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                                                                   EXHIBIT 10.1


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                                CREDIT AGREEMENT


                                  Dated as of


                               December 15, 1995


                                     Among


                         LANDMARK GRAPHICS CORPORATION,


                          THE LENDERS PARTIES HERETO,


                                      AND


                      ABN AMRO BANK N.V., HOUSTON AGENCY,
                                    AS AGENT


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                               TABLE OF CONTENTS
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SECTION 1.  DEFINITIONS; INTERPRETATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   1
         Section 1.1      Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   1
         Section 1.2      Interpretation  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  11

SECTION 2.  THE CREDIT FACILITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  12
         Section 2.1      Borrowings  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  12
         Section 2.2      Letters of Credit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  12
         Section 2.3      Types of Loans and Minimum Borrowing Amounts  . . . . . . . . . . . . . . . . . . . . . . .  15
         Section 2.4      Manner of Borrowing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  15
         Section 2.5      Interest Periods  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  17
         Section 2.6      Maturity of Loans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  17
         Section 2.7      Applicable Interest Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  17
         Section 2.8      Default Rate  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  18
         Section 2.9      Mandatory Prepayments of Loans  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  19
         Section 2.10     Optional Prepayments  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  19
         Section 2.11     The Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  20
         Section 2.12     Breakage Fees . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  20
         Section 2.13     Commitment Terminations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  21

SECTION 3.       FEES AND PAYMENTS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  21
         Section 3.1      Fees  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  21
         Section 3.2      Place and Application of Payments . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  22
         Section 3.3      Withholding Taxes   . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  22

SECTION 4.       CONDITIONS PRECEDENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  23
         Section 4.1      Initial Borrowing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  24
         Section 4.2      All Borrowings  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  25

SECTION 5.       REPRESENTATIONS AND WARRANTIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  26
         Section 5.1      Corporate Organization  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  26
         Section 5.2      Corporate Power and Authority; Validity . . . . . . . . . . . . . . . . . . . . . . . . . .  26
         Section 5.3      No Violation  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  26
         Section 5.4      Litigation  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  26
         Section 5.5      Use of Proceeds; Margin Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . .  27
         Section 5.6      Investment Company Act  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  27
         Section 5.7      Public Utility Holding Company Act  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  27
         Section 5.8      True and Complete Disclosure  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  27
         Section 5.9      Financial Statements  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  27
         Section 5.10     No Material Adverse Change  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
         Section 5.11     Labor Controversies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
         Section 5.12     Taxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
         Section 5.13     ERISA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
         Section 5.14     Consents  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
         Section 5.15     Capitalization  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
         Section 5.16     Intellectual Property . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  29
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         Section 5.17     Compliance with Statutes, Etc.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  29
         Section 5.18     Environmental Matters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  29
         Section 5.19     Existing Indebtedness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  29

SECTION 6.       COVENANTS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  29
         Section 6.1      Corporate Existence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  29
         Section 6.2      Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  30
         Section 6.3      Taxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  30
         Section 6.4      ERISA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  30
         Section 6.5      Insurance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  30
         Section 6.6      Financial Reports and Other Information . . . . . . . . . . . . . . . . . . . . . . . . . .  30
         Section 6.7      Lender Inspection Rights  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  32
         Section 6.8      Conduct of Business . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  32
         Section 6.9      Fiscal Years and Quarters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  32
         Section 6.10     Interest Rate Protection  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  32
         Section 6.11     New Subsidiaries  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  33
         Section 6.12     Limitation on Certain Restrictions on Subsidiaries; Dividends; Negative Pledges . . . . . .  33
         Section 6.13     Restrictions on Fundamental Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . .  33
         Section 6.14     Use of Property and Facilities; Environmental, Health and Safety Laws . . . . . . . . . . .  34
         Section 6.15     Liens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  34
         Section 6.16     Indebtedness  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  36
         Section 6.17     Advances, Investments, Loans and Guaranties . . . . . . . . . . . . . . . . . . . . . . . .  37
         Section 6.18     Modifications of Corporate Documents  . . . . . . . . . . . . . . . . . . . . . . . . . . .  38
         Section 6.19     Transfer of Assets  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  39
         Section 6.20     Transactions with Affiliates  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  39
         Section 6.21     Compliance with Laws  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  39
         Section 6.22     Assets of Foreign Subsidiaries  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  40
         Section 6.23     Fixed Charge Coverage Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  40
         Section 6.24     Total Funded Debt to EBITDA Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  40
         Section 6.25     Minimum Adjusted Net Worth  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  40

SECTION 7.       EVENTS OF DEFAULT AND REMEDIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  40
         Section 7.1      Events of Default . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  40
         Section 7.2      Non-Bankruptcy Defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  42
         Section 7.3      Bankruptcy Defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  42
         Section 7.4      Collateral for Undrawn Letters of Credit  . . . . . . . . . . . . . . . . . . . . . . . . .  43
         Section 7.5      Notice of Default . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  43
         Section 7.6      Expenses  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  43
         Section 7.7      Distribution and Application of Proceeds  . . . . . . . . . . . . . . . . . . . . . . . . .  43
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SECTION 8.       CHANGE IN CIRCUMSTANCES  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  44
         Section 8.1      Change of Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  44
         Section 8.2      Unavailability of Deposits or Inability to Ascertain LIBO Rate  . . . . . . . . . . . . . .  45
         Section 8.3      Increased Cost and Reduced Return . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  45
         Section 8.4      Lending Offices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  46
         Section 8.5      Discretion of Lender as to Manner of Funding  . . . . . . . . . . . . . . . . . . . . . . .  47
         Section 8.6      Substitution of Lender  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  47

SECTION 9.       THE AGENT  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  47
         Section 9.1      Appointment and Authorization of Agent  . . . . . . . . . . . . . . . . . . . . . . . . . .  47
         Section 9.2      Agent and its Affiliates  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  47
         Section 9.3      Action by Agent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  47
         Section 9.4      Consultation with Experts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  48
         Section 9.5      Liability of Agent; Credit Decision . . . . . . . . . . . . . . . . . . . . . . . . . . . .  48
         Section 9.6      Indemnity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  48
         Section 9.7      Resignation of Agent and Successor Agent  . . . . . . . . . . . . . . . . . . . . . . . . .  49

SECTION 10.      MISCELLANEOUS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  49
         Section 10.1     No Waiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  49
         Section 10.2     Non-Business Day  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  49
         Section 10.3     Documentary Taxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  49
         Section 10.4     Survival of Representations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  50
         Section 10.5     Survival of Indemnities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  50
         Section 10.6     Setoff  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  50
         Section 10.7     Notices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  50
         Section 10.8     Counterparts  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  51
         Section 10.9     Successors and Assigns  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  51
         Section 10.10    Sales and Transfers of Borrowings and Notes; Participations in Borrowings and Notes . . . .  52
         Section 10.11    Amendments, Waivers and Consents  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  54
         Section 10.12    Headings  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  54
         Section 10.13    Legal Fees, Other Costs and Indemnification . . . . . . . . . . . . . . . . . . . . . . . .  54
         Section 10.14    Governing Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  55
         Section 10.15    Binding Arbitration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  55
         Section 10.16    DTPA Waiver.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  56
         Section 10.17    Confidentiality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  57
         Section 10.18    Effectiveness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  57
         Section 10.19    Severability  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  57
         Section 10.20    Notice  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  57
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                               TABLE OF CONTENTS
                                  (CONTINUED)


EXHIBITS

         2.2     -    Form of Issuance Request
         2.4     -    Form of Borrowing Request
         2.6     -    Form of Certificate of Extension
         2.11    -    Form of Promissory Note
         4.1A    -    Form of Guaranty
         4.1B    -    Form of Legal Opinion
         6.6     -    Form of Compliance Certificate
         6.13    -    Form of Acquisition Report
         10.10   -    Form of Assignment Agreement

SCHEDULES

         5.1     -    List of Subsidiaries
         5.13    -    ERISA Disclosures
         5.18    -    Environmental Disclosures
         5.19    -    List of Existing Indebtedness
         6.17    -    List of Existing Investments






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         CREDIT AGREEMENT (the "Agreement"), dated as of December 15, 1995,
among Landmark Graphics Corporation (the "Borrower"), a Delaware corporation,
the lenders from time to time parties hereto (each a "Lender" and collectively,
the "Lenders") and ABN AMRO Bank N.V. ("ABN AMRO"), a Netherlands chartered
bank acting through its Houston agency, as agent for the Lenders (in such
capacity, the "Agent").

                                  WITNESSETH:

         WHEREAS, the Borrower desires to obtain commitments from each of the
Lenders to make loans to the Borrower and to participate in letters of credit
for the account of the Borrower; and

         WHEREAS, the Lenders are willing to extend such commitments to the
Borrower on the terms and subject to the conditions hereinafter set forth;

         NOW, THEREFORE, in consideration of the premises and of the mutual
covenants herein contained, the parties hereto agree as follows:

SECTION 1.  DEFINITIONS; INTERPRETATION.

         Section 1.1.     Definitions.  Unless otherwise defined herein, the
following terms used in this Agreement shall have the following meanings, which
meanings shall be equally applicable to both the singular and plural form of
such terms:

         "Acquisition" means a direct or indirect purchase by the Borrower or
any of its Subsidiaries after the date hereof for cash, stock or other
securities or other property, whether in one or more related transactions, of
all or substantially all of the assets or voting securities or other equity
interests of a Person or a business unit, division or group of a Person.

         "Adjusted LIBO" means, for any Borrowing of Eurodollar Loans, a rate
per annum determined in accordance with the following formula:

         Adjusted LIBO    =                             LIBO
                                               ---------------------
                                    100% - Eurodollar Reserve Percentage

         "Adjusted Net Worth" means as of any date, the sum of (i) Consolidated
Net Worth, (ii) goodwill amortization and non-cash, non-recurring write-offs,
each associated with an Acquisition, and (iii) merger costs associated with an
Acquisition expensed under the pooling of interest method of acquisition
accounting, subject to a limitation of five percent (5%) of the purchase price
thereof, all as determined in accordance with GAAP.

         "Affiliate" means for any Person,(i) any other Person that directly or
indirectly through one or more intermediaries controls, or is under common
control with, or is controlled by, such Person, and (ii) any other Person
owning beneficially or controlling 25% or more of the equity interests in such
Person.  As used in this definition, "control" means the power, directly or





                                      1
<PAGE>   7
indirectly, to direct or cause the direction of management or policies of a
Person (through ownership of voting securities or other equity interests, by
contract or otherwise).

         "Agent" means ABN AMRO Bank N.V., a Netherlands chartered bank acting
through its Houston agency, acting in its capacity as agent for the Lenders and
any successor agent appointed hereunder pursuant to Section 9.7.

         "Applicable Margin" means at such times and from time to time as the
relevant Total Funded Debt to EBITDA Ratio is in one of the following ranges,
the percentage per annum set forth opposite such Total Funded Debt to EBITDA
Ratio:

             Total Funded Debt to EBITDA Ratio                   Percentage
             ---------------------------------                   ----------
                                                                           
             Equal to or greater than 2.0 to 1.0                  1.00%    
             Less than 2.0 to 1.0                                 0.75%    
               but equal to or greater than 1.0 to 1.0                     
             Less than 1.0 to 1.0                                 0.625%   
                                                             
The Borrower shall give written notice to the Agent of any changes in the Total
Funded Debt to EBITDA Ratio as of the end of any calendar quarter which results
in a change to the Applicable Margin on or before forty-five (45) days after
the end of such calendar quarter, and any change to the Applicable Margin shall
be effective as of the forty-fifth day after the end of such calendar quarter.

         "Assignment Agreement" means an agreement in substantially the form of
Exhibit 10.10 whereby a Lender conveys part or all of its Commitments, Loans
and participations in Letters of Credit to another Person that thereupon
becomes a Lender, or increases its Commitments, outstanding Loans and
outstanding participations in Letters of Credit pursuant to Section 10.10.

         "Base Rate" means for any day the greater of:

                 (i)      the fluctuating commercial loan rate announced by the
Agent from time to time at its Chicago, Illinois office as its base rate for
U.S. Dollar loans in the United States of America in effect on such day (which
base rate may not be the lowest rate charged by the Agent on loans to any of
its customers), with any change in the Base Rate resulting from a change in
such announced rate to be effective on the date of the relevant change; and

                 (ii)     the sum of (x) the rate per annum (rounded upwards,
if necessary, to the nearest 1/16th of 1%) equal to the weighted average of the
rates on overnight federal funds transactions with members of the Federal
Reserve System arranged by federal funds brokers on such day, as published by
the Federal Reserve Bank of New York on the next Business Day, provided that
(A) if such day is not a Business Day, the rate on such transactions on the
immediately preceding Business Day as so published on the next Business Day
shall apply, and (B) if no such rate is published on such next Business Day,
the rate for such day shall be the average of the offered rates quoted to the
Agent by two (2) federal funds brokers of recognized


                                      2
<PAGE>   8
standing on such day for such transactions as selected by the Agent, plus (y)
1/2 of 1% (0.50%) per annum.

         "Base Rate Loan" means a Loan bearing interest prior to maturity at
the rate specified in Section 2.7(b).

         "Borrower" means Landmark Graphics Corporation, a Delaware
corporation.

         "Borrowing" means any extension of credit made by the Lenders by way
of Loans or Letters of Credit, including any Borrowings advanced, continued or
converted.  A Borrowing is "advanced" on the day Lenders advance funds
comprising such Borrowing to the Borrower, is "continued" (in the case of
Eurodollar Loans) on the date a new Interest Period commences for such
Borrowing, and is "converted" when such Borrowing is changed from one type of
Loan to the other, all as requested by the Borrower pursuant to Section 2.4(a).

         "Business Day" means any day other than a Saturday or Sunday on which
banks are not authorized or required to close in Houston, Texas, or New York,
New York and, if the applicable Business Day relates to the advance or
continuation of, conversion into, or payment on a Eurodollar Borrowing, on
which banks are dealing in United States Dollar deposits in the interbank
market in London, England.

         "Capitalized Lease Obligations" means, for any Person, the amount of
such Person's liabilities under all leases of real or personal property (or any
interest therein) which is required to be capitalized on the balance sheet of
such Person as determined in accordance with GAAP.

         "Cash Equivalents" means (i) securities issued or directly and fully
guaranteed or insured by the United States of America or any agency or
instrumentality thereof having maturities of not more than twelve (12) months
from the date of acquisition, (ii) U.S. dollar denominated time deposits,
certificates of deposit and bankers acceptances of any Lender, or of any bank
whose short-term senior unsecured debt rating from S&P is at least A or at
least A2 by Moody's, with maturities of not more than twelve (12) months from
the date of acquisition, (iii) commercial paper or Eurocommercial paper with a
rating of at least A-1 by S&P or at least P-1 by Moody's maturing within six
(6) months from the date of acquisition, (iv) repurchase obligations entered
into with any Lender, or any other Person whose senior unsecured debt rating is
at least A by S&P or at least A2 by Moody's, which is secured by a fully
perfected security interest in any obligation of the type described in clause
(i) above and has a market value at the time such repurchase agreement is
entered into of not less than 100% of the repurchase obligation of such Lender
or such other Person thereunder, (v) adjustable rate preferred stock issued by
any Person whose senior unsecured debt rating is at least A by S&P or at least
A2 by Moody's; (vi) tax-free variable rate demand notes whose rating is at
least A by S&P or at least A2 by Moody's, and (vii) money market funds which
have at least $1,000,000,000 in assets and which invest in securities of the
types described in clauses (i) through (vi) above.

         "Code" means the Internal Revenue Code of 1986, as amended.





                                      3
<PAGE>   9
         "Collateral Account" means the cash collateral account for outstanding
undrawn Letters of Credit defined in Section 7.4(b).

         "Commitment" means, relative to any Lender, such Lender's obligation
to make Loans pursuant to Section 2.1 and each Lender's L/C Commitment, as such
commitments may be reduced from time to time pursuant to this Agreement.

         "Commitment Amount" means an amount equal to $100,000,000, as such
amount may be reduced from time to time pursuant to the terms of this
Agreement.

         "Commitment Termination Date" means the earliest of (i) December 15,
1998, as such date may from time to time be extended pursuant to Section 2.6,
(ii) the date on which the Commitments are terminated in full or reduced to
zero pursuant to Section 2.13, or (iii) the occurrence of any Event of Default
described in Section 7.1(f) or (g) or the occurrence and continuance of any
other Event of Default and either (x) the declaration of the Loans to be due
and payable pursuant to Section 7.2, or (y) in the absence of such declaration,
the giving of written notice by the Agent, acting at the direction of the
Majority Lenders, to the Borrower that the Commitments have been terminated.

         "Compliance Certificate" means a certificate in the form of Exhibit
6.6.

         "Consolidated Net Income" means, for any period, the net income (or
loss), after provision for taxes, of the Borrower and its Subsidiaries on a
consolidated basis, determined in accordance with GAAP.

         "Consolidated Net Worth" means as of any date, the sum of the
Borrower's common and preferred stock and additional paid-in capital, plus
retained earnings (minus accumulated deficit), all as shown on the consolidated
balance sheet of the Borrower and its Subsidiaries and determined in accordance
with GAAP.

         "Credit" means the credit facility for making Loans and issuing
Letters of Credit described in Sections 2.1 and 2.2.

         "Credit Documents" means this Agreement, the Notes, the Letters of
Credit, the Subsidiary Guaranties and any other documents or instruments
executed by a Credit Party in connection with this Agreement.

         "Credit Party" means the Borrower and each Guarantor.

         "Default" means any event or condition the occurrence of which would,
with the passage of time or the giving of notice, or both, constitute an Event
of Default.

         "EBITDA" means, for any period, (i) Consolidated Net Income, plus (ii)
consolidated interest expense, plus (iii) the amount of all depreciation and
amortization expense deducted in determining Consolidated Net Income, plus (iv)
provisions for taxes based on income, plus (v)





                                      4
<PAGE>   10
non-recurring non-cash write-offs and non-cash merger costs from Acquisitions,
plus (vi) cash merger costs of an Acquisition expensed under the pooling of
interest method of acquisition accounting, subject to a limitation of five
percent (5%) of the purchase price thereof, plus (vii) extraordinary losses,
minus (viii) consolidated interest income, minus (ix) extraordinary gains, all
as determined in accordance with GAAP.

         "Effective Date" means the date this Agreement shall become effective
as defined in Section 10.18.

         "Environmental Claims" means any and all administrative, regulatory or
judicial actions, suits, demands, demand letters, claims, liens, notices of
non-compliance or violation, investigations or proceedings relating to any
Environmental Law ("Claims") or any permit issued under any Environmental Law,
including, without limitation, (a) any and all Claims by governmental or
regulatory authorities for enforcement, cleanup, removal, response, remedial or
other actions or damages pursuant to any applicable Environmental Law, and (b)
any and all Claims by any third party seeking damages, contribution,
indemnification, cost recovery, compensation or injunctive relief resulting
from Hazardous Materials or arising from alleged injury or threat of injury to
health, safety or the environment.

         "Environmental Law" means any federal, state or local statute, law,
rule, regulation, ordinance, code, policy or rule of common law now or
hereafter in effect, including any judicial or administrative order, consent,
decree or judgment relating to the environment, health, safety or Hazardous
Materials.

         "ERISA" means the Employee Retirement Income Security Act of 1974, as
amended.

         "Eurodollar Loan" means a Loan bearing interest before maturity at the
rate specified in Section 2.7(a).

         "Eurodollar Reserve Percentage" means, for any Borrowing of Eurodollar
Loans, the daily average for the applicable Interest Period of the maximum rate
at which reserves (including, without limitation, any supplemental, marginal
and emergency reserves) are imposed during such Interest Period by the Board of
Governors of the Federal Reserve System (or any successor) on "Eurocurrency
Liabilities", as defined in such Board's Regulation D (or in respect of any
other category of liabilities that includes deposits by reference to which the
interest rate on Eurodollar Loans is determined), subject to any amendments of
such reserve requirement by such Board or its successor, taking into account
any transitional adjustments thereto.

         "Event of Default" means any of the events or circumstances specified
in Section 7.1.

         "Fixed Charge Coverage Ratio" shall be calculated for any period on a
historic rolling four-quarter basis as the ratio of (a) EBITDA minus
capitalized research and development expenditures to (b) the sum of Fixed
Charges.  For purposes of calculating this ratio, (a) any Net Cash Proceeds
received from permitted Transfers to Persons other than the Borrower or any of
its Subsidiaries of any fixed or capital assets shall be netted against the
purchase price of any





                                      5
<PAGE>   11
fixed or capital assets purchased from Persons other than the Borrower or any
of its Subsidiaries during any fiscal quarter, and (b) the purchase price of
any fee interest in real property purchased by the Borrower or any of its
domestic Subsidiaries during any fiscal quarter shall be excluded if, and only
if, all Lenders elect in their sole discretion to obtain a Lien upon such
property pursuant to the provisions of Section 6.15(m).

         "Fixed Charges" means, without duplication, (i) scheduled principal
amortization of Indebtedness and required prepayments pursuant to Section 2.9,
plus (ii) all consolidated cash interest expense, minus (iii) consolidated
interest income, plus (iv) all expenditures for fixed or capital assets which
in accordance with GAAP would be classified as capital expenditures, plus (v)
principal payments of Capitalized Lease Obligations, plus (vi) all cash income
taxes paid, plus (vii) all cash distributions or dividends paid, all as
determined in accordance with GAAP.

         "GAAP" means generally accepted accounting principles from time to
time in effect, applied in a manner consistent with those used in the
preparation of the audited financial statements for the fiscal year ending June
30, 1995, referred to in Section 5.9.

         "Guarantors" all Material Subsidiaries which execute Subsidiary
Guaranties.

         "Guaranty" by any Person means all obligations (other than
endorsements in the ordinary course of business of negotiable instruments for
deposit or collection) of such Person guaranteeing or in effect guaranteeing
any Indebtedness, dividend or other obligation (including, without limitation,
obligations in connection with sales of any property) of any other Person (the
"primary obligor") in any manner, whether directly or indirectly, including,
without limitation, all obligations incurred through an agreement, contingent
or otherwise, by such Person: (i) to purchase such Indebtedness or obligation
or any property or assets constituting security therefor, (ii) to advance or
supply funds (x) for the purchase or payment of such Indebtedness or
obligation, or (y) to maintain working capital or other balance sheet
condition, or otherwise to advance or make available funds for the purchase or
payment of such Indebtedness or obligation, or (iii) to lease property or to
purchase securities or other property or services primarily for the purpose of
assuring the owner of such Indebtedness or obligation of the ability of the
primary obligor to make payment of the Indebtedness or obligation, or (iv)
otherwise to assure the owner of the Indebtedness or obligation of the primary
obligor against loss in respect thereof.  For the purpose of all computations
made under this Agreement, the amount of a Guaranty in respect of any
obligation shall be deemed to be equal to the maximum aggregate amount of such
obligation or, if the Guaranty is limited to less than the full amount of such
obligation, the maximum aggregate potential liability of such Person under the
terms of the Guaranty.

         "Hazardous Material" means (a) any asbestos, PCBs or dioxins or
insulation or other material composed of or containing asbestos, PCBs or
dioxins and (b) any petroleum product and any chemical, material or other
substance defined as "hazardous" or "toxic" or words with similar meaning and
effect under any Environmental Law.

         "Highest Lawful Rate" shall mean the maximum nonusurious interest
rate, if any, that any time or from time to time may be contracted for, taken,
reserved, charged or received on





                                      6
<PAGE>   12
the Loans under laws applicable to any of the Lenders which are presently in
effect or, to the extent allowed by applicable law, under such laws which may
hereafter be in effect and which allow a higher maximum nonusurious interest
rate than applicable laws now allow.  Determination of the rate of interest for
the purpose of determining whether the Loans are usurious under all applicable
laws shall be made by amortizing, prorating, allocating, and spreading, in
equal parts during the period of the full stated term of the Loans, all
interest at any time contracted for, taken, reserved, charged or received from
the Borrower in connection with the Loans.

         "Indebtedness" means, for any Person, the following obligations of
such Person, without duplication:  (i) obligations of such Person for borrowed
money; (ii) obligations of such Person representing the deferred purchase price
of property or services other than accounts payable arising in the ordinary
course of business; (iii) obligations of such Person evidenced by bonds, notes,
acceptances, debentures or other similar instruments of such Person or arising
out of letters of credit and banker's acceptances issued for such Person's
account; (iv) obligations of other Persons, whether or not assumed, secured by
Liens upon property or payable out of the proceeds or production from property
now or hereafter owned or acquired by such Person, but only to the extent of
such property's fair market value; (v) Capitalized Lease Obligations of such
Person and all obligations of such Person as lessee of real or personal
property (or any interest therein) under an operating lease entered into other
than in the ordinary course of business and intended as a disguised financing;
(vi) obligations under Interest Rate Protection Agreements, commodity hedge,
commodity swap, exchange, forward, future, collar or cap arrangements, fixed
price agreements and all other agreements or arrangements designed to protect
against fluctuations in commodity prices, and futures agreements, arrangements
or options designed to protect against fluctuations in currency exchange rates;
and (vii) obligations of such Person pursuant to a Guaranty of any of the
foregoing.  For purposes of this Agreement, the Indebtedness of any Person
shall include the Indebtedness of any partnership or joint venture in which
such Person is a general partner or joint venturer.

         "Initial Borrowing Date" means the date on which all conditions
precedent set forth herein to the initial Borrowings are satisfied or waived in
writing.

         "Interest Payment Date" means (a) for a Base Rate Loan, the last
Business Day of each calendar quarter such Loan is outstanding commencing
December 31, 1995, and (b) for a Eurodollar Loan, the last Business Day of each
Interest Period for such Loan (and, if the Interest Period shall exceed three
(3) months, on the Business Day occurring every three (3) months after the
commencement of such Interest Period).

         "Interest Period" means the period commencing on the date that a
Borrowing of Eurodollar Loans is advanced, continued or created by conversion
and ending on the date 1, 3, 6, or (if available from all the Lenders) 12
months thereafter as selected by the Borrower pursuant to the terms of this
Agreement.





                                      7
<PAGE>   13
         "Interest Rate Protection Agreement" shall mean any interest rate
swap, interest rate cap, interest rate collar, or other interest rate hedging
agreement or arrangement designed to protect against fluctuations in interest
rates.

         "L/C Commitments" means the commitments of the Lenders to participate
in the Letters of Credit pursuant to Section 2.2 in the percentages set forth
opposite their signatures hereto or pursuant to Section 10.10, as such
commitments may be reduced from time to time pursuant to this Agreement.

         "L/C Commitment Amount" means $15,000,000, as such amount may be
reduced from time to time pursuant to the terms of this Agreement.

         "L/C Documents" means the Letters of Credit, any Issuance Requests
with respect thereto or any draft or other document presented in connection
with a drawing thereunder and this Agreement.

         "L/C Obligations" means the undrawn face amounts of all outstanding
Letters of Credit and all unpaid Reimbursement Obligations.

         "Lender" means each Lender with a Commitment.

         "Lending Office" means the branch, office or affiliate of a Lender
specified on the appropriate signature page hereof, or designated pursuant to
Section 8.4.

         "Letter of Credit" means any of the letters of credit to be issued by
the Agent on behalf of the Lenders for the account of the Borrower pursuant to
Section 2.2(a).

         "LIBO Rate" means, for an Interest Period, a rate of interest per
annum (rounded upwards, if necessary, to the nearest whole multiple of 1/16 of
1%), equal to the arithmetic mean of the rates of interest per annum appearing
on Telerate Page 3750 (or any successor publication) two (2) Business Days
before the commencement of such Interest Period at or about 11:00 a.m. (London,
England time) for a period equal to such Interest Period and in an amount equal
or comparable to the principal amount of the Eurodollar Loan scheduled to be
made by the Agent as part of such Borrowing.  If for any reason rates are not
published as provided herein, the rate to be used shall be the rate per annum
at which U.S. Dollar deposits are offered to the Agent in the London interbank
eurodollar currency market two (2) Business Days prior to the commencement of
such Interest Period at or about 11:00 a.m. (London, England time) for a period
equal to such Interest Period and in an amount equal or comparable to the
principal amount of the Eurodollar Loan scheduled to be made by the Agent as
part of such Borrowing.

         "Lien" means any interest in any property or asset securing an
obligation owed to, or a claim by, a Person other than the owner of the
property or asset, whether such interest is based on the common law, statute or
contract, including, but not limited to, the lien arising from a mortgage,
encumbrance, pledge, conditional sale, security agreement, escrow arrangement
or trust receipt, or a lease, consignment or bailment for security purposes.





                                      8
<PAGE>   14
         "Loan" mean a Base Rate Loan or Eurodollar Loan, each of which is a
"type" of Loan hereunder.

         "Majority Lenders" means, at any time, Lenders then holding in the
aggregate at least fifty-one percent (51%) of the (a) the Commitment Amount or
(b) if the Commitments have terminated pursuant to the terms hereof, the
aggregate Obligations plus the undrawn face amounts of all outstanding Letters
of Credit.  The percentage set forth opposite each Lender's name on the
signature page hereto reflects the initial voting percentage of each Lender on
the Effective Date.

         "Material Adverse Effect" means a material adverse effect on the
business, properties or financial condition of the Borrower or the Borrower and
its Subsidiaries taken as a whole or on the ability of the Borrower or the
Borrower and the Guarantors (taken as a whole) to perform their Obligations
under this Agreement, the Notes or the other Credit Documents to which they are
a party.

         "Material Subsidiaries" means Munro Garrett International, Inc., a
Texas corporation, Geographix, Inc., a Colorado corporation, LMK Land Company,
a Delaware corporation, Landmark Graphics Europe/Africa, Inc., a Delaware
corporation, Landmark Graphics International, Inc., a Texas corporation,
Landmark America Latina, S.A., a Delaware corporation, and MGI Associates,
Inc., a Texas corporation, and any other domestic Subsidiary of the Borrower
which either has or acquires total assets of at least $3,500,000 or is the
direct or indirect domestic parent company of any foreign Subsidiary of the
Borrower which has or acquires total assets of at least $3,500,000.

         "Maturity Date" means December 15, 1998, as the same may be extended
pursuant to Section 2.6.

         "Moody's" means Moody's Investors Service, Inc., or any successor
thereto.

         "NationsBank" means NationsBank of Texas, N.A.

         "NationsBank Credit Facility" means that certain Letter Loan Agreement
dated as of October 31, 1994, among NationsBank, the Borrower, LMK Land
Company, Landmark America Latina, S.A., Landmark Graphics International, Inc.,
Landmark Graphics Europe/Africa, Inc., Landmark/ITA Ltd., Landmark/CAEX, Inc.,
Landmark Finance Corporation, CAEX Services, Inc. and MGI Associates, Inc., as
heretofore amended.

         "Net Cash Proceeds" means for any Transfer of an asset (including any
sale and leaseback of assets and any sale of accounts receivable), the cash
proceeds (including any cash payments actually received as a deferred payment
of principal pursuant to a note, installment receivable, purchase price
adjustment receivable or otherwise) of such Transfer net of (x) all legal fees,
accountant fees, investment banking fees, brokerage fees, survey costs, title
insurance premiums, required debt payments (other than pursuant hereto) and
other customary fees and expenses actually incurred and documented in
connection therewith, (y) taxes paid or payable





                                      9
<PAGE>   15
as a result thereof, and (z) purchase price adjustments reasonably expected to
be payable in connection therewith.

         "Note" means any of the promissory notes of the Borrower as defined in
Section 2.11.

         "Obligations" means all obligations of the Borrower to pay fees, costs
and expenses hereunder, to pay principal or interest on Loans and Reimbursement
Obligations and to pay any other obligations to the Agent or any Lender arising
under or in relation to any Credit Document, and all obligations of any other
Credit Party to make any payment or reimburse any fees, costs or expenses to
the Agent or any Lender arising under or in relation to any Credit Document.

         "PBGC" means the Pension Benefit Guaranty Corporation.

         "Percentage" means, for each Lender, the percentage of the Commitments
represented by such Lender's Commitment; provided that, if the Commitments are
terminated, each Lender's Percentage shall be calculated based on its
Commitment in effect immediately before such termination, subject to any
assignments by such Lender of Obligations pursuant to Section 10.10.

         "Permitted Liens" are the Liens defined in Section 6.15.

         "Person" means an individual, partnership, corporation, limited
liability company, association, trust, unincorporated organization or any other
entity or organization, including a government or any agency or political
subdivision thereof.

