EXHIBIT 10.21
 
                                   GUARANTY

To: The CIT Group/Equipment Financing, Inc.

Each of us severally requests you to extend credit to or to purchase security
agreements, leases, notes, accounts and or other obligations (herein generally
termed "paper) of or from or otherwise to do business with

ATG Inc.                                        Fremont                       CA
- --------------------------------------------------------------------------------
Company                                          City                      State

hereinafter called the "Company," and to induce you so to do and in
consideration thereof and of benefits to accrue to each of us therefrom, each of
us, as a primary obligor, jointly and severally and unconditionally guarantees
to you that the Company will fully and promptly pay and perform all its present
and future obligations to you, whether direct or indirect, joint or several,
absolute or contingent, secured or unsecured, matured or unmatured and whether
originally contracted with you or otherwise acquired by you, irrespective of any
invalidity or unenforceability of any such obligation or the insufficiency,
invalidity or unenforceability of any security therefor; and agrees, without
your first having to proceed against the Company or to liquidate paper or any
security therefor, to pay on demand all sums due and to become due to you from
the Company and all losses, costs, attorneys' fees or expenses which may be
suffered by you by reason of the Company's default or default of any of the
undersigned hereunder; and agrees to be bound by and on demand to pay any
deficiency established by a sale of paper and or security held, with or without
notice to us. This guaranty is an unconditional guarantee of payment and
performance. No guarantor shall be released or discharged, either in whole or in
part, by your failure or delay to perfect or continue the perfection of any
security interest in any property which secures the obligations of the Company
or any of us to you, or to protect the property covered by such security
interest.

No termination hereof shall be effected by the death of any or all of us. No
termination shall be effective except by notice sent to you by certified mail
return receipt requested naming a termination date effective not less than 90
days after the receipt of such notice by you; or effective as to any of us who
has not given such notice; or affect any transaction effected prior to the
effective date of termination.

Each of us waives: notice of acceptance hereof; presentment, demand, protest and
notice of nonpayment or protest as to any note or obligation signed, accepted,
endorsed or assigned to you by the Company; any and all rights of subrogation,
reimbursement, indemnity, exoneration, contribution or any other claim which any
of us may now or hereafter have against the Company or any other person directly
or contingently liable for the obligations guaranteed hereunder, or against or
with respect to the Company's property (including, without limitation, property
collateralizing its obligations to you), arising from the existence or
performance of this guaranty; all exemptions and homestead laws and any other
demands and notices required by law; all setoffs and counterclaims; and any duty
on your part (should such duty exist) to disclose to any of us any matter, fact
or thing related to the business operations or condition (financial or
otherwise) of the Company or its affiliates or property, whether now or
hereafter known by you.

You may at any time and from time to time, without our consent, without notice
to us and without affecting or impairing the obligation of any of us hereunder,
do any of the following:

(a) renew, extend (including extensions beyond the original term of the
    respective item of paper), modify, release or discharge any obligations of
    the Company, of its customers, of co-guarantors (whether hereunder or under
    a separate instrument) or of any other party at any time directly or
    contingently liable for the payment of any of said obligations;

(b) accept partial payments of said obligations;

(c) accept new or additional documents, instruments or agreements relating to or
    in substitution of said obligations;

(d) settle, release (by operation of law or otherwise), compound, compromise,
    collect or liquidate any of said obligations and the security therefor in
    any manner;

(e) consent to the transfer or return of the security, take and hold additional
    security or guaranties for said obligations;

(f) amend, exchange, release or waive any security or guaranty; or

(g) bid and purchase at any sale of paper or security and apply any proceeds or
    security, and direct the order and manner of sale.

If a claim is made upon you at any time for repayment or recovery of any
amount(s) or other value received by you, from any source, in payment of or on
account of any of the obligations of the Company guaranteed hereunder and you
repay or otherwise become liable for all or any part of such claim by reason of:

(a)  any judgment, decree or order of any court or administrative body having
     competent jurisdiction; or

(b) any settlement or compromise of any such claim,

we shall remain jointly and severally liable to you hereunder for the amount so
repaid or for which you are otherwise liable to

                                                                     Page 1 of 2


 
the same extent as if such amount(s) had never been received by you,
notwithstanding any termination hereof or the cancellation of any note or other
agreement evidencing any of the obligations of the Company. This guaranty shall
bind our respective heirs, administrators, representatives, successors, and
assigns, and shall inure to your successors and assigns, including, but not
limited to, any party to whom you may assign any item or items of paper, we
hereby waiving notice of any such assignment. All of your rights are cumulative
and not alternative.

By execution of this guaranty each guarantor hereunder agrees to waive all
rights to trial by jury in any action, proceeding, or counterclaim on any matter
whatsoever arising out of, in connection with, or related to this guaranty.

Executed 1/13, 1994.

INDIVIDUAL    NOTE: Individual guarantors must sign without titles. Sign "John
GUARANTORS          Smith," not "John Smith, President." Use street addresses, 
                    not P.O. Boxes.


 
/s/ Frank Chiu                                   Individually
- -----------------------------------------------                     
Frank Chiu
46970 Ocotillo Ct., Fremont, CA 94539            Home Address
- -----------------------------------------------  
/s/ Doreen Chiu                                  Individually
- -----------------------------------------------  
Doreen Chiu
46970 Ocotillo Ct., Fremont  CA 94539            Home Address
- -----------------------------------------------

_______________________________________________  Individually

_______________________________________________  Home Address

_______________________________________________  Individually

_______________________________________________  Home Address

WITNESS _______________________________________

HOME ADDRESS __________________________________


CORPORATE     NOTE:  Enter exact name of corporation on first blank line,
GUARANTORS           followed by city and state. 


 
                                                               
__________________________________________
Name of Corporation
                                                                 CORPORATE SEAL
__________________________________________
City & State


By _____________________ Title ___________                       ___________________________________________
   Have signed by President, Vice President or Treasurer.        Attest                            Secretary


__________________________________________
Name of Corporation
                                                                 CORPORATE SEAL
__________________________________________
City & State


By _____________________ Title ___________                       ___________________________________________
   Have signed by President, Vice President or Treasurer.        Attest                            Secretary
 

                                                                     Page 2 of 2