EXHIBIT 10.15
                                                                 PAGE 1 OF 5
                                 AMENDMENT NO. 1
                                       TO
                           THIRD AMENDED AND RESTATED
                     REVOLVING CREDIT AND SECURITY AGREEMENT

THIS AMENDMENT NO. 1 ("Amendment")  is entered into as of April 17, 1996,  among
GENERAL DATACOMM INDUSTRIES, INC., a corporation organized under the laws of the
State of Delaware,  GENERAL  DATACOMM,  INC., a corporation  organized under the
laws of the State of Delaware,  GDC REALTY, INC., a corporation  organized under
the laws of the State of Texas,  GDC  NAUGATUCK,  INC., a corporation  organized
under the laws of the State of Delaware, GENERAL DATACOMM INTERNATIONAL CORP., a
corporation  organized  under the laws of the  State of  Delaware,  GDC  FEDERAL
SYSTEMS, INC. (formerly known as GENERAL DATACOMM SYSTEMS,  INC.), a corporation
organized under the laws of the State of Delaware (each a "Borrower" and jointly
and severally, the "Borrowers"),  the undersigned financial institutions (each a
"Lender"  and  collectively,  "Lenders")  and THE  BANK OF NEW  YORK  COMMERCIAL
CORPORATION  ("BNYCC"),  a New York corporation,  as agent for Lenders (BNYCC in
such capacity, "Agent").
                                   BACKGROUND

Borrowers,  Lenders  and Agent  are  parties  to a Third  Amended  and  Restated
Revolving  Credit and  Security  Agreement  dated as of  November  30,  1995 (as
amended,  supplemented  or  otherwise  modified  from  time to time,  the  "Loan
Agreement")  pursuant to which Lenders provide  Borrowers with certain financial
accommodations.  Borrowers  have  requested that Lenders amend Sections 7.3, 7.8
and 7.17 of the Loan Agreement and Agent and Lenders are willing to do so on the
terms and conditions  hereafter set forth. NOW,  THEREFORE,  in consideration of
any loan or advance or grant of credit  heretofore  or hereafter  made to or for
the account of  Borrowers  by Lenders or Agent,  and for other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
parties hereto hereby agree as follows: 

1.  Definitions.  All capitalized  terms not otherwise defined herein shall have
the  meanings  given  to  them  in the  Loan  Agreement. 

2.  Amendment  to Loan Agreement. Subject to satisfaction of the conditions  
precedent set forth in Section 3 below, the Loan Agreement is hereby
amended as follows:  (a) Section 7.3 of the Loan  Agreement is hereby amended in
its entirety to provide as follows:



                                                                  EXHIBIT 10.15
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"7.3.  Guarantees.  Become  liable upon the obligations of any person,  firm or
corporation  by assumption,  endorsement or guaranty  thereof or otherwise
(other than to Lenders pursuant to this Agreement
or the other  Documents)  except  (a) as  disclosed  on  Schedule  7.3,  (b) the
endorsement  of checks  or  negotiable  instruments  in the  ordinary  course of
business,  (c) guarantees by GDC of the  obligations of any of its  Subsidiaries
under lease  arrangements  for real property entered into in the ordinary course
of business, provided, that the aggregate amount of indebtedness covered by such
guarantees does not at any time exceed the amount of rental  payments  permitted
under Section 7.11, (d) guarantees by Borrowers of the obligations of GDC or its
Subsidiaries  under leases of personal  property,  excluding  capital  equipment
subject to (f) below,  in the ordinary  course of business,  provided,  that the
aggregate  amount of  indebtedness  covered by such  guarantees  does not exceed
$5,000,000 at any time outstanding,  (e) guarantees by Borrowers relating to the
issuance of bid or  performance  bonds  required to be issued by any Borrower or
any Guarantor, provided, that the aggregate amount so guaranteed does not exceed
$5,000,000 at any time outstanding,  (f) guarantees by GDC of the obligations of
other Borrowers under capital equipment financing  arrangements,  provided, that
such financing  arrangements are permitted hereunder and the aggregate amount of
indebtedness  covered by such  guarantees  does not exceed the amount of capital
expenditures  permitted  pursuant  to Section  7.6,  (g)  non-financial  support
agreements  by GDC  relating to its  Subsidiaries,  provided,  that such support
agreements  are  substantially  similar to the support  agreement  issued by GDC
dated  June  30,  1989 in  favor  of  Sanwa  Business  Credit  Corporation,  (h)
guarantees of the obligations of another Borrower,  (i) guarantees by GDC of the
obligations  of  DataComm  Leasing  under  lease  financing  agreements  for the
discounting of leases of personal property manufactured or offered by GDC in the
ordinary course of business,  provided that the aggregate amount of indebtedness
covered by such guarantees does not exceed  $15,000,000 at any time  outstanding
and  (j)  guarantees  by  Borrowers  of the  obligations  of any  Guarantor  not
otherwise  covered by  subsections  (a)  through (i) above,  provided,  that the
aggregate  amount of  indebtedness  covered by such  guarantees  does not in the
aggregate exceed $500,000 at any time outstanding."

