1

                                                                    EXHIBIT 10.4


                                   TXEN, INC.

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

                              EMPLOYMENT AGREEMENT
                                      with
                               THOMAS L. PATTERSON

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


                            Dated: December 16, 1994


   2

                              EMPLOYMENT AGREEMENT

         THIS AGREEMENT is entered into on the 16 day of December, 1994, by and
among Thomas L. Patterson, residing at 1013 Vista Circle, Birmingham, Alabama
(herein called the "Employee"), TXEN, INC. (herein called "TXEN") with a
principal place of business at 10 Inverness Center Parkway, Suite 140,
Birmingham, Alabama 35242, and NICHOLS RESEARCH CORPORATION, with a principal
place of business located at 4040 Memorial Parkway South, Huntsville, Alabama
35802 (herein called "NRC").

                              W I T N E S S E T H:

         WHEREAS, TXEN Company is engaged in the business of managed care
administration and providing information systems and services to managed care
administrators;

         WHEREAS, NRC, as purchaser, and TXEN, as seller, entered into and
consummated a Convertible Preferred Stock Purchase Agreement dated as of the
date hereof (the "Purchase Agreement") whereby NRC acquired one share of
Preferred Stock of TXEN, and the Employee's continued employment with TXEN was a
material inducement to NRC to enter into the Purchase Agreement;

         WHEREAS, NRC has also entered into a Stock Purchase Option Agreement of
even date herewith giving NRC the option to purchase all of the capital stock of
TXEN owned by the Employee together with the capital stock owned by the other
shareholders of TXEN provided NRC converts the Preferred Stock into Class B
Common Stock; and

         WHEREAS, TXEN and NRC desire to obtain the services of the Employee as
President of TXEN and the Employee is willing to render such services to TXEN
upon the terms and conditions herein set forth;

         NOW, THEREFORE, in consideration of the mutual promises set forth
herein and other good and valuable consideration, the receipt of which is hereby
acknowledged, the parties agree as follows:

1.       Duties and Salary.

          (a)     TXEN agrees to employ the Employee and the Employee agrees to 
accept employment by TXEN on a full-time basis as


   3

President of TXEN at a base salary of $8,000 per month payable during the Term
of Employment, as hereinafter defined. Such salary shall be subject to increases
from time to time as authorized by the Board of Directors of TXEN (the "Board"),
provided any increase in compensation paid to the Employee shall require the
affirmative vote of the director or directors elected to the Board by NRC so
long as NRC owns any capital stock of TXEN.

          (b)     The Employee hereby agrees to undertake such travel as may be
required in the performance of his duties. The reasonable travel expenses of the
Employee shall be reimbursed in accordance with TXEN's reimbursement policy, in
effect from time to time.

          (c)     The Employee shall carry out his duties under the general
supervision of the Board or its designee.

          (d)     The Employee's duties shall include the duties and
responsibilities identified on Schedule I attached hereto. The Employee shall
perform such other tasks and duties as may be assigned by TXEN, from time to
time and TXEN reserves the right to change the office and/or position of the
Employee within TXEN, so long as such change is mutually acceptable. The
Employee shall devote his full time, attention, skill and efforts to the tasks
and duties assigned by TXEN. The Employee shall not provide services, for
compensation, to any other person or business entity while employed by TXEN
without approval of the Board and NRC.

          (e)     The Employee shall not be required to relocate beyond the
Birmingham, Alabama, metropolitan area without his consent.

2.       Term of Employment. This Agreement shall commence as of the date hereof
and shall end four years from the date hereof (the "Term of Employment"), unless
terminated earlier or extended as provided herein. Upon expiration of the
initial Term of Employment unless earlier terminated as provided herein, the
Term of Employment shall continue automatically month-to-month until terminated
by either party with at least thirty (30) days' prior written notice with or
without cause. Notwithstanding the foregoing, if NRC purchases all of the
capital stock of TXEN pursuant to the Stock Purchase Option Agreement, NRC may
elect to (1) immediately terminate the Employee's employment or (2) extend the
Employee's employment for one year after the purchase of all of the capital
stock of TXEN by NRC in which event the Term of Employment shall be extended by
such additional period, unless terminated earlier as provided herein.


   4

3.       Termination Before Expiration of Term of Employment. The termination of
the employment of the Employee during the Term of Employment may occur in one of
the following ways:

         (a)      By TXEN, for Cause. Termination by TXEN shall be deemed to be 
for cause only upon:

                  (i)      Employee's conviction of or pleading guilty to a 
                           felony;

                  (ii)     A good faith determination by the Board that the 
                           Employee has breached either this Agreement, the
                           Purchase Agreement or the Stock Purchase Option
                           Agreement;

                  (iii)    Refusal or failure by the Employee, without
                           reasonable excuse or proper authorization, to carry
                           out any reasonable instructions of the Board
                           consistent with Employee's rights or duties as set
                           forth in this Agreement;

                  (iv)     Material breach of this Agreement or any material 
                           breach of any agreement with NRC;

                  (v)      The Employee's demonstration of negligence or willful
                           misconduct in the execution of his duties, including
                           without limitation breach of fiduciary duty or the
                           duty of loyalty owed TXEN.