         "Plan" means an employee pension benefit plan covered by Title IV of
ERISA or subject to the minimum funding standards under Section 412 of the Code
that is either (i) maintained by the Borrower or any of its Subsidiaries, or
(ii) maintained pursuant to a collective bargaining agreement or any other
arrangement under which more than one employer makes contributions and to which
the Borrower or any of its Subsidiaries is then making or accruing an
obligation to make contributions or has within the preceding five (5) plan
years made or had an obligation to make contributions.

         "Reimbursement Obligation" means the obligations of the Borrower to
reimburse the Agent for each drawing under a Letter of Credit as described in
Section 2.2(c).

         "SEC" means the Securities and Exchange Commission.

         "S&P" means Standard & Poor's Rating Services, and any successor
thereto.

         "Security" has the same meaning as in Section 2(1) of the Securities
Act of 1933, as amended.

         "Subsidiary" means, for the Borrower, any corporation, limited
liability company or other entity of which more than fifty percent (50%) of the
outstanding stock or comparable       




                                      10
<PAGE>   16
equity interests having ordinary voting power for the election of the Board of
Directors of such corporation, the Managers of such limited liability company,
or similar governing body in the case of a non-corporation (irrespective of
whether or not, at the time, stock or other equity interests of any other class
or classes of such corporation, limited liability company or other entity shall
have or might have voting power by reason of the happening of any contingency)
is at the time directly or indirectly owned by the Borrower or by one or more
of its Subsidiaries.

         "Subsidiary Guaranties" means the Guaranties of the Material
Subsidiaries wherein the Material Subsidiaries guaranty the Borrower's
Obligations to the Agent and the Lenders, as such Guaranties are amended from
time to time.

         "Total Funded Debt" means, as of any date, on a consolidated basis for
the Borrower and its Subsidiaries, the sum of (i) indebtedness for borrowed
money, all obligations evidenced by bonds, debentures, notes or similar
instruments, and obligations to pay the deferred purchase price of property
which in accordance with GAAP would be shown on the consolidated balance sheet
as a liability, (ii) all obligations, contingent or otherwise, relative to the
face amount of letters of credit and banker's acceptances, and (iii) all
obligations as lessee under leases which are required to be recorded as
Capitalized Lease Obligations in accordance with GAAP.

         "Total Funded Debt to EBITDA Ratio" shall be calculated for any period
on a historic rolling four-quarter basis as the ratio of (a) Total Funded Debt
as of the last day of the calendar quarter to (b) EBITDA for the four quarters
then ended.

         "Transfer" means a sale, transfer, conveyance, assignment or other
disposition, including, without limitation, any transfer pursuant to an option
to purchase, any sale or assignment (with or without recourse) of any accounts
receivable and any sale and leaseback of assets, of an asset having a net book
value in excess of $100,000, but excluding any involuntary transfer by
operation of law, damage or destruction.

         "Unfunded Vested Liabilities" means, for any Plan at any time, the
amount (if any) by which the present value of all vested nonforfeitable accrued
benefits under such Plan exceeds the fair market value of all Plan assets
allocable to such benefits, all determined as of the then most recent valuation
date for such Plan, but only to the extent that such excess represents a
potential liability of the Borrower or any of its Subsidiaries to the PBGC or
the Plan.

         Section 1.2.  Interpretation.  The foregoing definitions shall be
equally applicable to the singular and plural forms of the terms defined.  All
references to times of day in this Agreement shall be references to Houston,
Texas time unless otherwise specifically provided.  All accounting terms used
herein or in any other Credit Document shall be interpreted, all accounting
determinations and computations hereunder or thereunder shall be made, and all
financial statements required to be delivered hereunder or thereunder shall be
prepared in accordance with GAAP applied in the preparation of the financial
statements referred to in Section 5.9.





                                      11
<PAGE>   17



SECTION 2.  THE CREDIT FACILITY.

         Section 2.1.     Borrowings.  Subject to the terms and conditions
hereof, each Lender severally and not jointly agrees to make one or more loans
(each a "Loan") to the Borrower from time to time before the Commitment
Termination Date on a revolving basis up to the amount of its commitment set
forth on the applicable signature page hereof or pursuant to Section 10.10 (for
each Lender, its "Commitment"), subject to any reductions thereof pursuant to
the terms of this Agreement.  No Lender shall be permitted or required to make
any Loan if, after giving effect thereto, (a) the aggregate principal amount of
the Loans of all Lenders, the undrawn face amounts of all Letters of Credit and
all Reimbursement Obligations outstanding of the Borrower hereunder would
exceed the Commitment Amount then in effect; or (b) all Loans of such Lender
would exceed the Percentage of such Lender of the Commitment Amount then in
effect.  Each Borrowing of Loans shall be made ratably from the Lenders in
proportion to their respective Percentages.  Loans may be repaid and all or any
portion of the principal amount reborrowed before the Maturity Date, subject to
the terms and conditions hereof.  Funding of any Loans shall be in U.S.
Dollars.

         Section 2.2.     Letters of Credit. (a) Letters of Credit.   Subject
to the terms and conditions hereof, the Agent agrees to issue, on behalf of the
Lenders and in reliance on their obligations under this Section 2.2, one or
more letters of credit (each a "Letter of Credit") for the Borrower's account
in an aggregate undrawn face amount at any time outstanding not to exceed the
L/C Commitment Amount on or before the Commitment Termination Date (subject to
Section 2.2(b)); provided that the Agent shall have no obligation to issue a
Letter of Credit if, after issuance thereof, (x) the aggregate principal amount
of the Loans of all Lenders, the undrawn face amounts of all Letters of Credit
and all Reimbursement Obligations outstanding of the Borrower hereunder would
thereby exceed the Commitment Amount then in effect, (y) the outstanding L/C
Obligations would thereby exceed the L/C Commitment Amount, or (z) the issuance
of such Letter of Credit would conflict with any legal or regulatory
restriction then applicable to the Agent or any other Lender as notified by
such other Lender to the Agent before the date of issuance of the Letter of
Credit.  Each Letter of Credit shall be issued in U.S. Dollars and shall be in
an initial face amount of at least $100,000.

        (b)     Issuance Procedure.  To request that the Agent issue a Letter
of Credit, the Borrower shall deliver to the Agent a duly executed Issuance
Request in the form of Exhibit 2.2 and such other documentation and
information as the Agent may reasonably request. Upon receipt of a properly
completed and executed Issuance Request and any other reasonably requested
documents or information at least three (3) Business Days prior to any
requested issuance date, the Agent will process such Issuance Request in
accordance with its customary procedures and issue the requested Letter of
Credit on the requested issuance date.  The Borrower may cancel any requested
issuance of a Letter of Credit prior to the issuance thereof. The Agent will
notify each Lender of the amount and expiration date of each Letter of Credit
it issues promptly upon issuance thereof. Each Letter of Credit shall have an
expiration date no later than the earlier of two (2) years from the 
issuance date and ten (10) Business Days before the Maturity Date. If the
Agent issues any Letters of Credit with expiration dates that automatically
extend unless the Agent gives notice that the expiration date will not so
extend, the Agent will give such notice of non-renewal before the time
necessary to prevent such automatic extension if before 

                                     12
<PAGE>   18
such required notice date (x) the expiration date of such Letter of Credit if so
extended would be later than ten (10) Business Days before the Maturity Date,
(y) the Commitment Termination Date shall have occurred, or (z) a Default or an
Event of Default exists and the Majority Lenders have given the Agent
instructions not to so permit the expiration date of such Letter of Credit to be
extended.  The Agent agrees to issue amendments to any Letter of Credit
increasing its amount, or extending its expiration date, at the request of the
Borrower subject to the conditions precedent for all Loans contained in Section
4.2 and the other terms and conditions of this Section 2.2.

         (c)     The Borrower's Reimbursement Obligations.  (i) The Borrower
hereby irrevocably and unconditionally agrees to reimburse the Agent for each
payment or disbursement made by the Agent to settle its obligations under any
draft drawn under a Letter of Credit (a "Reimbursement Obligation") within
three (3) Business Days from when such draft is paid with either funds not
borrowed hereunder or with a Borrowing subject to the terms and conditions
contained in this Agreement.  The Reimbursement Obligation shall bear interest
(which the Borrower hereby promises to pay) from and after the date such draft
is paid until the Reimbursement Obligation is paid at the lesser of the Highest
Lawful Rate or the Base Rate so long as the Reimbursement Obligation shall not
be past due, and thereafter at the default rate per annum as set forth in
Section 2.11(b), whether or not the Maturity Date shall have occurred.  If any
such payment or disbursement is reimbursed to the Agent on the date such
payment or disbursement is made by the Agent, interest shall be paid on the
reimbursable amount for one (1) day unless the Borrower shall have provided
sufficient funds to the Agent to honor such draft prior to 10:00 a.m. on the
same date the Agent obtains funds to honor such draft.

                 (ii)     The Agent shall use reasonable efforts to notify the
Borrower of any draft drawn on a standby Letter of Credit before any payment by
the Agent of such draft so as to give the Borrower an opportunity to provide
funds to the Agent to honor any such draft; provided, however, the failure of
the Agent to notify the Borrower pursuant to any of the provisions of this
Section 2.2(c) shall in no way impair or affect any Reimbursement Obligations
or give rise to any liability of the Agent or any Lender.  The Agent shall in
any event give the Borrower notice of any drawing on a Letter of Credit within
two (2) Business Days after such drawing is paid.

                 (iii)    The Borrower agrees for the benefit of the Agent and
each Lender that the obligations of the Borrower under this Section 2.2(c)
shall be absolute, unconditional and irrevocable, and shall be performed
strictly in accordance with the terms of this Agreement under all circumstances
whatsoever, including without limitation the following circumstances:

                          (1)     any lack of validity or enforceability of any
of the L/C Documents;

                          (2)     any amendment or waiver of or any consent to
depart from all or any of the provisions of any of the L/C Documents;

                          (3)      the existence of any claim, set-off, defense
or other right the Borrower may have at any time against a beneficiary of a
Letter of Credit (or any Person for whom a beneficiary may be acting), the
Agent, any Lender or any other Person, whether in connection with this
Agreement, another L/C Document or any unrelated transaction;

                                       13
<PAGE>   19

                          (4)     any statement or any other document presented
under a Letter of Credit proving to be forged, fraudulent, invalid or
insufficient in any respect or any statement therein being untrue or inaccurate
in any respect;

                          (5)     payment by the Agent under a Letter of Credit
against presentation to the Agent of a draft or certificate that does not
comply with the terms of the Letter of Credit, provided that the Agent's
determination that documents presented under the Letter of Credit comply with
the terms thereof did not constitute gross negligence or willful misconduct of
the Agent; or

                          (6)     any other act or omission to act or delay of 
any kind by the Agent, any Lender or any other Person or any other event or
circumstance whatsoever that might, but for the provisions of this Section
2.2(c), constitute a legal or equitable discharge of the Borrower's obligations
hereunder or under an Issuance Request.
        
        (d)     The Participating Interests.  Each Lender severally and not
jointly agrees to purchase from the Agent, and the Agent hereby agrees to sell
to each Lender, an undivided percentage participating interest, to the extent
of its Percentage, in each Letter of Credit issued by, and Reimbursement
Obligation owed to, the Agent in connection with a Letter of Credit.  Upon any  
failure by the Borrower to pay any Reimbursement Obligation in connection with
a Letter of Credit at the time required in Section 2.2(c), or if the Agent is
required at any time to return to the Borrower or to a trustee, receiver,
liquidator, custodian or other Person any portion of any payment by the
Borrower of any Reimbursement Obligation in connection with a Letter of Credit,
the Agent shall promptly give notice of same to each Lender, and the Agent
shall have the right to require each Lender to fund its participation in such
Reimbursement Obligation.  Each Lender (except the Agent to the extent it is
also a Lender) shall pay to the Agent an amount equal to its Percentage of such
unpaid or recaptured Reimbursement Obligation not later than the Business Day
it receives notice from the Agent to such effect, if such notice is received
before 2:00 p.m., or not later than the following Business Day if such notice
is received after such time.  If a Lender fails to timely pay such amount to
the Agent, it shall also pay to the Agent interest on such amount accrued from
the date payment of such amount was made by the Agent to the date of such
payment by the Lender at a rate per annum equal to the Base Rate in effect for
each such day and only after such payment shall such Lender be entitled to
receive its Percentage of each payment received on the relevant Reimbursement
Obligation and of interest paid thereon.  If any such Lender fails to pay such
amount to the Agent, any payments made by the Borrower with respect to the
relevant Reimbursement Obligation shall first be applied by the Agent to the
unfunded participation in such Reimbursement Obligation before any other
Lenders receive any payments or proceeds.  The several obligations of the
Lenders to the Agent under this Section 2.2(d) shall be absolute, irrevocable
and unconditional under any and all circumstances whatsoever and shall not be
subject to any set-off, counterclaim or defense to payment any Lender may have
or have had against the Borrower, the Agent, any other Lender or any other
Person whatsoever including, but not limited to, any defense based on the
failure of the demand for payment under the Letter of Credit to conform to the
terms of such Letter of Credit or the legality, validity, regularity or
enforceability of such Letter of Credit and INCLUDING BUT NOT LIMITED TO THOSE
RESULTING FROM THE AGENT'S OWN SIMPLE OR CONTRIBUTORY NEGLIGENCE.  Without
limiting the generality of the foregoing, such obligations shall not be
affected by any Default or Event of Default or by any 

                                       14
<PAGE>   20

subsequent reduction or termination of any Commitment of a Lender, and each
payment by a Lender under Section 2.2 shall be made without any offset,
abatement, withholding or reduction whatsoever.

         Section 2.3.     Types of Loans and Minimum Borrowing Amounts.
Borrowings of Loans may be outstanding as either Base Rate Loans or Eurodollar
Loans, as selected by the Borrower pursuant to Sections 2.4 and 2.5.  All
Borrowings advanced on the Initial Borrowing Date shall be advanced as Base
Rate Loans.  Each Borrowing shall be in a minimum amount of not less than
$1,000,000 and incremental multiples of $500,000.

         Section 2.4.     Manner of Borrowing.  (a) Notice to the Agent.  The
Borrower shall give notice to the Agent by no later than 11:00 a.m. (i) at least
three (3) Business Days before the date on which the Borrower requests the
Lenders to advance a Borrowing of Eurodollar Loans, and (ii) on the date the
Borrower requests the Lenders to advance a Borrowing of Base Rate Loans. The
Loans included in each Borrowing shall bear interest initially at the type of
rate specified in such notice of a new Borrowing.  Thereafter, the Borrower may
from time to time elect to change or continue the type of interest rate borne by
each Borrowing or, subject to Section 2.3's minimum amount requirement for each
outstanding Borrowing, a portion thereof, as follows: (i) if such Borrowing is
of Eurodollar Loans, the Borrower may continue part or all of such Borrowing as
Eurodollar Loans for an Interest Period specified by the Borrower or convert
part or all of such Borrowing into Base Rate Loans on the last day of the
Interest Period applicable thereto, or the Borrower may earlier convert part or
all of such Borrowing into Base Rate Loans so long as it pays the breakage fees
provided in Section 2.12, and all interest accrued on such Borrowing, and (ii)
if such Borrowing is of Base Rate Loans, the Borrower may convert all or part of
such Borrowing into Eurodollar Loans for an Interest Period specified by the
Borrower on any Business Day.  Notices of the continuation of a Borrowing of
Eurodollar Loans for an additional Interest Period or of the conversion of part
or all of a Borrowing of Eurodollar Loans into Base Rate Loans or of Base Rate
Loans into Eurodollar Loans must be given by no later than 11:00 a.m. at least
three (3) Business Days before the date of the requested continuation or
conversion.  The Borrower shall give such notices concerning the advance,
continuation, or conversion of a Borrowing by telephone or facsimile (which
notice shall be irrevocable once given and, if by telephone, shall be promptly
confirmed in writing).  Such written notice shall be in the form of a Borrowing
Request in the form of Exhibit 2.4 which shall specify the date of the requested
advance, continuation or conversion (which shall be a Business Day), the amount
of the requested Borrowing, whether any portion of the requested Borrowing shall
be used for funding any Acquisition, the type of Loans to comprise such new,
continued or converted Borrowing and, if such Borrowing is to be comprised of
Eurodollar Loans, the Interest Period applicable thereto.  The Borrower agrees
that the Agent may rely on any such telephonic or facsimile notice given by any
person it in good faith believes is an authorized representative of the Borrower
without the necessity of independent investigation and that, if any such notice
by telephone conflicts with any written confirmation, such telephonic notice
shall govern if the Agent has acted in reliance thereon.

         (b)     Notice to the Lenders.  The Agent shall give prompt
telephonic, telex or facsimile notice to each Lender of any notice received
from the Borrower pursuant to Sections 2.4 and 2.5 relating to a Borrowing.
The Agent shall give notice to the Borrower and each Lender by like means of
the interest rate applicable to each Borrowing of Eurodollar Loans (but, if
such 


                                       15
<PAGE>   21

notice is given by telephone, the Agent shall confirm such rate in
writing) promptly after the Agent has made such determination.

         (c)     Borrower's Failure to Notify.  If the Borrower fails to give
notice pursuant to Section 2.4(a) of the continuation or conversion of any
outstanding principal amount of a Borrowing of Eurodollar Loans or of a
Borrowing to pay an outstanding Reimbursement Obligation and has not notified
the Agent by 12:00 a.m. at least three (3) Business Days before the last day of
the Interest Period for such Borrowing of Eurodollar Loans or the day such
Reimbursement Obligation becomes due that it intends to repay such Borrowing or
such Reimbursement Obligation with funds not borrowed hereunder, the Borrower
shall be deemed to have requested, as applicable, the continuation of such
Borrowing as a Eurodollar Loan with an Interest Period of the same duration as
the prior Interest Period (provided that if such prior Interest Period is
twelve (12) months and such Interest Period shall not then be available to all
the Lenders, the Borrower shall be deemed to have requested an Interest Period
of six (6) months) or, subject to all other provisions hereof, the advance of a
new Borrowing of Base Rate Loans on such day in the amount of the Reimbursement
Obligation then due, which Borrowing shall be applied to pay the Reimbursement
Obligation then due.

         (d)     Disbursement of Loans.  Not later than 12:00 p.m. on the date
of any requested advance of a new Borrowing of Loans, each Lender, subject to
all other provisions hereof, shall pay to the Agent its Loan comprising its
ratable share of such Borrowing in funds immediately available in New York, New
York according to the disbursement instructions of the Agent.  The Agent shall
make the proceeds of each such Borrowing available in immediately available
funds to the Borrower on such date.  No Lender shall be responsible to the
Borrower for any failure by another Lender to fund its portion of a Borrowing,
and no such failure by a Lender shall relieve any other Lender from its
obligation, if any, to fund its portion of a Borrowing.

         (e)     Agent Reliance on Lender Funding.  (i) Unless the Agent shall
have been notified by a Lender before the date on which such Lender is
scheduled to make payment to the Agent of the proceeds of a Loan (which notice
shall be effective upon receipt) that such Lender does not intend to make such
payment, the Agent may assume that such Lender has made such payment when due
and in reliance upon such assumption may (but shall not be required to) make
available to the Borrower the proceeds of the Loan to be made by such Lender
and, if any Lender has not in fact made such payment to the Agent, such Lender
shall, on demand, pay to the Agent the amount made available to the Borrower
attributable to such Lender together with interest thereon for each day during
the period commencing on the date such amount was made available to the
Borrower and ending on (but excluding) the date such Lender pays such amount to
the Agent at a rate per annum equal to the interest rate attributable to such
Loan.  If such amount is not received from such Lender by the Agent immediately
upon demand, the Borrower will within five (5) Business Days after notice
thereof from the Agent repay to the Agent the proceeds of the Loan attributable
to such Lender with interest thereon at a rate per annum equal to the interest
rate applicable to such Loan.  The Borrower hereby reserves any and all rights,
claims and causes of action which it may have at law or in equity against any
such Lender.

                 (ii)     The Agent shall use reasonable efforts to verify that
each Lender has made payment to the Agent of the proceeds of the Loan to be
made by such Lender before making available to the Borrower the proceeds of the
Loan to be made by such Lender and shall advise 


                                       16
<PAGE>   22

the Borrower of such efforts upon the request of the Borrower; provided,
however, the failure of the Agent to so verify such payment or so advise the
Borrower pursuant to the provisions of this Section 2.5(e)(ii) shall in no way
impair, affect or delay the Borrower's obligation to repay any proceeds as
provided in Section 2.5(e)(i) or give rise to any liability of the Agent or any
Lender other than the defaulting Lender.

        Section 2.5. Interest Periods. As provided in Section 2.4(a), at
the time of each request for the advance or continuation of, or conversion
into, a Borrowing of Eurodollar Loans, the Borrower shall select an Interest
Period applicable to such Loans from among the available options; provided,
however, that:

        (a) the Borrower may not select an Interest Period for a Borrowing
of Loans that extends beyond the Maturity Date;

        (b) whenever the last day of any Interest Period would otherwise
be a day that is not a Business Day, the last day of such Interest Period shall
either be (i) extended to the next succeeding Business Day, or (ii) reduced to
the immediately preceding Business Day if the next succeeding Business Day is
in the next calendar month; and

        (c) if there exists no numerically corresponding day in the month
in which an Interest Period is to end, then such Interest Period shall end on
the last Business Day of such calendar month.

        Section 2.6. Maturity of Loans. Each Loan shall mature and become due 
and payable by the Borrower on the Maturity Date.  The Borrower may extend the
Commitments, the Commitment Termination Date and the Maturity Date for up to
two (2) additional one-year periods, provided that the Borrower gives written
notice substantially in the form of Exhibit 2.6 to the Agent of its election to
extend the Commitments, the Commitment Termination Date and the Maturity Date
for a one-year period on or before ninety (90) days before each of the first
and second anniversaries of the Effective Date and all of the Lenders consent
to such extension in their sole discretion on or before thirty (30) days before
such first or second anniversary of the Effective Date. The Agent shall
promptly notify each Lender of any such request of the Borrower, and each
Lender shall notify the Agent and the Borrower, no fewer than thirty (30) days
before such first or second anniversary of the Effective Date, whether in the
exercise of its sole discretion, it will extend the Commitments, the Commitment
Termination Date and the Maturity Date. Any Lender which shall not timely
notify the Agent whether it will extend the Commitments, the Commitment
Termination Date and the Maturity Date shall be deemed to not have agreed to
extend the Commitments, the Commitment Termination Date and the Maturity Date. 
No Lender shall have any obligation whatsoever to extend its Commitment, the
Commitment Termination Date or the Maturity Date.
        
        Section 2.7.   Applicable Interest Rates. (a) Eurodollar Loans.
Each Eurodollar Loan shall bear interest (computed on the basis of a 360 day
year and actual days elapsed) on the unpaid principal amount thereof from the
date such Loan is made until maturity (whether by acceleration or otherwise) or
conversion to a Base Rate Loan at a rate per annum equal to the lesser of (i)
the Highest Lawful Rate, or (ii) the sum of Adjusted LIBO plus the Applicable

                                      17
<PAGE>   23


Margin applicable to such Loan, payable on each Interest Payment Date for such
Loan and at maturity (whether by acceleration or otherwise) or conversion to a
Base Rate Loan.

         (b)     Base Rate Loans.  Each Base Rate Loan shall bear interest
(computed on the basis of a 365 or 366 day year, as applicable, and actual days
elapsed) on the unpaid principal amount thereof from the date such Loan is made
until maturity (whether by acceleration or otherwise) or conversion to a
Eurodollar loan at a rate per annum equal to the lesser of (i) the Highest
Lawful Rate, or (ii) the Base Rate, payable in arrears on each Interest Payment
Date for such Loan and at maturity (whether by acceleration or otherwise).

         (c)     Rate Determinations.  The Agent shall determine each interest
rate applicable to the Loans and Reimbursement Obligations hereunder and such
determination shall be rebuttable presumptive evidence of such interest rate
except in the case of manifest error or willful misconduct.

         Section 2.8.     Default Rate.  If any payment of principal on any
Loan is not made when due (whether by acceleration or otherwise), such Loan
shall bear interest (computed on the basis of a year of 360, 365 or 366 days,
as applicable, and actual days elapsed) from the date such payment was due
until paid in full, payable on demand, at a rate per annum equal to:

         (a)     for any Base Rate Loan the lesser of (i) the Highest Lawful
Rate, or (ii) the sum of two percent (2%) per annum plus the Base Rate from
time to time in effect (but not less than the Base Rate in effect at maturity);

         (b)     for any Eurodollar Loan the lesser of (i) the Highest Lawful
Rate, or (ii) the sum of two percent (2%) per annum plus the rate of interest
in effect thereon at the time of such default until the end of the Interest
Period for such Loan and, thereafter, at a rate per annum equal to the sum of
two percent (2%) per annum plus the Base Rate from time to time in effect (but
not less than the Base Rate in effect at maturity); and

         (c)     for any unpaid Reimbursement Obligations, the lesser of (i)
the Highest Lawful Rate, or (ii) the sum of two percent (2%) per annum plus the
Base Rate from time to time in effect (but not less than the Base Rate in
effect at maturity).

It is the intention of the Agent and the Lenders to conform strictly to usury
laws applicable to them.  Accordingly, if the transactions contemplated hereby
or the Loans would be usurious as to any of the Lenders under laws applicable
to it (including the laws of the United States of America and the State of
Texas or any other jurisdiction whose laws may be mandatorily applicable to
such Lender notwithstanding the other provisions of this Agreement, the Notes
or any other Credit Document), then, in that event, notwithstanding anything to
the contrary in this Agreement, the Notes or any other Credit Document, it is
agreed as follows:  (i) the aggregate of all consideration which constitutes
interest under laws applicable to the Lender that is contracted for, taken,
reserved, charged or received by the Lender under this Agreement, the Notes or
any other Credit Document or otherwise shall under no circumstances exceed the
Highest Lawful Rate, and any excess shall be credited by such Lender on the
principal amount 

                                       18
<PAGE>   24
of the Notes or to the Reimbursement Obligations (or, if the principal amount
of the Notes and all Reimbursement Obligations shall have been paid in full,
refunded by such Lender to the Borrower); and (ii) in the event that the
maturity of the Notes is accelerated by reason of an election of the holder or
holders thereof resulting from any Event of Default hereunder or otherwise, or
in the event of any required or permitted prepayment, then such consideration
that constitutes interest under laws applicable to the Lender may never include
more than the Highest Lawful Rate, and excess interest, if any, provided for in
this Agreement, the Notes, any other Credit Document or otherwise shall be
automatically canceled by such Lender as of the date of such acceleration or
prepayment and, if theretofore paid, shall be credited by the Lender on the
principal amount of the Notes or to the Reimbursement Obligations (or if the
principal amount of the Notes and all Reimbursement Obligations shall have been
paid in full, refunded by such Lender to the Borrower).  To the extent that
Article 5069-1.04 of the Texas Revised Civil Statutes is relevant to the Agent
and the Lenders for the purpose of determining the Highest Lawful Rate, the
Agent and the Lenders hereby elect to determine the applicable rate ceiling
under such Article by the indicated (Weekly) rate ceiling from time to time in
effect, subject to their right subsequently to change such method in accordance
with applicable law.  In the event the Loans and all Reimbursement Obligations
are paid in full by the Borrower prior to the full stated term of the Loans and
the interest received for the actual period of the existence of the Loans
exceeds the Highest Lawful Rate, the Lenders shall refund to the Borrower the
amount of the excess or shall credit the amount of the excess against amounts
owing under the Loans and, to the extent permitted by applicable law, none of   
the Agent or the Lenders shall be subject to any of the penalties provided by
law for contracting for, taking, reserving, charging or receiving interest in
excess of the Highest Lawful Rate.  Chapter 15 of Article 5069 of the Texas
Revised Civil Statutes, which regulates certain revolving credit loan accounts
and revolving tri-party accounts, shall not apply to this Agreement or the
Notes.

         Section 2.9.     Mandatory Prepayments of Loans.  If the aggregate
principal amount of outstanding Loans and L/C Obligations shall at any time for
any reason exceed the Commitment Amount then in effect, the Borrower shall,
immediately and without notice or demand, pay the amount of such excess to the
Agent for the ratable benefit of the Lenders as a prepayment of the Loans and,
if all Loans have been paid, a prefunding of Letters of Credit.  Any mandatory
prepayment pursuant hereto shall not be limited by the notice provision for
prepayments set forth in Section 2.4, but immediately upon determining the need
to make any such prepayment, the Borrower shall notify the Agent of such
required prepayment.  Each such prepayment shall be accompanied by a payment of
all accrued and unpaid interest on the Loans prepaid and any applicable
breakage fees pursuant to Section 2.12.

         Section 2.10.    Optional Prepayments.  The Borrower shall have the
privilege of prepaying Base Rate Loans without premium or penalty in whole or
in part at any time (but, if in part, then in an amount which is equal to or
greater than $1,000,000); provided, however, that the Borrower shall have given
notice of such prepayment to the Agent no later than 10:00 a.m. on the date of
such prepayment.  The Borrower shall have the privilege of prepaying Eurodollar
Loans (a) without premium or penalty in whole or in part (but, if in part, then
in an amount which is equal to or greater than $1,000,000) only on the last
Business Day of an Interest Period for such Loan, and (b) at any other time so
long as the breakage fees provided for in Section 

                                       19
<PAGE>   25

2.12 are paid; provided, however, that the Borrower shall have given notice
of such prepayment to the Agent no later than 10:00 a.m. at least three (3)
Business Days before the last Business Day of such Interest Period or the
proposed prepayment date.  Any such prepayments shall be made by the payment of
the principal amount to be prepaid and accrued interest thereon to the date of
such prepayment, together with any applicable breakage fees.  Optional
prepayments shall first be applied to any Reimbursement Obligations with
respect to Letters of Credit, then to the Loans. The Borrower may direct the
application of any optional prepayment hereunder to any of the Base Rate Loans
or Eurodollar Loans then outstanding.

         Section 2.11.    The Notes. (a)  The Loans outstanding to the Borrower
from each Lender shall be evidenced by a single promissory note of the Borrower
payable to each such Lender in the form of Exhibit 2.11 (each a "Note").

        (b)     Each holder of a Note shall record on its books and records or
on a schedule to its appropriate Note the amount of each Loan outstanding from  
it to the Borrower, all payments of principal and interest and the principal
balance from time to time outstanding thereon, the type of such Loan and, if a
Eurodollar Loan, the Interest Period and interest rate applicable thereto. Such
record, whether shown on the books and records of a holder of a Note or on a
schedule to its Note, shall be prima facie evidence as to all such matters;
provided, however, that the failure of any holder to record any of the
foregoing or any error in any such record shall not limit or otherwise affect
the obligation of the Borrower to repay all Loans outstanding to it hereunder
together with accrued interest thereon.  At the request of any holder of a Note
and upon such holder tendering to the Borrower the Note to be replaced, the
Borrower shall furnish a new Note to such holder to replace any outstanding
Note and at such time the first notation appearing on the schedule on the
reverse side of, or attached to, such new Note shall set forth the aggregate
unpaid principal amount of all Loans, if any, then outstanding thereon.

         Section 2.12.    Breakage Fees.  If any Lender incurs any loss, cost
or expense (including, without limitation, any loss, cost, expense or premium
incurred by reason of the liquidation or re-employment of deposits or other
funds acquired by such Lender to fund or maintain any Eurodollar Loan or the
relending or reinvesting of such deposits or amounts paid or prepaid to such
Lender) as a result of any of the following events other than any such
occurrence as a result of a change of circumstance described in Sections 8.1 or
8.2:

         (a)     any payment, prepayment or conversion of a Eurodollar Loan on
a date other than the last day of its Interest Period (whether by acceleration,
mandatory prepayment or otherwise); or

         (b)     any failure by the Borrower to borrow, prepay or convert a
Eurodollar Loan on the date specified in a notice given pursuant to Section
2.4(a),

then the Borrower shall pay to such Lender such amount as will reimburse such
Lender for such loss, cost or expense.  If any Lender makes such a claim for
compensation, it shall provide to the Borrower a certificate executed by an
officer of such Lender setting forth the amount of such loss, cost or expense
in reasonable detail (including an explanation of the basis for and the
computation of such loss, cost or expense), and the amounts shown on such
certificate shall be rebuttable presumptive evidence of such loss, cost or
expense absent manifest error.  Within ten 

                                       20
<PAGE>   26

(10) days of receipt of such certificate, the Borrower shall pay directly to 
such Lender such amount as will compensate such Lender for such loss, cost or 
expense as provided herein.

