indicate the portion (in denominations of
$1,000 or any integral multiple thereof) to be purchased:


     Your Signature:
                    -----------------------------------------------------------
                   (Sign exactly as your name appears on the other side of this
                   Convertible Note)

     Date:
          --------------------


     Signature Guarantee: *
                           -----------------------


- ------------------------- 
*Signature must be guaranteed by a commercial bank, trust company or member firm
of the New York Stock Exchange.

 
                                                                              18

                              ELECTION TO CONVERT

To Plasma & Materials Technologies, Inc.:

          The undersigned owner of this Convertible Note hereby irrevocably
exercises the option to convert this Convertible Note, or the portion below
designated, into Common Stock of PLASMA & MATERIALS TECHNOLOGIES, INC. in
accordance with the terms of the Indenture referred to in this Convertible Note,
and directs that the shares issuable and deliverable upon conversion, together
with any check in payment for fractional shares, be issued in the name of and
delivered to the undersigned, unless a different name has been indicated in the
assignment below.  If shares are to be issued in the name of a person other than
the undersigned, the undersigned will pay all transfer taxes payable with
respect thereto.

          Any Noteholder, upon the exercise of its conversion rights in
accordance with the terms of the Indenture and the Convertible Note, agrees to
be bound by the terms of the Registration Agreement relating to the Common Stock
issuable upon conversion of the Convertible Note.

Date:
     in whole ___             Portions of Convertible Note to be converted
                              ($1,000 or integral multiples thereof):
                                    $
                                     ------------------------------------------

                              Signature (for conversion only)

 
                                     ------------------------------------------

                                     Please Print or Typewrite Name and
                                     Address, Including Zip Code, and Social
                                     Note or Other Identifying Number

                                     ------------------------------------------
                                     Name
 
                                     ------------------------------------------
                                     Address

                                     ------------------------------------------
                                     Social Security Number

          Signature Guarantee: *
                                ------------------------------------------------
__________________

*Signature must be guaranteed by a commercial bank, trust company or member firm
of the New York Stock Exchange.

 
                                                                              19

                                                                     EXHIBIT B-1



          FORM OF CERTIFICATE FOR EXCHANGE OR REGISTRATION OF TRANSFER
            FROM RESTRICTED GLOBAL NOTE TO UNRESTRICTED GLOBAL NOTE
                (Pursuant to Section 2.6(a)(i) of the Indenture)


U.S. Trust Company of California, N.A.
c/o U.S. Trust Company of New York, N.A.
770 Broadway, 13th Floor
New York, New York 10003
Attention:  Corporate Trust Division

     Re:  7 1/8% Convertible Subordinated Notes due 2001 of Plasma & Materials
          Technologies, Inc. (the "Notes")

     Reference is hereby made to the Indenture, dated as of October 7, 1996 (the
"Indenture"), between Plasma & Materials Technologies, Inc., as issuer (the
"Company") and U.S. Trust Company of California, N.A., as trustee.  Capitalized
terms used but not defined herein shall have the meanings given to them in the
Indenture.

     This letter relates to the Notes which are evidenced by one or more
Restricted Global Notes (CUSIP No. 72753M AA7) and held with the Depositary in
the name of Cede & Co. (the "Transferor").  The Transferor has requested a
transfer of such beneficial interest in the Notes to a Person who will take
delivery thereof in the form of an equal principal amount of Notes evidenced by
one or more Unrestricted Global Notes (SINS No. USU 72608 AA71), which amount,
immediately after such transfer, is to be held with the Depositary through
Euroclear or Cedel or both (Common Code ____________________).