         If TXEN intends to terminate for cause, TXEN shall provide notice to
Employee of intent to terminate this Agreement, stating the termination
provision in this Agreement relied upon and setting forth in reasonable detail
the facts and circumstances claimed to provide a basis for termination under the
provisions so indicated, and shall provide Employee with an opportunity to cure
the alleged default or breach within thirty (30) days of receipt of the notice,
provided that if the matter is not curable within such thirty (30) day period,
the Employee shall not be deemed in default if the Employee commences
immediately to cure the matter and proceeds diligently thereafter to complete
the cure, further provided that the alleged breach or default must be cured
within ninety (90) days of receipt of the notice. TXEN shall not be required to
give more than one notice with respect to the same matter. Notwithstanding the
foregoing, no notice and no cure right shall be required with


                                     - 3 -
   5

respect to termination for cause under 3(a)(i) or an act involving theft of
information or property of TXEN.

         (b)      By TXEN, Without Cause. Any termination of Employee by TXEN 
for reasons other than as set forth in subsections 3(a)(i) through 3(a)(v)
above shall be a termination without cause. TXEN may terminate the employment of
Employee without cause by thirty (30) days' prior written notice at any time. If
NRC purchases all of the capital stock of TXEN pursuant to the Stock Purchase
Option Agreement, NRC may cause TXEN to terminate the employment of Employee
without cause immediately after the closing of such purchase and without giving
30 days, prior notice.

         (c)      By the Employee. The Employee may by written notice terminate 
his employment at any time during the Term of Employment:

                   (i)     For any reason other than for Good Reason (as
                           defined below) upon thirty (30) days' prior written
                           notice at any time.

                  (ii)     For "Good Reason," defined as termination because of 
                           a material breach by TXEN of this Agreement
                           including, without limitation, making a material
                           change in the Employee's duties, responsibilities or
                           authority as set forth in this Agreement, without his
                           express written consent. In all cases in which
                           Employee intends to terminate for Good Reason, the
                           Employee shall provide TXEN with notice of intent to
                           terminate this Agreement, stating the facts and
                           circumstances giving rise to a breach of this
                           Agreement claimed to provide a basis for termination
                           under the provisions so indicated, and shall provide
                           TXEN with an opportunity to cure the alleged default
                           or breach within thirty (30) days of receipt of the
                           notice, provided that if the matter is not curable
                           within such thirty (30) day period, TXEN shall not be
                           deemed in default if it commences immediately to cure
                           the matter and proceeds diligently thereafter to
                           complete the cure, further provided that the alleged
                           breach or default must be cured within ninety (90)
                           days of receipt of the notice. Employee shall not be
                           required to give more than one such notice with
                           respect to the same matter.


                                     - 4 -
   6

         (d)      Death of the Employee.

         (e)      Disability of Employee. If, during the Term of Employment, a 
                  physician selected by TXEN determines that the Employee has
                  become physically or mentally disabled so as to be unable to
                  carry out the normal and usual duties of his employment for
                  three (3) continuous months, and reasonable accommodation
                  cannot be made to allow the Employee to continue to perform
                  his duties full-time, his employment hereunder may be
                  terminated at the election of TXEN or the Employee.
                           
4.       Consequences of Termination. The termination of the employment of 
Employee will cause the following results:

         (a)      If the termination is by TXEN for cause, or is by the Employee
for any reason other than for Good Reason, TXEN will pay the Employee within
five (5) days after the date of termination any unpaid salary, the amount of any
accrued annual vacation pay to which he may be entitled under TXEN's vacation
plan, and benefits. All such compensation and benefits (if any) shall be paid
only through the date termination occurs.

         (b)      If the termination is by TXEN without cause or because of 
death or disability, TXEN shall pay to the Employee, in addition to the amounts
set forth in 4(a) above, an amount equal to fifty percent (50%) of the
Employee's monthly base salary then in effect in monthly installments over a
three-month period immediately following the termination.

         (c)      If the termination is by the Employee for Good Reason, TXEN 
shall pay to the Employee, in addition to the amounts set forth in 4(a) above,
an amount equal to fifty percent (50%) of the Employee's monthly base salary
then in effect in monthly installments over a three-month period immediately
following the termination.

