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                                                                   EXHIBIT 10.53

                                                                                

                         EXECUTIVE SEPARATION AGREEMENT

                                        

     THIS EXECUTIVE SEPARATION AGREEMENT (the "Agreement") is entered into this
__ day of January, 1998, between Retix ("Company") and Philip Mantle
("Employee").


     WHEREAS, the Company and Employee have mutually agreed to terminate the
employment relationship and to establish a consulting arrangement between them.


     NOW, THEREFORE, IT IS AGREED as follows:


                    I.  TERMS OF SEPARATION AND TRANSITION

                                        

     1.  Employee's resignation as Senior Vice President of Sales and Marketing
was effective as of the close of business on July 15, 1997 (the "Termination
Date").  Employee's resignation from any other positions with any other entity
which may be deemed to be an affiliate of the Company and its former subsidiary
Retix U.K. Ltd. ("Retix U.K.") shall also be effective on the Termination Date.

     2.  In contemplation of the separation, the parties agree Employee's
termination has arisen as a result of a "constructive termination" under Section
5(e)(iii) of Employee's Employment Agreement with the Company and Retix U.K.
dated November 1, 1995 (the "Employment Agreement") and the confirming letter
executed by Employee and the Company dated May 17, 1996 (the "Confirming
Letter").  As a result, the Company and Employee agree:

         (a) Employee shall continue to receive his base salary at the annual
rate of U.S. $180,000 through July 15, 1998, payable on Retix's normal pay dates
for its employees. Should Employee accept full time employment with another
organization prior to July 15, 1998, a lump sum payout of the remaining unpaid
salary continuation shall be payable immediately.

         (b) Employee shall continue to receive the balance of one-half of a
U.S. $50,000 bonus being paid over a twelve month period through July 15, 1998
on Retix' normal pay dates in addition to the salary continuation provided in
the prior paragraph.

         (c) In addition to the payments provided otherwise in this Agreement,
Employee shall receive U.S. $105,000 for his assistance to the Company in its
development of the strategic plan for its former Sonoma Systems subsidiary, such
amount to be paid in the sums of U.S. $70,000 upon execution of this Agreement
by both parties and U.S. $35,000 on July 1, 1998.

         (d) the Benefit and Pension Schemes outlined in the Employment
Agreement shall continue to be provided through July 15, 1998, except such
Schemes shall terminate on the date of any lump sum payout of amounts owing to
Employee under Section 2 (a) of this Agreement.
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         (e) As contemplated by the Company and Employee in the Employment
Agreement, shares of the Company's Common Stock issued upon the prior exercise
by Employee of options to purchase such shares issued to Employee (consisting of
an option to purchase of 300,000 shares issued December 29, 1995 and an
additional option to purchase 100,000 shares issued on March 18, 1996) shall
continue to vest and be released from the applicable Company repurchase option
through July 15, 1998. On July 15, 1998, 50 percent of the then unvested shares
described in the preceding sentence shall also be released from the applicable
Company repurchase option, with the balance of any shares remaining then
unvested being canceled by the Company in satisfaction of the relevant portion
of principal of the applicable promissory notes provided by Employee to the
Company in connection with the earlier exercise of the underlying stock options.

         (f) As contemplated by the Employment Agreement, the parties confirm
that any notes provided by the Employee to the Company in connection with the
exercise of stock options described in the preceding paragraph shall be paid in
full by Employee not later than four years following the Termination Date. If
Employee requests the release of any shares of the Company's Common Stock held
as security for the payment of such notes by Employee in connection with the
proposed sale or other disposition of such shares by Employee, Employee agrees
to repay at least that percentage of the then outstanding principal owed under
all such notes as is equal to the percentage of shares then held by the Company
as security as a condition to the release of such shares.

         (g) Employee hereby releases Retix U.K., a former subsidiary of the
Company, from all remaining obligations under the Employment Agreement and the
Company hereby assumes all such obligations.

                          II.  CONSULTING RELATIONSHIP

     3.  Employee will make himself available at reasonable times and places to
perform consulting services for the Company during the period beginning on the
Termination Date and ending July 15, 1999 (the "Consulting Term").  Such
services will include:


         (a) continuing reasonable and customary transition support as requested
by the Company's current executive officers during the first nine months
following the Termination Date. Such support, generally in the form of
telephonic, fax or e-mail communication, shall be with respect to areas within
the general scope of Employee's duties while he was an executive officer of the
Company, e.g. strategic and product planning and key account relationships in
which Employee participated in a meaningful way. No additional compensation
shall be paid for such transition support unless extraordinary in nature, in
which case it shall be at Employee's option to provide such extraordinary
support and for such additional compensation as may be agreed between the
Company and Employee.


         (b) additional services concerning business strategy, market
development, major account opportunities or such other subjects as may be agreed
between the Company and Employee. All consulting assignments and pertinent
terms, including compensation, shall be determined by Employee and the Chief
Executive Officer or the Board of Directors of the 
<PAGE>
 
Company.


     4.  Employee agrees that he will from time to time during the Consulting
Term keep the Company advised as to Employee's progress in performing any agreed
upon services and that Employee will, as requested by the Company, prepare
written reports with respect thereto.

     5.   The Company shall reimburse Employee for reasonable expenses incurred
on behalf of Company during the Consulting Term with respect to the provision of
consulting services, provided that such expenses are substantiated in accordance
with Company policies.

     6.  Employee understands and agrees that his obligations to the Company
under his existing Retix Employee Proprietary Information and Inventions
Agreement between Employee and Company dated November 1, 1995 (the "Proprietary
Information Agreement"), a copy of which is attached hereto as Exhibit A, shall
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continue through the Consulting Term and shall thereafter survive termination of
his relationship with Company under this Agreement.