     In connection with such request and in respect of such Notes, the
Transferor hereby certifies that such transfer has been effected in compliance
with the transfer restrictions applicable to the Global Notes and pursuant to
and in accordance with Rule 903 or Rule 904 under the United States Securities
Act of 1933, as amended (the "Securities Act"), and accordingly the Transferor
hereby further certifies that:

     (1) The offer of the Notes was not made to a person in the United States;

     (2)  either:

          (a)  at the time the buy order was originated, the transferee was
               outside the United States or the Transferor and any person acting
               on its behalf reasonably believed and believes that the
               transferee was outside the United States; or

 
                                                                              20

          (b) the transaction was executed in, on or through the facilities of a
designated offshore securities market and neither the Transferor nor any person
acting on its behalf knows that the transaction was prearranged with a buyer in
the United States;

     (3)  no directed selling efforts have been made in contravention of the
          requirements of Rule 904(b) of Regulation S;

     (4)  the transaction is not part of a plan or scheme to evade the
          registration requirements of the Securities Act; and

     (5)  upon completion of the transaction, the beneficial interest being
          transferred as described above is to be held with the Depositary
          through Euroclear or Cedel or both (Common Code _________).

     Upon giving effect to this request to exchange a beneficial interest in a
Restricted Global Note for a beneficial interest in an Unrestricted Global Note,
the resulting beneficial interest shall, be subject to the restrictions on
transfer applicable to Unrestricted Global Notes pursuant to the Indenture and
the Securities Act.

     This certificate and the statements contained herein are made for your
benefit and the benefit of the Company and Salomon Brothers Inc and Unterberg
Harris, c/o Salomon Brothers, Seven World Trade Center, New York, New York, the
initial purchasers of such Notes being transferred., Terms used in this
certificate and not otherwise defined in the Indenture have the meanings set
forth in Regulation S under the Securities Act.


                         _______________________________________________
                         [Insert Name of Transferor]


                         By:_____________________________________________
                              Name:
                              Title:

Dated: _______________, ______

cc:  Plasma & Materials Technologies, Inc.
     Salomon Brothers Inc
     Unterberg Harris

 
                                                                              21

                                                                     EXHIBIT B-2


          FORM OF CERTIFICATE FOR EXCHANGE OR REGISTRATION OF TRANSFER
            FROM UNRESTRICTED GLOBAL NOTE TO RESTRICTED GLOBAL NOTE
               (Pursuant to Section 2.6(a)(ii) of the Indenture)


U.S. Trust Company of California, N.A.
c/o U.S. Trust Company of New York, N.A.
770 Broadway, 13th Floor
New York, New York 10003
Attention:  Corporate Trust Division

     Re:  7 1/8% Convertible Subordinated Notes due 2001 of Plasma & Materials
          Technologies, Inc. (the "Notes")

     Reference is hereby made to the Indenture, dated as of October 7, 1996 (the
"Indenture"), between Plasma & Materials Technologies, Inc., as issuer (the
"Company") and U.S. Trust Company of California, N.A., as trustee.  Capitalized
terms used but not defined herein shall have the meanings given to them in the
Indenture.

     This letter relates to the Notes which are evidenced by one or more
Unrestricted Global Notes (SINS No. USU 72608AA71) and held with the Depositary
through [Euroclear] [Cedel] (Common Code ___________________________) in the
name of _____________________________ (the "Transferor").  The Transferor has
requested a transfer of such beneficial interest in the Notes to a Person who
will take delivery thereof in the form of an equal principal amount of Notes
evidenced by one or more Restricted Global Notes (CUSIP No. 72753M AA7), to be
held with the Depositary.

     In connection with such request and in respect of such Notes, the
Transferor hereby certifies that:

                                  [CHECK ONE]

     [_]  such transfer is being effected pursuant to and in accordance with
          Rule 144A under the United States Securities Act of 1933, as amended
          (the "Securities Act"), and, accordingly, the Transferor hereby
          further certifies that the Notes are being transferred to a Person
          that the Transferor reasonably believes is purchasing the Notes for
          its own account, or for one or more accounts with respect to which
          such Person exercises sole investment discretion, and such Person and
          each such account is a "qualified institutional buyer" within the
          meaning of Rule 144A in a transaction meeting the requirements of Rule
          144A;

 
                                                                              22
                                 or

     [_]  such transfer is being effected pursuant to and in accordance with
          Rule 144 under the Securities Act;

                                       or

     [_]  such transfer is being effected pursuant to an effective registration
          statement under the Securities Act;

                                       or

     [_]  such transfer is being effected pursuant to an exemption from the
          registration requirements of the Securities Act other than Rule 144A
          or Rule 144, and the Transferor hereby further certifies that the
          Notes are being transferred in compliance with the transfer
          restrictions applicable to the Global Notes and in accordance with the
          requirements of the exemption claimed, which certification is
          supported by an Opinion of Counsel, provided by the Transferor or the
          transferee (a copy of which the Transferor has attached to this
          certification) in form reasonably acceptable to the Company and to the
          Registrar, to the effect that such transfer is in compliance with the
          Securities Act;

and such Notes are being transferred in compliance with any applicable blue sky
securities laws of any state of the United States.