        Section 2.13.    Commitment Terminations.  The Borrower shall have the
right at any time and from time to time, upon five (5) Business Days' prior and
irrevocable written notice to the Agent, to terminate or reduce the Commitments 
or L/C Commitments without premium or penalty, in whole or in part, any partial
termination to be (a) in an amount not less than $1,000,000 and in integral
multiples of $500,000 as determined by the Borrower, and (b) allocated ratably
among the Lenders in proportion to their respective Commitments and L/C
Commitments, as applicable; provided that the Commitment Amount may not be
reduced to an amount less than the sum of the aggregate principal amount of
outstanding Loans plus the aggregate undrawn face amount of outstanding Letters
of Credit plus any unpaid Reimbursement Obligations, and the L/C Commitment
Amount may not be reduced to an amount less than the aggregate undrawn face
amount of outstanding Letters of Credit plus any unpaid Reimbursement
Obligations, in each case after giving effect to payments on such proposed
termination or reduction date, unless the Borrower provides to the Agent cash
collateral in an amount sufficient to cover such shortage or back to back
letters of credit from a bank(s) or financial institution(s) satisfactory to
the Majority Lenders in an amount equal to the undrawn face amount of any
outstanding Letters of Credit with an expiration date of at least five (5) days
after the expiration date of any Letter of Credit and which provide that the
Agent may make a drawing thereunder in the event that it pays a drawing under
such Letter of Credit.  The Agent shall give prompt notice to each Lender of
any such termination of Commitments. Any termination of Commitments or L/C
Commitments pursuant to this Section 2.13 is permanent and may not be
reinstated.

SECTION 3.       FEES AND PAYMENTS.

         Section 3.1.     Fees.  (a) Commitment Fee.  For the period from the
Effective Date to and including the Maturity Date, the Borrower shall pay to
the Agent for the ratable account of the Lenders, a commitment fee (computed on
a basis of a 360 day year, and actual days elapsed) on the average daily
difference between (x) the Commitment Amount, and (y) the sum of the
outstanding Loans and the L/C Obligations, such fee to be calculated from time
to time at the rate per anum set forth opposite the relevant Total Funded Debt
to EBITDA Ratio set forth below:

                 Total Funded Debt to EBITDA Ratio              Commitment Fee
                 -----------------------------------            --------------

                 Equal to or greater than 2.0 to 1.0                0.30%
                 Less than 2.0 to 1.0                               0.25%

Such fees shall be payable in arrears commencing on March 31, 1996, and on the
last day of each calendar quarter thereafter and on the Maturity Date, unless
the Commitments are terminated in whole on an earlier date, in which event the
commitment fee with respect thereto for the period to, but not including, the
date of such termination shall be paid in whole on the date of such
termination.  Any change to the commitment fee as a result of a change in the
Total Funded Debt to EBITDA Ratio shall be effective as of the first day of the
next calendar quarter.


                                       21
<PAGE>   27

         (b)     Letter of Credit Fees.  Commencing upon the date of issuance
or extension of any Letter of Credit, the Borrower shall pay to the Agent
quarterly in advance for the ratable account of the Lenders a nonrefundable fee
equal to a percentage per annum of the face amount of such Letter of Credit
equal to the Applicable Margin, subject to a $250.00 minimum fee, calculated on
the basis of a 360 day year and actual days elapsed and based on the scheduled
expiration date of the Letter of Credit.  Such fee shall be payable by the
Borrower thereafter in advance on the last day of March, June, September and
December of each year, with the last such payment on the date any such Letter
of Credit expires.  In addition, the Borrower shall pay to the Agent solely for
the Agent's account in connection with each Letter of Credit the standard
administrative and amendment fees and expenses for letters of credit
established by the Agent from time to time and as agreed between the Agent and
the Borrower.

         (c)     Agent Fees.  The Borrower shall pay to the Agent the fees
agreed to in writing between the Agent and the Borrower.

         Section 3.2.     Place and Application of Payments.  (a) All payments
of principal of and interest on the Loans, of Reimbursement Obligations, and of
all other amounts payable by the Borrower under the Credit Documents shall be
made by the Borrower to the Agent by no later than 2:30 p.m. on the due date
thereof at the office of the Agent in New York, New York (or such other
location as the Agent may designate to the Borrower) for the benefit of the
Lenders entitled to such payments.  Any payments received by the Agent from the
Borrower after 2:30 p.m. shall be deemed to have been received on the next
Business Day.  Such payments shall be made in U.S. Dollars in immediately
available funds at the place of payment without setoff or counterclaim.  The
Agent will, on the same day each payment is received or deemed to have been
received in accordance with this Section 3.2, cause to be distributed like
funds to the Lenders ratably in accordance with the aggregate amount of
Obligations owed to each Lender.

         (b)     If any payment received by the Agent under any Credit Document
is insufficient to pay in full all amounts then due and payable to the Agent
and the Lenders under the Credit Documents, such payment shall be distributed
by the Agent and applied by the Agent and the Lenders in the order set forth in
Section 7.7.  In calculating the amount of Obligations owing each Lender other
than for principal and interest on Loans and Reimbursement Obligations and fees
under Section 3.1, the Agent shall only be required to include such other
Obligations that Lenders have certified to the Agent in writing are due to such
Lenders.

         Section 3.3.     Withholding Taxes.  (a) Payments Free of Withholding.
Except as otherwise required by law and subject to Section 3.3(b), each payment
by the Borrower or any Guarantors under this Agreement or any other Credit
Document shall be made without withholding for or on account of any present or
future taxes (other than overall net income taxes on the recipient) imposed by
or within the jurisdiction in which Borrower or such Guarantors is domiciled,
any jurisdiction from which Borrower or Guarantors makes any payment, or (in
each case) any political subdivision or taxing authority thereof or therein.
If any such withholding is so required, Borrower or Guarantors, as applicable,
shall make the withholding, pay the amount withheld to the appropriate
governmental authority before penalties attach thereto or interest accrues
thereon and forthwith pay such additional amount as may be necessary to ensure
that the net amount actually received by each Lender and the Agent is free and
clear of such taxes (including such taxes on such additional amount) and is
equal to the amount that Lender or the Agent (as the case may be) would have
received had such withholding not been 


                                       22
<PAGE>   28
made.  If the Agent or any Lender pays any amount in respect of any such
taxes, penalties or interest, Borrower or Guarantors, as applicable, shall
reimburse the Agent or that Lender for the payment on demand in the currency in
which such payment was made.  If such Borrower or Guarantors pays any such
taxes, penalties or interest, it shall deliver official tax receipts evidencing
the payment or certified copies thereof, or other satisfactory evidence of
payment if such tax receipts have not yet been received by the Borrower or
Guarantors (with such tax receipts to be promptly delivered when actually
received), to the Lender or Agent on whose account such withholding was made
(with a copy to the Agent if not the recipient of the original) within fifteen
(15) days of such payment.

        (b)     U.S. Withholding Tax Exemptions.  Each Lender that is not a
United States person (as such term is defined in Section 7701(a)(30) of the
Code) shall submit to the Borrower and the Agent on or before the Initial
Borrowing Date, two duly completed and signed copies of either Form 1001
(entitling such Lender to a complete exemption from withholding under the Code
on all amounts to be received by such Lender, including fees, pursuant to the
Credit Documents) or Form 4224 (relating to all amounts to be received by such
Lender, including fees, pursuant to the Credit Documents) of the United States
Internal Revenue Service.  Thereafter and from time to time, each Lender shall
submit to the Borrower and the Agent such additional duly completed and signed  
copies of one or the other of such forms (or such successor forms as shall be
adopted from time to time by the relevant United States taxing authorities) as
may be (i) notified by the Borrower, directly or through the Agent, to such
Lender, and (ii) required under then-current United States law or regulations
to avoid United States withholding taxes on payments in respect of all amounts
to be received by such Lender, including fees, pursuant to the Credit
Documents.  Upon the request of the Borrower, each Lender that is a United
States person shall submit to the Borrower a certificate to the effect that it
is such a United States person.

         (c)     Inability of Lender to Submit Forms.  If any Lender
determines, as a result of any change in applicable law, regulation or treaty,
or in any official application or interpretation thereof, that it is unable to
submit to the Borrower or Agent any form or certificate that such Lender is
obligated to submit pursuant to subsection (b) of this Section 3.3 or that such
Lender is required to withdraw or cancel any such form or certificate
previously submitted or any such form or certificate otherwise becomes
ineffective or inaccurate, such Lender shall promptly notify the Borrower and
Agent of such fact and the Lender shall to that extent not be obligated to
provide any such form or certificate and will be entitled to withdraw or cancel
any affected form or certificate, as applicable.

SECTION 4.       CONDITIONS PRECEDENT.

         The obligation of each Lender to fund or make any Loan hereunder and
of the Agent to issue, extend (or permit the extension of) the expiration date
of, or to increase the amount of, any Letter of Credit is subject to the
following conditions precedent, all in form and substance satisfactory to the
Lenders (and which shall be evidenced by the making or advancing of any Loan or
the issuance, extension, or increase of any Letter of Credit) and in sufficient
number of signed counterparts to provide one for each Lender (except for the
Notes, of which only one original shall be signed for each Lender):


                                       23
<PAGE>   29

         Section 4.1.     Initial Borrowing.  Before or concurrently with the
Initial Borrowing Date, the Agent shall have received:

         (a)     Notes.  The duly executed Notes of the Borrower;

         (b)     Guaranties.  The duly executed Guaranty of each Material
Subsidiary of the Borrower in substantially the form of Exhibit 4.1A;

         (c)     Certificates of Officers of Credit Parties.  Certificates of
the Secretary or Assistant Secretary and the President or Vice President of
each Credit Party containing specimen signatures of the persons authorized to
execute Credit Documents on each Credit Party's behalf, together with (x)
copies of resolutions of the Board of Directors or other appropriate body of
each Credit Party authorizing the execution and delivery of the Credit
Documents to which it is a party and of all other legal documents or
proceedings taken by the Credit Parties in connection with the execution and
delivery of the Credit Documents and (y) copies of each Credit Party's
Certificate or Articles of Incorporation and bylaws or other governing
documents;

        (d)     Lien Searches.  The results of recent lien searches and Uniform
Commercial Code searches in each of the applicable jurisdictions showing
no Liens on any of the property or assets of any Credit Party other than
Permitted Liens, or evidence that any such Liens other than Permitted Liens
have been terminated or will be terminated concurrently with the Initial
Borrowing Date;

         (e)     Certificate of Financial Condition.  A certificate of the
Chief Financial Officer of the Borrower documenting the solvency of the
Borrower and its Subsidiaries on a consolidated basis, after giving effect to
the Borrowings on the Initial Borrowing Date hereunder, and certifying as true,
correct and complete the most recent financial statements described in Section
5.9;

         (f)     Insurance Certificate.  A certificate from the Borrower
attaching a schedule describing in reasonable detail the insurance maintained
by the Borrower and its Subsidiaries;

         (g)     Fees.  Payment of all fees and all expenses incurred through
the Effective Date then due and owing to the Agent pursuant to this Agreement;

         (h)     Compliance Certificate.  A duly executed Compliance
Certificate;

         (i)     Consents.  Certified copies of all documents evidencing any
necessary corporate action, consents and governmental approvals (if any) with
respect to the Credit Documents or any other document provided herein;

         (j)     NationsBank Releases.  Evidence that the promissory notes and
all other obligations under the NationsBank Credit Facility have been or will
be paid in full with the proceeds of the initial Borrowing hereunder and
evidence that all Liens under the NationsBank Credit Facility have been or will
be released;


                                       24
<PAGE>   30

         (k)     Opinion of Counsel.  The opinion of Winstead Sechrest &
Minick, P.C., legal counsel to the Credit Parties, in substantially the form
attached as Exhibit 4.1B and covering such additional matters as the Lenders
may reasonably require;

         (l)     Commitments.  Commitments from the Lenders in an aggregate
amount of $100,000,000; and

         (m)     Other Documents.  Such other documents as the Agent may 
reasonably request.

         Section 4.2.     All Borrowings.  At the time of each new or increased
Borrowing hereunder (including the issuance of, increase in the amount of, or
extension of the expiration date of, a Letter of Credit and the initial
Borrowing hereunder):

         (a)     Notices.  In the case of a Borrowing, the Agent shall have
received the Borrowing Request notice required by Section 2.4, and in the case
of the issuance, extension or increase of a Letter of Credit, the Agent shall
have received a duly completed Issuance Request for such Letter of Credit, as
the case may be, meeting the requirements of Section 2.2(b);

         (b)     Warranties True and Correct.  Each of the representations and
warranties of the Borrower and its Subsidiaries set forth herein and in the     
Credit Documents shall be true and correct in all material respects as of the
date of such new Borrowing, except as a result of the transactions permitted
hereunder or except to the extent that any such representation or warranty
relates solely to an earlier date, in which case it shall have been true and
correct as of such earlier date;

         (c)     No Default.  No Default or Event of Default shall have
occurred and be continuing or would occur as a result of such Borrowing; and

         (d)     Regulation U; Other Laws.  The Borrowings to be made by the
Borrower shall not result in the Borrower or any Lender being in non-compliance
with or in violation of Regulation U and shall not be prohibited by Regulations
G, T and X or any other legal requirement imposed by the banking laws of the
United States of America.

Each request for a new or increased Borrowing and each request for the issuance
of, increase in the amount of, or extension of the expiration date of, a Letter
of Credit shall be deemed to be a representation and warranty by the Borrower
on the date of such Borrowing, issuance of, increase in the amount of, or
extension of the expiration date of, such Letter of Credit (a) that all
conditions precedent to such Borrowing have been satisfied or fulfilled, (b)
that all of the representations and warranties contained in this Agreement are
true and correct on the date thereof as if made on the date thereof except to
the extent such representation or warranty relates to an earlier date, in which
case it shall have been true and correct as of such earlier date, and (c) no
Default or Event of Default shall have occurred and be continuing or will occur
as a result of any such Borrowing or issuance of, increase in the amount of, or
extension of the expiration date of such Letter of Credit.  If a Default or an
Event of Default shall have occurred and be continuing, the Borrower may not
convert any Base Rate Loan into an Eurodollar Loan or continue any Eurodollar
Loan unless the Majority Lenders consent, subject to the applicability of the
provisions of Section 2.8 regarding default rates of interest.  If the Majority
Lenders do not so consent, any Eurodollar Loan which has not been accelerated
pursuant to the terms hereof 

                                       25
<PAGE>   31

shall automatically convert into a Base Rate Loan at the end of the applicable
Interest Period unless prior to such time, such Default or Event of Default
shall have been cured or waived pursuant to the terms hereof.
        
SECTION 5.       REPRESENTATIONS AND WARRANTIES.

         The Borrower represents and warrants to each Lender and the Agent as
follows:

         Section 5.1.     Corporate Organization. (a) The Borrower and each of
its Subsidiaries: (i) is a duly organized and existing corporation in good
standing under the laws of the jurisdiction of its organization; (ii) has all
necessary corporate power to own the property and assets it uses in its
business and otherwise to carry on its present business and the business it
currently proposes to transact; and (iii) is duly licensed or qualified and in
good standing in each jurisdiction in which the nature of the business
transacted by it or the nature of the property owned or leased by it makes such
licensing or qualification necessary.

         (b)     As of the Effective Date, the Borrower has no Subsidiaries
other than those Subsidiaries listed on Schedule 5.1. Schedule 5.1
correctly sets forth, as of the Effective Date, the percentage ownership
(direct and indirect) of the Borrower in each class of capital stock of each of
its Subsidiaries and also identifies the direct owner thereof.

         Section 5.2.     Corporate Power and Authority; Validity.  Each Credit
Party has the corporate power and authority to execute, deliver and carry out
the terms and provisions of the Credit Documents to which it is a party and has
taken all necessary corporate action to authorize the execution, delivery and
performance of such Credit Documents.  Each Credit Party has duly executed and
delivered each Credit Document to which it is a party and each such Credit
Document constitutes the legal, valid and binding obligation of such Credit
Party enforceable against it in accordance with its terms, subject as to
enforcement only to bankruptcy, insolvency, reorganization, moratorium or other
similar laws affecting the enforcement of creditors' rights generally and
equitable principles relating to or limiting creditors' rights generally.

         Section 5.3.     No Violation.  Neither the execution, delivery or
performance by any Credit Party of the Credit Documents to which it is a party
nor compliance by it with the terms and provisions thereof, nor the
consummation of the transactions contemplated herein or therein, will (a)
contravene any applicable provision of any law, statute, rule or regulation, or
any applicable order, writ, injunction or decree of any court or governmental
instrumentality, (b) conflict with or result in any breach of any term,
covenant, condition or other provision of, or constitute a default under, or
result in the creation or imposition of (or the obligation to create or impose)
any Lien other than any Permitted Lien as provided in Section 6.15 upon any of
the property or assets of the Borrower or any of its Subsidiaries under the
terms of any contractual obligation to which the Borrower or any of its
Subsidiaries is a party or by which they or any of their properties or assets
are bound or to which they may be subject or (iii) violate or conflict with any
provision of the certificate or articles of incorporation or by-laws of the
Borrower or any of its Subsidiaries.

         Section 5.4.     Litigation.  There are no actions, suits or
proceedings (including, without limitation, derivative actions) pending or, to
the knowledge of the Borrower, threatened 

                                       26
<PAGE>   32

involving the Borrower or any of its Subsidiaries that are likely to            
have a Material Adverse Effect.

         Section 5.5.     Use of Proceeds; Margin Regulations.  (a)  The
proceeds of the Loans shall be used (i) to refinance outstanding amounts under
the NationsBank Credit Facility, (ii) for general corporate purposes, including
to provide working capital, to fund drawing under Letters of Credit and for
Acquisitions, and (iii) to purchase, redeem or otherwise acquire shares of the
capital stock of the Borrower up to a maximum amount of $5,000,000 in any
fiscal year.

         (b)     Neither the Borrower nor any of its Subsidiaries is engaged in
the business of extending credit for the purpose of purchasing or carrying
margin stock.  No proceeds of any Loan will be used to purchase or carry any
"margin stock" (as defined in Regulation U of the Board of Governors of the
Federal Reserve System), to extend credit for the purpose of purchasing or
carrying any "margin stock," or for a purpose which violates Regulations G, T,
U or X of the Board of Governors of the Federal Reserve System.  After
application of the proceeds of any of the Borrowings and any acquisitions
permitted hereunder, less than 25% of the assets of each of the Borrower and
each of its Subsidiaries consists of "margin stock."

         Section 5.6.     Investment Company Act.  Neither the Borrower nor 
any of its Subsidiaries is an "investment company" or a company "controlled" by
an "investment company," within the meaning of the Investment Company Act of
1940, as amended.
        
         Section 5.7.     Public Utility Holding Company Act.  Neither the
Borrower nor any of its Subsidiaries is a "holding company," or a "subsidiary
company" of a "holding company," or an "affiliate" of a "holding company" or of
a "subsidiary company" of a "holding company," within the meaning of the Public
Utility Holding Company Act of 1935, as amended.

         Section 5.8.     True and Complete Disclosure.  All factual
information heretofore or contemporaneously furnished by the Borrower or any of
its Subsidiaries in writing to the Agent or any Lender in connection with any
Credit Document or any transaction contemplated therein is, and all other such
factual information hereafter furnished by any such Persons in writing to the
Agent or any Lender in connection herewith, any of the other Credit Documents
or the Loans, will be true and accurate in all material respects on the date of
such information and not incomplete by omitting to state any material fact
necessary to make such information not misleading at such time in light of the
circumstances under which such information was provided.

         Section 5.9.     Financial Statements.  The financial statements
heretofore delivered to the Lenders (i) for the Borrower's fiscal year ending
on or before June 30, 1995, and for the Borrower's fiscal quarter ending on or
before September 30, 1995, have been prepared in accordance with GAAP applied
on a basis consistent, except as otherwise noted therein, with the Borrower's
financial statements for the previous fiscal year, and (ii) for periods ending
on or after September 30, 1995, will be prepared in accordance with GAAP
applied on a basis consistent, except as otherwise noted therein, with the
Borrower's financial statements for the previous fiscal year.  Each of such
annual and other financial statements fairly presents on a consolidated basis
the financial position of the Borrower, as of the dates thereof, and the
results of operations for the periods covered thereby, subject in the case of
interim financial statements, to normal year-end audit adjustments and omission
of certain footnotes as permitted by the SEC.  

                                       27
<PAGE>   33

The Borrower and its Subsidiaries have no material contingent liabilities or
material Indebtedness other than those disclosed in the financial statements
referred to in this Section 5.9.

         Section 5.10.    No Material Adverse Change.  There has been no
material adverse change in the (i) business, properties, operations or
financial condition of the Borrower or the Borrower and its Subsidiaries, taken
as a whole, since September 30, 1995, in the case of the initial Borrowing, or
since such date or the date of the last financial statement delivered pursuant
to Section 6.6 in the case of subsequent Borrowings, (ii) affecting the rights
and remedies of the Lenders in any material respect under and in connection
with this Agreement, the Notes and the Credit Documents; or (iii) in the
ability of the Borrower or of the Borrower and Guarantors (taken as a whole) to
perform their Obligations under this Agreement, the Notes or the other Credit
Documents to which they are a party.

         Section 5.11.    Labor Controversies.  There are no labor
controversies pending or, to the best knowledge of the Borrower, threatened
against the Borrower or any of its Subsidiaries that could reasonably be
expected to have a Material Adverse Effect.

         Section 5.12.    Taxes.  The Borrower and its Subsidiaries have filed
all United States federal tax returns and all other tax returns required to be  
filed, whether in the United States or in any foreign jurisdiction and have
paid all taxes, rates, assessments, fees and governmental charges
(collectively, "Taxes") due and no claims are being asserted for Taxes except
such Taxes, if any, as are being contested in good faith and for which reserves
have been provided in accordance with GAAP or where such failure to file or pay
any such Taxes could not reasonably be foreseen to have a Material Adverse
Effect.  No liens for Taxes have been filed or asserted except such liens
related to Taxes which are being contested in good faith and for which reserves
have been provided in accordance with GAAP. The charges, accruals and reserves
on the books of the Borrower and its Subsidiaries for Taxes and other
governmental charges have been determined in accordance with GAAP.

         Section 5.13.    ERISA.  With respect to each Plan, the Borrower and
its Subsidiaries have fulfilled their obligations under the minimum funding
standards of, and are in compliance in all material respects with, ERISA and
with the Code to the extent applicable to it, and have not incurred any
liability under Title IV of ERISA to the PBGC or a Plan other than a liability
to the PBGC for premiums under Section 4007 of ERISA except as described in
reasonable detail in Schedule 5.13.  Neither the Borrower nor any of its
Subsidiaries has any contingent liability with respect to any post-retirement
benefits under a welfare plan as defined in ERISA, other than liability for
continuation coverage described in Part 6 of Title I of ERISA.

         Section 5.14.    Consents.  At the time of consummation thereof, all
consents and approvals of, and filings and registrations with, and all other
actions of, all governmental agencies, authorities or instrumentalities
required to consummate the Borrowings hereunder have been obtained or made and
are or will be in full force and effect.

         Section 5.15.    Capitalization.  All outstanding shares of the
Borrower and its Material Subsidiaries have been duly and validly issued, are
fully paid and nonassessable.  None of the Material Subsidiaries has
outstanding any securities convertible into or exchangeable for its capital
stock or outstanding any rights to subscribe for or to purchase, or any options
for the purchase of, or any agreement providing for the issuance (contingent or
otherwise) of, or any calls, commitments or claims of any character relating
to, its capital stock.


                                       28
<PAGE>   34


         Section 5.16.    Intellectual Property.  The Borrower and its
Subsidiaries own or hold valid licenses to use all the material patents,
trademarks, permits, service marks, and trade names, that are necessary to the
operation of the business of the Borrower and its Subsidiaries as presently
conducted.

         Section 5.17.    Compliance with Statutes, Etc.  The Borrower and its
Subsidiaries are in compliance with all applicable statutes, regulations and
orders of, and all applicable restrictions imposed by, all governmental bodies,
domestic and foreign, in respect of the conduct of their businesses and the
ownership of their properties, except such non-compliance as could not
reasonably be expected to, individually or in the aggregate, have a Material
Adverse Effect.

         Section 5.18.    Environmental Matters.  (a)  Except as described in
reasonable detail in Schedule 5.18, the Borrower and its Subsidiaries have
complied in all material respects with, and on the date of each Borrowing will
be in compliance in all material respects with, all applicable Environmental
Laws and the requirements of any permits issued under such Environmental Laws.
To the best knowledge of the Borrower, there are no pending, past or threatened
Environmental Claims against the Borrower or any of its Subsidiaries on any     
real property owned or operated by the Borrower or any of its Subsidiaries
except as described in reasonable detail in Schedule 5.18.  To the best
knowledge of the Borrower, there are no conditions or occurrences on any real
property owned or operated by the Borrower or any of its Subsidiaries or on any
property adjoining or in the vicinity of any such real property that would
reasonably be expected to form the basis of an Environmental Claim against the
Borrower or any of its Subsidiaries or any such real property that individually
or in the aggregate would reasonably be expected to have a Material Adverse
Effect under any applicable Environmental Law.

         (b)     To the best of the Borrower's knowledge (i) Hazardous
Materials have not at any time been generated, used, treated or stored on, or
transported to or from, any real property owned or operated by the Borrower or
any of its Subsidiaries in a manner that has violated or would reasonably be
expected to violate any Environmental Law, and (ii) Hazardous Materials have
not at any time been released on or from any real property owned or operated by
the Borrower or any of its Subsidiaries, in each case except as could not
reasonably be expected to have a Material Adverse Effect.

         Section 5.19.    Existing Indebtedness.  Schedule 5.19 contains a
complete list of all Indebtedness (other than the Obligations hereunder and
Indebtedness permitted by Section 6.16(c) through (j)) of the Borrower and its
Subsidiaries on the Effective Date after giving effect to the use of the
proceeds of the Loans made on the Effective Date, in each case showing the
aggregate principal amount thereof and the name of the respective borrower and
any other entity which directly or indirectly guaranteed such Indebtedness.

SECTION 6.       COVENANTS.

         The Borrower covenants and agrees that, so long as any Note, Letter of
Credit, Reimbursement Obligation or any other Obligation is outstanding or any
Commitment is outstanding hereunder, unless the Majority Lenders shall
otherwise consent in writing:

         Section 6.1.     Corporate Existence.  Each of the Borrower and its
Subsidiaries will preserve and maintain its corporate existence except for the
dissolution of any Subsidiaries whose 

                                       29
<PAGE>   35
assets are transferred to the Borrower or any of its Subsidiaries
orexcept as otherwise expressly permitted herein.

         Section 6.2.     Maintenance.  Each of the Borrower and the Guarantors
will maintain, preserve and keep its properties and equipment necessary to the
proper conduct of its business in reasonably good repair, working order and
condition (normal wear and tear excepted) and will from time to time make all
reasonably necessary repairs, renewals, replacements, additions and betterments
thereto so that at all times such properties and equipment are reasonably
preserved and maintained; provided, however, that nothing in this Section 6.2
shall prevent the Borrower or any Guarantor from discontinuing the operation or
maintenance of any such properties or equipment if such discontinuance is, in
the judgment of the Borrower or any Guarantor, as applicable, desirable in the
conduct of their businesses.

         Section 6.3.     Taxes.  Each of the Borrower and its Subsidiaries 
will duly pay and discharge all Taxes upon or against it or its properties
before payment is delinquent and before penalties accrue thereon, unless and 
to the extent that the same is being contested in good faith and by appropriate
proceedings and reserves have been established in conformity with GAAP or where
such failure could not reasonably be expected to have a Material Adverse
Effect.  Each of the Borrower and its Subsidiaries will not permit any liens
for Taxes to be filed except such liens related to Taxes which are being
contested in good faith and for which reserves have been provided in accordance
with GAAP.
        
         Section 6.4.     ERISA.  Each of the Borrower and its Subsidiaries
will promptly pay and discharge all obligations and liabilities arising under
ERISA with respect to each Plan of a character which if unpaid or unperformed
might result in the imposition of a material Lien against any of their
properties or assets and will promptly notify the Agent of (i) the occurrence
of any reportable event (as defined in ERISA) relating to a Plan (other than a
multi-employer plan, as defined in ERISA, so long as the event thereunder
cannot reasonably be foreseen to have a Material Adverse Effect), other than
any such event with respect to which the PBGC has waived notice by regulation,
(ii) receipt of any notice from PBGC of its intention to seek termination of
any Plan or appointment of a trustee therefor, (iii) its or any of its
Subsidiaries' intention to terminate or withdraw from any Plan, and (iv) the
occurrence of any event that could result in the incurrence of any material
liability, fine or penalty, or any material increase in the contingent
liability of the Borrower or any Subsidiary, in connection with any
post-retirement benefit under a welfare plan (as defined in ERISA).

         Section 6.5.     Insurance.  Each of the Borrower and its Subsidiaries
will insure, and keep insured, with responsible insurance companies, all
insurable property and assets owned by it of a character and to the extent as
is customarily maintained by companies similarly situated and operating like
property or assets (subject to self-insured retentions) and insure employers'
and public and product liability risks, all with responsible insurance
companies reasonably acceptable to the Agent.  The Borrower will on or before
September 30th of each fiscal year and upon the request of the Agent, furnish a
certificate from an officer of the Borrower setting forth the nature and extent
of the insurance maintained pursuant to this Section 6.5.

         Section 6.6.     Financial Reports and Other Information.  (a) The
Borrower and its Subsidiaries will maintain a system of accounting in such
manner as will enable preparation of financial statements in accordance with
GAAP and will furnish to the Lenders and their respective authorized
representatives such information about the business and financial condition 

                                       30
<PAGE>   36

of the Borrower and its Subsidiaries as any Lender may reasonably request; and,
without any request, will furnish to the Agent:

                 (i)      within sixty (60) days after the end of each of the
first three (3) fiscal quarters of each fiscal year of the Borrower, the
consolidated balance sheet of the Borrower and its Subsidiaries as at the end
of such fiscal quarter and the related consolidated statements of income and
retained earnings and of cash flows for such fiscal quarter and for the portion
of the fiscal year ended with the last day of such fiscal quarter, all of which
shall be in reasonable detail in the form filed with the SEC, and certified by
the chief financial officer of the Borrower that they fairly present the
financial condition of the Borrower and its Subsidiaries as of the dates
indicated and the results of their operations and changes in their cash flows
for the periods indicated and that they have been prepared in accordance with
GAAP, subject to normal year-end audit adjustments and omission of any
footnotes as permitted by the SEC;

                 (ii)     within 120 days after the end of each fiscal year of
the Borrower, the consolidated balance sheet of the Borrower and its
Subsidiaries as at the end of such fiscal year and the related consolidated
statements of income and retained earnings and of cash flows for such fiscal
year and setting forth consolidated comparative figures for the preceding
fiscal year audited by an independent nationally recognized accounting firm and
in the form filed with the SEC;

                 (iii)     as soon as available, but in no event later than
August 15th of each year, a preliminary projection, and no later than September
15th of each year, a final projection of Borrower's consolidated balance sheet
and consolidated income, retained earnings and cash flows for its current
fiscal year showing such projected budget for each fiscal quarter of the
Borrower ending during such year; and

                 (iv)     within ten (10) days after the sending or filing
thereof, copies of all financial statements, projections, documents and other
communications that the Borrower sends to its stockholders or files with the
SEC or any similar governmental authority.

The Agent will forward promptly to the Lenders the information provided by the
Borrower pursuant to (i) through (iv) above.

         (b)     Each financial statement furnished to the Lenders pursuant to
subsections (i) and (ii) of Section 6.6(a) shall be accompanied by (A) a
written certificate signed by the Borrower's chief financial officer, in his or
her capacity as such, to the effect that (1) no Default or Event of Default
then exists or, if any such Default or Event of Default exists as of the date
of such certificate, setting forth a description of such Default or Event of
Default and specifying the action, if any, taken by the Borrower to remedy the
same, and (2) the representations and warranties contained herein are true and
correct in all material respects as though made on the date of such
certificate, except to the extent that any such representation or warranty
relates solely to an earlier date, in which case it was true and correct as of
such earlier date, and (B) a Compliance Certificate in the form of Exhibit 6.6
showing the Borrower's compliance with the covenants set forth herein.