         (d)      In the event of the Employee's death or disability, the 
following provisions will apply:

                  (i)      Upon his death, the Employee's estate will be 
                           entitled to receive the amount set forth in Section
                           4(b) and the benefits set forth in any plans of


                                     - 5 -
   7

                           TXEN then in effect and applicable under the
                           circumstances. The Employee or his estate shall be
                           entitled to no other compensation or benefits the
                           event of death.

                  (ii)     Upon termination on account of disability, Employee 
                           will be entitled to receive the amount set forth in
                           Section 4(b) and the benefits set forth in any plans
                           of TXEN then in effect and applicable under the
                           circumstances. The Employee or his personal
                           representative shall be entitled to no other
                           compensation or benefits in the event of disability.

         (e)      The Employee shall not be required to mitigate the amount of
payment provided for in this Section 4 by seeking employment.

         (f)      The amounts set forth above in this Section 4 shall be paid 
and received in complete discharge of any other obligation of TXEN (or NRC) to
Employee resulting from termination of his employment.

5.       Fringe Benefits.

         The Employee shall participate in any group health insurance, vacation
and sick leave plans, and other benefit plans available to all employees of TXEN
in accordance with their terms and conditions which may be amended or terminated
by TXEN at any time.

6.       Non-Disclosure Covenants and Proprietary Matters.


                                     - 6 -
   8

         (a)      Unless authorized or instructed in writing by TXEN and NRC, 
the Employee shall not, except as required in the conduct of TXEN's business,
during or at any time after the Term of Employment, disclose to others, or use,
any of NRC's or TXEN's inventions or discoveries or their respective secret or
confidential information or data (oral, written, or in machine readable form)
which the Employee may obtain during the course of or in connection with the
Employee's employment, including such inventions, discoveries, information,
know-how or data relating to machines, equipment, products, systems, software,
contracts, contract performance, research and/or development, designs,
compositions, formulae, processes, manufacturing procedures or business methods,
whether or not developed by the Employee, by others in NRC or TXEN or obtained
by NRC or TXEN from third parties, and irrespective of whether or not such
inventions, discoveries, information, knowledge or data have been identified by
NRC or TXEN as secret or confidential, unless and until, and then to the extent
and only to the extent that, such inventions, discoveries, information,
knowledge or data become available to the public otherwise than by the
Employee's act or omission.

         (b)      The Employee shall not, except as required in the conduct of
TXEN's business, disclose to others, or use, any of the information (which, if
disclosed or used, could be harmful to NRC or TXEN) relating to present and
prospective customers of NRC or TXEN, business dealings with such customers,
prospective sales and advertising programs and agreements with representatives
or prospective representatives of NRC or TXEN, present or prospective sources of
supply or any other business arrangements o NRC or TXEN, including but not
limited to customers, customer lists, costs, prices and earnings, whether or not
such information is developed by the Employee, by others in NRC or TXEN or
obtained by NRC OR TXEN from third parties, and irrespective of whether or not
such information has been identified by NRC or TXEN as secret or confidential,
unless and until, and then to the extent and only to the extent that, such
information becomes available to the public otherwise than by the Employee's act
or omission.

         (c)      The Employee agrees to disclose immediately to TXEN or any
persons designated by it and to assign to TXEN or its successors or assigns, all
inventions made, discovered, or first reduced to practice by the Employee,
solely or jointly with others, during the Term of Employment or within a period
of six months from the date of termination of such employment (either during or


                                     - 7 -
   9

outside of the Employee's working hours and either on or off TXEN's premises),
which inventions are made, discovered or conceived either in the course of such
employment, or with the use of TXEN's time, material, facilities or funds, or
which are directly related to any investigations or obligations undertaken by
TXEN; and the Employee hereby grants and agrees to grant the right to TXEN and
its nominees to obtain, for its own benefit and in its own name (entirely at its
expense) patents and patent applications including original, continuation,
reissue, utility and design patents, and applications, patents of addition,
confirmation patents, registration patents, petty patents, utility models, and
all other types of patents and the like, and all renewals and extensions of any
of them for those inventions in any and all countries; and the Employee shall
assist TXEN, at TXEN's expense, without further charge during the term of the
Employee's employment, and after termination of the Employee's employment at the
same base salary rate (excluding any bonuses, incentive or deferred compensation
or other benefits and based upon a forty hour work week) as during the last year
of the Employee's employment (determined on an hourly basis for this purpose),
through counsel designated by TXEN, to execute, acknowledge, and deliver all
such further papers, including assignments, applications for Letters Patent (of
the United States or of any foreign country), oaths, disclaimers or other
instruments and to perform such further acts, including giving testimony or
furnishing evidence in the prosecution or defense of appeals, interferences,
suits and controversies relating to any aforesaid inventions as may reasonably
be deemed necessary by TXEN or its nominees to effectuate the vesting or
perfecting in TXEN or its nominees of all right, title and interest in and to
said inventions, applications and patents. Notwithstanding the foregoing, the
Employee need not take any action called for under this Section 6(c) which will
cause undue personal hardship to the Employee.

