LOAN AGREEMENT


     This Loan Agreement  (this  "Agreement")  dated as of June 30, 1998, by and
between NationsBank,  N.A., a national banking association ("Bank") and National
Instruments Corporation, a Delaware corporation ("Borrower").

     In  consideration of the Loans described below and the mutual covenants and
agreements  contained herein, and intending to be legally bound hereby, Bank and
Borrower agree as follows:

     1.  Definitions and Reference Terms. In addition to any other terms defined
herein,  the  following  terms  shall have the  meaning  set forth with  respect
thereto:

          A.  "Advance"  means an advance of the  proceeds of the Line of Credit
     (as defined below) or a portion of the unpaid principal balance of the Term
     Note, as applicable,  subject to the terms, conditions, and requirements of
     this Agreement and the Loans.

          B. "Applicable  Margin" means the interest margin over the LIBOR Rate,
     for  Advances,  which is based on the Senior Debt to EBITDA Ratio as of and
     for the most recent four (4) quarter period ending on or before the date of
     determination,  such Applicable  Margin being set forth opposite such ratio
     below:

                Senior Debt to EBITDA Ratio       Applicable Margin
                ---------------------------       -----------------

                Less than 0.35 to 1.0             0.5% [50 basis points]

                Greater than or equal to          0.65% [65 basis points]
                0.35 to 1.0 but less than or
                equal to 0.75 to 1.0

                Greater than 0.75 to 1.0 but      .75% [75 basis points]
                less than 1.0 to 1.0

                Greater than or equal to          0.95% [95 basis points]
                1.0 to 1.0 but less than
                or equal to 1.25 to 1.0

                Greater than 1.25 to 1            1.15% [115 basis points]

The Senior Debt to EBITDA Ratio shall be  determined  from the then most current
quarterly or annual  financial  statements  of Borrower  and related  compliance
certificate  delivered by Borrower to Bank pursuant to Section  5.B.(iv) of this
Agreement.  The adjustment,  if any, to the Applicable Margin shall be effective
commencing  on the fifth (5th)  Business  Day after  delivery of such  financial
statements (and related compliance  certificate).  If Borrower fails at any time
to furnish to Bank such financial statements and related compliance  certificate
and such failure  continues for more than thirty (30) days after written  notice
of such failure,  then the maximum Applicable Margin shall apply until such time
as such  financial  statements  (and  related  compliance  certificates)  are so
delivered.

          C. "Alternate  Rate" means the sum of a LIBOR Rate plus the Applicable
     Margin per annum.


          D.  "Business  Day"  shall  mean a day on  which  Bank is open for the
     conduct of  substantially  all of its  banking  business  at its  principal
     office in Austin,  Texas and a day on which  dealings are carried on in the
     London interbank market.

          E.   "Continue",   "Continuation",   and  "Continued"   refer  to  the
     continuation  pursuant to Section  3.C.  below of a LIBOR  Advance from one
     LIBOR Interest Period to the next LIBOR Interest Period.

          F.  "Conversion"  and  "Converted"  refer to a conversion  pursuant to
     Section  1(e) below of one type of an  Advance  to another  type of Advance
     (i.e..,  from an  Advance  bearing  interest  at the Prime  Rate to a LIBOR
     Advance, or vice versa).

                                     Page 20



          G.  "Dollars"  and "$" means U.S.  Dollars,  the  lawful  money of the
     United States of America.

          H. "EBITDA"  means for any period:  (i)  Borrower's  consolidated  net
     income of such period,  determined after deduction of any minority interest
     income, plus (ii) all amounts deducted therefrom during such period, all in
     conformity with GAAP, for interest, taxes, depreciation and amortization.

          I.  "Eurodollar  Reserve  Percentage"  shall mean, for each term of an
     Advance,  the maximum reserve  requirement  including any  supplemental and
     emergency reserves (expressed as a percentage)  applicable during such term
     to member banks of the Federal  Reserve System in respect of  "Eurocurrency
     liabilities"  under  Regulation  D of the Board of Governors of the Federal
     Reserve System,  or such substituted or amended reserve  requirement as may
     be hereafter  applicable to member banks of the Federal  Reserve  System in
     respect  of  such  Eurocurrency   liabilities  or  other  foreign  currency
     liabilities of the nature contemplated by this Agreement.