         (c)     Promptly upon receipt thereof, the Borrower will provide the
Agent with a copy of each report or "management letter" submitted to the
Borrower or any of its Subsidiaries by 

                                       31
<PAGE>   37

its independent accountants in connection with any annual, interim or special
audit made by them of the books and records of the Borrower or any of its
Subsidiaries.

         (d)     Promptly after obtaining knowledge of any of the following,
the Borrower will provide the Agent with written notice in reasonable detail
of:

                 (i)      any pending or threatened material Environmental
Claim against the Borrower or any of its Subsidiaries or any real property
owned or operated by the Borrower or any of its Subsidiaries;

                 (ii)     any condition or occurrence on any real property
owned or operated by the Borrower or any of its Subsidiaries that results in
material noncompliance by the Borrower or any of its Subsidiaries with any
Environmental Law; and

                 (iii)    the taking of any material removal or remedial action
in response to the actual or alleged presence of any Hazardous Material on any
real property owned or operated by the Borrower or any of its Subsidiaries.

         (e)     The Borrower will promptly (and in any event within three (3)
Days after an executive officer of the Borrower has actual knowledge thereof)
give written notice to the Agent of:  (i) the occurrence of any Default or
Event of Default; (ii) any litigation or governmental proceeding of the type
described in Section 5.4; (iii) any circumstance that has had or is likely to
have a Material Adverse Effect; and (iv) any event which would result in a
breach of, or is likely to result in a breach of, Sections 6.23, 6.24 or 6.25.

         Section 6.7.     Lender Inspection Rights.  Upon reasonable notice
from the Agent or any Lender, the Borrower will permit the Agent or any Lender
(and such Persons as the Agent or such Lender may reasonably designate) during
normal business hours at such entity's sole expense unless a Default or Event
of Default shall have occurred and be continuing, in which event at the
Borrower's expense, to visit and inspect any of the properties of the Borrower
or any of its Subsidiaries, to examine all of their books and records, to make
copies and extracts therefrom, and to discuss their respective affairs,
finances and accounts with their respective officers, employees and independent
public accountants (and by this provision the Borrower authorizes such
accountants to discuss with the Agent and any Lender (and such Persons as the
Agent or such Lender may reasonably designate) the affairs, finances and
accounts of the Borrower and its Subsidiaries), as often as may be reasonably
requested.

         Section 6.8.     Conduct of Business.  The Borrower and its
Subsidiaries will not engage in any line of business other than the businesses
any of them engage in as of the date hereof and any reasonably related
businesses that involve information technology.

         Section 6.9.     Fiscal Years and Quarters.  Borrower will, for
financial reporting purposes, maintain for itself and its Subsidiaries a fiscal
year that ends on June 30 of each year and fiscal quarters that end on
September 30, December 31, March 31 and June 30 of each year.

         Section 6.10.    Interest Rate Protection.  The Borrower shall notify
the Agent in writing of the proposed terms and conditions and proposed
counterparty of any Interest Rate Protection Agreement, and the Agent shall
have the right of last refusal to elect to enter into an Interest Rate
Protection Agreement on the same terms and conditions and shall notify the
Borrower in 

                                       32
<PAGE>   38

writing within one (1) Business Day after receipt of notice from
the Borrower of any such election by it.

         Section 6.11.    New Subsidiaries.  The Borrower shall cause any (a)
Material Subsidiary of the Borrower which is formed or acquired or (b)
Subsidiary which becomes a Material Subsidiary after the Effective Date to
become a Guarantor with respect to, and jointly and severally liable with all
other Guarantors for, all the obligations under this Agreement and the Notes
within thirty (30) days following such event.

         Section 6.12.    Limitation on Certain Restrictions on Subsidiaries;
Dividends; Negative Pledges.  (a) The Borrower and its Subsidiaries will not
directly or indirectly, create or otherwise permit to exist or become effective
any restriction on the ability of any Subsidiaries of the Borrower to (i) pay
dividends or make any other distributions on its capital stock or any other
interest or participation in its profits owned by the Borrower or pay any
Indebtedness owed to the Borrower, or (ii) make loans or advances to the
Borrower or any of its Subsidiaries, except for restrictions existing under or
by reason of applicable law or this Agreement and the other Credit Documents and
except for any restrictions existing in connection with any Subsidiary acquired
by the Borrower after the Initial Borrowing Date, in which case the Borrower
shall either promptly cause the removal or release of any such restrictions or
not advance the proceeds of any Loan to such Subsidiary even if otherwise
permitted by this Agreement.

         (b)     The Borrower shall not redeem, purchase or otherwise acquire
any shares of its capital stock directly or indirectly out of the proceeds of
any Borrowing other than as permitted herein, or declare or pay any dividends
on its capital stock, make any distribution or payment to stockholders, or set
aside any funds for such purpose, and not permit any of its Subsidiaries to do
any of the same except: (i) any Subsidiary of the Borrower may declare and pay
dividends or make distributions to the Borrower and make payments to the
Borrower on any obligations or liabilities, including Indebtedness, owing to
the Borrower; (ii) capital stock of the Borrower may be purchased (or the
purchase thereof funded) or otherwise acquired by any of the Borrower or its
Subsidiaries for any Code Section 401(K) plan, Code Section 423 plan or Plan of
the Borrower or any of its Subsidiaries so long as no Default or Event of
Default shall have occurred and be continuing or would occur as a result of
such payment; and (iii) the Borrower may redeem, purchase or otherwise acquire
shares of its capital stock, or set aside funds for such purpose, in an amount
of up to $5,000,000 in any fiscal year out of the proceeds of Borrowings.

         (c)     The Borrower shall not, and will not permit any Subsidiary to,
make any deposit for any of the purposes restricted or prohibited in clauses
(a) or (b) above.

         (d)     The Borrower and its Subsidiaries shall not enter into any
negative pledge agreement or any other agreement (i) prohibiting the creation
or assumption of any Lien upon its properties, revenues or assets, whether now
owned or hereafter acquired except as then contained in the documentation
evidencing any permitted Indebtedness assumed in connection with a permitted
Acquisition, or (ii) prohibiting or restricting the ability of the Borrower or
any Subsidiary to amend or otherwise modify this Agreement or any Credit
Document.

         Section 6.13.    Restrictions on Fundamental Changes.  (a) Neither the
Borrower nor any of its Subsidiaries shall be a party to any merger into or
consolidation with, or purchase or 

                                       33
<PAGE>   39

otherwise acquire all or substantially all of the assets or stock of any other
Person, or sell all or substantially all of its assets or stock, except (i) a
Subsidiary of the Borrower may merge into or consolidate with the Borrower or
another Subsidiary of the Borrower; or (ii) the Borrower or any of its
Subsidiaries may merge into, or consolidate with, or purchase or otherwise
acquire all or substantially all of the assets or stock of any other Person 
if upon the consummation of any such merger, consolidation, purchase or
acquisition, (A) the Borrower or such Subsidiary is the surviving corporation
in any such merger or consolidation, (B) such merger, consolidation, purchase
or acquisition is non-hostile in nature, (C) such Person is in similar lines of
business as the Borrower and its Subsidiaries, (D) the Borrower shall have
delivered to the Agent within ten (10) Business Days prior to the consummation
of such Acquisition a report signed by an executive officer of the Borrower in
the form of Exhibit 6.13 which shall contain calculations demonstrating on a
trailing four (4) quarter pro forma basis the Borrower's compliance with
Sections 6.23, 6.24 and 6.25 (such calculations to use historical financial
results except for the normalization of dividends, distributions or bonuses to
any prior owner and of corporate overhead costs that will not recur after the
Acquisition date and except for any appropriate adjustments for non-GAAP
reporting) and a statement of sources and uses of funds for such Acquisition,
all as reasonably satisfactory to the Agent, provided that the Borrower will
not have to deliver such report if the Acquisition price (whether in cash
and/or the value of stock or property and taking into account any deferred
purchase price and any earn out portion of such price calculated at the time of
the Acquisition based upon the reasonable projections of the Borrower, in each
case using the discounted present value thereof as provided in Section 6.16(f))
(x) is less than $10,000,000 if there shall be no outstanding Loans as of such
date or (y) is less than $5,000,000 if there shall be outstanding Loans as of
such date; provided that no Default or Event of Default shall have occurred and
be continuing or would otherwise be existing as a result of such merger,
consolidation, purchase or Acquisition.

         (b)     The Borrower and its Subsidiaries may issue additional capital
stock or ownership interests so long as no dividends or distributions are
required to be paid on such capital stock or interests and so long as there is
no mandatory redemption or liquidating distribution of any such stock or
interest before the Maturity Date, provided that none of the Subsidiaries may
issue preferred stock or ownership interests or enter into an agreement which
prohibits or restricts the payment of dividends or distributions to its parent
company.  The Borrower shall not take any action, or permit any of its
Subsidiaries to take any action, which will result in a decrease in the
percentage of the outstanding shares of capital stock of, or in the percentage
of the partnership interests or other ownership interests in, any of the
Subsidiaries of the Borrower to less than fifty-one percent (51%) thereof.

         Section 6.14.    Use of Property and Facilities; Environmental, Health
and Safety Laws.  The Borrower and its Subsidiaries shall comply in all
material respects with all Environmental Laws applicable to or affecting the
properties or business operations of the Borrower or any Subsidiary.

         Section 6.15.    Liens.  The Borrower and its Subsidiaries shall not
create, incur, assume or suffer to exist any Lien of any kind on any property
or asset of any kind of the Borrower or any Subsidiary, except the following:

         (a)     Liens arising in the ordinary course of business by operation
of law in connection with worker's compensation, unemployment insurance, old
age benefits, social security obligations, taxes, assessments, statutory
obligations or other similar charges, good faith 

                                       34
<PAGE>   40

deposits, pledges or other Liens in connection with bids, performance bonds,
contracts or leases to which the Borrower or the Subsidiary is a party or
other deposits required to be made in the ordinary course of business; provided
that in each case the obligation secured is not for Indebtedness and is not
overdue or, if overdue, is being contested in good faith by appropriate
proceedings and reserves in conformity with GAAP have been provided therefor;

         (b)     mechanics', workmen's, materialmen's, landlords', carriers' or
other similar Liens arising in the ordinary course of business (or deposits to
obtain the release of such Liens) related to obligations not overdue or, if
overdue, that are being contested in good faith by appropriate proceedings and
reserves in conformity with GAAP have been provided therefor;

         (c)     Liens for taxes or assessments or other government charges or
levies not yet due or which are being contested in good faith by appropriate
proceedings and reserves in conformity with GAAP have been provided therefor;

         (d)     Liens securing Indebtedness permitted by Sections 6.16(b) or
(e) up to an aggregate amount of $7,500,000, provided that such Liens do not
encumber cash, deposit accounts, Cash Equivalents, accounts receivable,
intellectual property, the office building located at 15150 Memorial Drive,
Houston, Texas, stock or interests in Subsidiaries or other permitted equity
securities;

         (e)     any extension, renewal or replacement (or successive
extensions, renewals or replacements) in whole or in part of any Lien referred
to in the foregoing subsection (d), provided that the principal amount of
Indebtedness secured thereby does not exceed the principal amount secured at
the time of such extension, renewal or replacement, and that such extension,
renewal or replacement is limited to the property already subject to the Lien
so extended, renewed or replaced;

         (f)     Liens on property securing Indebtedness aggregating no greater
than $500,000, provided the Borrower cause the release or bonding around of any
such Liens within thirty (30) days of the discovery by the Borrower of any such
Lien;

         (g)     rights reserved to or vested in any municipality or
governmental, statutory or public authority by the terms of any right, power,
franchise, grant, license or permit, or by any provision of law, to terminate
such right, power, franchise, grant, license or permit or to purchase, condemn,
expropriate or recapture or to designate a purchaser of any of the property of
a Person;

         (h)     rights reserved to or vested in any municipality or
governmental, statutory or public authority to control, regulate or use any
property of a Person;

         (i)     rights of a common owner of any interest in property held by a
Person and such common owner as tenants in common or through other common
ownership;

         (j)     encumbrances (other than to secure the payment of
Indebtedness), easements, restrictions, servitudes, permits, conditions,
covenants, exceptions or reservations in any property or rights-of-way of a
Person for the purpose of roads, pipelines, transmission lines, transportation
lines, distribution lines, removal of gas, oil, coal, metals, steam, minerals,
timber or other natural resources, and other like purposes, or for the joint or
common use of real 

                                       35
<PAGE>   41

property, rights-of-way, facilities or equipment, or defects, irregularities
and deficiencies in title of any property or rights-of-way;

         (k)     zoning, planning and environmental laws and ordinances and
municipal regulations;

         (l)     financing statements filed by lessors of property in the
ordinary course of business (but only with respect to the property so leased);
and

         (m)     Liens against real property acquired by the Borrower or any of
its domestic Subsidiaries if the Borrower shall have given written notice to    
the Agent of its desire to grant, or have a domestic Subsidiary grant, as the
case may be, a first priority Lien upon such property for the benefit of the
Agent and the Lenders to secure the payment of the Obligations, and all Lenders
elect in their sole discretion to obtain a Lien upon such property.  Any such
Lien shall be evidenced by documentation reasonably satisfactory to the Agent
and shall be accompanied by evidence of the priority of such Lien, information
concerning Environmental Claims and other matters affecting or concerning such
property and an opinion of counsel to the Borrower or such domestic Subsidiary
as to the validity of such Lien and such other matters as reasonably requested
by the Agent, all as reasonably satisfactory to the Agent; and

         (n)     Liens created by any Credit Document.

         Section 6.16.    Indebtedness.  The Borrower and its Subsidiaries
shall not contract, assume or suffer to exist any Indebtedness except:

         (a)     Indebtedness under the Credit Documents;

         (b)     existing Indebtedness outstanding on the Initial Borrowing
Date and listed on Schedule 5.19, and any subsequent extensions, renewals or
refinancings thereof so long as such Indebtedness is not increased in amount,
the maturity date thereof is not made earlier in time, the interest rate per
annum applicable thereto is not increased, any amortization of principal
thereunder is not shortened and the payments thereunder are not increased,
provided that item 2 thereof shall be included within the aggregate total
permitted by Section 6.16(f) and item 3 thereof shall be included within the
aggregate total permitted by Section 6.16(e);

         (c)     Indebtedness under any Interest Rate Protection Agreements
entered into to protect the Borrower against fluctuations in interest rates on
Obligations under the Loans;

         (d)     Indebtedness incurred in connection with the Liens permitted
by Section 6.15;

         (e)     subordinated Indebtedness (so long as the scheduled maturity
date thereof is beyond the Maturity Date and no principal payments are
scheduled or paid before the Maturity Date), Capitalized Lease Obligations,
purchase money Indebtedness on assets acquired, Indebtedness in connection with
an investment permitted by Section 6.17(j), and Indebtedness assumed in
connection with a permitted Acquisition, all of which, together with any
Indebtedness under a payment Guaranty of the indebtedness of another Person
permitted pursuant to Section 6.17(h), shall not exceed $13,000,000 in the
aggregate at any one time until September 30, 1996, after which time such
Indebtedness shall not exceed $10,000,000 in the aggregate at any one time,
provided that such aggregate Indebtedness may exceed $13,000,000 or
$10,000,000, 


                                       36
<PAGE>   42

as applicable, at any one time, but not exceed $20,000,000, solely as a
result of assumed Indebtedness in connection with an Acquisition, in which
event the Borrower shall have a period of thirty (30) days from the date of
such Acquisition to reduce such aggregate Indebtedness to $13,000,000 or
$10,000,000, as applicable, or less, and provided further the aggregate amount
of Indebtedness permitted hereunder shall increase after September 30, 1996, to
the extent and by the amount the outstanding permitted Indebtedness in
connection with the deferred purchase price of permitted Acquisitions is less
than $5,000,000 (as calculated in accordance with Section 6.16(f)), such
additional Indebtedness hereunder, however, not to increase by greater than
$3,000,000 and to increase for only so long as item 3 on Schedule 5.19 shall be
outstanding;

         (f)     Indebtedness not to exceed $5,000,000 at any one time in
connection with the deferred purchase price of a permitted Acquisition, such
Indebtedness to be calculated based upon the discounted present value of the
scheduled deferred payment stream using a discount rate equal to the average
rate of interest per annum then accruing on Eurodollar Loans, or if no
Eurodollar Loans are then outstanding, at the Base Rate and Indebtedness not to
exceed $5,000,000 at any one time in connection with the earn out provisions of
a permitted Acquisition, such Indebtedness to be calculated based upon the
discounted present value of the projected payment stream using a discount rate
as described above and calculated at the time of the Acquisition based upon the
reasonable projections of the Borrower, all such Indebtedness to be in addition
to the Indebtedness permitted in Section 6.16(e);

         (g)     unsecured intercompany loans and advances from any Subsidiary
of the Borrower to the Borrower or any Guarantor, from the Borrower or any
Subsidiary of the Borrower to a foreign Subsidiary of the Borrower for
operating expenses and capital expenditures incurred by such foreign Subsidiary
in the ordinary course of its business, or from the Borrower or any Guarantor
to any Guarantor or any domestic Subsidiary so long as any such loans or
advances are for operating expenses and capital expenditures incurred by such
Subsidiary in the ordinary course of its business;

         (h)     Indebtedness under unsecured foreign exchange futures
agreements, arrangements or options designed to protect against fluctuations in
currency exchange rates from time to time entered into in accordance with
customary industry practice;

         (i)     Indebtedness permitted by Section 6.17(h) and (i); and

         (j)     Indebtedness incurred in connection with letters of credit or
performance or bid bonds in the event ABN AMRO or ABN AMRO as Agent is unable
to issue same, so long as the undrawn face amount of all such letters of credit
and bonds, together with the aggregate undrawn face amount of all Letters of
Credit, does not exceed in the aggregate the L/C Commitment Amount.

         Section 6.17.    Advances, Investments, Loans and Guaranties.  The
Borrower and its Subsidiaries shall not lend money or make advances to any
Person, or purchase or acquire any stock, obligations or securities of, or any
other interest in, or make any capital contribution to, any Person, or enter
into any Guaranties except:

         (a)     investments in Cash Equivalents, deposit accounts and up to
$500,000 in publicly traded equity securities;

                                       37
<PAGE>   43


         (b)     receivables owing to the Borrower or a Subsidiary created or
acquired in the ordinary course of business and payable on customary trade
terms of the Borrower or such Subsidiary and in compliance with the
arm's-length requirements of Section 6.20;

         (c)     investments (including debt obligations) received in
connection with the bankruptcy or reorganization of suppliers and customers and
in settlement of delinquent obligations of, and other disputes with, customers
and suppliers arising in the ordinary course of business;

         (d)     deposits made in the ordinary course of business consistent
with past practices to secure the performance of leases;

         (e)     unsecured intercompany loans and advances as permitted by
Section 6.16(g);

         (f)     the purchase or acquisition of stock in the Borrower for a
Code Section 401K plan, Code Section 423 plan or Plan of the Borrower or any of
its Subsidiaries;

         (g)     as permitted by Sections 6.12 and 6.13;

         (h)     performance Guaranties incurred in the ordinary course of
business in respect of obligations of the Borrower or its Subsidiaries incurred
in the ordinary course of business, (provided such Guaranties and the
obligations so guaranteed are of the type normally incurred in the industry
from time to time for the type of project involved and are Guaranties of
performance and not of payment or of the price of stock) and unsecured payment
Guaranties of Indebtedness permitted by Section 6.16 or of indebtedness of
another Person as limited by Section 6.16(e);

         (i)     Guaranties by the Borrower or any Subsidiary of any
Indebtedness of any Subsidiary of the Borrower permitted by Section 6.16; and

         (j)     existing investments as reasonably described in Schedule 6.17,
additions to such existing investments and investments in the ordinary course
of business of the Borrower and its Subsidiaries in any Person involved in the
development, marketing or distribution of products, services or technologies
reasonably related to any of the businesses of the Borrower and its
Subsidiaries provided that all such investments are made through a limited
liability entity (excepting any existing investments or additions thereto), no
Borrowing hereunder is used to finance any such investment, no Indebtedness is
incurred in connection therewith or such Indebtedness is included within the
limitation on Indebtedness in Section 6.16(e) and all such investments
(including any future required capital contributions) do not exceed in the
aggregate five percent (5%) of the total assets of the Borrower and its
Subsidiaries on a consolidated basis in any fiscal year.

         Section 6.18.    Modifications of Corporate Documents.  Neither the
Borrower nor any of its Subsidiaries shall amend, modify or change in any way
materially adverse to the interests of the Lenders, its Certificate or Articles
of Incorporation or by-laws or other corporate governance documents.  None of
the Subsidiaries shall enter into any agreement related to its capital stock
(including any shareholders' agreement) the effect of which could result in the
Borrower or a Subsidiary of the Borrower failing to directly or indirectly own
at least fifty-one percent (51%) thereof.



                                       38
<PAGE>   44

         Section 6.19.    Transfer of Assets.  The Borrower and its
Subsidiaries shall not permit any Transfer of an asset except:

         (a)     the Transfer of inventory and equipment in the ordinary course
of business;

         (b)     the retirement or replacement of assets in the ordinary course
of business;

         (c)     the Transfer of any non-cash assets among the Borrower or any
Subsidiary of the Borrower; provided that the Borrower or a domestic Subsidiary
may not Transfer any non-cash assets to a foreign Subsidiary except for a
Transfer of assets for tax purposes not to exceed in the aggregate $5,000,000
net book value (without giving effect to the $100,000 amount in the definition
of Transfer in Section 1.1) in any fiscal year so long as no Default or Event
of Default shall have occurred and be continuing and the Borrower shall comply
in all respects with Section 6.11;

         (d)     any Transfer permitted by Section 6.13;

         (e)     the Liens permitted by Section 6.15;

         (f)     the Transfer of assets (excluding interests in real property)
acquired in an Acquisition or otherwise and outside the core businesses of the
Borrower and its Subsidiaries not to exceed in the aggregate $5,000,000 in net
book value in any fiscal year, or, to the extent such aggregate value is
exceeded during any such period, the Borrower demonstrates to the reasonable
satisfaction of the Agent that it would have complied with Sections 6.23, 6.24
and 6.25 as if the Transfer had occurred at the end of the previous fiscal
quarter;

         (g)     the Transfer of interests in real property (excluding the
office building located at 15150 Memorial Drive, Houston, Texas) not to exceed
in the aggregate $5,000,000 in net book value in any fiscal year; and

         (h)     the Transfers of any assets not otherwise covered by this
Section 6.19 not to exceed in the aggregate $1,000,000 in net book value in any
fiscal year.

         Section 6.20.    Transactions with Affiliates.  Except as otherwise
specifically permitted herein, the Borrower and its Subsidiaries shall not
enter into or be a party to any material transaction or arrangement with any
Affiliate of such Person, including without limitation, the purchase from, sale
to or exchange of property with, any merger or consolidation with or into, or
the rendering of any service by or for, any Affiliate, except pursuant to the
reasonable requirements of the Borrower's or such Subsidiary's business and
upon fair and reasonable terms no less favorable to the Borrower or such
Subsidiary than would be able to be obtained in a comparable arm's-length
transaction with a Person other than an Affiliate.

         Section 6.21.    Compliance with Laws.  Without limiting any of the 
other covenants of the Borrower in this Section 6, the Borrower and its
Subsidiaries shall conduct their business and otherwise be, in compliance in
all material respects with all applicable laws, regulations, ordinances and
orders of any governmental or judicial authorities; provided, however, that
this Section 6.21 shall not require the Borrower or any Subsidiary to comply
with any such law, regulation, ordinance or order if it shall be contesting
such law, regulation, ordinance or order
        
                                       39
<PAGE>   45

 
in good faith by appropriate proceedings and reserves in conformity with
GAAP have been provided therefor.

         Section 6.22.    Assets of Foreign Subsidiaries.  If as a result of
any merger, consolidation, purchase or Acquisition permitted pursuant to Section
6.13, the assets owned by the Borrower's foreign Subsidiaries (excluding
intercompany receivables) exceed twenty percent (20%) of the total assets of the
Borrower and its Subsidiaries on a consolidated basis, the Borrower shall within
thirty (30) days cause sixty-five percent (65%) of (a) the stock of the foreign
Subsidiary acquired or formed in connection therewith or which acquires such
assets and (b) thereafter any foreign Subsidiary which acquires total assets of
at least $3,500,000 to be pledged to the Agent for the benefit of the Lenders
(any such pledge to be evidenced by documentation reasonably satisfactory to the
Agent and to be accompanied by an opinion of counsel to the Borrower and any
applicable Subsidiary as to the validity of such Lien and such other matters as
reasonably requested by the Agent in form and substance reasonably satisfactory
to the Agent).

         Section 6.23.    Fixed Charge Coverage Ratio.  The Borrower will not
permit the Fixed  Charge Coverage Ratio as of the end of the relevant calendar
quarter to be less than the ratio set forth opposite such quarter set forth
below:

                     Period                         Fixed Charge Coverage Ratio

         December 31, 1995 and March 31, 1996               1.50 to 1.0
         June 30, 1996, September 30, 1996,                 1.75 to 1.0
         December 31, 1996 and March 31, 1997              
         June 30, 1997 and thereafter                       1.85 to 1.0

         Section 6.24.    Total Funded Debt to EBITDA Ratio.  The Borrower will
as of the end of each calendar quarter maintain a ratio of Total Funded Debt to
EBITDA of no greater than 3.0 to 1.0.

         Section 6.25.    Minimum Adjusted Net Worth.  The Borrower will as of
the end of each calendar quarter maintain an Adjusted Net Worth of not less
than $139,400,000, as adjusted forty-five (45) days after the end of each
fiscal quarter beginning February 15, 1996, by adding fifty percent (50%) of
the cumulative positive Consolidated Net Income, if any, of the Borrower and
its Subsidiaries for the fiscal quarter ending December 31, 1995, and for each
fiscal quarter thereafter.

SECTION 7.       EVENTS OF DEFAULT AND REMEDIES.

         Section 7.1.     Events of Default.  Any one or more of the following
shall constitute an Event of Default:

         (a)     default in the payment when due of the principal amount of any
Loan or any Reimbursement Obligation, or default in the payment when due of any
interest thereon or any fees payable hereunder and the continuance thereof for
three (3) Business Days;

         (b)     default in the observance or performance of any covenant set
forth in Sections 6.12(b), 6.13, 6.23, 6.24 and 6.25;

                                       40
<PAGE>   46

         (c)     default in the observance or performance of any provision
hereof or of any other Credit Document not mentioned in (a) or (b) above, which
is not remedied within thirty (30) days after notice thereof to the Borrower by
the Agent;

         (d)     any representation or warranty made herein or in any other
Credit Document by the Borrower or any Subsidiary proves untrue in any material
respect as of the date of the issuance or making, or deemed making or issuance,
thereof;

         (e)     default occurs in the payment when due of Indebtedness in an
aggregate principal amount of $1,000,000 or more of the Borrower or any
Subsidiary after any applicable grace period therefor, and such default
continues for a period of time sufficient to permit the holder or beneficiary
of such Indebtedness, or a trustee therefor, to cause the acceleration of the
maturity of any such Indebtedness or any mandatory unscheduled prepayment,
purchase, or other early funding thereof or default occurs in the payment of
any reimbursement obligation due and owing, after any applicable grace period
and written notice to the Borrower, to the Agent under any letter of credit
issued by the Agent for the account of the Borrower or any of its Subsidiaries;

         (f)     the Borrower or any Subsidiary (i) has entered involuntarily
against it an order for relief under the United States Bankruptcy Code or a
comparable action is taken under any bankruptcy or insolvency law of another
country or political subdivision of such country, (ii) does not pay, or admits
its inability to pay, its debts generally as they become due, (iii) makes an
assignment for the benefit of creditors, (iv) applies for, seeks, consents to,
or acquiesces in, the appointment of a receiver, custodian, trustee, examiner,
liquidator or similar official for it or any substantial part of its property,
(v) institutes any proceeding seeking to have entered against it an order for
relief under the United States Bankruptcy Code or any comparable law, to
adjudicate it insolvent, or seeking dissolution, winding up, liquidation,
reorganization, arrangement, adjustment or composition of it or its debts under
any law relating to bankruptcy, insolvency or reorganization or relief of
debtors or fails to file an answer or other pleading denying the material
allegations of any such proceeding filed against it, (vi) makes any board of
directors resolution in direct furtherance of any matter described in clauses
(i)-(v) above, or (vii) fails to contest in good faith any appointment or
proceeding described in Section 7.1(f);

         (g)     a custodian, receiver, trustee, examiner, liquidator or
similar official is appointed for the Borrower or any Subsidiary or any
substantial part of its property, or a proceeding described in Section
7.1(f)(v) is instituted against the Borrower or any Subsidiary and such
appointment continues undischarged or such proceeding continues undismissed or
unstayed for a period of sixty (60) days, or the Borrower or any Guarantor
dissolves (except as permitted in Section 6.1) or makes any board of directors
resolution in direct furtherance of any such dissolution;

         (h)     the Borrower or any Subsidiary fails within sixty (60) days
(or such earlier date as any steps to execute on such judgment or order take
place) to pay, bond or otherwise discharge any judgment or order for the
payment of money in excess of $1,000,000, which is not stayed on appeal or
otherwise being appropriately contested in good faith in a manner that stays
execution;

         (i)     the Borrower or any Subsidiary fails to pay when due an amount
aggregating in excess of $1,000,000 that it is liable to pay to the PBGC or to
a Plan under Title IV of ERISA; or a notice of intent to terminate a Plan
having Unfunded Vested Liabilities of the Borrower or any of its Subsidiaries
in excess of $1,000,000 (a "Material Plan") is filed under Title IV of ERISA;
or the PBGC institutes proceedings under Title IV of ERISA to terminate or to
cause 

                                       41
<PAGE>   47

a trustee to be appointed to administer any Material Plan or a proceeding
is instituted by a fiduciary of any Material Plan against the Borrower or any
Subsidiary to collect any liability under Section 515 or 4219(c)(5) of ERISA
and such proceeding is not dismissed within thirty (30) days thereafter; or a
condition exists by reason of which the PBGC would be entitled to obtain a
decree adjudicating that any Material Plan must be terminated;

         (j)     any Credit Party, any Person acting on behalf of a Credit 
Party, or any governmental authority challenges the validity of any Credit
Document or such Credit Party's obligations thereunder or any Credit Document
ceases to be in full force and effect; or
        
         (k)     any event of default or default described in any Interest Rate
Protection Agreement or futures agreement permitted pursuant to Section 6.16(c)
and (g) with a notional amount of $1,000,000 or greater shall occur after any
applicable grace period therefor.

         Section 7.2.     Non-Bankruptcy Defaults.  When any Event of Default
other than those described in subsections (f) or (g) of Section 7.1 has
occurred and is continuing, the Agent shall, by notice to the Borrower: (a) if
so directed by the Majority Lenders, terminate the remaining Commitments and
all other obligations of the Lenders hereunder on the date stated in such
notice (which may be the date thereof); (b) if so directed by the Majority
Lenders, declare the principal of and the accrued interest on all outstanding
Notes to be forthwith due and payable and thereupon all outstanding Notes,
including both principal and interest thereon, shall be and become immediately
due and payable together with all other amounts payable under the Credit
Documents without further demand, presentment, protest or notice of any kind,
including, but not limited to, notice of intent to accelerate and notice of
acceleration, each of which is expressly waived by the Borrower; and (c) if so
directed by the Majority Lenders, demand that the Borrower immediately pay to
the Agent (to be held by the Agent pursuant to Section 7.4) the full amount
then available for drawing under each outstanding Letter of Credit, and the
Borrower agrees to immediately make such payment and acknowledge and agree that
the Lenders would not have an adequate remedy at law for failure by the
Borrower to honor any such demand and that the Agent, for the benefit of the
Lenders, shall have the right to require the Borrower to specifically perform
such undertaking whether or not any drawings or other demands for payment have
been made under any Letter of Credit.  The Agent, after giving notice to the
Borrower pursuant to Section 7.1(c) or this Section 7.2, shall also promptly
send a copy of such notice to the other Lenders, but the failure to do so shall
not impair or annul the effect of such notice.