         (d)      The Employee agrees to disclose immediately to TXEN or any
persons designated by it and to assign to TXEN, at its option, or its successors
or assigns, all works of authorship, including all writings, computer programs,
software, and firmware, written or created by the Employee solely or jointly
with others, during the course of his employment by TXEN (either during or
outside of the Employee's working hours and either on or off TXEN's premises),
which works are made or conceived either in the course of such employment, or
with the use of TXEN's time, material, facilities or funds, or which are
directly related to any investigations or


                                     - 8 -
   10

obligations undertaken by TXEN; and the Employee hereby agrees that all such
works are works made for hire, of which TXEN is the author and the beneficiary
of all rights and protections afforded by the law of copyright in any and all
countries; and the Employee will assist TXEN at TXEN's expense without further
charges during the term of his employment, and after termination of his
employment at the same base salary rate (excluding any bonuses, incentive or
deferred compensation or other benefits) as during the last year of his
employment (determined on an hourly basis for this purpose assuming a forty hour
work week), through counsel designated by TXEN, to execute, acknowledge, and
deliver all such further papers, including assignments, applications for
copyright registration (in the United States or in any foreign country), oaths,
disclaimers or other instruments, and to perform such further acts, including
giving testimony or furnishing evidence in the prosecution or defense of
appeals, interferences, suits and controversies relating to any aforesaid works,
as may be deemed necessary by TXEN or by its nominees to effectuate the vesting
or perfecting in TXEN or its nominees of all rights and interest in and to said
works and copies thereof, including the exclusive rights of copying and
distribution.

         (e)      The Employee shall keep complete, accurate and authentic 
accounts, notes, data and records of all inventions made, discovered or
developed and all works of authorship written or created by the Employee as
aforesaid in the manner and form requested by TXEN.

         (f)      All computer or other hardware, computer software, computer
programs, source codes, object codes, magnetic tapes, printouts, samples, notes,
records, reports, documents, customer lists, photographs, catalogues and other
writings, whether copyrightable or not, relating to or dealing with TXEN's or
NRC's business and plans, and those of others entrusted to TXEN or NRC, which 
are prepared or created by the Employee or which may come into his possession
during or as a result of his employment, are the property of TXEN or NRC, as
applicable, and upon termination of his employment, the Employee agrees to
return all such computer software, computer programs, source codes, object
codes, magnetic tapes, printouts, samples, notes, records, reports, documents,
customer lists, photographs, catalogues and writings and all copies thereof to
TXEN or NRC.


                                     - 9 -
   11

7.       Non-Solicitation and Non-Competition. During the Restriction Period (as
hereinafter defined) within the United States of America, the Employee shall not
directly or indirectly:

         (a)      Solicit the business of TXEN from any customer of TXEN or any
entity controlled by TXEN or solicit any employees of TXEN to leave the employ
of TXEN.

         (b)      Directly or indirectly, hire any employees or former employees
of TXEN or any entity controlled by TXEN within one year of the date of
termination of his employment with TXEN or cause any entity with which the
Employee is affiliated to hire any such employees or former employees of TXEN.

         (c)      Engage in, represent in any way or be connected with, as
consultant, officer, director, partner, employee, sales representative,
proprietor, stockholder or otherwise (except for the ownership of a less than 1%
stock interest in a publicly-traded corporation where Employee is not in a
management or control position), any business competing with the business of 
TXEN as conducted by TXEN on the date hereof or during the period of Employee's
employment by TXEN.

         (d)      As used herein, the Restriction Period shall mean the period 
while the Employee is employed by TXEN and the following periods:

                  (i)      36 months after the date the Employee ceases to be 
         employed by TXEN and/or

                  (ii)     60 months after NRC purchases all of the capital 
         stock of TXEN pursuant to the Stock Purchase Option Agreement.

         The above periods in sections 7(d)(i) and 7(d)(ii) shall not be
mutually exclusive. For example, if NRC purchases the capital stock of TXEN more
than 36 months after the Employee ceases to be employed by TXEN, the Restriction
Period of 7(d)(ii) shall apply even though the Restriction Period of 7(d)(i)
also applied. Similarly, if the Employee ceases to be employed by TXEN more than
60 months after NRC purchases the capital stock of TXEN, the Restriction Period
of section 7(d)(i) shall apply even though the Restriction Period of 7(d)(ii)
also applied.


                                     - 10 -
   12

8.       No Conflict. Employee represents and warrants that he is not a party to
or otherwise subject to or bound by the terms of any contract, agreement or
understanding which in any manner would limit or otherwise affect his ability to
perform his obligations hereunder, including without limitation any contract,
agreement or understanding containing terms and provisions similar in any manner
to those contained in Sections 6 and 7 hereof. Employee covenants to indemnify
and hold NRC, TXEN and any of their affiliates harmless from any cost or damages
(including attorneys' fees and expenses) resulting from any breach of the
provisions of this Agreement.