     Upon giving effect to this request to exchange a beneficial interest in
Unrestricted Global Notes for a beneficial interest in Restricted Global Notes,
the resulting beneficial interest shall be subject to the restrictions on
transfer applicable to Restricted Global Notes pursuant to the Indenture and the
Securities Act.

     This certificate and the statements contained herein are made for your
benefit and the benefit of the Company and Salomon Brothers Inc., c/o Salomon
Brothers, Seven World Trade Center, New York, New York, the initial purchasers
of such Notes being transferred.


                         _______________________________________________
                         [Insert Name of Transferor]


                         By:_____________________________________________
                              Name:
                              Title:

Dated: _______________, ______

 
                                                                              23

cc:  Plasma & Materials Technologies, Inc.
     Salomon Brothers Inc
     Unterberg Harris

 
                                                                              24

                                                                     EXHIBIT B-3


                FORM OF CERTIFICATE FOR EXCHANGE OR REGISTRATION
                       OF TRANSFER OF CERTIFICATED NOTES
                 (Pursuant to Section 2.6(b) of the Indenture)


U.S. Trust Company of California, N.A.
c/o U.S. Trust Company of New York, N.A.
770 Broadway, 13th Floor
New York, New York 10003
Attention:  Corporate Trust Division

     Re:  7 1/8% Convertible Subordinated Notes due 2001 of Plasma & Materials
          Technologies, Inc. (the "Notes")

     Reference is hereby made to the Indenture, dated as of October 7, 1996 (the
"Indenture"), between Plasma & Materials Technologies, Inc., as issuer (the
"Company") and U.S. Trust Company of California, N.A., as trustee.  Capitalized
terms used but not defined herein shall have the meanings given to them in the
Indenture.

     In connection with such request and in respect of the Notes surrendered to
the Trustee herewith for exchange (the "Surrendered Notes"), the holder of such
Surrendered Notes hereby certifies that:

                                  [CHECK ONE]

     [_]  the Surrendered Notes are being transferred pursuant to and in
          accordance with Rule 144A under the United States Securities Act of
          1933, as amended (the "Securities Act"), and, accordingly, the
          Transferor hereby further certifies that the Surrendered Notes are
          being transferred to a Person that the Transferor reasonably believes
          is purchasing the Surrendered Notes for its own account, or for one or
          more accounts with respect to which such Person exercises sole
          investment discretion, and such Person and each such account is a
          "qualified institutional buyer" within the meaning of Rule 144A, in
          each case in a transaction meeting the requirements of Rule 144A;

                                       or

     [_]  the Surrendered Notes are being transferred in a transaction permitted
          by Rule 144 under the Securities Act;

                                       or

 
                                                                              25

     [_]  the Surrendered Notes are being transferred pursuant to an effective
          registration statement under the Securities Act;

                                       or

     [_]  such transfer is being effected pursuant to an exemption from the
          registration requirements of the Securities Act other than Rule 144A
          or Rule 144, and the Transferor hereby further certifies that the
          Notes are being transferred in compliance with the transfer
          restrictions applicable to the Global Notes and in accordance with the
          requirements of the exemption claimed, which certification is
          supported by an Opinion of Counsel, provided by the transferor or the
          transferee (a copy of which the Transferor has attached to this
          certification) in form reasonably acceptable to the Company and to the
          Registrar, to the effect that such transfer is in compliance with the
          Securities Act;

and the Surrendered Notes are being transferred in compliance with any
applicable blue sky securities laws of any state of the United States.