          J. "Foreign  Currency Advance" shall mean an advance under the Line of
     Credit which is in a foreign currency (that is, not in Dollars).

          K. "Foreign Currency Rate" shall mean, in relation to the term of each
     Foreign Currency Advance, a fixed per annum rate for such term equal to the
     quotient  produced by dividing  (a) the sum of (i) the  percentage  rate of
     interest  determined by Bank at or about 10:00 a.m.  Austin,  Texas time on
     the second  Business Day preceding the anticipated  date of advance,  to be
     the per  annum  rate at  which  deposits  of the type of  foreign  currency
     denominated  during  such term are  offered  to Bank by prime  banks in the
     London foreign currency  deposits market,  at the time of determination and
     in accordance  with the usual practice in such market,  for delivery on the
     first day of such term and for the  number of days  comprised  therein,  in
     amounts  of such  currency  equal (as  nearly  as may be) to the  principal
     amount of the advance,  and (ii) an additional  percentage rate of interest
     not to exceed  one-half of one percent (1/2 of 1%) per annum to  compensate
     Bank  for  making  advances  having  a  Dollar   Equivalent  of  less  than
     $1,000,000.00  each,  by (b) the  remainder  produced  by  subtracting  the
     Eurodollar  Reserve  Percentage  (expressed as a decimal in one  hundredths
     [e.g., 100% = 1.0; 1.0% = .01; etc.]) from 1.0.

          L. "Hazardous Materials" means (i) any "hazardous waste" as defined by
     the Resource  Conservation and Recovery Act of 1976 (42 U.S.C. Section 6901
     et  seq.),  as  amended  from  time to time,  and  regulations  promulgated
     thereunder;  (ii) any "hazardous substance" as defined by the Comprehensive
     Environmental  Response,  Compensation and Liability Act of 1980 (42 U.S.C.
     Section  9601 et seq.)  ("CERCLA"),  as  amended  from  time to  time,  and
     regulations  promulgated  thereunder;  (iii) asbestos; (iv) polychlorinated
     biphenyls;  (v) any  substance  the presence of which on any of  Borrower's
     property is prohibited by any  governmental  authority;  and (vi) any other
     substance which by any governmental  requirement  requires special handling
     in its collection, storage, treatment or disposal.

          M.  "Indebtedness"  means the indebtedness and obligations of Borrower
     to Bank under the Note, the Term Note, this  Agreement,  and any other Loan
     Documents.

          N.  "LIBOR  Rate"  shall  mean an  interest  rate per  annum  (rounded
     upwards,  if  necessary,  to the nearest 1/100 of 1%) appearing on Telerate
     Page 3750 (or any successor page) as the London interbank  offered rate for
     deposits in Dollars at approximately  11:00 a.m. (London time) two Business
     Days prior to the first day of the applicable  LIBOR Interest  Period for a
     term  comparable to such LIBOR  Interest  Period,  as adjusted from time to
     time in Bank's sole discretion,  for the applicable  reserve  requirements,
     deposit insurance  assessment rates, and other regulatory costs. If for any
     reason such rate is not  available,  the term "LIBOR Rate" shall mean,  for
     any LIBOR  Advance for any LIBOR  Interest  Period  therefor,  the rate per
     annum (rounded upwards, if necessary, to the nearest 1/100 of 1%) appearing
     on  Reuters  Screen  LIBO Page as the  London  interbank  offered  rate for
     deposits in Dollars at approximately  11:00 a.m. (London time) two Business
     Days  prior to the  first  day of such  LIBOR  Interest  Period  for a term
     comparable to such LIBOR Interest Period,  as adjusted from time to time in
     Bank's sole discretion,  for the applicable reserve  requirements,  deposit
     insurance assessment rates, and other regulatory costs, provided,  however,
     if more  than one rate is  specified  on  Reuters  Screen  LIBO  Page,  the
     applicable rate shall be the arithmetic mean of all such rates.