9.       Survival of Covenants, Effect.

         (a)      The covenants on the part of the Employee contained or 
referred to in Sections 6 and 7 above shall survive termination of this
Agreement, and the existence of any claim or cause of action of the Employee
against TXEN or NRC, whether predicated on this Agreement or otherwise. The
Employee agrees that a remedy at law for any breach of the foregoing covenants
contained or referred to in Sections 6 and 7 would be inadequate, that TXEN and
NRC would suffer irreparable harm as a result and that NRC and/or TXEN shall be
entitled to a temporary and permanent injunction or an order for specific
performance of such covenants without the necessity of proving actual damage to
NRC or TXEN and without the posting of any bond or other security. Any breach of
this Agreement by TXEN or NRC shall not release the Employee from his
obligations under Sections 6 and 7 hereof.

         (b)      The Employee hereby represents and acknowledges that NRC and 
TXEN are relying on the covenants in Sections 6 and 7 in entering into this
Agreement and the Purchase Agreement and other agreements related thereto and
that the restrictions in Sections 6 and 7 are fair and reasonable. The Employee
acknowledges that TXEN does business throughout the United States and that the
geographic scope of the covenants in Section 7 is therefore reasonable and
necessary to protect the interests of TXEN.

         (c)      It is the intent of the parties that the provisions of 
Sections 6 and 7 shall be enforced to the fullest extent permissible under the
laws and public policies of each jurisdiction in which enforcement is sought. If
any particular provision of Sections 6 and 7 shall be adjudicated to be invalid
or unenforceable, such provision(s) of Sections 6 and 7 shall be


                                     - 11 -
   13

deemed amended to provide restrictions to the fullest extent permissible and
consistent with applicable law and policies, and such amendment shall apply only
with respect to the particular jurisdiction in which such adjudication is made.
If such deemed amendment is not allowed by the adjudicating body, the offending
provision, only, shall be deleted and the remainder of Sections 6 and 7 shall
not be effected.

10.      Assignment.

         The rights and obligations of TXEN under this Agreement may be assigned
by TXEN to NRC or to any other successors in interest of TXEN and/or NRC of that
part of the business of TXEN or NRC to which this Agreement applies or to their
respective affiliates. This Agreement may not be assigned and any duties of the
Employee may not be delegated by the Employee, but any amounts owing to the
Employee upon his death shall inure to the benefit of his estate.

11.      Notices.

         All notices or other communications which may be or are required to be
given, served or sent by either party to the other party pursuant to this
Agreement shall be in writing, addressed to its/his residence or place of
business as set forth above, and shall be mailed by first-class certified mail,
return receipt requested, postage prepaid, next-day air delivery, or transmitted
by facsimiles or hand delivery. Such notice or other communication shall be
deemed sufficiently given, served, sent or received for all purposes at such
time as it is delivered to the addressee or at such time as delivery is refused
by the addressee upon presentation. Each party may designate by notice in
writing an address to which any notice or communication may thereafter be so
given, served or sent. Any notice or other communication sent by Employee to
TXEN shall also be sent, at the same time, to NRC. Notices hand delivered to 
TXEN or NRC must be delivered to an officer of TXEN and NRC and all other
notices shall be sent to the attention of the Board, in the case of TXEN, or to
the President, in the case of NRC.

12.      Applicable Law Jurisdiction.


                                     - 12 -
   14

         This Agreement has been negotiated and executed in the State of
Alabama, and it shall be governed by, construed and enforced in accordance with
the internal substantive laws and not the choice of law rules of the State of
Alabama.

13.      Effectiveness/Interpretation.

         The parties acknowledge and agree that this Agreement has been
negotiated at arm's length between parties equally sophisticated and
knowledgeable in the matters dealt with herein. Each party has been represented
by counsel of its or his own choosing. Accordingly, any rule of law or legal
decision that would require interpretation of any ambiguities in the Agreement
against the party that drafted it is not applicable and is waived.

14.      Third Party Beneficiary.

         NRC is a third party beneficiary to this entire Agreement but shall
have no liability to pay the compensation due Employee and to perform the other
obligations of TXEN hereunder. NRC is not a guarantor of any of the TXEN
obligations hereunder.

15.      Severability.

         If any of the articles, sections, paragraphs, clauses or provisions of
this Agreement shall be held by a court of last resort to be invalid, the
remainder of this Agreement shall not be affected thereby.