         Section 7.3.     Bankruptcy Defaults.  When any Event of Default
described in subsections (f) or (g) of Section 7.1 has occurred and is
continuing, then all outstanding Notes shall immediately become due and payable
together with all other amounts payable under the Credit Documents without
presentment, demand, protest or notice of any kind, each of which is expressly
waived by the Borrower; and all obligations of the Lenders to extend further
Credit pursuant to any of the terms hereof shall immediately terminate and the
Borrower shall immediately pay to the Agent (to be held by the Agent pursuant
to Section 7.4) the full amount then available for drawing under all
outstanding Letters of Credit, the Borrower acknowledging that the Lenders and
the Agent would not have an adequate remedy at law for failure by the Borrower
to honor any such demand and that the Lenders and the Agent shall have the
right to require the Borrower to specifically perform such undertaking whether
or not any drawings or other demands for payment have been made under any of
the Letters of Credit.


                                       42
<PAGE>   48

         Section 7.4.     Collateral for Undrawn Letters of Credit.  (a) If the
prepayment of the amount available for drawing under any or all outstanding
Letters of Credit is required under Section 7.2 or 7.3, the Borrower shall
forthwith pay the amount required to be so prepaid, to be held by the Agent as
provided in subsection (b) below.

         (b)     All amounts prepaid pursuant to subsection (a) above shall be
held by the Agent in a separate collateral account (such account, and the
credit balances, properties and any investments from time to time held therein,
and any substitutions for such account, any certificate of deposit or other
instrument evidencing any of the foregoing and all proceeds of and earnings on
any of the foregoing being collectively called the "Collateral Account") as
security for, and for application by the Agent (to the extent available) to,
the reimbursement of any drawing under any Letter of Credit then or thereafter
made by the Agent, and to the payment of the unpaid balance of any Loans and
all other Obligations.  The Collateral Account shall be held in the name of the
Borrower, but subject to the exclusive dominion and control of the Agent for
the benefit of the Agent and the Lenders.  If and when requested by the
Borrower, the Agent shall invest funds held in the Collateral Account from time
to time in direct obligations of, or obligations the principal of and interest
on which are unconditionally guaranteed by, the United States of America with a
remaining maturity of six (6) months or less, provided that the Agent is
irrevocably authorized to sell investments held in the Collateral Account when
and as required to make payments out of the Collateral Account for application
to amounts due and owing from the Borrower to the Agent or Lenders.  When and
if (i) the Borrower shall have made payment of all such obligations referred to
in subsection (a) above, (ii) all relevant preference or other disgorgement
periods relating to the receipt of such payments have passed, and (iii) no
Letters of Credit, Commitments, Loans, Reimbursement Obligations or other
Obligations remain outstanding hereunder, the Agent shall repay to the Borrower
any remaining amounts held in the Collateral Account.

         Section 7.5.     Notice of Default.  The Agent shall give notice to
the Borrower under Sections 7.1(c) and 7.2 promptly upon being requested to do
so by the Majority Lenders and shall thereupon notify all the Lenders thereof.

         Section 7.6.     Expenses.  The Borrower agrees to pay to the Agent
and each Lender all reasonable expenses incurred or paid by the Agent or such
Lender, including reasonable attorneys' fees and court costs (including the
allocated cost of in-house staff counsel to any of the Lenders provided that
any such attorneys' fees shall not be duplicative to outside counsel and such
allocation of costs shall be reasonable), in connection with any Default or
Event of Default by the Borrower hereunder or in connection with the
enforcement of any of the Credit Documents.

         Section 7.7.     Distribution and Application of Proceeds.  After the
occurrence of and during the continuance of an Event of Default, any payment to
the Agent or any Lender hereunder or under any Guaranty of any Material
Subsidiary, from any cash collateral or otherwise shall be paid to the Agent to
be distributed and applied as follows (unless otherwise agreed by the Agent and
all Lenders):

         (a)     First, to the payment of any and all reasonable costs and
expenses of the Agent, including without limitation, reasonable attorneys' fees
and out-of-pocket costs and expenses as provided by this Agreement or by any
other Credit Document, incurred in connection with the 

                                       43
<PAGE>   49

collection of such payment or in respect of the enforcement of any rights
of the Agent or the Lenders under this Agreement or any other Credit Document;

         (b)     Second, to the payment of any and all reasonable costs and     
expenses of the Lenders, including without limitation, reasonable attorneys'
fees and out-of-pocket costs and expenses as provided by this Agreement or by
any other Credit Document, incurred in connection with the collection of such
payment or in respect of the enforcement of any rights of the Lenders under
this Agreement or any other Credit Document; pro rata in the proportion in
which the amount of such costs and expenses unpaid to each such Lender bears to
the aggregate amount of the costs and expenses unpaid to all Lenders
collectively, until all such fees, costs and expenses have been paid in full;

         (c)     Third, to the payment of any unpaid fees to the Agent or any
Lender as provided by this Agreement or any other Credit Document, pro rata in
the proportion in which the amount of such fees unpaid to the Agent and each
such Lender bears to the aggregate amount of the fees unpaid to the Agent and
all Lenders collectively, until all such fees have been paid in full;

         (d)     Fourth, to the payment of accrued and unpaid interest on the
Notes or the Reimbursement Obligations to the date of such application, pro
rata in the proportion in which the amount of such interest, accrued and unpaid
to each such Lender bears to the aggregate amount of such interest accrued and
unpaid to all Lenders collectively, until all such accrued and unpaid interest
has been paid in full;

         (e)     Fifth, to the payment of the outstanding principal amount of
each of the Notes and the amount of the outstanding Reimbursement Obligations
(reserving cash collateral for all undrawn face amounts of any outstanding
Letters of Credit), pro rata in the proportion in which the outstanding
principal amount of such Notes and the amount of such outstanding Reimbursement
Obligations owing to each such Lender, together with the undrawn face amounts
of such outstanding Letters of Credit, bears to the aggregate amount of all
outstanding Notes, outstanding Reimbursement Obligations and the undrawn face
amounts of all outstanding Letters of Credit.  In the event that any such
Letters of Credit, or any portions thereof, expire without being drawn, any
cash collateral therefore shall be distributed pro rata by the Agent until the
principal amount of all Notes and Reimbursement Obligations shall have been
paid in full; and

         (f)     Sixth, to the payment of any other outstanding Obligations,
pro rata in the proportion in which the outstanding Obligations owing to each
such Lender bears to the aggregate amount of such Obligations until all
Obligations have been paid in full.

SECTION 8.       CHANGE IN CIRCUMSTANCES.

         Section 8.1.     Change of Law.  Notwithstanding any other provisions
of this Agreement or any Note, if at any time any change in applicable law or
regulation or in the interpretation thereof makes it unlawful for any Lender to
make or continue to maintain Eurodollar Loans, such Lender shall promptly give
notice thereof to the Borrower and such Lender's obligations to make or
maintain Eurodollar Loans under this Agreement shall terminate until it is no
longer unlawful for such Lender to make or maintain Eurodollar Loans.  The
Borrower shall prepay on demand the outstanding principal amount of any such
affected Eurodollar Loans, together with all interest accrued thereon;
provided, however, subject to all of the terms and conditions

                                       44
<PAGE>   50

of this Agreement, the Borrower may then elect to borrow the principal amount
of the affected Eurodollar Loans from such Lender by means of Base Rate Loans
from such Lender that shall not be made ratably by the Lenders but only by such
affected Lender.

         Section 8.2.     Unavailability of Deposits or Inability to Ascertain
LIBO Rate.  If on or before the first day of any Interest Period for any
Borrowing of Eurodollar Loans the Agent determines (after consultation with
other Lenders) that, due to changes in circumstances since the date hereof,
adequate and fair means do not exist for determining LIBO Rate or such rate
will not accurately reflect the cost to the Majority Lenders of funding
Eurodollar Loans for such Interest Period, the Agent shall give notice of such
determination to the Borrower and the Lenders, whereupon until the Agent
notifies the Borrower and Lenders that the circumstances giving rise to such
suspension no longer exist, the obligations of the Lenders to make Eurodollar
Loans shall be suspended.

         Section 8.3.     Increased Cost and Reduced Return.  (a) If, on or
after the date hereof, the adoption of or any change in any applicable law,
rule or regulation, or any change in the interpretation or administration
thereof by any governmental authority, central bank or comparable agency
charged with the interpretation or administration thereof, or compliance by any
Lender (or its Lending Office), including the Agent in its capacity as the
issuer of Letters of Credit or Agent Letters of Credit, with any request or
directive (whether or not having the force of law) of any such authority,
central bank or comparable agency:

                 (i)      subjects any Lender (or its Lending Office) to any
tax, duty or other charge related to any Eurodollar Loan, Letter of Credit,
Agent Letters of Credit or Reimbursement Obligation, or its participation in
any thereof, or its obligation to advance or maintain Eurodollar Loans, issue
Letters of Credit or Agent Letters of Credit, or to participate therein, or
shall change the basis of taxation of payments to any Lender (or its Lending
Office) of the principal of or interest on its Eurodollar Loans, Letters of
Credit, or participations therein, or any other amounts due under this
Agreement related to its Eurodollar Loans, Letters of Credit, Agent Letters of
Credit, Reimbursement Obligations, or participations therein, or its obligation
to make Eurodollar Loans, issue Letters of Credit, or acquire participations
therein (except for changes in the rate of tax on the overall net income of
such Lender or its Lending Office imposed by the jurisdiction in which such
Lender's principal executive office or Lending Office is located); or

                 (ii)     imposes, modifies or deems applicable any reserve,
special deposit or similar requirement (including, without limitation, any such
requirement imposed by the Board of Governors of the Federal Reserve System,
but excluding for any Eurodollar Loan any such requirement included in an
applicable Eurodollar Reserve Percentage) against assets of, deposits with or
for the account of, or credit extended by, any Lender (or its Lending Office)
or imposes on any Lender (or its Lending Office) or on the interbank market any
other condition affecting its Eurodollar Loans, its Letters of Credit, its
Agent Letters of Credit, any Reimbursement Obligation owed to it, or its
participation in any thereof, or its obligation to advance or maintain
Eurodollar Loans, issue Letters of Credit, issue Agent Letters of Credit or to
participate in any thereof;

and the result of any of the foregoing is to increase the cost to such Lender
(or its Lending Office) of advancing or maintaining any Eurodollar Loan,
issuing or maintaining a Letter of 

                                       45
<PAGE>   51

Credit or an Agent Letter of Credit, or participating therein, or to reduce the
amount of any sum received or   receivable by such Lender (or its Lending
Office) in connection therewith under this Agreement or its Note(s), by an      
amount deemed by such Lender to be material, then, within thirty (30) days
after receipt of a certificate from such Lender (with a copy to the Agent
pursuant to subsection (c) below), the Borrower shall be obligated to pay to
such Lender such additional amount or amounts as will compensate such Lender
for such increased cost or reduction.

         (b)     If, after the date hereof, the Agent or any Lender shall have
determined that the adoption after the date hereof of any applicable law, rule
or regulation regarding capital adequacy, or any change therein (including,
without limitation, any revision in the Final Risk-Based Capital Guidelines of
the Board of Governors of the Federal Reserve System (12 CFR Part 208, Appendix
A; 12 CFR Part 225, Appendix A) or of the Office of the Comptroller of the
Currency (12 CFR Part 3, Appendix A), or in any other applicable capital rules
heretofore adopted and issued by any governmental authority), or any change in
the interpretation or administration thereof by any governmental authority,
central bank or comparable agency charged with the interpretation or
administration thereof, or compliance by the Agent or any Lender (or its
Lending Office) with any request or directive regarding capital adequacy
(whether or not having the force of law) of any such authority, central bank or
comparable agency, has or would have the effect of reducing the rate of return
on the Agent's or such Lender's capital, or on the capital of any corporation
controlling the Agent or such Lender, as a consequence of its obligations
hereunder to a level below that which the Agent or such Lender could have
achieved but for such adoption, change or compliance (taking into consideration
the Agent's or such Lender's policies with respect to capital adequacy) by an
amount deemed by the Agent or such Lender to be material, then from time to
time, within thirty (30) days after its receipt of a certificate from the Agent
or such Lender (with a copy to the Agent pursuant to subsection (c) below), the
Borrower shall pay to the Agent or such Lender such additional amount or
amounts as will compensate the Agent or such Lender for such reduction.

         (c)     The Agent and each Lender that determines to seek compensation
under this Section 8.3 shall notify the Borrower and, in the case of a Lender
other than the Agent, the Agent of the circumstances that entitle the Agent or
Lender to such compensation.  The Agent and each Lender shall use reasonable
efforts to avoid the need for, or reduce the amount of, such compensation,
including without limitation, the designation of a different Lending Office, if
such action or designation will not, in the sole judgment of the Agent or such
Lender, be otherwise disadvantageous to it; provided that the foregoing shall
not in any way affect the rights of any Lender or the obligations of the
Borrower under this Section 8.3, and provided further that no Lender shall be
obligated to make its Eurodollar Loans hereunder at any office located in the
United States of America.  A certificate of the Agent or any Lender claiming
compensation under this Section 8.3 and setting forth the additional amount or
amounts to be paid to it hereunder shall be rebuttable presumptive evidence
thereof in the absence of manifest error.  In determining such amount, such
Lender may use any reasonable averaging and attribution methods.

         Section 8.4.     Lending Offices.  The Agent and each Lender may, at
its option, elect to make its Loans hereunder at the Lending Office for each
type of Loan available hereunder or at such other of its branches, offices or
affiliates as it may from time to time elect and designate in a written notice
to the Borrower and the Agent subject to Section 8.3(c).

                                       46
<PAGE>   52
 
         Section 8.5.     Discretion of Lender as to Manner of Funding. 
Notwithstanding any other provision of this Agreement, each Lender shall be
entitled to fund and maintain its funding of all or any part of its Loans in
any manner it sees fit.

         Section 8.6.     Substitution of Lender.  If (a) any Lender has
demanded compensation or given notice of its intention to demand compensation
under Section 8.3, (b) the Borrower is required to pay any additional amount to
any Lender under Section 2.12, (c) any Lender has not consented to any
requested extension of the Maturity Date pursuant to Section 2.6, or (d) any
Lender is unable to submit any form or certificate required under Section
3.3(b) or withdraws or cancels any previously submitted form with no
substitution therefore, the Borrower shall have the right, with the assistance
of the Agent, to seek a substitute lender or lenders reasonably satisfactory to
the Agent (which may be one or more of the Lenders) to replace any such Lender
under this Agreement.  The Lender to be so replaced shall cooperate with the
Borrower and substitute lender to accomplish such substitution on the terms of
Section 10.10, as applicable, provided that all such Lender's Commitments are
replaced.

SECTION 9.       THE AGENT.

         Section 9.1.     Appointment and Authorization of Agent.  Each Lender
hereby appoints ABN AMRO Bank N.V. as the Agent under the Credit Documents and
hereby authorizes the Agent to take such action as Agent on its behalf and to
exercise such powers under the Credit Documents as are delegated to the Agent
by the terms thereof, together with such powers as are reasonably incidental
thereto.

         Section 9.2.     Agent and its Affiliates.  The Agent shall have the
same rights and powers under the Credit Documents as any other Lender and may
exercise or refrain from exercising such rights and power as though it were not
the Agent, and the Agent and its Affiliates may accept deposits from, lend
money to, and generally engage in any kind of business with the Borrower or any
of its Subsidiaries or Affiliates as if it were not the Agent under the Credit
Documents.  The term Lender as used in all Credit Documents, unless the context
otherwise clearly requires, includes the Agent in its individual capacity as a
Lender.  References herein to the Agent's Loans, or to the amount owing to the
Agent for which an interest rate is being determined, refer to the Agent in its
individual capacity as a Lender.

         Section 9.3.     Action by Agent.  The obligations of the Agent under
the Credit Documents are only those expressly set forth therein.  Without
limiting the generality of the foregoing, the Agent shall not be required to
take any action concerning any Default or Event of Default, except as expressly
provided in Sections 7.2 and 7.5.  Unless and until the Majority Lenders give
such direction the Agent may take or refrain from taking such actions as it
deems appropriate and in the best interest of all the Lenders.  In no event,
however, shall the Agent be required to take any action in violation of
applicable law or of any provision of any Credit Document, and the Agent shall
in all cases be fully justified in failing or refusing to act hereunder or
under any other Credit Document unless it first receives any further assurances
of its indemnification from the Lenders that it may require, including
prepayment of any related expenses and any other protection it requires against
any and all costs, expenses, and liabilities it may incur in taking or
continuing to take any such action.  The Agent shall be entitled to assume that
no Default or Event of Default exists unless notified in writing to the
contrary by a Lender or the Borrower.  In all cases in which the Credit
Documents do not require the Agent


                                       47
<PAGE>   53

to take specific action, the Agent shall be fully justified in using its
discretion in failing to take or in taking any action thereunder.  Any
instructions of the Majority Lenders, or of any other group of Lenders called
for under specific provisions of the Credit Documents, shall be binding on all
the Lenders and holders of Notes.

         Section 9.4.     Consultation with Experts.  The Agent may consult
with legal counsel, independent public accountants and other experts selected
by it and shall not be liable for any action taken or omitted to be taken by it
in good faith in accordance with the advice of such counsel, accountants or
experts.

         Section 9.5.     Liability of Agent; Credit Decision.  Neither the
Agent nor any of its directors, officers, agents, or employees shall be liable
for any action taken or not taken by it in connection with the Credit Documents
(i) with the consent or at the request of the Majority Lenders or (ii) in the
absence of its own gross negligence or willful misconduct.  Neither the Agent
nor any of its directors, officers, agents or employees shall be responsible
for or have any duty to ascertain, inquire into or verify (i) any statement,
warranty or representation made in connection with this Agreement, any other
Credit Document or any Borrowing; (ii) the performance or observance of any of
the covenants or agreements of the Borrower or any Subsidiary contained herein
or in any other Credit Document; (iii) the satisfaction of any condition
specified in Section 4 hereof, except receipt of items required to be delivered
to the Agent; or (iv) the validity, effectiveness, genuineness, enforceability,
value, worth or collectability hereof or of any other Credit Document or of any
other documents or writing furnished in connection with any Credit Document;
and the Agent makes no representation of any kind or character with respect to
any such matters mentioned in this sentence.  The Agent may execute any of its
duties under any of the Credit Documents by or through employees, agents, and
attorneys-in-fact and shall not be answerable to the Lenders or any other
Person for the default or misconduct of any such agents or attorneys-in-fact
selected with reasonable care.  The Agent shall not incur any liability by
acting in reliance upon any notice, consent, certificate, other document or
statement (whether written or oral) believed by it to be genuine or to be sent
by the proper party or parties.  In particular and without limiting any of the
foregoing, the Agent shall have no responsibility for confirming the accuracy
of any Compliance Certificate or other document or instrument received by it
under the Credit Documents.  The Agent may treat the payee of any Note as the
holder thereof until written notice of transfer shall have been filed with the
Agent signed by such owner in form satisfactory to the Agent.  Each Lender
acknowledges that it has independently and without reliance on the Agent or any
other Lender obtained such information and made such investigations and
inquiries regarding the Borrower and its Subsidiaries as it deems appropriate,
and based upon such information, investigations and inquiries, made its own
credit analysis and decision to extend credit to the Borrower in the manner set
forth in the Credit Documents.  It shall be the responsibility of each Lender
to keep itself informed about the creditworthiness and business properties,
assets, liabilities, condition (financial or otherwise) and prospects of the
Borrower and the Subsidiaries, and the Agent shall have no liability whatsoever
to any Lender for such matters.  The Agent shall have no duty to disclose to
the Lenders information that is not required by any Credit Document to be
furnished by the Borrower or any Subsidiaries to the Agent at such time, but is
voluntarily furnished to the Agent (either in its capacity as Agent or in its
individual capacity).

        Section 9.6.     Indemnity.  The Lenders shall ratably, in accordance   
with their Percentages, indemnify and hold the Agent, and its directors,
officers, employees, agents and 

                                     48

<PAGE>   54

representatives harmless from and against any liabilities, losses,
costs or expenses suffered or incurred by it or by any security trustee under
any Credit Document or in connection with the transactions contemplated
thereby, regardless of when asserted or arising, except to the extent they are
promptly reimbursed for the same by the Borrower and except to the extent that
any event giving rise to a claim was caused by the gross negligence or willful
misconduct of the party seeking to be indemnified.  The obligations of the
Lenders under this Section 9.6 shall survive termination of this Agreement.

         Section 9.7.     Resignation of Agent and Successor Agent.  The Agent
may resign at any time upon at least thirty (30) days' prior written notice to
the Lenders and the Borrower.  Upon any such resignation of the Agent, the
Majority Lenders, with the consent of the Borrower, which consent shall not be
unreasonably withheld, shall have the right to appoint a successor Agent.  If
no successor Agent shall have been so appointed by the Majority Lenders and
shall have accepted such appointment within thirty (30) days after the retiring
Agent's giving of notice of resignation, then the retiring Agent may, on behalf
of the Lenders and with the consent of the Borrower, which consent shall not be
unreasonably withheld or delayed, appoint a successor Agent, which shall be any
Lender hereunder or any commercial bank organized under the laws of the United
States of America or of any State thereof and having a combined capital and
surplus of at least $1,000,000,000.  Upon the acceptance of its appointment as
the Agent hereunder, such successor Agent shall thereupon succeed to and become
vested with all the rights and duties of the retiring Agent under the Credit
Documents, and the retiring Agent shall be discharged from its duties and
obligations thereunder.  After any retiring Agent's resignation hereunder as
Agent, the provisions of this Section 9 and all protective provisions of the
other Credit Documents shall inure to its benefit as to any actions taken or
omitted to be taken by it while it was Agent.

SECTION 10.  MISCELLANEOUS.

         Section 10.1.    No Waiver.  No delay or failure on the part of the
Agent or any Lender, or on the part of the holder or holders of any Notes, in
the exercise of any power, right or remedy under any Credit Document shall
operate as a waiver thereof or as an acquiescence in any default, nor shall any
single or partial exercise thereof preclude any other or further exercise of
any other power, right or remedy.  The powers, rights and remedies under the
Credit Documents of the Agent, the Lenders and the holder or holders of any
Notes are cumulative to, and not exclusive of, any powers, rights or remedies
any of them would otherwise have.

         Section 10.2.    Non-Business Day.  If any payment of principal or
interest on any Loan, any Reimbursement Obligation or of any other Obligation
shall fall due on a day which is not a Business Day, interest or fees (as
applicable) at the rate, if any, such Loan, Reimbursement Obligation or other
Obligation bears for the period prior to maturity shall continue to accrue on
such Obligation from the stated due date thereof to and including the next
succeeding Business Day, on which the same shall be payable.

         Section 10.3.    Documentary Taxes.  The Borrower agrees that it will
pay any documentary, stamp or similar taxes payable in respect to any Credit
Document, including interest and penalties, in the event any such taxes are     
assessed irrespective of when such assessment is made and regardless whether
any credit is then in use or available hereunder.





                                       49
<PAGE>   55

         Section 10.4.    Survival of Representations.  All representations and
warranties made herein or in certificates given pursuant hereto shall survive
the execution and delivery of this Agreement and the other Credit Documents,
and shall continue in full force and effect with respect to the date as of
which they were made as long as the Borrower has any Obligation hereunder or
any Commitment hereunder is in effect.

         Section 10.5.    Survival of Indemnities.  All indemnities and all
provisions relative to reimbursement to the Lenders of amounts sufficient to
protect the yield of the Lenders with respect to the Loans and the L/C
Obligations, including, but not limited to, Section 2.12, Section 8.3 and
Section 10.13 hereof, shall survive the termination of this Agreement and the
other Credit Documents and the payment of the Loans and all other Obligations
for a period of one (1) year.

         Section 10.6.    Setoff.  In addition to any rights now or hereafter
granted under applicable law and not by way of limitation of any such rights,
upon the occurrence of, and throughout the continuance of, any Event of
Default, each Lender and each subsequent holder of any Note is hereby
authorized by the Borrower and each Guarantor at any time or from time to time,
without notice to the Borrower, the Guarantor or any other Person, any such
notice being hereby expressly waived, to set off and to appropriate and to
apply any and all deposits (general or special, including, but not limited to,
Indebtedness evidenced by certificates of deposit, whether matured or
unmatured, but not including trust accounts, and in whatever currency
denominated) and any other Indebtedness at any time held or owing by that
Lender or that subsequent holder to or for the credit or the account of any of
the Borrower or any Guarantor, whether or not matured, against and on account
of the obligations and liabilities of any of the Borrower or any Guarantor to
that Lender or that subsequent holder under the Credit Documents, including,
but not limited to, all claims of any nature or description arising out of or
connected with the Credit Documents irrespective of whether or not (a) that
Lender or that subsequent holder shall have made any demand hereunder, or (b)
the principal of or the interest on the Loans, the L/C Obligations or any other
amounts due hereunder shall have become due and payable and although said
obligations and liabilities, or any of them, may be contingent or unmatured.
Each Lender agrees with each other Lender a party hereto that if such Lender
receives and retains any payment, whether by setoff or application of deposit
balances or otherwise, on any of the Loans or L/C Obligations in excess of its
ratable share of payments on all such Obligations then owed to the Lenders
hereunder, then such Lender shall purchase for cash at face value, but without
recourse, ratably from each of the other Lenders such amount of the Loans or
L/C Obligations, or participations therein, held by each such other Lender as
shall be necessary to cause such Lender to share such excess payment ratably
with all the other Lenders; provided, however, that if any such purchase is
made by any Lender, and if such excess payment or part thereof is thereafter
recovered from such purchasing Lender, the related purchases from the other
Lenders shall be rescinded ratably and the purchase price restored as to the
portion of such excess payment so recovered, but without interest.

        Section 10.7.    Notices.  Except as otherwise specified herein, all
notices under the Credit Documents shall be in writing (including cable,
telecopy or telex) and shall be given to a party hereunder at its address,      
telecopier number or telex number set forth below or such other address,
telecopier number or telex number as such party may hereafter specify by notice
to the Agent and the Borrower, given by courier, by United States certified or
registered mail, by




                                       50
<PAGE>   56
telegram or by other telecommunication device capable of creating a written
record of such notice and its receipt.  Notices under the Credit Documents to
the Lenders and the Agent shall be addressed to their respective addresses,
telecopier or telex number, or telephone numbers set forth on the signature
pages hereof, and to the Borrower to:

                                  Landmark Graphics Corporation
                                  15150 Memorial Drive
                                  Houston, Texas 77079-4304
                                  Attention:  Director of Treasury Operations
                                  Telephone:  (713) 560-1514
                                  Fax:        (713) 560-1382

with copies to it's General Counsel at the same location and

                                  Mr. James A. Markus
                                  Winstead Sechrest & Minick P.C.
                                  1201 Elm Street, Suite 5400
                                  Dallas, Texas  75270
                                  Telephone:  (214) 745-5100
                                  Fax:        (214) 745-5390

         Each such notice, request or other communication shall be effective
(i) if given by telecopier, when such telecopy is transmitted to the telecopier
number specified in this Section 10.7, on the signature pages hereof or
pursuant to Section 10.10 and a confirmation of receipt of such telecopy has
been received by the sender, (ii) if given by telex, when such telex is
transmitted to the telex number specified in this Section 10.7, on the
signature pages hereof or pursuant to Section 10.10 and the answerback is
received by sender, (iii) if given by courier, when delivered, (iv) if given by
mail, five (5) days after such communication is deposited in the mail,
certified or registered with return receipt requested, or (v) if given by any
other means, when delivered at the addresses specified in this Section 10.7, on
the signature pages hereof or pursuant to Section 10.10; provided that any
notice given pursuant to Section 2 shall be effective only upon receipt.

         Section 10.8.    Counterparts.  This Agreement may be executed in any
number of counterparts, and by the different parties on different counterpart
signature pages, each of which when executed shall be deemed an original, but
all such counterparts taken together shall constitute one and the same
Agreement.

         Section 10.9.    Successors and Assigns.  This Agreement shall be
binding upon the Borrower, each of the Lenders and the Agent and their
respective successors and assigns, and shall inure to the benefit of the
Borrower, each of the Lenders and the Agent and their respective successors and
assigns, including any subsequent holder of any Note; provided, however, the
Borrower may not assign any of its rights or obligations under this Agreement
or any other Credit Document without the written consent of all Lenders and the
Agent.


                                       51
<PAGE>   57



         Section 10.10. Sales and Transfers of Borrowings and Notes;
Participations in Borrowings and Notes.

         (a)     Any Lender may at any time sell to one or more commercial
banking institutions, ("Participants") participating interests in any Borrowing
owing to such Lender, any Note held by such Lender, any Commitment of such
Lender or any other interest of such Lender hereunder, provided that no Lender
may sell any participating interests in any such Borrowing, Note, Commitment or
other interest hereunder without also selling to such Participant the
appropriate pro rata share of all its Borrowings, Notes, Commitments and other
interests hereunder, and provided further that no Lender shall transfer, grant
or assign any participation under which the Participant shall have rights to
approve any amendment to or waiver of this Agreement except to the extent such
amendment or waiver would (i) increase the amount of such Lender's Commitment
and such increase would affect such Participant, (ii) reduce the principal of,
or interest on, any of such Lender's Borrowings, or any fees or other amounts
payable to such Lender hereunder and such reduction would affect such
Participant, (iii) postpone any date fixed for any scheduled payment of
principal of, or interest on, any of such Lender's Borrowings, or any fees or
other amounts payable to such Lender hereunder and such postponement would
affect such Participant, or (iv) release any collateral security for any
Obligation (including, without limitation, any Guaranty), except as otherwise
specifically provided in any Credit Document.  In the event of any such sale by
a Lender of participating interests to a Participant, such Lender's obligations
under this Agreement to the other parties to this Agreement shall remain
unchanged, such Lender shall remain solely responsible for the performance
thereof, such Lender shall remain the holder of any such Note for all purposes
under this Agreement and the Borrower and the Agent shall continue to deal
solely and directly with such Lender in connection with such Lender's rights
and obligations under this Agreement.  The Borrower agrees that if amounts
outstanding under this Agreement and the Notes are due and unpaid, or shall
have been declared or shall have become due and payable upon the occurrence of
an Event of Default, each Participant shall be deemed to have the right of
setoff in respect of its participating interest in amounts owing under this
Agreement and any Note to the same extent as if the amount of its participating
interest were owing directly to it as a Lender under this Agreement or any
Note, provided that such right of setoff shall be subject to the obligation of
such Participant to share with the Lenders, and the Lenders agree to share with
such Participant, as provided in Section 10.6.  The Borrower also agrees that
each Participant shall be entitled to the benefits of Sections 2.12 and 8.3
with respect to its participation in the Commitments and the Borrowings
outstanding from time to time, provided that no  Participant shall be entitled
to receive any greater amount pursuant to such Sections than the transferor
Lender would have been entitled to receive in respect of the amount of the
participation transferred.

        (b)     Any Lender may at any time sell to any Lender or any affiliate
thereof, and, with the prior written consent of the Agent and the Borrower
(which shall not be unreasonably withheld or delayed), to one or more
commercial banking institution ("Purchasing Lenders"), all or any part of its
rights and obligations under this Agreement and the Notes, pursuant to an
Assignment Agreement in the form attached as Exhibit 10.10 hereto, executed by
such Purchasing Lender and such transferor Lender (and, in the case of a
Purchasing Lender which is not then a Lender or an affiliate thereof, by the
Borrower and the Agent) and delivered to the Agent; provided that each such
sale to a Purchasing Lender shall be in an amount of $5,000,000  

                                       52
<PAGE>   58

or more, or if in a lesser amount, such sale shall be of all of the Lender's
rights and obligations under this Agreement and all of the Notes payable to it
to one commercial banking institution. Notwithstanding the above, any Lender may
sell to one or more commercial banking institutions, all or any part of their
rights and obligations under this Agreement and the Notes with only the consent
of the Agent (which shall not be unreasonably withheld or delayed) if an Event
of Default shall have occurred and be continuing.  No Lender may sell any Loans
to a Purchasing Lender without also selling to such Purchasing Lender the
appropriate pro rata share of its Borrowings, Notes, Commitments and other
interests hereunder, including participations in Letters of Credit hereunder.
Upon such execution, delivery and acceptance from and after the effective date
of the transfer determined pursuant to such Assignment Agreement, (x) the
Purchasing Lender thereunder shall be a party hereto and, to the extent provided
in such Assignment Agreement, have the rights and obligations of a Lender
hereunder with a Commitment as set forth herein and (y) the transferor Lender
thereunder shall, to the extent provided in such Assignment Agreement, be
released from its obligations under this Agreement (and, in the case of an
Assignment Agreement covering all or the remaining portion of a transferor
Lender's rights and obligations under this Agreement, such transferor Lender
shall cease to be a party hereto).  Such Assignment Agreement shall be deemed to
amend this Agreement to the extent, and only to the extent, necessary to reflect
the addition of such Purchasing Lender and the resulting adjustment of
Commitments and Percentages arising from the purchase by such Purchasing Lender
of all or a portion of the rights and obligations of such transferor Lender
under this Agreement, the Notes and the other Credit Documents.  On or prior to
the effective date of the transfer determined pursuant to such Assignment
Agreement, the Borrower, at its own expense, shall execute and deliver to the
Agent in exchange for any surrendered Note, a new Note as appropriate to the
order of such Purchasing Lender in an amount equal to the Commitments assumed by
it pursuant to such Assignment Agreement, and, if the transferor Lender has
retained a Commitment or Borrowing hereunder, a new Note to the order of the
transferor Lender in an amount equal to the Commitments or Borrowings retained
by it hereunder.  Such new Notes shall be dated the Initial Borrowing Date and
shall otherwise be in the form of the Notes replaced thereby.  The Notes
surrendered by the transferor Lender shall be returned by the Agent to the
Borrower marked "cancelled."