                                     Page 21



          O. "LIBOR  Advance"  shall mean an Advance that bears  interest at the
     Alternate Rate.

          P.  "LIBOR  Interest  Period"  shall  mean with  respect  to any LIBOR
     Advance,  a certain  period  established  by the proper  exercise of a Rate
     Option (as defined  below).  That  certain  period  shall begin on the date
     specified  in the notice that is given to exercise  that Rate  Option,  and
     shall end (a) immediately  before the numerically  corresponding day in the
     first, second, third, sixth, or twelfth calendar month after the month that
     includes such commencement day, or (b) if such first, second, third, sixth,
     or twelfth calendar month has no such numerically  corresponding  day, then
     at the end of the last day of such month.

          Q.  "Loan"  shall mean and  include  any loan  described  in Section 2
     hereof and any  subsequent  loan made by Bank to Borrower which states that
     it is subject to this Agreement,  and any one or more Loans may be referred
     to as the "Loans."
 
          R.  "Loan  Documents"  means  this  Loan  Agreement  and  any  and all
     promissory  notes  executed  by  Borrower  in favor  of Bank and all  other
     documents,  instruments,  guarantees,  certificates and agreements executed
     and/or  delivered by Borrower,  any  guarantor or third party in connection
     with any Loan.

          S. "Maturity Date" means December 31, 1999.

          T. "Maximum  Lawful Rate" means the maximum  lawful  interest rate for
     the Loan and Note, as determined  under Texas law, and shall be the "weekly
     ceiling"  (as  defined in Chapter  303 of the Texas  Finance  Code  [and/or
     Articles 1D.002 and 1D.003 of the Texas Credit Title] and formerly referred
     to as the "Indicated  (Weekly) Ceiling" in Article  1.04(a)(1) of the Texas
     Credit Code [Article 5069-1.04 of VATS]).  Further,  to the extent that any
     other lawful rate ceiling  exceeds the rate ceiling so determined  then the
     higher rate ceiling shall apply.

          U. "Senior Debt" means the Indebtedness and any other  indebtedness of
     Borrower  permitted under this Agreement  which is not  subordinated to the
     Indebtedness.

          V. "Senior Debt to EBITDA Ratio" means,  as of any date,  the ratio of
     (a) the aggregate  amount of Senior Debt of the Borrower,  as of such date,
     to (b) EBITDA of Borrower,  for the four (4) fiscal quarter  periods ending
     on the date of determination.

          W.  "Tangible Net Worth" means the amount by which total assets exceed
     total liabilities in accordance with GAAP.

          X. Accounting Terms. All accounting terms not specifically  defined or
     specified herein shall have the meanings generally attributed to such terms
     under generally accepted accounting  principles ("GAAP"), as in effect from
     time  to  time,   consistently  applied,  with  respect  to  the  financial
     statements referenced in Section 4.H. hereof.

     2. Loans.

          A.  Revolving  Line of  Credit  Loan.  Bank  hereby  agrees  to make a
     revolving  line of credit loan to Borrower in the aggregate  principal face
     amount of  $20,000,000.00  (the "Line of Credit").  The obligation to repay
     the  Line of  Credit  and  all  Advances  thereunder  is  evidenced  by the
     promissory note in the stated  principal  amount of  $20,000,000.00,  dated
     June 30, 1998, executed by Borrower, and payable to the order of Bank, (the
     promissory note or notes together with any and all renewals,  extensions or
     rearrangements  thereof  being  hereafter  collectively  referred to as the
     "Note")  having a maturity date,  repayment  terms and interest rate as set
     forth in the Note.

               i. Revolving  Credit  Feature.  The Loan provides for a revolving
          line of credit  under which  Borrower  may from time to time,  borrow,
          repay and re-borrow funds.