16.      Entire Agreement.

         The foregoing contains the entire agreement between the parties
relating to the subject matter of this Agreement, and may not be altered or
amended except by an instrument in writing approved by TXEN and NRC and signed
by the parties hereto, and this Agreement supersedes all prior understandings
and agreements relating to employment of the Employee by TXEN. The parties
acknowledge that any prior oral or written agreements between NRC and the
Employee, if any, are hereby terminated. The parties acknowledge that the
Employee and NRC have also entered into the Purchase Agreement and Stock
Purchase Option Agreement which shall be in addition to and not in lieu of the
provisions of this Agreement.


                                     - 13 -
   15

         IN WITNESS WHEREOF, TXEN and NRC have caused this Agreement to be
executed by their duly authorized officers and the Employee has hereunto set his
hand as of the date first above written.

                                          TXEN, INC.

                                          By:  Thomas L. Patterson
                                             -----------------------------------
                                             Thomas L. Patterson, President


                                          NICHOLS RESEARCH CORPORATION

                                          By:
                                             -----------------------------------
                                             Its:
                                                 -------------------------------

                                          Thomas L. Patterson
                                          --------------------------------------
                                          Thomas L. Patterson, Employee


                                     - 14 -
   16

                                   SCHEDULE I

                              Duties of Employees

THOMAS L. PATTERSON, PRESIDENT

(i)      to promote the growth of and manage the business and day to day 
         operations of TXEN;

(ii)     to perform the duties normally associated with the Office of President
         or such other office to which Employee may be nominated and appointed
         by the Board, subject to control and direction of the Board;

(iii)    to train and supervise TXEN's employees and to perform or cause to be
         performed quality control for projects and contracts performed by TXEN;

(iv)     to manage and/or actually assist in the bidding and performance of 
         major or material projects and contracts undertaken by TXEN;

(v)      to direct and supervise the sale and marketing of TXEN's contracts,
         services and products and, if requested, the contracts, services and
         products of NRC;

(vi)     to perform such other and/or different duties as may be determined or
         delegated by the Board, consistent with the duties of the President.


   17

                       AMENDMENT TO EMPLOYMENT AGREEMENT


                    ---------------------------------------
                    
                           NICHOLS SELECT CORPORATION

                                       AND

                               THOMAS L. PATTERSON

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


                             Dated: August 29, 1997


   18

                        AMENDMENT TO EMPLOYMENT AGREEMENT

         THIS AMENDMENT TO CERTAIN EMPLOYMENT AGREEMENT, dated 16th of December,
1994, is entered into on this the 29th day of August, 1997, by NICHOLS SELECT
CORPORATION, a Delaware corporation and the wholly owned subsidiary of NRC and
Thomas L. Patterson ("Employee"). Unless otherwise defined, capitalized terms
used herein shall have the meaning ascribed to such terms in the Employment
Agreement or Merger Agreement (hereinafter defined).

                              W I T N E S S E T H:

         WHEREAS, Nichols Research Corporation ("NRC"), SELECT, a wholly owned
subsidiary of NRC, TXEN, Inc. ("TXEN"), and the holders of all of the $0.002 par
value Class A Common Stock of TXEN (the "Shareholders") have entered into and
consummated an Agreement of Merger dated as of August 27, 1997 (the "Merger
Agreement") whereby TXEN merged with and into SELECT;

         WHEREAS, the Employee's continued employment with SELECT was a material
inducement to SELECT and NRC to enter into the Merger Agreement;

         WHEREAS, the Employee owned Class A Common Stock of TXEN and received a
portion of the Merger Consideration;

         WHEREAS, NRC, pursuant to Section 2 of Employment Agreement has elected
to extend Employee's Term of Employment after the Effective Date of the merger
of TXEN into SELECT; and

         WHEREAS, NRC, SELECT, and Employee mutually desire that Employee 
continue to be employed by SELECT;

         NOW, THEREFORE, in consideration of the mutual covenants herein
contained, the undersigned parties do hereby amend the Employment Agreement as
follows:

                  1.       SELECT agrees to the continued employment of the 
Employee, and the Employee agrees to accept continued employment by SELECT on a
full-time basis as President of SELECT with the same Duties and Salary as set
forth in the Employment Agreement, except that Employee shall report to the
Chief Executive Officer of SELECT.

                  2.       Section 2 of said Employment Agreement is amended to 
read as follows:

                           2.       Term of Employment. This Agreement shall
                           commence as of the Effective Date of the Merger


   19

                           Agreement and shall end two (2) years from
                           the date hereof (the "Term of Employment"), unless
                           terminated earlier or extended as provided herein.

                  3.       Unless the context requires otherwise, all references
         to TXEN, Inc., in the Employment Agreement shall mean SELECT.

         Except as amended. above, the Employment Agreement shall remain in full
force and effect according to its terms and conditions.

         IN WITNESS WHEREOF, the parties have hereunto executed this Amendment
to Employment Agreement on the date and year first above written.