         (c)     Upon its receipt of an Assignment Agreement executed by a
transferor Lender, a Purchasing Lender and the Agent (and, in the case of a
Purchasing Lender that is not then a Lender or an affiliate thereof, by the
Borrower), together with payment by the transferor Lender to the Agent
hereunder of a registration and processing fee of $3,500, the Agent shall (i)
promptly accept such Assignment Agreement, and (ii) on the effective date of
the transfer determined pursuant thereto give notice of such acceptance and
recordation to the Lenders and the Borrower.

        (d)     If, pursuant to this Section 10.10 any interest in this
Agreement or any Note is transferred to any transferee which is organized under
the laws of any jurisdiction other than the United States of America or any
State thereof, the transferor Lender shall cause such transferee, concurrently
with the effectiveness of such transfer, (i) to represent to the transferor
Lender (for the benefit of the transferor Lender, the Agent and the Borrower)
that under applicable law and treaties no taxes will be required to be withheld 
by the Agent, the Borrower or the transferor Lender with respect to any
payments to be made to such transferee in respect of the Loans or the L/C
Obligations, (ii) to furnish to the transferor Lender (and, in the case of any
Purchasing 

                                       53
<PAGE>   59

Lender, the Agent and the Borrower) either U.S. Internal Revenue Service 
Form 4224 or U.S. Internal Revenue Service Form 1001 (wherein such transferee 
claims entitlement to complete exemption from U.S. federal withholding tax on 
all interest payments hereunder), and (iii) to agree (for the benefit of the
transferor Lender, the Agent and the Borrower) to provide the transferor Lender
(and, in the case of any Purchasing Lender, the Agent and the Borrower) a new
Form 4224 or Form 1001 upon the expiration or obsolescence of any previously
delivered form and comparable statements in accordance with applicable U.S. laws
and regulations and amendments duly executed and completed by such transferee,
and to comply from time to time with all applicable U.S. laws and regulations
with regard to such withholding tax exemption.

         Section 10.11.  Amendments, Waivers and Consents.  Any provision of
the Credit Documents may be amended or waived if, but only if, such amendment
or waiver is in writing and is signed by (a) the Borrower, (b) the Majority
Lenders, and (c) if the rights or duties of the Agent are affected thereby, the
Agent; provided that:

         (i)     no amendment or waiver shall (A) increase the Commitment
Amount without the consent of all Lenders or increase any Commitment of any
Lender without the consent of such Lender, (B) postpone the Maturity Date
without the consent of all Lenders or reduce the amount of or postpone the date
for any scheduled payment of any principal of or interest on any Loan or
Reimbursement Obligation or of any fee payable hereunder without the consent of
each Lender owed any such Obligation, or (c) release any collateral security
for any Obligation (including, without limitation, any Guaranty without the
consent of all Lenders); and

         (ii)    no amendment or waiver shall, unless signed by each Lender,
change the provisions of this Section 10.11 or the definitions of Majority
Lenders or affect the number of Lenders required to take any action under any
other provision of the Credit Documents.

         Section 10.12.  Headings.  Section headings used in this Agreement are
for reference only and shall not affect the construction of this Agreement.

         Section 10.13.  Legal Fees, Other Costs and Indemnification.  The
Borrower, upon demand by the Agent, agrees to pay the reasonable fees and
disbursements of legal counsel to the Agent in connection with the preparation
and execution of the Credit Documents, and any amendment, waiver or consent
related thereto, whether or not the transactions contemplated therein are
consummated.  The Borrower further agrees to indemnify each Lender, the Agent,
and their respective directors, officers, employees and attorneys
(collectively, the "Indemnified Parties"), against all losses, claims, damages,
penalties, judgments, liabilities and expenses (including, without limitation,
all reasonable attorneys' fees and other reasonable expenses of litigation or
preparation therefor, including the allocated cost of in- house staff counsel
to any of the Lenders, provided that any such attorneys' fees shall not be
duplicative to outside counsel and such allocation of costs shall be
reasonable, whether or not the indemnified Person is a party thereto) which any
of them may pay or incur arising out of or relating to (a) any Credit Document,
the Loans or the application or proposed application by any of the Borrower of
the proceeds of any Loan, REGARDLESS OF WHETHER SUCH CLAIMS OR ACTIONS ARE
FOUNDED IN WHOLE OR IN PART UPON THE ALLEGED SIMPLE OR CONTRIBUTORY NEGLIGENCE
OF ANY OF THE INDEMNIFIED PARTIES AND/OR ANY OF THEIR RESPECTIVE DIRECTORS,
OFFICERS, EMPLOYEES OR


                                       54
<PAGE>   60
ATTORNEYS OTHER THAN THOSE WHICH ARISE FROM THE GROSS NEGLIGENCE OR WILLFUL
MISCONDUCT OF THE PARTY CLAIMING INDEMNIFICATION, (b) any investigation
of any third party or any governmental authority, litigation or other
proceeding related to any use made or proposed to be made by the Borrower of
the proceeds of the Borrowings, or any transaction financed or to be financed
in whole or in part, directly or indirectly with the proceeds of any Borrowing,
and (c) any investigation of any third party or any governmental authority,
litigation or proceeding related to any environmental cleanup, audit,
compliance or other matter relating to any Environmental Law or the presence of
any Hazardous Material (including, without limitation, any losses, liabilities,
damages, injuries, costs, expenses or claims asserted or arising under any
Environmental Law), regardless of whether caused by, or within the control of
the Borrower.  The Borrower, upon demand by the Agent or a Lender at any time,
shall reimburse the Agent or Lender for any reasonable legal or other expenses
incurred in connection with investigating or defending against any of the
foregoing except if the same is directly due to the gross negligence or willful
misconduct of the Indemnified Party.

         Section 10.14. Governing Law.  This Agreement and the other Credit
Documents, and the rights and duties of the parties thereto, shall be construed
in accordance with and governed by the internal laws of the State of Texas.

         Section 10.15. Binding Arbitration.

         (a)  Any controversy or claim ("claim"), whether based on contract,
tort, statute or other legal or equitable theory (including but not limited to
any claim of fraud, misrepresentation or fraudulent inducement or any question
of validity or effect of this Agreement including this clause) arising out of
or related to this Agreement, any other Credit Document or the Loans (including
any amendments or extensions of any of thereof), or the breach or termination
thereof shall be settled by arbitration administered by the American
Arbitration Association (the "AAA") under its Commercial Arbitration Rules then
in effect (the "AAA Rules") and this provision.  The arbitration shall be
governed by the United States Arbitration Act, 9 U.S.C. Sections 1-16 to the
exclusion of any provision of state law inconsistent therewith or which would
produce a different result, and judgment upon the award rendered by the
arbitrator may be entered by any court having jurisdiction.

         (b)  The arbitration shall be held in Houston, Texas.  There shall be
appointed a panel of three arbitrators, under the AAA Rules.  The Commercial
Arbitration Tribunal (as defined in the AAA Rules) shall determine the claims
of the parties and render a final award in accordance with the substantive law
of the State of Texas, excluding the conflicts provisions of such law.  The
Commercial Arbitration Tribunal shall set forth the reasons for the award in
writing.  The Commercial Arbitration Tribunal shall not be empowered to award
punitive damages.

         (c)  The obligation to arbitrate any claim shall extend to the
successors and assigns of the parties.  The parties shall use their best
efforts to cause the obligation to arbitrate any claim to extend to any
officer, director, employee, shareholder, agent, trustee, affiliate, or
subsidiary.  The terms hereof shall not limit any obligations of a party to
defend, indemnify or hold harmless another party against court proceedings or
other claims, losses, damages or expenses.





                                       55
<PAGE>   61

         (d)  The Commercial Arbitration Tribunal shall order the parties to
promptly exchange copies of all exhibits and witness lists, and, if requested
by a party, to produce other relevant documents, to answer up to twenty-five
interrogatories (including subparts), to respond to up to twenty-five requests
for admissions (which shall be deemed admitted if not denied) and to produce
for deposition and, if requested, at the hearing all witnesses that such party
has listed and up to four other persons within such party's control.  Any
additional discovery shall only occur by agreement of the parties or as ordered
by the arbitrator upon a finding of good cause.

         (e)  Each party shall bear its own costs, expenses and attorney's
fees; provided that if court proceedings to stay litigation or compel
arbitration are necessary, the party who unsuccessfully opposes such
proceedings shall pay all reasonable associated costs, expenses, and attorney's
fees in connection with such court proceeding.

         (f)  In order to prevent irreparable harm, the arbitrator shall have
the power to grant temporary or permanent injunctive or other equitable relief.
Prior to the appointment of an arbitrator, a party may, notwithstanding any
other provision of this Agreement, seek temporary injunctive relief from any
court of competent jurisdiction; provided that the party seeking such relief
shall (if arbitration has not already been commenced) simultaneously commence
arbitration.  Such court ordered relief shall not continue more than 10 days
after the appointment of the arbitrator (or in any event for longer than 60
days).

         (g)     Nothing in this Agreement or any other Credit Document shall
be deemed to (i) limit the applicability of any otherwise applicable statutes
of limitation or repose or any waivers contained in this Agreement or any other
Credit Document; or (ii) be a waiver by the Agent or any Lender of the
protection afforded to it by 12 U.S.C. Section 91 or any substantially
equivalent state law; or (iii) limit the right of the Agent or any Lender
hereto (A) to exercise self-help remedies including, but not limited to,
setoff, (B) to foreclose against any real or personal property collateral, or
(C) to obtain from a court provisional or ancillary remedies including but not
limited to, injunctive relief, writ of possession or the appointment of a
receiver.  The Agent or any Lender may exercise such self-help rights,
foreclose upon such property, or obtain such provisional or ancillary remedies
before, during, or after the pendency of any arbitration proceeding brought
pursuant to this Agreement.  Neither this exercise of self-help remedies nor
the institution or maintenance of an action for foreclosure or provisional or
ancillary remedies shall constitute a waiver of the right of any party,
including the claimant in any such action, to arbitrate the merits of the
controversy or claim occasioning resort to such remedies.

        SECTION 10.16. DTPA WAIVER.  THE BORROWER HEREBY REPRESENTS, WARRANTS
AND AGREES WITH THE AGENT AND THE LENDERS THAT (A) IT IS NOT IN A SIGNIFICANTLY
DISPARATE BARGAINING POSITION, (B) IT IS REPRESENTED BY LEGAL COUNSEL OF ITS
CHOICE IN THE TRANSACTIONS CONTEMPLATED HEREBY AND HAS CONSULTED WITH SUCH      
COUNSEL IN CONNECTION WITH THIS WAIVER, (C) THE BORROWER IS A BUSINESS CUSTOMER
WITH ASSETS OF $25,000,000 OR MORE, (D) IT HAS KNOWLEDGE AND EXPERIENCE IN
FINANCIAL AND BUSINESS MATTERS THAT ENABLE IT TO EVALUATE THE MERITS AND RISKS
OF THE TRANSACTIONS CONTEMPLATED HEREBY, AND (E) THIS AGREEMENT AND THE OTHER
CREDIT DOCUMENTS ARE NOT A RESULT OF ANY DISPARITY IN BARGAINING POSITION
BETWEEN




                                       56
<PAGE>   62
IT AND THE AGENT AND THE LENDERS, WERE NEGOTIATED BY THE PARTIES HERETO ON AN
ARMS-LENGTH BASIS AND REPRESENT THE BARGAINED-FOR AGREEMENT OF THE PARTIES
HERETO.  THE BORROWER HEREBY VOLUNTARILY WAIVES THE PROVISIONS OF THE DECEPTIVE
TRADE PRACTICES ACT - CONSUMER PROTECTION ACT, SECTION 17.41 ET SEQ., TEXAS
BUSINESS & COMMERCE CODE.

         Section 10.17. Confidentiality.  Each Lender agrees it will not
disclose without the Borrower's consent (other than to its employees, auditors,
counsel or other professional advisors, to its Affiliates or to another Lender)
any information concerning the Borrower or any of its Subsidiaries furnished
pursuant to any of the Credit Documents; provided that any Lender may disclose
any such information (a) that has become generally available to the public, (b)
if required or appropriate in any report, statement or testimony submitted to
any federal or state regulatory body having or claiming to have jurisdiction
over such Lender, (c) if required or appropriate in response to any summons or
subpoena or in connection with any litigation, (d) in order to comply with the
mandatory provisions of any law, order, regulation or ruling applicable to such
Lender, (e) to any prospective or actual permitted transferee in connection
with any contemplated or actual permitted transfer of any of the Notes or any
interest therein by such Lender, and (f) in connection with the exercise of any
remedies by the Agent or any Lender; provided that such actual or prospective
transferee executes an agreement with such Lender containing provisions
substantially identical to those contained in this Section 10.17 prior to such
transferee's receipt of any such information.

         Section 10.18. Effectiveness.  This Agreement shall become effective
on the date (the "Effective Date") on which each Credit Party, the Agent, and
each Lender has signed and delivered to the Agent a counterparty signature page
hereto or, in the case of a Lender, the Agent has received telex or facsimile
notice that such a counterpart has been signed and mailed to the Agent.

         Section 10.19.  Severability.  Any provision of this Agreement that is
prohibited or unenforceable in any jurisdiction shall, as to such jurisdiction,
be ineffective to the extent of such prohibition or unenforceability without
invalidating the remaining provisions hereof, and any such prohibition or
unenforceability in any jurisdiction shall not invalidate or render
unenforceable such provision in any other jurisdiction.

         Section 10.20.  Notice.  The Credit Documents constitute the entire
understanding among the Credit Parties, the Lenders, and the Agent and
supersede all earlier or contemporaneous agreements, whether written or oral,
concerning the subject matter of the Credit Documents.  THIS WRITTEN AGREEMENT
TOGETHER WITH THE OTHER CREDIT DOCUMENTS REPRESENTS THE FINAL AGREEMENT BETWEEN
THE PARTIES AND  MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR,
         




                                       57
<PAGE>   63


CONTEMPORANEOUS, OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES.  THERE ARE NO
UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

         IN WITNESS WHEREOF, the parties hereto have caused this Agreement to
be duly executed and delivered in Houston, Texas by their duly authorized
officers as of the day and year first above written.

                                   BORROWER:

                                   LANDMARK GRAPHICS CORPORATION


                                   By: /s/ WILLIAM H. SEIPPEL
                                      -------------------------------------
                                   Name:   William H. Seippel
                                        -----------------------------------
                                   Title:  Chief Financial Officer
                                         ----------------------------------


                                     58
<PAGE>   64
                                  LENDERS:

Percentage:      23.0%            ABN AMRO BANK N.V., Houston Agency, as Agent
                                  and as a Lender 
Initial Commitment Amount:
$23,000,000
                                  By: /s/ CHARLES W. RANDALL
                                      -------------------------------------
                                  Name:  Charles W. Randall 
                                  Title: Group Vice President

Address:

ABN AMRO Bank N.V.,               By: /s/ KENNETH S. WOMACK
  Houston Agency                      -------------------------------------
Three Riverway, Suite 1600        Name:  Kenneth S. Womack       
Houston, TX  77056                Title: Assistant Vice President
Telephone:  (713) 964-3351
Fax:        (713) 629-7533

with copies to:

Ms. Linda Boardman
ABN AMRO Bank N.V.
335 Madison Avenue
New York, New York  10017
Telephone:  (212) 370-8509
Fax:        (212) 682-0364

and

Ms. Lisa J. Mellencamp
Hutcheson & Grundy, L.L.P.
1200 Smith Street, Suite 3300
Houston, TX  77002
Telephone:  (713) 951-2877
Fax:        (713) 951-2925





                                       59
<PAGE>   65
Percentage:      20.0%                     FIRST INTERSTATE BANK OF TEXAS, N.A.
Initial Commitment Amount:
$20,000,000
                                           By: /s/ MARC A. DUNMIRE
                                              -------------------------------
                                           Name:   Marc A. Dunmire
                                                -----------------------------
                                           Title:  Vice President
                                                 ----------------------------
Address:

1000 Louisiana, 3rd Floor
Houston, TX  77002
Telephone:  (713) 250-7240
Fax:        (713) 250-1048
Attention:  Mr. Marc Dunmire


                                       60
<PAGE>   66
Percentage:      20.0%                     NBD BANK

Initial Commitment Amount:
$20,000,000
                                           By: /s/ LARRY E. SCHUSTER
                                              -------------------------------
                                           Name:   Larry E. Schuster
                                                -----------------------------
                                           Title:  Vice President
                                                 ----------------------------
Address:

611 Woodward Avenue
Detroit, MI  48226
Telephone:  (313) 225-3444
Fax:        (313) 225-2649
Attention:  Mr. William McCaffrey


                                       61
<PAGE>   67
Percentage:      10.0%                     FLEET NATIONAL BANK OF MASSACHUSETTS

Initial Commitment Amount:
$10,000,000
                                           By:/s/ THOMAS W. DAVIES
                                              -------------------------------
                                           Name:  Thomas W. Davies      
                                                -----------------------------
                                           Title: Vice President
                                                 ----------------------------
Address:

75 State Street
Boston, MA  02109
Telephone:  (617) 346-1645
Fax:        (617) 347-1633
Attention:  Mr. Thomas W. Davies


                                       62
<PAGE>   68
Percentage:      10.0%                     THE BANK OF NOVA SCOTIA, ATLANTA
                                           AGENCY
Initial Commitment Amount:
$10,000,000
                                           By:/s/ F. C. H. ASHBY
                                              ----------------------------------
                                           Name:  F. C. H. Ashby
                                                --------------------------------
                                           Title: Senior Manager Loan Operations
                                                 -------------------------------
             
Address:

The Bank of Nova Scotia,
Atlanta Agency
600 Peachtree Street NE, Suite 2700
Atlanta, GA 30308
Telephone:  (404) 877-1500
Fax:        (404) 888-8998
Attention:  Loan Administration

with a copy to:

The Bank of Nova Scotia
1100 Louisiana, Suite 300
Houston, TX  77002
Telephone:   (713) 759-3426
Fax:         (713) 752-2425
Attention:   Mr. John White


                                       63
<PAGE>   69
Percentage:      10.0%                    THE SANWA BANK, LIMITED, DALLAS AGENCY

Initial Commitment Amount:
$10,000,000
                                          By: /s/ L. J. PERENYI
                                             -------------------------------
                                          Name:   L. J. Perenyi
                                               -----------------------------
                                          Title:  Vice - President
                                                ----------------------------
Address:

The Sanwa Bank, Limited, Dallas Agency
4100 W. Texas Commerce Tower
2200 Ross Avenue
Dallas, TX  75201
Telephone:  (214) 744-5555
Fax:        (214) 741-6535
Attention:  Mr. Lad Perenyi


                                       64
<PAGE>   70
Percentage:      7.0%                      THE FUJI BANK LTD.

Initial Commitment Amount:
$7,000,000
                                           By: S. DAVID L. KELLEY
                                              -------------------------------
                                           Name:  David L. Kelley
                                                -----------------------------
                                           Title: Vice President and 
                                                  Senior Manager
                                                 ----------------------------
Address:

The Fuji Bank Ltd.
1221 McKinney Street
Houston, TX  77010
Telephone:   (713) 650-7850
Fax:         (713) 759-0048
Attention:   Mr. David Kelley


                                       65
<PAGE>   71
                                  EXHIBIT 2.2

                            FORM OF ISSUANCE REQUEST
<PAGE>   72


                                 EXHIBIT 2.2

                              ISSUANCE REQUEST



                            ______________, 199__



ABN AMRO Bank N.V., Houston Agency, As Agent
Three Riverway, Suite 1600
Houston, Texas  77056

Attention:  Mr. Kenneth S. Womack, Vice President

       Re:    Landmark Graphics Corporation

Ladies and Gentlemen:

         This Issuance Request is delivered to you pursuant to Section 2.2 of
that certain Credit Agreement (as amended, supplemented and restated from time
to time, the "Credit Agreement") dated as of December ___, 1995, by and among
the financial institutions from time to time parties thereto (collectively, the
"Lenders"), ABN AMRO Bank N.V., as Agent for the Lenders, and Landmark Graphics
Corporation (the "Borrower").  Any term defined in the Credit Agreement and
used in this Issuance Request shall have the meaning given to it in the Credit
Agreement.

                 The Borrower hereby requests that the Agent issue (check as
applicable) [__] a Letter of Credit [__] an Agent Letter of Credit (the
"Applicable Letter of Credit") on ___________________, 199____ in the initial
face amount of $_________________ [and in the form attached hereto].*

                 The beneficiary of the requested Applicable Letter of Credit
will be ______________________________________________, and such Applicable
Letter of Credit will be in support of _____________________________________
_____________________________________________________________________________
[provide description] and will have a stated expiry date of
____________________ , 199___.





__________________________________

     *   Include where the Borrower is providing the form  of Letter of Credit
or Agent Letter of Credit requested to be issued.

<PAGE>   73
___________, 199__
Page 2



The following documents will be required upon presentation:

                             [Provide Description]

         _______________________________________________________________
         _______________________________________________________________
         _______________________________________________________________

                 A completed Application with respect to the Applicable Letter
of Credit is attached.**

Date:  ___________________, 199__.


                                                   LANDMARK GRAPHICS CORPORATION



                                                   By:__________________________
                                                   Name:________________________
                                                   Title:_______________________





__________________________________

     **Attach Agent's most recent applicable forms with qualifying language as
on the attached forms.

<PAGE>   74
                                  EXHIBIT 2.4

                           FORM OF BORROWING REQUEST
<PAGE>   75



                                  EXHIBIT 2.4

                               BORROWING REQUEST


                             ______________, 199__


ABN AMRO Bank N.V., Houston Agency, As Agent
Three Riverway, Suite 1600
Houston, Texas  77056

Attention:  Mr. Kenneth S. Womack, Vice President

       Re:    Landmark Graphics Corporation

Ladies and Gentlemen:

         This Borrowing Request is delivered to you pursuant to Section 2.4 of
that certain Credit Agreement (as amended, supplemented and restated from time
to time, the "Credit Agreement") dated as of December ___, 1995, by and among
the financial institutions from time to time parties thereto (collectively, the
"Lenders"), ABN AMRO Bank N.V., Houston Agency, as Agent for the Lenders, and
Landmark Graphics Corporation (the "Borrower").  Any term defined in the Credit
Agreement and used in this request shall have the meaning given to it in the
Credit Agreement.

<TABLE>
<S>     <C>      <C>
___      1.      LOANS

         ___     A.       The Borrower hereby requests that Loans be made by the Lenders in accordance with each such
                          Lender's Commitment pursuant to the terms and conditions of the Credit Agreement in the
                          aggregate principal amount for all such Loans of $___________________ on ____________, 199___
                          and that  (check as applicable) [___] $_______________________ of such Loans shall be Eurodollar
                          Loans having an Interest Period of _________________ month(s); and/or [___] $______________
                         ___________ of such Loans shall be Base Rate Loans.

        ___     B.       The Borrower hereby requests (check as applicable) [___] a rollover of [___] all or [___] $_______     
                         ____________________________ of such Loans to Eurodollar Loans having an Interest Period of ____
                         month(s); [___] a conversion of [___] all or [___] $__________________________________ of such
                         Loans to Base Rate Loans; and/or [___] a conversion of [___] all or [___] $________________


</TABLE>
<PAGE>   76
[S]              [C]
                     of such Loans to Eurodollar Loans having an Interest 
                     Period of ______ months(s).

         ___     C.  The Borrower hereby certifies that $______________________
                     of the proceeds of the above requested Loans will be used 
                     for an Acquisition, the total Acquisition price 
                     (calculated as provided in the Credit Agreement) is 
                     $ _______________________) and, if applicable, the
                     Borrower has provided the report required pursuant to
                     Section 6.13 of the Credit Agreement containing 
                     calculations demonstrating on a trailing four (4)-quarter 
                     pro forma basis the Borrower's compliance with Sections 
                     6.23, 6.24 and 6.25 of the Credit Agreement and containing
                     a statement of the sources and uses of funds for such 
                     Acquisition and the Borrower is not aware of any changes 
                     to the information contained in such report.

___      2.      LETTERS OF CREDIT

                 The Borrower hereby requests that the Agent issue a Letter of
                 Credit pursuant to Section 2.2 of the Credit Agreement.
                 Attached hereto is a duly executed Issuance Request and an
                 Application.

___      3.      AGENT LETTERS OF CREDIT

                 The Borrower hereby requests that the Agent issue an Agent
                 Letter of Credit pursuant to Section 2.2 of the Credit
                 Agreement.  Attached hereto is a duly executed Issuance
                 Request and an Application.

         The Borrower hereby certifies to the Agent and each Lender to the
extent a new Borrowing is requested hereunder, that all conditions precedent
set forth in Section 4 of the Credit Agreement have been satisfied or waived in
writing and that this Borrowing Notice constitutes a representation and
warranty by the Borrower that on the date hereof all representations and
warranties set forth therein are true and correct in all respects except to the
extent the representation or warranty relates to an earlier date, in which case
it shall have been true and correct as of such earlier date.  The Borrower
hereby agrees that if prior to the time of the making of the Loans or the
issuance of a Letter of Credit or an Agent Letter of Credit, as the case may
be, as requested hereby, any matter certified herein by it will not be true and
correct in all respects at such time as if then made, it will immediately so
notify the Agent in writing.

         To the extent a new Borrowing is requested hereunder, Schedule 1
attached to this Borrowing Notice and incorporated herein for all purposes
shows the availability under the Credit Agreement.  The Borrower hereby
certifies that each amount thereon is correctly stated.

         Please wire transfer the proceeds of the Loans to the following
accounts of the following Persons at the financial institutions indicated
respectively:


                                     -2-
<PAGE>   77
<TABLE>
<CAPTION>
                                         Account                                                   
Amount to be             ----------------------------------------            Name, Address, etc. of
 Transferred                    Name               Account No.                  Transferee Bank
 -----------            ---------------------      -----------                  ---------------
<S>                     <C>                        <C>                 <C>
___________             _________________          ____________        __________________________________________________

                                                                       __________________________________________________
                                                                                                                         
                                                                       __________________________________________________


                                                                       Attn: ____________________________________________


___________             _________________          ____________        __________________________________________________

                                                                       __________________________________________________
                                                                                                                         
                                                                       __________________________________________________


                                                                       Attn: ____________________________________________


</TABLE>


         The undersigned certifies that he is the officer of the Borrower as
designated below, and that as such he is authorized to execute this Borrowing
Notice on behalf of the Borrower.

         Date:____________________,  199__.

                                                   LANDMARK GRAPHICS CORPORATION


                                                   By:__________________________
                                                   Name:________________________
                                                   Title:_______________________


                                     -3-
<PAGE>   78
                        SCHEDULE 1 TO BORROWING REQUEST
                        _______________________________

(COMPLETE FOR REQUESTS FOR LOANS, LETTERS OF CREDIT AND AGENT LETTERS OF
CREDIT)

<TABLE>
<CAPTION>

<S>     <C>      <C>                                                             <C>
A.      LOANS:

        1.       Commitment Amount                                               $100,000,000
                                                                               
        2.       Outstanding principal amount of all Loans                       $___________
                                                                               
        3.       Outstanding L/C Obligations (including Agent Letters          
                 of Credit)                                                      $___________
                                                                               
        4.       Available Credit (1 minus the sum of 2 plus 3)                  $___________
                                                                               
        5.       Principal Amount of requested Loans                             $___________
                                                                               
        6.       Remaining available Credit                                      $___________
                 after giving effect to requested Loans (4 minus 5)            

B.      LETTERS OF CREDIT:

        1.       L/C Commitment Amount                                           $ 15,000,000   
                                                                                                
        2.       Outstanding L/C Obligations (including Agent Letters                           
                 of Credit)                                                      $___________   
                                                                                                
        3.       Available L/C Commitment Amount (1 minus 2)                     $___________   
                                                                                                
        4.       Face amount of requested Letters of Credit                      $___________   
                                                                                                
        5.       Remaining available L/C Commitment Amount                                      
                 after giving effect to requested Letters of Credit                             
                 (3 minus 4)                                                     $___________   

C.      AGENT LETTERS OF CREDIT:

        1.       Agent L/C Commitment Amount                                     $  1,000,000  
                                                                                               
        2.       L/C Obligations with respect to Agent Letters of Credit         $___________  
                                                                                               
        3.       Available Agent L/C Commitment Amount                           $___________  
                                                                                               
        4.       Face amount of requested Agent Letters of Credit                $___________  
                                                                                               
        5.       Remaining available Agent L/C Commitment                        $___________  
                 Amount after giving effect to requested Agent Letters           
                 of Credit (3 minus 4)
</TABLE>


<PAGE>   79
                                  EXHIBIT 2.6

                        FORM OF CERTIFICATE OF EXTENSION
<PAGE>   80



                                  EXHIBIT 2.6

                            CERTIFICATE OF EXTENSION


         This Certificate of Extension is being furnished pursuant to that
certain Credit Agreement dated as of December ___, 1995 (as amended from time to
time, herein called the "Credit Agreement") by and among Landmark Graphics
Corporation (the "Borrower"), certain lending institutions from time to time
parties thereto (the "Lenders") and ABN AMRO Bank N.V., Houston Agency, as
Agent for the Lenders.  Unless otherwise defined, capitalized terms used herein
shall have the same meaning as in the Credit Agreement.


                   Extension of Maturity Date and Commitments
                   __________________________________________


         Pursuant to Section 2.6 of the Credit Agreement and subject to the
provisions of the Credit Agreement, the Borrower hereby certifies that the
scheduled Commitment Termination Date (as in effect on the date hereof) is
___________ _________________ and that the Maturity Date (as in effect on the
date hereof) is ______________________________, and requests one of the
following:

_____    (1)     An extension of the Commitments for one (1) additional year
                 and a concomitant extension of the Commitment Termination Date
                 to _________________, 199__, and an extension of the Maturity
                 Date to the same date.

_____    (2)     The termination of the Commitments on the current Commitment
                 Termination Date.

         The Borrower hereby certifies to the Agent and each Lender that the
representations and warranties of the Borrower contained in the Credit
Agreement are true and correct as of the date hereof (except to the extent such
representations and warranties relate solely to an earlier date) and that no
Default or Event of Default has occurred and is continuing.

         EXECUTED this ___ day of _________________, _____.

                                      LANDMARK GRAPHICS CORPORATION


                                      By:__________________________ 
                                      Name:________________________ 
                                      Title:_______________________ 
                                                                  


<PAGE>   81
                                  EXHIBIT 2.11

                            FORM OF PROMISSORY NOTE
<PAGE>   82


                                  EXHIBIT 2.11

                                 REVOLVING NOTE

$___________________                                          December 15, 1995 
                  


         FOR VALUE RECEIVED, the undersigned unconditionally promises to pay to
the order of _________________________ (the "Lender"), at the payment office of
the Agent (as hereinafter defined) located in New York City, New York, on or
before December 15, 1998, or such later date as the Maturity Date (as defined
in the Credit Agreement as hereinafter defined) may be extended pursuant to
Section 2.6 of the Credit Agreement, the principal sum of
__________________________________________________ ($_____________) or, if
less, the aggregate unpaid principal amount of all Loans (as defined in the
Credit Agreement) made by the Lender to the undersigned pursuant to the Credit
Agreement, as shown, at Lender's option, either on the grid schedule attached
hereto (and any continuation thereof), or in the records of the Lender.