                                     Page 22



               ii. Letter of Credit  Subfeature.  As a subfeature under the Line
          of Credit, Bank may from time to time up to and including November 30,
          1999,  issue  letters of credit for the account of Borrower  (each,  a
          "Letter of Credit" and collectively,  "Letters of Credit");  provided,
          however, that the form and substance of each Letter of Credit shall be
          subject  to  approval  by Bank in its sole  discretion;  and  provided
          further that the aggregate  undrawn amount of all outstanding  Letters
          of  Credit  shall  not at any time  exceed  the  amount  available  to
          Borrower  under the Line of  Credit.  Each  Letter of Credit  shall be
          issued for a term not to exceed one year,  as  designated by Borrower,
          provided,  however,  that no Letter of Credit shall have an expiration
          date more than ninety days after the Maturity  Date,  unless agreed to
          by Bank (in Bank's sole and absolute  discretion)  at the time of such
          Letter of Credit's issuance.  The pricing and fees for any such Letter
          of Credit  shall be at the  Bank's  standard  rates at the time of the
          issuance of any Letter of Credit. The undrawn amount of all Letters of
          Credit  plus  any and all  amounts  paid  by Bank in  connection  with
          drawings  under any  Letter of Credit  for which the Bank has not been
          reimbursed shall be reserved under the Line of Credit and shall not be
          available  for  advances  thereunder.  Each draft paid by Bank under a
          Letter of Credit  shall be deemed an advance  under the Line of Credit
          and  shall be  repaid  in  accordance  with  the  terms of the Line of
          Credit;  provided however, that if the Line of Credit is not available
          for any reason  whatsoever,  at the time any draft is paid by Bank, or
          if advances are not available  under the Line of Credit in such amount
          due to any  limitation of borrowing  set forth  herein,  then the full
          amount of such drafts shall be immediately  due and payable,  together
          with  interest  thereon,  from the date such amount is paid by Bank to
          the date such  amount is fully  repaid  by  Borrower,  at that rate of
          interest  applicable  to  advances  under the Line of Credit.  In such
          event,  Borrower agrees that Bank, at Bank's sole discretion may debit
          Borrower's deposit account with Bank for the amount of such draft.

          B. Term Loan.  The term loan evidenced by the Real Estate Lien Note in
     the  original  principal  amount of  $8,480,000.00,  dated August 25, 1994,
     executed by  Borrower,  and payable to the order of  NationsBank  of Texas,
     N.A.  (the "Term  Note") shall also be subject to and governed by the terms
     and conditions of this Agreement.  Bank is the owner and holder of the Term
     Note as successor by merger to NationsBank of Texas,  N.A. All  collateral,
     including  without   limitation  the  real  property,   which  secured  the
     indebtedness  evidenced by the Term Note has been or will be released.  The
     Term Note shall be and hereby is  modified  to permit  Borrower  to elect a
     Rate  Option in the manner  and  subject  to the  limitations  set forth in
     Section 3.A-E. hereof. Except to the extent modified by this Agreement, all
     terms of the Term Note continue in full force and effect, without change.

     3. Interest Rate Options; Repayment Provisions for Line of Credit. The Note
shall bear interest as provided in this  Agreement  and the Note.  The principal
balance of the Note from time to time  remaining  unpaid prior to maturity shall
bear interest at a rate per annum (the "Contract  Rate") that is equal to either
the "Prime Rate" or the  "Alternate  Rate",  but in any event never greater than
the "Maximum  Lawful Rate", as those terms are defined in this Agreement and the
Note,  depending on the interest rate option  selected by Borrower in accordance
with this Agreement and the Note.