     7.  Employee and the Company acknowledge and agree that Section 11 (Non
competition Covenant) of the Employment Agreement shall continue to apply
through July 15, 1998 as a result of payments Employee is receiving pursuant to
the Employment Agreement.  Employee may engage in other employment, consulting
or businesses other than as provided in such Section 11 provided such activity
does not preclude him from making himself available to provide periodic
consulting services to the Company.

     8.  Nothing in this Agreement shall in any way be construed to constitute
Consultant as an agent, employee or representative of the Company and Employee
shall perform the consulting services contemplated in this Article II as an
independent contractor.

                            III.  RELEASE OF CLAIMS

     9.  Employee agrees that the foregoing provisions represent settlement in
full of all outstanding obligations owed to Employee by the Company or Retix
U.K.  Employee and the Company, on behalf of themselves, and their respective
heirs, executors, officers, directors, employees, investors, shareholders,
administrators, predecessor and successor corporations,  and assigns, hereby
fully and forever release each other and their respective heirs, executors,
officers, directors, employees, investors, shareholders, administrators,
predecessor and successor corporations, and assigns, from, and agree not to sue
concerning, any claim, duty, obligation or cause of action relating to any
matters of any kind, whether presently known or unknown, suspected or
unsuspected, that any of them may possess arising from any omissions, acts or
facts that have occurred up until and including the Effective Date of this
Agreement relating to Employee's employment with the Company or Retix U.K.
including, without limitation,

          (a) any and all claims relating to or arising from Employee's
employment relationship with the Company or Retix U.K. and the termination of
that relationship;
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          (b) any and all claims relating to, or arising from, Employee's right
to purchase, or actual purchase of shares of stock of the Company;

          (c) any and all claims for wrongful discharge of employment; breach of
contract, both express and implied; breach of a covenant of good faith and fair
dealing, both express and implied; negligent or intentional infliction of
emotional distress; negligent or intentional misrepresentation; negligent or
intentional interference with contract or prospective economic advantage; and
defamation;

          (d) any and all claims for violation of any United Kingdom or U.S.
federal, state or municipal statute, including, but not limited to, Title VII of
the U.S. Civil Rights Act of 1964, the U.S. Civil Rights Act of 1991, the U.S.
Age Discrimination in Employment Act of 1967,  the Americans with Disabilities
Act of 1990, the U.S. Fair Labor Standards Act, and the California Fair
Employment and Housing Act;

          (e) any and all claims arising out of any other laws and regulations
relating to employment or employment discrimination; and

          (f) any and all claims for attorneys' fee and costs.

     The Company and Employee agree that the release set forth in this section
shall be and remain in effect in all respects as a complete general release as
to the matters released.  This release does not extend to any obligations
incurred under this Agreement.

     10.  Employee acknowledges that he is waiving and releasing any rights he
may have under the U.S. Age Discrimination in Employment Act of 1967 ("ADEA")
and that this waiver and release is knowing and voluntary.  Employee and the
Company agree that this waiver and release does not apply to any rights or
claims that may arise under ADEA after the Effective Date of this Agreement.
Employee acknowledges that the consideration given for this waiver and release
Agreement is in addition to anything of value to which Employee was already
entitled.  Employee further acknowledges that he has been advised by this
writing that:

          (a) he should consult with an attorney prior to executing this
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Agreement;

          (b) he has at least twenty-one (21) days within which to consider this
Agreement;

          (c) he has at least seven (7) days following the execution of this
Agreement by the parties to revoke the Agreement; and

          (d) this Agreement shall not be effective (the "Effective Date") until
the revocation period has expired

                         IV.  OTHER PROVISIONS; GENERAL

     11.  Each party agrees to refrain from any disparagement, defamation,
slander of the other, or tortious interference with the contracts and
relationships of the other.
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     12. Employee retains any rights to indemnification that he may have under
applicable law. The Company will continue to be obligated to indemnify and
defend Employee to the full extent required by applicable law and pursuant to
any rights under the Company's Articles of Incorporation and Bylaws and the
Indemnification Agreement between the Company and Employee dated as of September
27, 1995.

     13.  This Agreement together with the written agreements referenced in this
Agreement represent the entire agreement and understanding between the Company
and Employee concerning Employee's separation from the Company and Retix U.K.,
and together supersede and replace any and all prior agreements and
understanding concerning Employee's relationship with the Company and Retix U.K.
and his compensation by the Company and Retix U.K.

     14.  This Agreement may only be amended in writing signed by Employee and
the Chief Executive Officer of the Company.

     15.  This Agreement shall be governed by the laws of the United Kingdom.

     16.  This Agreement is effective seven days after it has been signed by
both parties.

     17.  This Agreement may be executed in counterparts, and each counterpart
shall have the same force and effect as an original and shall constitute an
effective, binding agreement on the part of each of the undersigned.

     18.  This Agreement is executed voluntarily and without any duress or undue
influence on the part or behalf of the parties hereto, with the full intent of
releasing all claims.  The parties acknowledge that:

          (a)  They have read this Agreement;

          (b) They have been represented in the preparation, negotiation, and
execution of this Agreement by legal counsel of their own choice or that they
have voluntarily declined to seek such counsel;

          (c) They understand the terms and consequences of this Agreement and
of the releases it contains;

          (d) They are fully aware of the legal and binding effect of this
Agreement.

     IN WITNESS THEREOF, the parties have executed this Agreement on the
respective dates set forth below.

                                    RETIX


Dated:  January ____, 1998        By _______________________________
                                     Bruce Brown, President & CEO
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                                    EMPLOYEE


Dated:  January ____, 1998           _______________________________
                                     Philip Mantle
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                                   EXHIBIT A
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                       PROPRIETARY INFORMATION AGREEMENT