         The undersigned also promises to pay interest on the unpaid principal
amount hereof from time to time outstanding from the date hereof until maturity
(whether by acceleration or otherwise) and, after maturity, until paid, at the
rates per annum and on the dates specified in the Credit Agreement; provided,
however, that in no event shall such interest exceed the Highest Lawful Rate
(as hereinafter defined).

         All payments of principal and interest hereunder shall be made in
lawful money of the United States of America in freely transferable United
States dollars.

         "Highest Lawful Rate" shall mean the maximum nonusurious interest
rate, if any, that any time or from time to time may be contracted for, taken,
reserved, charged or received on this Note under laws applicable to the payee
which are presently in effect or, to the extent allowed by applicable law,
under such laws which may hereafter be in effect and which allow a higher
maximum nonusurious interest rate than applicable laws now allow.
Determination of the rate of interest for the purpose of determining whether
the Loans represented hereby are usurious under all applicable laws shall be
made by amortizing, prorating, allocating, and spreading, in equal parts during
the period of the full stated term of the Loans represented hereby, all
interest at any time contracted for, charged, or received from the undersigned
in connection with such Loans.

         It is the intention of the payee to conform strictly to usury laws
applicable to it.  Accordingly, if the transactions contemplated hereby or the
Loans represented hereby would be usurious as to the payee under laws
applicable to it (including the laws of the United States of America and the
state of Texas or any other jurisdiction whose laws may be mandatorily
applicable to such payee notwithstanding the other provisions of this Note or
the Credit Agreement), then, in that event, notwithstanding anything to the
contrary in this Note, the Credit





<PAGE>   83
Agreement or any other instrument or agreement entered into in connection with
this Note, it is agreed as follows:  (i) the aggregate of all consideration
which constitutes interest under laws applicable to the payee that is
contracted for, taken, reserved, charged or received by the payee under this
Note, the Credit Agreement, or under any of the aforesaid agreements or
instruments entered into in connection with this Note or otherwise shall under
no circumstances exceed the Highest Lawful Rate, and any excess shall be
credited by the payee on the principal amount of this Note (or, if the
principal amount of this Note shall have been paid in full, refunded by the
payee to the undersigned); and (ii) in the event that the maturity of this Note
is accelerated by reason of an election of the holder or holders thereof
resulting from any Event of Default under the Credit Agreement or otherwise, or
in the event of any required or permitted prepayment, then such consideration
that constitutes interest under laws applicable to the payee may never include
more than the Highest Lawful Rate, and excess interest, if any, provided for in
this Note, the Credit Agreement or otherwise shall be automatically canceled by
the payee as of the date of such acceleration or prepayment and, if theretofore
paid, shall be credited by the payee on the principal amount of this Note (or
if the principal amount of this Note shall have been paid in full, refunded by
the payee to the undersigned), and in each case, to the extent permitted by
applicable law, the payee shall not be subject to any of the penalties provided
by law for contracting for, taking, reserving, charging or receiving interest
in excess of the Highest Lawful Rate.  To the extent that Article 5069-1.04 of
the Texas Revised Civil Statutes is relevant to payee for the purpose of
determining the Highest Lawful Rate, payee hereby elects to determine the
applicable rate ceiling under such Article by the indicated (weekly) rate
ceiling from time to time in effect, subject to payee's right subsequently to
change such method in accordance with applicable law.  Chapter 15 of Article
5069 of the Texas Revised Civil Statutes, which regulates certain revolving
credit loan accounts and revolving tri-party accounts, shall not apply to this
Note.

         This Note is one of the Notes referred to in and is entitled to the
benefits of that certain Credit Agreement dated as of December 15, 1995 (as the
same may be amended, modified, supplemented, extended, rearranged and/or
restated from time to time, the "Credit Agreement"), entered into by and among
Landmark Graphics Corporation, as Borrower, certain financial institutions from
time to time parties thereto, as Lenders, and ABN AMRO Bank N.V., Houston
Agency, as Agent.  Reference is hereby made to the Credit Agreement for a
statement of the prepayment rights and obligations of the undersigned, and for
a statement of the terms and conditions under which the due date of this Note
may be accelerated.  Upon the occurrence of any Event of Default as specified
in the Credit Agreement, the principal balance hereof and the interest accrued
hereon may be declared to be forthwith due and payable in accordance with the
Credit Agreement, and any indebtedness of the holder hereof to the undersigned
may be appropriated and applied hereon.

         In additional to and not in limitation of the foregoing, the
undersigned further agrees, subject only to any limitation imposed by
applicable laws, to pay all reasonable expenses, including reasonable
attorneys' fees and legal expenses, incurred by the holder of this Note in
endeavoring to collect any amounts payable hereunder which are not paid when
due, whether by acceleration or otherwise.




                                     -2-
<PAGE>   84
         All parties hereto, whether as makers, endorsees, or otherwise,
severally waive presentment for payment, demand, protest, notice of intent to
accelerate, notice of acceleration, notice of dishonor and all other notices
whatsoever.

         THIS NOTE SHALL BE DEEMED TO BE A CONTRACT MADE UNDER THE LAWS OF THE
STATE OF TEXAS AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS,
WITHOUT REGARD TO PRINCIPLES OF CONFLICTS OF LAW.

                                                   LANDMARK GRAPHICS CORPORATION



                                                   By:__________________________
                                                   Name:________________________
                                                   Title:_______________________




                                     -3-
<PAGE>   85
                          LOANS AND PRINCIPAL PAYMENTS
                          ----------------------------
                                                                  
<TABLE>
<CAPTION>                                                                                                
   Date                   Type of Loan Made                   Amount of Principal Repaid                 
-------------------------------------------------------------------------------------------              
                  Base Rate         Eurodollar Rate        Base Rate        Eurodollar Rate              
-------------------------------------------------------------------------------------------                              
   <S>            <C>               <C>                    <C>              <C>                          
-------------------------------------------------------------------------------------------              

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

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

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

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

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

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

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

   Date              Unpaid Principal Balance                                 Notation
-------------------------------------------------------------------------------------------  
                  Base Rate       Eurodollar Rate         Total               Made By 
-------------------------------------------------------------------------------------------
   <S>            <C>             <C>                     <C>                 <C>
-------------------------------------------------------------------------------------------

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

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

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

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

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

</TABLE>
                                     -4-
<PAGE>   86
                                  EXHIBIT 4.1A

                                FORM OF GUARANTY
<PAGE>   87


                                  EXHIBIT 4.1A

                                    GUARANTY

                 THIS GUARANTY (this "Guaranty") dated as of December ___,
1995, is from ______________________, a _____________ corporation (the
"Guarantor"), to the Lenders referred to hereinafter and ABN AMRO Bank N.V.
("ABN AMRO"), a Netherlands chartered bank, acting through its Houston agency,
as Agent for the Lenders (herein in such capacity, together with its successors
in such capacity, the "Agent").

                              W I T N E S S E T H:

                 A.       Landmark Graphics Corporation (the "Borrower"), a
Delaware corporation, the various financial institutions (collectively, the
"Lenders") as are or may from time to time become parties thereto, and the
Agent have entered into that certain Credit Agreement dated as of December 15,
1995 (herein, as the same may be amended, modified, supplemented, extended,
rearranged, and/or restated from time to time, the "Credit Agreement"),
pursuant to which, upon the terms and conditions therein set forth, the Lenders
have agreed to (a) make loans to the Borrower, which loans are evidenced by
promissory notes of the Borrower (herein, as amended, modified, supplemented,
extended, rearranged and/or restated from time to time, together with any
promissory note given in amendment, modification, supplementation, extension,
rearrangement and/or substitution thereof or therefor, collectively called the
"Notes"), each dated December 15, 1995 in the original aggregate principal
amount of $100,000,000, payable to the order of the Lenders, respectively, and
(b) issue and participate in Letters of Credit (as defined in the Credit
Agreement) for the account of the Borrower.  Capitalized terms used herein
without definition shall have the meanings assigned in the Credit Agreement.

                 B.       As a condition precedent to the making of the initial
Loans and the issuance of the Letters of Credit under the Credit Agreement, the
Guarantor is required to execute and deliver this Guaranty.

                 C.       The Guarantor has duly authorized the execution,
delivery and performance of this Guaranty.

                 D.       It is in the best interests of the Guarantor to
execute this Guaranty inasmuch as the Guarantor will derive substantial direct
and indirect benefits from the Loans made from time to time to the Borrower and
the issuance of and participation in Letters of Credit, as the case may be, by
the Lenders or the Agent, as the case may be, pursuant to the Credit Agreement.

         NOW THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, and in order to induce the
Lenders to make Loans (including the initial Loans) to the Borrower and to
issue and participate in Letters of Credit pursuant to the Credit Agreement,
the Guarantor agrees, for the benefit of each Lender and the Agent, as follows:





<PAGE>   88
                                   ARTICLE I

                                    GUARANTY

        1.1     Guaranty.  For value received, and in consideration of any loan
or other financial accommodation, heretofore or hereafter at any time made or
granted to the Borrower by the Lenders, the Guarantor hereby unconditionally
guarantees the full and prompt payment when due, whether by acceleration or
otherwise, and at all times thereafter, of all obligations of the Borrower to
the Lenders and the Agent and their successors and assigns, howsoever created,
arising or evidenced, whether direct or indirect, primary or secondary,
absolute or contingent, joint or several, or now or hereafter existing or due
or to become due, including, without limitation, all such amounts which would
become due but for the operation of the automatic stay under Section 362(a) of
the United States Bankruptcy Code, 11 U.S.C. Section 362(a), and the operation
of Sections 502(b) and 506(b) of such Bankruptcy Code, 11 U.S.C. Section 
502(b) and Section 506(b), under and in connection with the Credit Agreement,
including, without limitation under (a) the Notes, and (b) the Letters of
Credit, including any Reimbursement Obligations with respect thereto (all such
obligations being hereinafter collectively called the "Liabilities"), and the
Guarantor further agrees to pay all reasonable expenses (including reasonable
attorneys' fees and legal expenses) paid or incurred by the Agent and the
Lenders in endeavoring to collect the Liabilities, or any part thereof, and in
enforcing this Guaranty.  Anything herein contained to the contrary
notwithstanding, the amount of this Guaranty, however, shall not exceed the
greater of
        
         (a)     an amount $1.00 less than the amount which, if paid by the
                 Guarantor would render the Guarantor insolvent, and

         (b)     an amount equal to the value of all benefits received by the
                 Guarantor as a result of the execution, delivery, and
                 performance by the Borrower of the Credit Agreement and each
                 other Credit Document (as defined in the Credit Agreement),
                 including all loans, advances, and contributions, if any, made
                 by the Borrower to the Guarantor, and the making of Loans to,
                 and the issuance of Letters of Credit, if any, on behalf of,
                 the Borrower.

                 The term "insolvent" as used herein, means, with respect to
the Guarantor on a particular date, that on such date

         (a)     the fair salable value of the property of the Guarantor is
                 less than the total amount of liabilities (including
                 contingent, subordinated, unmatured and unliquidated
                 liabilities) of the Guarantor;

         (b)     the present fair salable value of the assets of the Guarantor
                 is less than the amount that will be required to pay the
                 probable liabilities of the Guarantor as they become absolute
                 and matured;




                                     -2-
<PAGE>   89
         (c)     the Guarantor is not able to realize upon its assets and pay
                 its debts and other liabilities, contingent obligations, and
                 other commitments as they mature in the normal course of
                 business; or

         (d)     the Guarantor has an unreasonably small capital.

         1.2.    Bankruptcy.  The Guarantor hereby agrees that, in the event of
the dissolution or insolvency of the Borrower or the Guarantor, or the
inability or failure of the Borrower or the Guarantor to pay its debts as they
become due, or an assignment by the Borrower or the Guarantor for the benefit
of creditors, or the commencement of any case or proceeding in respect of the
Borrower or the Guarantor under any bankruptcy, insolvency or similar laws, and
if such event shall occur at a time when any of the Liabilities may not then be
due and payable, the Guarantor will pay to the Agent and the Lenders forthwith
the full amount which would be payable hereunder by the Guarantor as if all
Liabilities were then due and payable.

         1.3.    Setoff.  In addition to any rights now or hereafter granted
under applicable law and not by way of limitation of any such rights, upon the
occurrence of, and throughout the continuance of, any Event of Default under
the Credit Agreement, each Lender and each subsequent holder of any Note is
hereby authorized by the Guarantor without notice to the Borrower, the
Guarantor or any other Person, any such notice being hereby expressly waived,
to set off and to appropriate and to apply any and all deposits (general or
special, including, but not limited to, Indebtedness evidenced by certificates
of deposit, whether matured or unmatured, but not including trust accounts, and
in whatever currency denominated) and any other Indebtedness at any time held
or owing by that Lender or that subsequent holder to or for the credit or the
account of the Guarantor, whether or not matured, against and on account of the
obligations and liabilities of any of the Borrower or the Guarantor to that
Lender or that subsequent holder under the Credit Documents, including, but not
limited to, all claims of any nature or description arising out of or connected
with the Credit Documents irrespective of whether or not (a) that Lender or
that subsequent holder shall have made any demand hereunder, or (b) the
principal of or the interest on the Loans, the L/C Obligations or any other
amounts due hereunder shall have become due and payable and although said
obligations and liabilities, or any of them, may be contingent or unmatured.

         1.4.    Guaranty Absolute, etc.  This Guaranty shall in all respects
be a continuing, absolute and unconditional Guaranty, and shall remain in full
force and effect (notwithstanding, without limitation, the dissolution of the
Borrower or the Guarantor or that at any time or from time to time all
Liabilities may have been paid in full), until all Liabilities (including any
renewals, extensions and/or rearrangements of any thereof) and all interest
thereon and all reasonable expenses (including reasonable attorneys' fees and
legal expenses) paid or incurred by the Agent and the Lenders in endeavoring to
collect the Liabilities and in enforcing this Guaranty shall have been finally
paid in full and all Commitments (as defined in the Credit Agreement) have been
permanently terminated.

         1.5.    Reinstatement.  The Guarantor further agrees that, if at any
time all or any part of any payment theretofore applied by the Agent or any
Lender to any of the Liabilities is or 


                                     -3-

<PAGE>   90

must be rescinded or returned by the Agent or a Lender for any reason
whatsoever (including, without limitation, the insolvency, bankruptcy or
reorganization of the Borrower), such Liabilities shall, for the purposes of
this Guaranty, to the extent that such payment is or must be rescinded or
returned, be deemed to have continued in existence, notwithstanding such
application by the Agent or such Lender, and this Guaranty shall continue to be
effective or be reinstated, as the case may be, as to such Liabilities, all as
though such application by the Agent or such Lender had not been made.
        
         1.6     Rights of Agent and Lenders.  The Agent or any Lender may,
from time to time, at its sole discretion and without notice to the Guarantor,
take any or all of the following actions:

                 (a)      retain or obtain a lien upon or a security interest
         in any property to secure any of the Liabilities or any obligation
         hereunder;

                 (b)      retain or obtain the primary or secondary obligation
         of any obligor or obligors, in addition to the Guarantor, with respect
         to any of the Liabilities;

                 (c)      extend or renew for one or more periods (whether or
         not longer than the original period), alter or exchange any of the
         Liabilities, or release or compromise any obligation of the Guarantor
         hereunder or any obligation of any nature of any other obligor with
         respect to any of the Liabilities;

                 (d)      extend or renew for one or more periods (whether or
         not longer than the original period) or release, compromise, alter or
         exchange any obligations of any nature of any obligor with respect to
         any such property securing any of the Liabilities; or

                 (e)      resort to the Guarantor for payment of any of the
         Liabilities, whether or not the Agent or any Lender shall have
         proceeded against any other obligor primarily or secondarily obligated
         with respect to any of the Liabilities (all of the actions referred to
         in this clause being hereby expressly waived by the Guarantor).

         1.7.    Application of Payments.  Any amounts received by the Agent or
any Lender from whatsoever source on account of the Liabilities may be applied
by it toward the payment of such of the Liabilities, and in such order of
application, as the Agent or such Lender may from time to time elect.

         1.8.    Waiver.  (a)  The Guarantor hereby expressly waives:

                       (i)     notice of the acceptance by the Agent and the 
                 Lenders of this Guaranty;
                       (ii)    notice of the existence or creation or
                 non-payment of all or any of the Liabilities;




                                     -4-
<PAGE>   91

                          (iii)   presentment for payment, demand, protest,
                 notice of intent to accelerate, notice of acceleration, notice
                 of dishonor and all other notices whatsoever; and

                          (iv)    all diligence in collection or protection of
                 or realization upon the Liabilities or any thereof, any
                 obligation hereunder, or any security for or guaranty of any
                 of the foregoing.

                 (b)      No delay on the part of the Agent or any Lender in
         the exercise of any right or remedy shall operate as a waiver thereof,
         and no single or partial exercise by the Agent or any Lender of any
         right or remedy shall preclude other or further exercise thereof or
         the exercise of any other right or remedy; nor shall any modification
         or waiver of any of the provisions of this Guaranty be binding upon
         the Agent or any Lender except as expressly set forth in a writing
         duly signed and delivered on behalf of the Agent and the Lenders.  No
         action of the Agent or any Lender permitted hereunder shall in any way
         affect or impair the rights of the Agent or any Lender and the
         obligations of the Guarantor under this Guaranty.  The obligations of
         the Guarantor under this Guaranty shall be absolute and unconditional
         irrespective of any circumstance whatsoever which might constitute a
         legal or equitable discharge or defense of the Guarantor.  The
         Guarantor hereby acknowledges that there are no conditions to the
         effectiveness of this Guaranty.

         1.9.    Subrogation.  No payment made by or for the account of the
Guarantor pursuant to this Guaranty shall entitle the Guarantor by subrogation
or otherwise to demand or receive any payments by the Borrower or from or out
of any properties of the Borrower until the Liabilities shall have been paid in
full.  The Guarantor shall not exercise any right or remedy against the
Borrower or any properties of the Borrower by reason of any performance by the
Guarantor of this Guaranty until the Liabilities shall have been paid in full.

         1.10.   Excess Liabilities.  The creation or existence from time to
time of Liabilities in excess of the amount to which the right of recovery
under this Guaranty is limited, if any, is hereby authorized, without notice to
the Guarantor, and shall in no way affect or impair the rights of the Agent or
any Lender and the obligation of the Guarantor under this Guaranty.

         1.11.   Successors, Transferees and Assigns.  The Agent and each
Lender may, from time to time, without notice to the Guarantor, assign or
transfer any or all of the Liabilities or any interest therein in accordance
with the terms of the Credit Agreement; and, notwithstanding any such
assignment or transfer or any subsequent assignment or transfer thereof, such
Liabilities shall be and remain Liabilities for the purposes of this Guaranty,
and each and every immediate and successive assignee or transferee of any of
the Liabilities or of any interest therein shall, to the extent of the interest
of such assignee or transferee in the Liabilities, be entitled to the benefits
of this Guaranty to the same extent as if such assignee or transferee were the
transferring Agent or Lender; provided, however, that, unless the transferring
Agent or Lender, as the case may be, shall otherwise consent in writing, the
transferring Agent or Lender, as the case may be, shall have an unimpaired
right, prior and superior to that of any such assignee or 




                                     -5-

<PAGE>   92

transferee, to enforce this Guaranty, for the benefit of the transferring Agent
or Lender, as the case may be, as to those of the Liabilities which the
transferring Agent or Lender, as the case may be, has not assigned or
transferred.
        
                                   ARTICLE II

                         REPRESENTATIONS AND WARRANTIES

         2.1     Independent Means of Obtaining Information.  The Guarantor
hereby represents and warrants to the Agent and each Lender that it now has and
will continue to have independent means of obtaining information concerning the
affairs, operations, financial condition, business and prospects of the
Borrower.

         2.2     Authorization; No Conflict.  The Guarantor hereby further 
represents and warrants to the Agent and each Lender that

                 (a)      the execution and delivery of this Guaranty, and the
         performance by the Guarantor of its obligations hereunder, are within
         the Guarantor's corporate powers and have been duly authorized by all
         necessary corporate action on the part of the Guarantor; and

                 (b)      this Guaranty has been duly executed and delivered on
         behalf of the Guarantor and is the legal, valid and binding obligation
         of the Guarantor, enforceable in accordance with its terms subject as
         to enforcement only to bankruptcy, insolvency, reorganization,
         moratorium or other similar laws affecting the enforcement of
         creditors' rights generally and equitable principles relating to or
         limiting creditors' rights generally, the making and performance of
         which do not and will not contravene or conflict with the articles of
         incorporation and by-laws or other corporate governance documents of
         the Guarantor or violate or constitute a default under any law, any
         presently existing requirement or restriction imposed by any judicial,
         arbitral or governmental instrumentality or any agreement, instrument
         or indenture by which the Guarantor is bound.

         2.3     Validity and Binding Nature.  This Guaranty shall be binding
upon the Guarantor, and upon the successors and assigns of the Guarantor, and
shall include any successor or successors, whether immediate or remote, to such
corporation; provided, however, that the Guarantor may not assign any of its
obligations hereunder without the prior written consent of the Agent and all
Lenders except as may be provided in the Credit Agreement.


                                     -6-
<PAGE>   93
                                  ARTICLE III

                            MISCELLANEOUS PROVISIONS

         3.1.    Governing Law; Severability.  THIS GUARANTY SHALL BE CONSTRUED
IN ACCORDANCE WITH AND GOVERNED BY THE LAWS OF THE STATE OF TEXAS, WITHOUT
REGARD TO PRINCIPLES OF CONFLICTS OF LAWS.  Wherever possible, each provision
of this Guaranty shall be interpreted in such manner as to be effective and
valid under applicable laws, but if any provision of this Guaranty shall be
prohibited by or invalid under such laws, such provision shall be ineffective
to the extent of such prohibition or invalidity, without invalidating the
remainder of such provision or the remaining provisions of this Guaranty.

         3.2     DTPA WAIVER.  THE GUARANTOR HEREBY REPRESENTS, WARRANTS AND
AGREES WITH THE AGENT AND THE LENDERS THAT (A) IT IS NOT IN A SIGNIFICANTLY
DISPARATE BARGAINING POSITION, (B) IT IS REPRESENTED BY LEGAL COUNSEL OF ITS
CHOICE IN THE TRANSACTIONS CONTEMPLATED HEREBY AND HAS CONSULTED WITH SUCH
COUNSEL IN CONNECTION WITH THIS WAIVER, (C) THE GUARANTOR IS A BUSINESS
CUSTOMER WITH EITHER ASSETS OF $25,000,000 OR MORE OR IS OWNED OR CONTROLLED BY
A CORPORATION OR ENTITY WITH ASSETS OF $25,000,000 OR MORE, (D) IT HAS
KNOWLEDGE AND EXPERIENCE IN FINANCIAL AND BUSINESS MATTERS THAT ENABLE IT TO
EVALUATE THE MERITS AND RISKS OF THE TRANSACTIONS CONTEMPLATED HEREBY, AND (E)
THIS GUARANTY, THE CREDIT AGREEMENT AND THE OTHER CREDIT DOCUMENTS ARE NOT A
RESULT OF ANY DISPARITY IN BARGAINING POSITION BETWEEN IT AND THE AGENT AND THE
LENDERS, WERE NEGOTIATED BY THE PARTIES HERETO ON AN ARMS-LENGTH BASIS AND
REPRESENT THE BARGAINED-FOR AGREEMENT OF THE PARTIES HERETO.  THE GUARANTOR
HEREBY WAIVES VOLUNTARILY THE PROVISIONS OF THE DECEPTIVE TRADE PRACTICES ACT -
CONSUMER PROTECTION ACT, SECTION 17.41 ET SEQ., TEXAS BUSINESS & COMMERCE CODE.

         3.3     Binding Arbitration.

         (a)  Any controversy or claim ("claim"), whether based on contract,
tort, statute or other legal or equitable theory (including but not limited to
any claim of fraud, misrepresentation or fraudulent inducement or any question
of validity or effect of this Agreement including this clause) arising out of
or related to this Guaranty, the Credit Agreement, any other Credit Document or
the Loans (including any amendments or extensions of any of thereof), or the
breach or termination thereof shall be settled by arbitration administered by
the American Arbitration Association Commercial Arbitration Rules then in
effect (the "AAA Rules") and this provision.  The arbitration shall be governed
by the United States Arbitration Act, 9 U.S.C. Sections 1-16 to the exclusion
of any provision of state law inconsistent therewith or which would




                                     -7-
<PAGE>   94
produce a different result, and judgment upon the award rendered by the
arbitrator may be entered by any court having jurisdiction.

         (b)  The arbitration shall be held in Houston, Texas.  There shall be
appointed a panel of three arbitrators under the AAA Rules.  The Commercial
Arbitration Tribunal (as defined in the AAA Rules) shall determine the claims
of the parties and render a final award in accordance with the substantive law
of the State of Texas, excluding the conflicts provisions of such law.  The
Commercial Arbitration Tribunal shall set forth the reasons for the award in
writing.  The Commercial Arbitration Tribunal shall not be empowered to award
punitive damages.

         (c)  The obligation to arbitrate any claim shall extend to the
successors and assigns of the parties.  The parties shall use their best
efforts to cause the obligation to arbitrate any claim to extend to any
officer, director, employee, shareholder, agent, trustee, affiliate, or
subsidiary.  The terms hereof shall not limit any obligations of a party to
defend, indemnify or hold harmless another party against court proceedings or
other claims, losses, damages or expenses.

         (d)  The Commercial Arbitration Tribunal shall order the parties to
promptly exchange copies of all exhibits and witness lists, and, if requested
by a party, to produce other relevant documents, to answer up to twenty-five
interrogatories (including subparts), to respond to up to twenty-five requests
for admissions (which shall be deemed admitted if not denied) and to produce
for deposition and, if requested, at the hearing all witnesses that such party
has listed and up to four other persons within such party's control.  Any
additional discovery shall only occur by agreement of the parties or as ordered
by the arbitrator upon a finding of good cause.

         (e)  Each party shall bear its own costs, expenses and attorney's
fees; provided that if court proceedings to stay litigation or compel
arbitration are necessary, the party who unsuccessfully opposes such
proceedings shall pay all reasonable associated costs, expenses, and attorney's
fees in connection with such court proceeding.

         (f)  In order to prevent irreparable harm, the arbitrator shall have
the power to grant temporary or permanent injunctive or other equitable relief.
Prior to the appointment of an arbitrator, a party may, notwithstanding any
other provision of this Guaranty, seek temporary injunctive relief from any
court of competent jurisdiction; provided that the party seeking such relief
shall (if arbitration has not already been commenced) simultaneously commence
arbitration.  Such court ordered relief shall not continue more than 10 days
after the appointment of the arbitrator (or in any event for longer than 60
days).

         (g)     Nothing in this Guaranty, the Credit Agreement or any other
Credit Loan Document shall be deemed to (i) limit the applicability of any
otherwise applicable statutes of limitation or repose or any waivers contained
in this Guaranty, the Credit Agreement or any other Credit Document; or (ii) be
a waiver by the Agent or any Lender of the protection afforded to it by 12
U.S.C. Section  91 or any substantially equivalent state law; or (iii) limit
the right of the Agent or any Lender hereto (A) to exercise self-help remedies
including, but not limited to, setoff, (B) to foreclose against any real or
personal property collateral, or (C) to obtain from a court provisional or
ancillary remedies including but not limited to, injunctive relief, writ of




                                     -8-
<PAGE>   95
possession or the appointment of a receiver.  The Agent or any Lender may
exercise such self-help rights, foreclose upon such property, or obtain such
provisional or ancillary remedies before, during, or after the pendency of any
arbitration proceeding brought pursuant to this Guaranty.  Neither this
exercise of self-help remedies nor the institution or maintenance of an action
for foreclosure or provisional or ancillary remedies shall constitute a waiver
of the right of any party, including the claimant in any such action, to
arbitrate the merits of the controversy or claim occasioning resort to such
remedies.

         3.4     Notices.  Except as otherwise specified herein, all notices
under this Guaranty shall be in writing (including cable, telecopy or telex)
and shall be given to the Guarantor at its address, telecopier number or telex
number set forth on the signature page hereof or such other address, telecopier
number or telex number as the Guarantor may hereafter specify by notice to the
Agent, given by courier, by United States certified or registered mail, by
telegram or by other telecommunication device capable of creating a written
record of such notice and its receipt.  Each such notice, request or other
communication shall be effective (i) if given by telecopier, when such telecopy
is transmitted to the telecopier number specified in this Section on the
signature pages hereof and a confirmation of receipt of such telecopy has been
received by the sender, (ii) if given by telex, when such telex is transmitted
to the telex number specified on the signature pages hereof and the answerback
is received by sender, (iii) if given by courier, when delivered, (iv) if given
by mail, five (5) days after such communication is deposited in the mail,
certified or registered with return receipt requested, or (v) if given by any
other means, when delivered at the addresses specified on the signature page
hereof.

         IN WITNESS WHEREOF, the Guarantor has caused this Guaranty to be duly
executed and delivered by its duly authorized officer as of the date first
above written.

                                           _____________________________________



                                           By:__________________________________
                                           Name:________________________________
                                           Title:_______________________________
                                                                                
Address:
__________________________________
__________________________________
__________________________________




                                     -9-
<PAGE>   96
                                  EXHIBIT 4.1B

                             FORM OF LEGAL OPINION
<PAGE>   97
                    [WINSTEAD SECHREST & MINICK LETTERHEAD]


                               December 15, 1995


ABN AMRO Bank N.V., Houston Agency
First Interstate Bank of Texas, N.A.
NBD Bank
Fleet National Bank of Massachusetts
The Bank of Nova Scotia, Atlanta Agency
The Sanwa Bank, Limited, Dallas Agency
The Fuji Bank Ltd.

        Re:  Credit Agreement dated as of December 15, 1995 by and among
        Landmark Graphics Corporation, certain commercial lending institutions
        named above (the "Lenders"), and ABN AMRO Bank N.V., Houston Agency, as
        Agent for itself and the other Lenders (the "Credit Agreement")


Ladies and Gentlemen:

      We have acted as counsel to Landmark Graphics Corporation, a Delaware 
corporation (the "Borrower"), and certain domestic subsidiaries of the Borrower 
listed on Schedule I attached hereto and made a part hereof (each a "Guarantor" 
and collectively, the "Guarantors") in connection with the negotiation, 
execution and delivery of the Credit Agreement, the Subsidiary Guaranties of 
the Guarantors and related documents (collectively, the "Loan Documents"). This 
Opinion Letter is provided to you pursuant to Section 4.1(k) of the Credit 
Agreement. Except as otherwise indicated herein, capitalized terms used in this 
Opinion Letter are defined as set forth in the Credit Agreement or the Accord 
(see below).

     This Opinion Letter is governed by, and shall be interpreted in accordance 
with, the Legal Opinion Accord (the "Accord") of the ABA Section of Business
Law  (1991).  As a consequence, it is subject to a number of qualifications, 
exceptions, definitions, limitations on coverage and other limitations, all as 
more particularly described in the Accord, and this Opinion Letter should be 
read in conjunction therewith. The law covered by the opinions expressed herein 
is limited to the Federal Law of the United States, the General Corporation 
Law of the State of Delaware and the Law of the State of Texas.

     As to questions of fact material to such opinions, we have, where relevant 
facts were not independently verified or established by us, relied upon factual 
representations made by the Borrower in Section 5 of the Credit Agreement and 
certifications by officers of the Borrower and the Guarantors.

     The provisions of Sections 1 through 9 and 19 through 21, inclusive, of 
the Accord shall be applicable to those opinions expressed below that are not 
specifically addressed by the Accord.
<PAGE>   98
     Based upon and subject to the foregoing and the other qualifications and 
limitations stated in this Opinion Letter, we are of the opinion that:

     1.   Each of the Borrower and the Guarantors is a corporation validly 
          existing and in good standing under the laws of the state of its 
          incorporation.