                                     Page 23



          A.  Interest  Rate Options The Contract  Rate for each Advance  (other
     than Foreign Currency  Advances) shall be determined in accordance with the
     provisions of this Section 3.A.,  subject to the other terms and conditions
     of this  Agreement  and the  Notes.  The  "Contract  Rate"  shall  mean the
     interest  rate per annum  applicable  to an  Advance as  determined  by the
     provisions of this Agreement.  On any day that is within the LIBOR Interest
     Period for a LIBOR Advance,  the Contract Rate for that LIBOR Advance shall
     equal the lesser of (i) the Alternate Rate for that LIBOR Interest  Period,
     or (ii) the Maximum Lawful Rate;  and, at all times,  the Contract Rate for
     all unpaid principal indebtedness that is not part of a LIBOR Advance shall
     equal the lesser of (i) the Prime Rate, or (ii) the Maximum Lawful Rate. On
     any  Business  Day  that is at  least  two (2)  Business  Days  before  the
     beginning of a LIBOR Interest Period,  Borrower may exercise an option (the
     "Rate  Option")  to  designate   either  (i)  the   outstanding   principal
     indebtedness  or Advance  which is to bear  interest at the Prime Rate,  or
     (ii) the LIBOR  Advance to which a LIBOR  Interest  Period and an Alternate
     Rate shall  apply.  Subject to the  provisions  of Sections  3.B.  and 3.D.
     below,  Borrower may exercise the Rate Option by either (i) giving  written
     notice of such exercise to Bank,  which notice shall identify the principal
     indebtedness,  or Advance,  affected by the Rate Option, the amount of such
     Advance, and, in the case of any LIBOR Advance, the first day of such LIBOR
     Interest  Period and the length of such LIBOR  Interest  Period (one month,
     two months,  three months,  six months, or one year), or (ii) giving notice
     to Bank in any other manner that is  acceptable to Bank. If the Rate Option
     is so exercised and Borrower  elects an Alternate  Rate, then for the LIBOR
     Advance  identified in such notice,  a LIBOR Interest  Period of the length
     specified in that notice shall begin on the date  specified in that notice,
     subject to the terms and conditions of the Note.

          B.  Limitations  on Rate  Options.  Each LIBOR  Advance  must be in an
     amount of $500,000.00 or a greater  integral  multiple of $100,000.00.  Any
     notice that is given to  exercise a Rate  Option  with  respect to the Note
     electing the  Alternate  Rate shall specify  either one month,  two months,
     three  months,  six  months,  or twelve  months as the  length of the LIBOR
     Interest Period established by that exercise.  For purposes of the Note and
     this  Agreement,  a LIBOR  Advance  "matures"  on the last day of the LIBOR
     Interest Period that is applicable to that LIBOR Advance.  Borrower may not
     exercise a Rate Option  electing  the  Alternate  Rate that would  create a
     LIBOR Advance that matures after the Maturity Date.

          C. Continuations; Conversions.

               i. Continuations. Borrower shall have the right to continue LIBOR
          Advances  by  giving  Bank   written   notice   specifying:   (i)  the
          Continuation  date;  (ii)  the  amount  of  the  LIBOR  Advance  to be
          Continued;  and  (iii)  the  duration  of the  LIBOR  Interest  Period
          applicable  thereto,  which  notice shall be  irrevocable  and must be
          given by Borrower  not later than 11:00 a.m.  Austin,  Texas time on a
          Business Day that is at least two (2)  Business  Days before each such
          Continuation.  If  Borrower  shall  fail to give  Bank the  notice  as
          specified above for a continuation of a LIBOR Advance prior to the end
          of the LIBOR Interest Period  applicable  thereto,  such LIBOR Advance
          shall be automatically converted to the Prime Rate.

               ii.  Conversions.  Borrower  shall  have the right to  convert an
          Advance  bearing  interest  at the  Prime  Rate at any time to a LIBOR
          Advance by giving Bank written notice  specifying:  (i) the Conversion
          Date;  (ii) the amount of the Advance to be  Converted;  and (iii) the
          duration of the LIBOR Interest Period applicable thereto, which notice
          shall be  irrevocable  and must be given by Borrower to Bank not later
          than 11:00 a.m. Austin,  Texas time on a Business Day that is at least
          two (2) Business Days before each such Conversion.

After the  occurrence  and during the  continuance  of an Event of  Default,  no
outstanding Advances may be Converted into, or Continued as, a LIBOR Advance.