     This certificate and the statements contained herein are made for your
benefit and the benefit of the Company and Salomon Brothers Inc and Unterberg
Harris, c/o Salomon Brothers, Seven World Trade Center, New York, New York, the
initial purchasers of such Notes being transferred.  Terms used in this
certificate and not otherwise defined in the Indenture have the meanings set
forth in Regulation S under the Securities Act.

                         _______________________________________________
                         [Insert Name of Transferor]


                         By:_____________________________________________
                              Name:
                              Title:

Dated: _______________, ______

cc:  Plasma & Materials Technologies, Inc.
     Salomon Brothers Inc
     Unterberg Harris

 
                                                                              26

                                                                     EXHIBIT B-4


          FORM OF CERTIFICATE FOR EXCHANGE OR REGISTRATION OF TRANSFER
          FROM RESTRICTED GLOBAL NOTE OR UNRESTRICTED PERMANENT GLOBAL
                     NOTE TO CERTIFICATED CONVERTIBLE NOTE
                 (Pursuant to Section 2.6(c) of the Indenture)


U.S. Trust Company of California, N.A.
c/o U.S. Trust Company of New York, N.A.
770 Broadway, 13th Floor
New York, New York 10003
Attention:  Corporate Trust Division

     Re:  7 1/8% Convertible Subordinated Notes due 2001 of Plasma & Materials
          Technologies, Inc. (the "Notes")

     Reference is hereby made to the Indenture, dated as of October 7, 1996 (the
"Indenture"), between Plasma & Materials Technologies, Inc., as issuer (the
"Company") and U.S. Trust Company of California, N.A., as trustee.  Capitalized
terms used but not defined herein shall have the meanings given to them in the
Indenture.

     In connection with such request and in respect of the Notes surrendered to
the Trustee herewith for exchange (the "Surrendered Notes"), the holder of such
Surrendered Notes hereby certifies that:

                                  [CHECK ONE]

     [_]  the Surrendered Notes are being transferred to the beneficial owner of
          such Notes;

                                       or

     [_]  the Surrendered Notes are being transferred pursuant to and in
          accordance with Rule 144A under the United States Securities Act of
          1933, as amended (the "Securities Act"), and, accordingly, the
          Transferor hereby further certifies that the Surrendered Notes are
          being transferred to a person that the Transferor reasonably believes
          is purchasing the Surrendered Notes for its own account, or for one or
          more accounts with respect to which such person exercises sole
          investment discretion, and such Person and each such account is a
          "qualified institutional buyer" within the meaning of Rule 144A, in
          each case in a transaction meeting the requirements of Rule 144A;

                                       or

 
                                                                              27

     [_]  the Surrendered Notes are being transferred in a transaction permitted
          by Rule 144 under the Securities Act;

                                       or

     [_]  the Surrendered Notes are being transferred pursuant to an effective
          registration statement under the Securities Act;

                                       or

     [_]  such transfer is being effected pursuant to an exemption from the
          registration requirements of the Securities Act other than Rule 144A
          or Rule 144, and the Transferor hereby further certifies that the
          Notes are being transferred in compliance with the transfer
          restrictions applicable to the Global Notes and in accordance with the
          requirements of the exemption claimed, which certification is
          supported by an Opinion of Counsel, provided by the transferor or the
          transferee (a copy of which the Transferor has attached to this
          certification) in form reasonably acceptable to the Company and to the
          Registrar, to the effect that such transfer is in compliance with the
          Securities Act;

and the Surrendered Notes are being transferred in compliance with any
applicable blue sky securities laws of any state of the United States.

     This certificate and the statements contained herein are made for your
benefit and the benefit of the Company and Salomon Brothers Inc and Unterberg
Harris, c/o Salomon Brothers, Seven World Trade Center, New York, New York, the
initial purchasers of such Notes being transferred.  Terms used in this
certificate and not otherwise defined in the Indenture have the meanings set
forth in Regulation S under the Securities Act.

                         _______________________________________________
                         [Insert Name of Transferor]


                         By:_____________________________________________
                              Name:
                              Title:

Dated: _______________, ______

cc:  Plasma & Materials Technologies, Inc.
     Salomon Brothers Inc
     Unterberg Harris

 

Exhibit C to this Exhibit 4.1 is filed concurrently herewith as Exhibit 10.20.