     2.   Each of the Borrower and the Guarantors (other than Geographix, Inc.) 
          has the corporate power and authority to execute, deliver and perform
          its obligations under the Loan Documents to which it is a party. The 
          Loan Documents have been duly authorized by all necessary corporate 
          action on the part of the Borrower and the Guarantors (other than 
          Geographix, Inc.), as the case may be, and have been duly executed 
          and delivered by the Borrower and the Guarantors (other than 
          Geographix, Inc.), as the case may be.

     3.   The Loan Documents to which the Borrower is a party are enforceable 
          against the Borrower. The Subsidiary Guaranty to which a Guarantor is 
          a party is enforceable against such Guarantor.

     4.   Execution and delivery by the Borrower and each Guarantor of, and 
          performance of its agreements in, the Loan Documents to which it is 
          a party do not (a) violate its Constituent Documents, (b) breach or 
          otherwise violate any existing obligation of the Borrower or a 
          Guarantor under any Court Order, or (c) violate applicable provisions
          of statutory law or regulation.

     5.   No consent, approval, waiver, license or authorization or other 
          action by or filing with any governmental authority, court or
          arbitrator is required under Texas or federal statutes or regulations
          in connection with the execution and delivery by the Borrower and the
          Guarantors of the Loan Documents, except for those already obtained
          or completed.

     6.   Neither the Borrower nor any of the Guarantors is an "investment 
          company" or a company "controlled" by an "investment company," within
          the meaning of the Investment Company Act of 1940, as amended.

     7.   Neither the Borrower nor any of the Guarantors is a "holding 
          company," or a "subsidiary company" of a "holding company," or an 
          "affiliate" of a "holding company" or of a "subsidiary company" of a 
          "holding company," within the meaning of the Public Utility Holding 
          Company Act of 1935, as amended.

     In rendering the opinion expressed in paragraphs 3 and 4 above with 
respect to Geographix, Inc., we have assumed that (i) Geographix, Inc. has the 
corporate power and authority to execute, deliver and perform its obligations 
under the Subsidiary Guaranty to which it is a party, (ii) such Subsidiary 
Guaranty has been duly authorized by all necessary corporate action on the part 
of Geographix, Inc. and (iii) such Subsidiary Guaranty has been duly executed 
and delivered by Geographix, Inc.

     We hereby confirm to you, pursuant to the request set forth in Section 5.4 
of the Credit Agreement, that there are no actions or proceedings against the 
Borrower or any of its
           

          



  
<PAGE>   99
Subsidiaries pending, or overtly threatened in writing, before any court, 
governmental agency or arbitrator which are likely to have a Material Adverse 
Effect.

     To the extent not specifically modified above, this Opinion Letter 
modifies the Accord, pursuant to Section 21 of the Accord, as follows:

     (i)     With respect to the Opinion expressed in paragraph 6 above, we 
             have addressed legal issues under the Investment Company Act of
             1940, as amended, which legal issues would otherwise be excluded
             by Accord Section 19; and.

    (ii)     With respect to the Opinion expressed in paragraph 7 above, we 
             have addressed legal issues under the Public Utility Holding
             Company Act of 1935, as amended, which legal issues would otherwise
             be excluded by Accord Section 19.

     This Opinion Letter may be relied upon by you only in connection with the 
transaction contemplated in the Credit Agreement and may not be used or relied 
upon by you or any other person (other than an assignee or participant of a 
Lender) for any purpose whatsoever, except to the extent authorized in the 
Accord, without in each instance our prior written consent.


                                        Very truly yours,

                                        WINSTEAD SECHREST & MINICK P.C.


                                        By: /s/ JAMES A. MARKUS
                                            ------------------------------------
                                            James A. Markus 


<PAGE>   100
                                   Schedule 1



                                   Guarantors
                                   ----------


1.   LMK Land Company, a Delaware corporation

2.   Landmark America Latina, S.A., a Delaware corporation

3.   Landmark Graphics International, Inc., a Texas corporation

4.   Landmark Graphics Europe/Africa, Inc., a Delaware corporation

5.   MGI Associates, Inc., a Texas corporation

6.   Munro Garrett International, Inc., a Texas corporation

7.   Geographix, Inc., a Colorado corporation
<PAGE>   101
                                  EXHIBIT 6.6

                         FORM OF COMPLIANCE CERTIFICATE
<PAGE>   102


                                  EXHIBIT 6.6

                             COMPLIANCE CERTIFICATE

                 Landmark Graphics Corporation (the "Borrower"), the financial
institutions from time to time parties thereto (collectively, the "Lenders"),
and ABN AMRO Bank N.V., Houston Agency, as Agent for the Lenders, have executed
and delivered that certain Credit Agreement (as amended, supplemented and
restated from time to time, the "Credit Agreement") dated as of December 15,
1995.  Any term defined in the Credit Agreement and used in this Compliance
Certificate shall have the meaning given to it in the Credit Agreement.

                 The undersigned, solely in his capacity as Chief Financial
Officer or Treasurer (as noted below) of the Borrower, hereby certifies to the
Agent and each of the Lenders that:

         A.      The attached financial statements are (check one) [  ]
quarterly financial statements [  ] annual financial statements as required by
Section 6.6 of the Credit Agreement and are the consolidated balance sheet of
the Borrower and its Subsidiaries and the related consolidated statements of
income and retained earnings and of cash flows as at the date thereof and for
the period covered thereby.  Such financial statements fairly present the
financial condition of the Borrower and its Subsidiaries as of the dates
indicated and the results of their operations and changes in their cash flows
for the periods indicated, and have been prepared in accordance with GAAP,
other than the omission of any footnotes as permitted at such time by the SEC
and subject to normal year-end audit adjustments for any such financial
statements that are quarterly financial statements.

         B.      As of the date of the attached financial statements and with
respect to the Borrower and its Subsidiaries on a consolidated basis:

                 1.      FIXED CHARGE COVERAGE RATIO (historic rolling
                         four-quarters)
                   
                         a.    EBITDA                            $____________
                                                                              
                         b.    Capitalized research                           
                               and development costs             $____________
                                                                              
                         c.    Total of a minus b                $____________
                                                                              
                         d.    Principal amortization of                      
                               Indebtedness and required                      
                               prepayments                       $____________
                                                                              
                         e.    Consolidated cash interest                     
                               expense less consolidated                      
                               interest income                   $____________
                           
                         f.    Capital expenditures (Net Cash
                               Proceeds of permitted third party 
                           




<PAGE>   103

                               Transfers to be netted against 
                               purchase price of assets purchased
                               during quarter)                     $____________

                         g.    Principal payments of
                               Capitalized Lease 
                               Obligations                         $____________

                         h.    Cash income taxes paid              $____________
             
                         i.    Cash distributions or dividends 
                               paid                                $____________
             
                         j.    Sum of d through i                  $____________
             
                         k.    Fixed Charge Coverage Ratio             
                               (Ratio of c to j; not less than -       
                               12/31/95 and 3/31/95 1.50 to 1.0    
                               6/30/96 up to and including             
                               3/31/97 1.75 to 1.0                   
                               6/30/97 and thereafter 1.85 to 1.0) ____ to _____

                 2.       TOTAL FUNDED DEBT TO EBITDA (historic rolling
                          four-quarters)

                          a.   Total Funded Debt                   $___________ 
             

                               i.     Indebtedness for borrowed 
                                      money, bonds, debentures, 
                                      notes, or similar
                                      instruments, plus deferred 
                                      purchase price               $___________ 
                                 
                               ii.    Letters of credit and
                                      banker's acceptances         $___________ 
                                  
                               iii.   Capitalized Leases           $___________ 
                                      

                          b.      EBITDA                           $___________ 

                          c.      Total Funded Debt to EBITDA 
                                  Ratio (Ratio of a to b; not 
                                  greater than 3:00 to 1:00)       ____ to _____
                                                


                                     -2-
<PAGE>   104
            3.       ADJUSTED NET WORTH

                     a.      Adjusted Net Worth:

                             i.  Consolidated Net Worth        $___________
            

                            ii.  Goodwill amortization 
                                 and non-cash,
                                 non-recurring writeoffs, 
                                 each associated with an 
                                 Acquisition
                                                                $___________

                           iii.  Merger costs under 
                                 pooling of interests 
                                 (5% limitation)                $___________
                                    
                            iv.  Adjusted Net Worth (sum 
                                 of i through iii)              $___________
                                      
                                                     
                     b.      Minimum Required Adjusted Net Worth:

                             i.  Adjusted Net Worth as 
                                 of 9/30/95                     $139,400,000 

                            ii.  50% of Consolidated Net 
                                 Income for then most 
                                 recent ending fiscal 
                                 quarter                        $___________

                           iii.  50% of cumulative 
                                 Consolidated Net Income 
                                 for all fiscal quarters 
                                 ending 12/31/95 through 
                                 the most recent ending 
                                 fiscal quarter                 $___________ 
            
                            iv.  Minimum Adjusted Net 
                                 Worth (sum of i and iii)       $___________
            
                     c.      Overage (Shortage) 
                             (a(iv)-b(iv))                      $___________
            

         C.      All of the representations and warranties contained in the
Credit Agreement are true and correct in all respects on the date hereof as if
made on the date hereof except, (i) to the extent such representation and
warranty relates to an earlier date in which case it shall have been true and
correct as of such earlier date, and (ii) as to the following matters:
[Describe or attach a schedule of all such representations and warranties that
are no longer true or correct and, if applicable, what action the Borrower has
taken or proposes to take with respect thereto].

            _____________________________________________________
            _____________________________________________________
            _____________________________________________________
                     


                                     -3-
<PAGE>   105
         D.      (Check EITHER 1 or 2)

                 [__] 1.  As of the date hereof, no Default or Event of Default
has occurred and is continuing.

                 [__] 2.  As of the date hereof, no Default or Event of Default
has occurred and is continuing except the following matters:  [Describe all
such Defaults or Events of Default, specifying the nature, duration and status
thereof and what action the Borrower has taken or proposes to take with respect
thereto].

            _____________________________________________________
            _____________________________________________________
            _____________________________________________________
                         

         E.      The Borrower or a Subsidiary of the Borrower has made the
following permitted Acquisitions during the past fiscal quarter: [List only if
an Acquisition Report was not provided to the Agent in connection with such
Acquisition]

                 1.   Name of entity or division: __________________________
                                        
                 2.   Acquisition of: [stock or assets]_____________________
                                                   
                 3.   Acquisition price (calculated as provided in Section 
                      6.13): _________________


Date: _____________________, 199____.

                                                   LANDMARK GRAPHICS CORPORATION



                                                   By:__________________________
                                                   Name:________________________
                                                   Title:_______________________




                                     -4-
<PAGE>   106
                                  EXHIBIT 6.13

                           FORM OF ACQUISITION REPORT
<PAGE>   107


                                  EXHIBIT 6.13

                               ACQUISITION REPORT

                 Landmark Graphics Corporation (the "Borrower"), the financial
institutions from time to time parties thereto (collectively, the "Lenders"),
and ABN AMRO Bank N.V., Houston Agency, as Agent for the Lenders, have executed
and delivered that certain Credit Agreement (as amended, supplemented and
restated from time to time, the "Credit Agreement") dated as of December   ,
1995.  Any term defined in the Credit Agreement and used in this Acquisition
Report shall have the meaning given to it in the Credit Agreement.

                 The undersigned, solely in his or her capacity as Chief
Financial Officer or Treasurer (as noted below) of the Borrower, hereby
certifies to the Agent and each of the Lenders that:

         A.      The Borrower intends to make an Acquisition of the [stock or
assets] of the following entity or division:________________________________ . 
The Acquisition price (calculated as provided in Section 6.13) is $____________
_____________.  The sources for payment of the Acquisition price and uses of 
such funds and/or property are as follows:  [list sources, including cash of
Borrower/stock/deferred purchase price/earn out position of purchase
price/Borrowing/other property and uses of such funds and/or property]

Sources:        ___________________     Uses:  ___________________
                ___________________            ___________________
                ___________________            ___________________

         B.      The following calculations demonstrate on a trailing four
(4)-quarter pro forma basis the Borrower's compliance with Sections 6.23, 6.24
and 6.25 of the Credit Agreement [any adjustments for non-GAAP reporting of the
acquired entity are detailed on attached schedule]:

<TABLE>
<CAPTION>
1.       FIXED CHARGE COVERAGE RATIO               Borrower and
         (historic rolling four-quarters)          Its Subsidiaries                   Acquisition              Combined  
                                                   ----------------                  -------------           ------------
         <S>     <C>      <C>                      <C>                               <C>                     <C>
         a.      EBITDA                            $____________                     $__________             $___________

                 i.       Add back distributions,
                          dividends and bonuses         -0-    
                          to prior owner)          $____________                     $__________             $___________
                                                                                                       

                 ii.      Add back corporate
                          overhead non-recurring        -0-
                          after Acquisition date   $____________                     $__________             $___________
                                                                                                                         
                                                        -0-
         b.      Adjusted EBITDA (sum              $____________                     $__________             $___________
                                                                                                                         
                 of a, a(i) and a(ii))
</TABLE>
<PAGE>   108
<TABLE>
         <S>     <C>                                        <C>                       <C>                     <C>        
         c.      Capitalized research                                                                                    
                 and development costs                      $____________             $__________             $___________
                                                                                                                         
         d.      Total of b minus c                         $____________             $__________             $___________
                                                                                                                         
         e.      Principal amortization of                                                                               
                 Indebtedness and required                                                                               
                 prepayments (include                                                                                    
                 assumed Indebtedness in                                                                                 
                 connection with                                                                                         
                 Acquisition)                               $____________             $__________            $____________
                                                                             
         f.      Consolidated cash interest                                  
                 expense less consolidated                                   
                 interest income (1 year interest                            
                 on revolver funding to be drawn                             
                 for Acquisition and include interest                        
                 on assumed Indebtedness in                                  
                 connection with Acquisition)               $____________             $___________           $____________
                                                                                         
         g.      Capital expenditures (Net Cash                                          
                 Proceeds of permitted third                                             
                 party Transfers to be netted                                            
                 against purchase price of assets                                        
                 purchased during quarter)                  $____________             $___________           $____________
                                                                                         
         h.      Principal payments of                                                   
                 Capitalized Lease                                                       
                 Obligations                                $____________             $___________           $____________ 
                                                                                                                           
         i.      Cash income taxes paid                     $____________             $___________           $____________ 
                 (as adjusted for effect of                                                                                
                 revolver funding to be                                                                                    
                 drawn for Acquisition)                                                                                    
                                                                                                                           
         j.      Cash distributions or dividends                                           -0-                             
                 paid                                       $____________             $____________          $____________ 
                                                                                                                           
                                                                                                                           
         k.      Sum of e through j                         $____________             $___________           $____________ 
                                                                                                                           
         l.      Fixed Charge Coverage Ratio                                                                               
                 (Ratio of d to k; not less than -                                                                         
                 12/31/95 and 3/31/95                       1.50 to 1.0                                                    
                 6/30/96 up to and including                                                                               
                 3/31/97                                    1.75 to 1.0                                                    
                 6/30/97 and thereafter                     1.85 to 1.0)                                     ____ to ____  
</TABLE>
        
<TABLE>  
<CAPTION>                                                                                                                  
2.       TOTAL FUNDED DEBT TO EBITDA                        Borrower and                                                   
         (historic rolling four-quarters)                   Its Subsidiaries          Acquisition              Combined    
                                                            ----------------          -----------            ------------- 
         <S>                                                <C>                       <C>                    <C>
         a.      Total Funded Debt (include any                                                                            
                 revolver funding to be drawn                                                                              
                 for Acquisition and assumed                                                                               
                 Indebtedness in connection                                                                                
                 with Acquisition)                          $____________             $___________           $____________ 

</TABLE>


                                     -2-
<PAGE>   109

<TABLE>

         <S>     <C>                               <C>                      <C>                            <C>
         b.      Adjusted EBITDA                   $____________            $___________                   $____________

         c.      Total Funded Debt to EBITDA
                 Ratio (Ratio of a to b; not
                 greater than 3:00 to 1:00)                                                                 ____ to ____
</TABLE>                 


<TABLE>
<CAPTION>
3.       ADJUSTED NET WORTH                                                                                  COMBINED    
                                                                                                            ------------  
         <S>     <C>                                                                                        <C>
         a.      Adjusted Net Worth (reconciliation is
                 detailed on attached schedule):

                 i.       Consolidated Net Worth                                                            $____________

                 ii.      Goodwill amortization and
                          non-cash, non-recurring writeoffs,
                          each associated with an
                          Acquisition                                                                       $____________

                 iii.     Merger costs under pooling of
                          interests (5% limitation)                                                         $____________

                 iv.      Adjusted Net Worth (sum of i through iii)                                         $____________

         b.      Minimum Required Adjusted Net Worth:

                 i.       Adjusted Net Worth as of 9/30/95                                                  $ 139,400,000

                 ii.      50% of Consolidated Net Income
                          for then most recent ending
                          fiscal quarter                                                                    $____________

                 iii.     50% of cumulative Consolidated Net
                          Income for all fiscal quarters
                          ending 12/31/95 through the most
                          recent ending fiscal quarter                                                      $____________

                 iv.      Minimum Adjusted Net Worth (sum
                          of i and iii)                                                                     $____________

         c.      Overage (Shortage) (a(iv)-b(iv))                                                           $____________
</TABLE>


Date: _____________________, 199____.

                                                   LANDMARK GRAPHICS CORPORATION



                                                   By:_________________________
                                                   Name:_______________________
                                                   Title:______________________




                                     -3-
<PAGE>   110
                                 EXHIBIT 10.10

                          FORM OF ASSIGNMENT AGREEMENT
<PAGE>   111


                                 EXHIBIT 10.10

                      ASSIGNMENT AND ASSUMPTION AGREEMENT


        This Assignment Agreement (this "Agreement") dated as of _____________,
199__, is by and among ______________________________________ (the "Assignor"),
_____________________________ (the "Assignee"), Landmark Graphics Corporation,
a Delaware corporation (the "Borrower"), and ABN AMRO Bank N.V., Houston 
Agency, as Agent for the Lenders (as hereinafter defined) (in such capacity,
the "Agent").
        
                                  WITNESSETH:

         WHEREAS, the Agent, as agent for the financial institutions
(collectively, the "Lenders") now or hereafter parties to that certain Credit
Agreement (as amended, supplemented and restated from time to time, the "Credit
Agreement") dated as of December 15, 1995, by and among the Borrower, the
Lenders, including the Assignor as one such Lender, and the Agent;

         WHEREAS, the Assignor has agreed to make certain Loans to and
participate in Letters of Credit for the account of the Borrower in accordance
with the terms of the Credit Agreement, with the maximum aggregate amount of
the Assignor's Loans and participation in Letters of Credit outstanding not to
exceed the Assignor's Commitment; and

         WHEREAS, on a pro rata basis, the Assignor proposes to sell and assign
to the Assignee, and the Assignee proposes to buy and accept from the Assignor,
a _____ percent (_____%) interest (the "Assigned Interest") in the rights and
obligations of the Assignor under the Credit Documents with the effect that the
Assignee will have a maximum Commitment of $________________, resulting in a
Percentage of ______%;

         NOW, THEREFORE, in consideration of the foregoing and the mutual
agreements contained herein, the parties hereto agree as follows:

         SECTION 1.  Definitions.  Any term defined in the Credit Agreement and
used in this Agreement shall have the meaning ascribed to it in the Credit
Agreement.  Section 1.1 of the Credit Agreement is hereby incorporated into
this Agreement by reference.

         SECTION 2.  Assignment.  The Assignor hereby assigns and sells,
without recourse or warranty except as specifically set forth herein, to the
Assignee the Assigned Interest in the rights and obligations of the Assignor
under the Credit Documents.  The Assignee hereby purchases and accepts, without
recourse or warranty except as specifically set forth herein, from the Assignor
all of such rights and obligations of the Assignor, including the corresponding
portion of (a) the principal amount of the Loans made by the Assignor, (b) the
participation of the Assignor in the Letters of Credit, if any, and (c) any
Reimbursement Obligations of the Borrower owing to the Assignor outstanding on
the date hereof.  As of the date hereof, the Assignee's Percentage of the
outstanding principal balance of the Loans and Reimbursement Obligations of the
Borrower is $____________.  Subject to the execution and delivery hereof


<PAGE>   112
by the Assignor, the Assignee, the Borrower and the Agent on the date hereof,
(a) the Assignee shall succeed, on a pro rata basis, to the rights and
interests, and be obligated to perform the obligations of, a Lender under the
Credit Documents with a Percentage of _______%, and shall be considered a
Lender for all purposes; (b) the Assignee shall deliver to the Assignor, in
immediately available funds, the Assignee's Percentage of the outstanding Loans
(minus an amount equal to the Assignee's Percentage of any Letter of Credit fee
paid by the Borrower to the Assignor pursuant to the terms of the Credit
Agreement for the remaining portion of the calendar quarter), and (c) the
Percentage of the Assignor as of the date hereof shall be reduced by the
Percentage acquired by the Assignee, and the Assignor shall be released from
its obligations under the Credit Documents which have been so assigned to and
accepted by the Assignee.  The Assignee shall participate in all outstanding
Letters of Credit as provided in the Credit Documents.

         SECTION 3.  Payments.  Commitment fees accrued to the date hereof with
respect to the Assignor's Percentage of the Commitment pursuant to Section 3.1
of the Credit Agreement are for the account of the Assignor and such fees
accruing from and including the date hereof with respect to the Assigned
Interest are for the account of the Assignee.  All payments of principal of and
accrued interest on the Loans and of Reimbursement Obligations are to be made
by the Borrower to the Agent; the Agent shall divide such payments among the
Lenders as their interests may appear, with all interest accruing on the Loans
of the Assignor and Reimbursement Obligations before the date hereof to belong
to the Assignor.  Each of the Assignor and the Assignee hereby agrees that if
it receives any amount from the Borrower under the Credit Documents which is
for the account of the other party hereto, it shall receive the same for the
account of such other party to the extent of such other party's interest
therein and shall promptly pay the same to such other party.  The rights of the
Assignor and the Assignee under this Section are in addition to other rights
and remedies which the Assignor or the Assignee may have.

         SECTION 4.  Consent of the Borrowers and the Agent.  This Agreement is
conditioned upon the consent of the Borrower and the Agent to the extent
required by Section 10.10(b) of the Credit Agreement.  The execution of this
Agreement by the Borrower and the Agent is evidence of any such consent.
Pursuant to Section 10.10(b) of the Credit Agreement, (a) the Assignor agrees
to deliver its current Note(s) executed by the Borrower to the Borrower, marked
"Renewed" or its equivalent, and simultaneously therewith (b) the Borrower
agrees to execute and deliver new Notes payable to the order of the Assignee
and, if applicable, to the Assignor to evidence the assignment and acceptance
provided for herein.

         SECTION 5.  The Assignor.  The Assignor (a) represents and warrants to
the Assignee that it is the legal and beneficial owner of the Assigned Interest
and that such Assigned Interest is free and clear of any Lien; (b) makes no
representation or warranty and assumes no responsibility with respect to (i)
any statements, warranties or representations made in or in connection with the
Credit Documents or the execution, legality, validity, enforceability,
genuineness, sufficiency or value of the Credit Documents or any document
furnished pursuant thereto and (ii) the financial condition of the Borrower or
the performance or observance by the Borrower or any other Credit Party of any
of its obligations under the Credit Documents.




                                     -2-
<PAGE>   113
         SECTION 6.  The Assignee.  The Assignee (a) confirms that it has
received a copy of the Credit Documents, together with such other documents and
information as it has deemed appropriate to make its own credit analysis and
decision to enter into this Agreement; (b) agrees that it will, independently
and without reliance upon the Agent, the Assignor or any other Lender and based
on such documents and information as it shall deem appropriate at the time,
continue to make its own credit decisions in taking or not taking action under
the Credit Documents; (c) appoints and authorizes the Agent to take such action
as agent on behalf of the Assignee and to exercise such powers under the Credit
Documents as are delegated to the Agent by the terms thereof, together with
such powers as are reasonably incidental thereto; and (d) agrees that it will
perform in accordance with their terms all of the obligations which by the
terms of the Credit Documents are required to be performed by it as a Lender.
If the Assignee is organized under the laws of any jurisdiction other than the
United States of America or any State thereof, the Assignee hereby (a)
represents to the Assignor, the Agent and the Borrower that under applicable
law and treaties no taxes will be required to be withheld by the Agent, the
Borrower or the Assignor with respect to any payments to be made to such
Assignor in respect of the Loans or the Letters of Credit, (b) furnishes to the
Assignor, the Agent and the Borrower either U.S. Internal Revenue Service Form
4224 or U.S. Internal Revenue Service Form 1001 (wherein the Assignee claims
entitlement to complete exemption from U.S. federal withholding tax on all
interest payments hereunder), and (c) agrees for the benefit of the Assignor,
the Agent and the Borrower to provide the Assignor, the Agent and the Borrower
a new Form 4224 or Form 1001 upon the expiration or obsolescence of any
previously delivered form and comparable statements in accordance with
applicable U.S.  laws and regulations and amendments duly executed and
completed by the Assignee, and to comply from time to time with all applicable
U.S. laws and regulations with regard to such withholding tax exemption.

         SECTION 7.  Notices and Payment Instructions.  All notices in
connection herewith shall be given in accordance with Section 10.7 of the
Credit Agreement.  The address of the Assignee for notices hereunder and
thereunder, together with payment instructions for amounts to be paid to the
Assignee under the Credit Agreement, shall be initially as set forth on the
signature pages hereof.

         SECTION 8.  Miscellaneous.  This Agreement (a) embodies the entire
agreement and understanding between the parties with respect to the subject
matter hereof and supersedes all prior agreements, consents and understandings
relating to such subject matter, (b) is a Credit Document, and (c) shall be
governed by and construed in accordance with the laws of the State of Texas.




                                     -3-
<PAGE>   114
         IN WITNESS WHEREOF, the parties have caused this Agreement to be
executed and delivered by their duly authorized officers as of the date first
above written.

                                      [NAME OF ASSIGNOR]



                                      By:____________________________________
                                      Name:__________________________________
                                      Title:_________________________________
                                                                             
                                                                             
                                                                             
                                      [NAME OF ASSIGNEE]                     
                                                                             
                                                                             
                                                                             
                                      By:____________________________________
                                      Name:__________________________________
                                      Title:_________________________________
                                                                             
                                                                             
                                      [Insert Address]                       
                                      _______________________________________
                                      Attention:_____________________________
                                      Telecopy No.: (___)____________________
                                                                             

                                      Send payments to:

                                      ________________________________________
                                      ________________________________________
                                      ________________________________________

                                      [Reference: Landmark Graphics Corporation]




                                     -4-
<PAGE>   115
                                      LANDMARK GRAPHICS CORPORATION


                                      By:______________________________________
                                      Name:____________________________________
                                      Title:___________________________________
                                                                               
                                                                               
                                      ABN AMRO BANK N.V., HOUSTON              
                                      AGENCY, AS AGENT                         
                                                                               
                                      By:______________________________________
                                      Name:____________________________________
                                      Title:___________________________________
                                                                               
                                                                               
                                                                               
                                      By:______________________________________
                                      Name:____________________________________
                                      Title:___________________________________
                                                                               



                                     -5-
<PAGE>   116
                                  SCHEDULE 5.1

                              LIST OF SUBSIDIARIES

<TABLE>
<CAPTION>
Name of                                            Jurisdiction of                         Percentage 
Subsidiary                                           Organization                       Ownership Interest
----------                                         ---------------                      ------------------

<S>                                                  <C>                                      <C>
LMK Land Company                                     Delaware                                 100%
                                                   
Landmark America Latina, S.A.                        Delaware                                 100%
                                                   
LANDMARK Graphics International, Inc.                Texas                                    100%
                                                   
Landmark Graphics Europe/Africa, Inc.                Delaware                                 100%
                                                   
Landmark/ITA Ltd.                                    Canada                                   100%
                                                   
Landmark/CAEX, Inc.                                  Delaware                                 100%
                                                   
Landmark Finance Corporation                         Delaware                                 100%
                                                   
CAEX Services, Inc.                                  Delaware                                 100%
                                                   
MGI Associates, Inc.                                 Texas                                    100%
                                                   
GeoGraphix, Inc.                                     Colorado                                 100%
                                                   
Technologies Acquisition Corporation                 Texas                                    100%
                                                   
Landmark Sales Corporation (FSC)                     Barbados                                 100%
                                                   
Landmark E.A.M.E., Ltd.                              England                                  100%
                                                   
Landmark Graphics (Nigeria) Ltd.                     Nigeria                                  100%
                                                   
PT Landmark Concurrent                             
 Solumi Indonesia                                    Indonesia                                 80%
                                                   
Landmark Graphics (Malaysia) Sdn. Bhd.               Malaysia                                 100%
                                                   
Landmark Graphics Columbia S.A.                      Colombia                                  95%
                                                   
Landmark Graphics Venezuela C.A.                     Venezuela                                100%
                                                   
Landmark Graphics do Brasil Ltda.                    Brazil                                   100%
</TABLE>




                                      1
<PAGE>   117
<TABLE>
<S>                                                    <C>                                      <C>
Landmark de Argentina, S.A.                            Argentina                                100%

Landmark de Mexico, S.A. de C.V.                       Mexico                                   100%

Stratamodel (FSC)                                      Barbados                                 100%

MGI Associates, Inc.                                   Texas                                    100%

Munro Garrett International, Inc.                      Texas                                    100%

Munro Garrett (Asia Pacific) Pty, Ltd.                 Australia                                100%

Monro Garrett Inc.                                     Alberta                                  100%

Munro Garrett International Limited                    Scotland                                 100%

Munro Engineering Intl. Pte. Ltd.                      Singapore                                100%
</TABLE>





                                      2
<PAGE>   118
                                 SCHEDULE 5.13

                               ERISA DISCLOSURES



                                     NONE.
<PAGE>   119
                                 SCHEDULE 5.18

                           ENVIRONMENTAL DISCLOSURES



                                     NONE.

<PAGE>   120
                                 SCHEDULE 6.17

                          LIST OF EXISTING INVESTMENTS


1.   Investment in 87,013 shares of common stock and 4,000 shares of redeemable 
     preferred stock of 3DX Technologies, Inc. ("3DX"), formerly Novera Energy 
     Inc. The redeemable stock has a liquidation preference of $100 per share 
     and is mandatorily redeemable in two equal installments on November 9,  
     2002 and 2003. This investment has a net book value of $851,000.

2.   Outstanding note receivable of $250,000 from Integra Geoservices Inc. 
     ("Integra") arising out of the Asset Purchase Agreement between Integra 
     and Landmark/ITA Ltd. in April 1994.

3.   Borrower acquired an option to purchase the equity interests of 619068 
     Alberta, Ltd. exercisable no later than October 31, 1997 at an exercise 
     price which is based on 619068 Alberta, Ltd.'s financial results. In no 
     event will the net present value of the option price be less than $8.0 
     million.
    
<PAGE>   121
                                 SCHEDULE 5.19

                         LIST OF EXISTING INDEBTEDNESS


1.   $10,000,000 five-year term loan and $25,000,000 revolving credit facility 
     with NationsBank. Obligations are collateralized by the Borrower's 
     headquarters site and undeveloped land adjacent thereto. No amounts are 
     outstanding in either facility, and such facilities will be terminated 
     upon consummation of the new credit facility.

2.   Obligations relating to deferred purchase price payments relating to 
     certain former shareholders of MGI Associates, Inc. Remaining payments are 
     as follows:

                          Due Date               Payment
                          --------               -------

                    September 30, 1996           $2,248,150
                    September 30, 1997           $2,843,755

3.   Borrower acquired an option to purchase the equity interests of 619068 
     Alberta, Ltd. in exchange for a NationsBank line of credit guarantee of 
     $5.0 million. Currently, 619068 Alberta, Ltd. has $3.0 million outstanding
     under the credit line guarantee which is presently secured by Borrower's  
     headquarters site and undeveloped land adjacent thereto. Upon consummation 
     of the new credit facility, the credit line guarantee will be secured by 
     the undeveloped land only.

4.   Security Agreement with Texas Copy collateralized by a Canon 8350 Copy 
     System.

5.   $5,000,000 line of credit with ABN AMRO Bank N.V. pursuant to which 
     approximately $1,800,000 of letters of credit are outstanding. This line 
     of credit will be reduced to $2,000,000 upon consummation of the new 
     credit facility.

6.   Letters of credits in the current amount of $96,000 issued by Hong Kong & 
     Shanghai Banking Corporation for the account of certain Subsidiaries of 
     Borrower.