                                          NICHOLS SELECT CORPORATION
                                                                

                                          By: /s/ Michael J, Mruz
                                             -----------------------------------
                                             Michael J. Mruz,
                                             Its:  Chief Executive Officer


                                          /s/ Thomas L. Patterson           
                                          --------------------------------------
                                          Thomas L. Patterson, Employee         


                                     - 2 -
   20

                  AMENDMENT NUMBER TWO TO EMPLOYMENT AGREEMENT

               =================================================
                            NICHOLS TXEN CORPORATION

                                       AND

                               THOMAS L. PATTERSON

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

                               Dated: June 1, 1998


   21

                  AMENDMENT NUMBER TWO TO EMPLOYMENT AGREEMENT

         THIS AMENDMENT NUMBER TWO TO EMPLOYMENT AGREEMENT, dated December 16,
1994, as amended August 29, 1997 (the "Employment Agreement"), is entered into
on this the 1st day of June, 1998, by NICHOLS TXEN CORPORATION, formerly known
as NICHOLS SELECT CORPORATION, a Delaware corporation and the wholly owned
subsidiary of NRC ("Nichols TXEN"), and Thomas L. Patterson, ("Employee").
Unless otherwise defined, capitalized terms used herein shall have the meaning
ascribed to such terms in the Employment Agreement or Merger Agreement
(hereinafter defined).

                              W I T N E S S E T H:

         WHEREAS, Nichols Research Corporation ("NRC"), NICHOLS SELECT 
CORPORATION ("Nichols Select"), a Wholly owned subsidiary of NRC, TXEN, Inc.
("TXEN'), and the holders of all of the $0.002 par value Class A Common Stock of
TXEN (the "Shareholders") entered into and consummated an Agreement of Merger
dated as of August 27, 1997 (the "Merger Agreement") whereby TXEN merged with
and into Nichols Select with Nichols Select as the surviving corporation;

         WHEREAS, Nichols Select changed its name to Nichols TXEN after the 
merger;     

         WHEREAS, Employee entered into the Employment Agreement with TXEN which
has been assumed by Nichols TXEN; and

         WHEREAS, Nichols TXEN, and Employee mutually desire to amend the 
Employment Agreement;  

         NOW, THEREFORE, in consideration of the mutual covenants herein
contained, the undersigned parties do hereby amend the Employment Agreement as
follows:

                  1.       Section 1(a) is hereby deleted in its entirety and a 
         new Section 1(a) is hereby substituted as follows:

                           Nichols TXEN agrees to employ the Employee, and the
                           Employee agrees to accept employment by Nichols TXEN
                           on a part-time basis averaging approximately 20 hours
                           per week beginning June 1, 1998, and ending January
                           31, 1999, at the hourly rate of Seventy-Five and
                           60/100 Dollars ($75.60), which shall be the
                           Employee's base salary. Effective February 1, 1999,
                           the Employee shall work on a part-time basis
                           averaging approximately ten (10) hours per week at an
                           hourly rate of Seventy-Nine and 08/100 Dollars


   22

                           ($79.08), which shall be the Employee's base salary.

         2.       Section 1(d) is hereby deleted in its entirety and a new 
Section l(d) is hereby substituted as follows:

                  Employee shall be employed in the position of Chairman of the
                  Board of Directors of Nichols TXEN until such time as he is
                  removed from that position by death, resignation, or action of
                  the Nichols TXEN Board of Directors. Employee's duties shall
                  include the duties and responsibilities identified on Schedule
                  I-A attached hereto. The Employee shall perform such other
                  tasks and duties as may be reasonably assigned by Nichols
                  TXEN, from time to time.

         3.       Section 5 entitled Fringe Benefits is hereby deleted in its
entirety and a new Section 5 is hereby substituted as follows:
                                   

                  Employee shall participate in any group health insurance,
                  vacation, and sick leave plans, and other benefits available
                  to part-time employees of Nichols TXEN in accordance with
                  their terms and conditions which may be amended or terminated
                  by Nichols TXEN at any time. In addition, the Employee shall
                  be allowed to purchase the prevailing Blue Cross/Blue Shield
                  group coverage offered to full-time employees by directly
                  reimbursing the Company on a monthly basis for the cost of the
                  premiums therefor. Employee may continue this purchase of
                  health care coverage at the applicable monthly insured rate
                  until the plan terminates or until the Employee attains age
                  65, whichever occurs first. If the Employee's spouse is
                  younger than the Employee, then his spouse may continue to
                  purchase such insurance by paying to Nichols TXEN the premium
                  cost for individual coverage until age 65 or until the plan
                  terminates, whichever occurs first. If group health insurance
                  coverage with Blue Cross/Blue Shield is terminated and group
                  health insurance coverage is placed with another insurer,
                  health maintenance organization (HMO), or other provider of
                  such coverage, the Employee and his


   23

                  spouse shall be entitled to obtain health insurance coverage
                  by paying the premium cost therefor in the same manner as
                  permitted with respect to the Blue Cross/Blue Shield plan,
                  provided such insurer, HMO, or other provider approves such
                  participation by Employee and/or his spouse.