         (b) The references to the amount "$25,000,000" in Section 7.8 and 
7.17 of the Loan Agreement are hereby deleted and the following amount is 
substituted therefor:

                    "$2,000,000".

         3. Conditions of Effectiveness.  This Amendment shall become effective
upon  satisfaction  of the  following  conditions  precedent:  Agent  shall have
received  (i) four (4)  copies  of this  Amendment  executed  by  Borrowers  and
consented  and  agreed  to by  Guarantors  and  (ii)  such  other  certificates,
instruments, documents, agreements and opinions of counsel as may be required by
Agent,  Lenders or their  counsel,  each of which shall be in form
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                                                                  EXHIBIT 10.15
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 and substance satisfactory  to  Agent,  Lenders  and their  counsel.

  4.  Representations  and Warranties. Each Borrower hereby represents and
 warrants as follows:

(a)This Amendment and the Loan Agreement,  as amended hereby,  constitute legal,
valid and binding obligations of Borrowers and are enforceable against Borrowers
in accordance with their respective  terms.

(b) Upon the effectiveness of this Amendment, each Borrower hereby reaffirms all
covenants,  representations  and  warranties  made in the Loan  Agreement to the
extent  the same are not  amended  hereby  and  agree  that all such  covenants,
representations  and  warranties  shall be deemed to have been  remade as of the
effective date of this Amendment.

(c) No Event of Default or Default has occurred and is continuing or would exist
after  giving  effect  to  this  Amendment.   (d)  Borrowers  have  no  defense,
counterclaim or offset with respect to the Loan Agreement.

5. Effect on the Loan Agreement.

(a) Upon the  effectiveness  of  Section 2 hereof,  each  reference  in the Loan
Agreement to "this Agreement,"  "hereunder," "hereof," "herein" or words of like
import  shall mean and be a reference to the Loan  Agreement as amended  hereby.

(b) Except as  specifically  amended herein,  the Loan Agreement,  and all other
documents,  instruments and agreements  executed and/or  delivered in connection
therewith,  shall remain in full force and effect,  and are hereby  ratified and
confirmed.

(c) The  execution,  delivery  and  effectiveness  of this  Amendment  shall not
operate  as a waiver of any  right,  power or remedy  of Agent or  Lenders,  nor
constitute  a waiver  of any  provision  of the  Loan  Agreement,  or any  other
documents,  instruments  or agreements  executed  and/or  delivered  under or in
connection therewith.
      
6. Governing Law. This Amendment  shall be binding upon and inure to the benefit
of the parties hereto and their  respective  successors and assigns and shall be
governed by and construed in accordance with the laws of the State of New York.
       
7.  Headings.  Section  headings  in this  Amendment  are  included  herein  for
convenience  of reference only and shall not constitute a part of this Amendment
for any other purpose.
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                                                                 EXHIBIT 10.15 
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8. Counterparts.  This Amendment may be executed by the parties hereto in one or
more  counterparts,  each of which shall be deemed an original  and all of which
when taken together shall constitute one and the same agreement.
     
IN WITNESS WHEREOF, this Amendment has been duly executed as of the day and year
first written above.
                                            GENERAL DATACOMM INDUSTRIES, INC.
                                            GENERAL DATACOMM, INC.
                                            GDC REALTY, INC.
                                            GDC NAUGATUCK, INC.
                                            GENERAL DATACOMM INTERNATIONAL CORP.
                                            GDC FEDERAL SYSTEMS, INC.

                                           By:________________________________
                                            Dennis J. Nesler, the Vice-       
                                            President of each of the
                                            foregoing corporations
                                            
                                             1579 Straits Turnpike
                                             Middlebury, Connecticut 06762-1299

                                            THE BANK OF NEW YORK COMMERCIAL
                                            CORPORATION

                                            By:_______________________________
                                               Name:
                                               Its:

                                               1290 Avenue of the Americas
                                               New York, New York 10104
                                               Commitment Percentage: 100%

                                            THE BANK OF NEW YORK COMMERCIAL
                                             CORPORATION, as Agent

                                            By:_______________________________
                                               Name:
                                               Its:

CONSENTED AND AGREED TO:

DATACOMM RENTAL CORPORATION

By:__________________________
   Name:  William S. Lawrence
   Its:  Senior Vice President

GENERAL DATACOMM LTD.

By:__________________________
   Name:  William S. Lawrence
   Its:  Senior Vice President

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                                                                 EXHIBIT 10.15 
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GENERAL DATACOMM FRANCE S.A.R.L.

By:__________________________
   Name:  William S. Lawrence
   Its:  Senior Vice President

GENERAL DATACOMM DE MEXICO S.A. DE C.V.

By:__________________________
   Name:  William S. Lawrence
   Its:  Senior Vice President


GENERAL DATACOMM PTY LIMITED


By:__________________________
   Name:  William S. Lawrence
   Its:  Senior Vice President

GENERAL DATACOMM S.A.R.L.

By:__________________________
   Name:  William S. Lawrence
   Its: Senior Vice President

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