         Except as amended above, the Employment Agreement shall remain in full
force and effect according to its terms and conditions.

         IN WITNESS WHEREOF, the parties have hereunto executed this Amendment
Number Two to Employment Agreement on the date and year first above written.

                                          NICHOLS TXEN CORPORATION


                                          By: /s/ PAUL D. REAVES
                                             -----------------------------------
                                             PAUL D. REAVES
                                             Its: Chief Executive Officer

                                          /S/ THOMAS L. PATTERSON
                                          --------------------------------------
                                          Thomas L. Patterson, Employee


                                     - 3 -


   24
                                                                  










                 AMENDMENT NUMBER THREE TO EMPLOYMENT AGREEMENT

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


                            NICHOLS TXEN CORPORATION

                                       AND

                               THOMAS L. PATTERSON

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


                             DATED: NOVEMBER 6, 1998


   25






                             AMENDMENT NUMBER THREE
                                       TO
                              EMPLOYMENT AGREEMENT


         THIS AMENDMENT NUMBER THREE TO EMPLOYMENT AGREEMENT, dated December 16,
1994, as amended August 29, 1997, and June 1, 1998 (the "Employment Agreement"),
is entered into on this the 6th day of November, 1998, by NICHOLS TXEN
CORPORATION, formerly known as NICHOLS SELECT CORPORATION, a Delaware
corporation ("Nichols TXEN"), and THOMAS L. PATTERSON, ("Employee"). Unless
otherwise defined, capitalized terms used herein shall have the meaning ascribed
to such terms in the Employment Agreement or Merger Agreement (hereinafter
defined).

                              W I T N E S S E T H:

         WHEREAS, Nichols Research Corporation ("NRC"), NICHOLS SELECT
CORPORATION ("Nichols Select"), a wholly owned subsidiary of NRC, TXEN, Inc.
("TXEN"), and the holders of all of the $0.002 par value Class A Common Stock of
TXEN (the "Shareholders") entered into and consummated an Agreement of Merger
dated as of August 27, 1997 (the "Merger Agreement") whereby TXEN merged with
and into Nichols Select with Nichols Select as the surviving corporation (the
"Merger");

         WHEREAS, Nichols Select changed its name to Nichols TXEN after the
Merger;

         WHEREAS, Employee entered into the Employment Agreement with TXEN which
has been assumed by Nichols TXEN; and

         WHEREAS, Nichols TXEN and Employee mutually desire to amend the
Employment Agreement;

         NOW, THEREFORE, in consideration of the mutual covenants herein
contained, the undersigned parties do hereby amend the Employment Agreement as
follows:

         1. References in the Employment Agreement to TXEN, Nichols Select or
Select shall mean Nichols TXEN wherever the context requires in light of the
Merger and change in name of Nichols Select to Nichols TXEN.

         2. Section 2 of the Employment Agreement and Section 2 of the August
29, 1997, Amendment to the Employment Agreement are deleted and there is hereby
substituted a new Section 2 of the Employment Agreement, as follows:

            "This Employment Agreement shall commence as of the effective date
            of the Merger Agreement and shall end on the later of

   26

                           (i)      August 28, 1999; or
                           (ii)     Two years after the date a registration
                                    statement initially registering the
                                    Company's common stock under the Securities
                                    Act of 1933 is declared effective by the
                                    Securities and Exchange Commission, provided
                                    such registration statement is declared
                                    effective before August 28, 1999.

                           The period between the commencement date and the
                           termination date as set forth above shall be the
                           `Term of Employment,' unless terminated earlier or
                           extended as provided herein. Upon expiration of the
                           initial Term of Employment unless earlier terminated
                           as provided herein, the Term of Employment shall
                           continue automatically month-to-month until
                           terminated by either party with at least thirty (30)
                           days prior written notice with or without cause."

         3. This Amendment is effective on the date hereof.

         4. Except as amended above, the Employment Agreement shall remain in
full force and effect according to its terms and conditions.

         IN WITNESS WHEREOF, the parties have hereunto executed this Amendment
Number Three to Employment Agreement on the date and year first above written.

                                       NICHOLS TXEN CORPORATION


                                       By: /s/ Paul D. Reaves
                                          -------------------------------------
                                           PAUL D. REAVES
                                           Its:  Chief Executive Officer

                                          /s/ Thomas L. Patterson
                                          -------------------------------------
                                          Thomas L. Patterson, Employee