                                     Page 24



          D. Special Provisions Regarding the Alternate Rate.

               i. Unavailability.  If Bank determines (which determination shall
          be  presumed  correct  absent  evidence  of  error)  on any  date  for
          determining  the Alternate Rate for any LIBOR Advance,  that by reason
          of any one (1) or more  changes  arising  on or after  the date of the
          Note affecting the interbank eurodollar market,  Dollar deposits in an
          amount  substantially equal to that LIBOR Advance (and/or for a period
          substantially  equal to the relevant  LIBOR  Interest  Period) are not
          generally  available in the London interbank  market,  or adequate and
          fair means do not exist for  ascertaining  the LIBOR Rate on the basis
          provided for herein and in this  Agreement,  then the  Alternate  Rate
          will not be available for that LIBOR Advance and the Contract Rate for
          that Advance shall equal the Prime Rate until Bank  notifies  Borrower
          that such circumstances no longer exist.

               ii.  Increased  Cost. At any time, that Bank shall actually incur
          increased  costs, or reductions in the amounts  received or receivable
          hereunder, with respect to a LIBOR Advance because of any change on or
          after the date of the Note in any applicable law,  governmental  rule,
          regulation,   guideline,   or  order  (or  in  the  interpretation  or
          administration  thereof and including the  introduction of any new law
          or  governmental  rule,  regulation,  guideline or order),  including,
          without   limitation,   the   imposition,   modification,   or  deemed
          applicability  of any reserve,  deposit,  or similar  requirements  as
          related to the  computation  of the LIBOR Rate (such as, for  example,
          but not limited to, a change in official reserve requirements, but, in
          all events,  excluding  reserves  required  under  Regulation D to the
          extent included in the computation of LIBOR Rate); then Borrower shall
          pay to Bank,  on demand,  such  additional  amounts (in the form of an
          increased rate of, or a different  method of calculating,  interest or
          otherwise as Bank  determines in its reasonable  discretion) as may be
          required to compensate  Bank for such increased costs or reductions in
          amounts  receivable  hereunder  (written  notice as to the  additional
          amounts  owed to Bank,  showing  the  basis for  calculation  thereof,
          shall, absent evidence of error, be binding on all parties hereto).

               iii. Illegality.  At any time, that the initiation,  or continued
          use, of the Alternate  Rate as the Contract  Rate has become  unlawful
          under Bank's good faith interpretation of any law,  governmental rule,
          regulation, guideline, or order (or would conflict with any such rule,
          regulation,  guideline  or order not having the force of law),  or has
          become impractical as a result of a contingency  occurring on or after
          the date of this Agreement which materially and adversely  affects the
          interbank  eurodollar market,  then the Alternate Rate shall no longer
          be available  as the Contract  Rate and any exercise by Borrower of an
          option  to have  the  Contract  Rate be the  Alternate  Rate  shall be
          ineffective.

          E. Prime Rate.  The "Prime Rate" is one of the  interest  rate options
     available  to  Borrower  under the Note.  The "Prime  Rate"  means the rate
     established  and  quoted  from time to time by  NationsBank,  N.A.  (or its
     successor)  as its  prime  lending  rate.  If the  Prime  Rate is no longer
     available,  Bank,  in its sole and absolute  discretion,  will choose a new
     index which is based upon  comparable  information.  Regardless of the term
     that may be used from time to time to  describe  such  Prime  Rate (such as
     "base rate" or "prime rate"),  such interest rate does not necessarily mean
     the lowest interest rate charged to other borrowers.  Borrower acknowledges
     that the fluctuations of the Prime Rate may not necessarily correspond with
     future increases or decreases in interest rates charged by other lenders or
     market interest rates in general. Any change in the Contract Rate resulting
     from a change in the level of the Prime  Rate  shall be  effective  without
     notice to Borrower on the same date as the change in the Prime Rate.

          F. Foreign Currency  Advances.  If Borrower requests and Bank accepts,
     Advances  under  the  Line of  Credit  may be made  in a  foreign  currency
     designated  by  Borrower   ("Foreign  Currency   Advances").   The  foreign
     currencies in which it is contemplated  at this time that Foreign  Currency
     Advances may feasibly be made include the following:  Japanese Yen,  French
     Francs,  British  Pounds,  Deutsche  Marks,  Italian  Liras,  Swiss Francs,
     Norwegian Kroners, Swedish Kroners,  Australian Dollars,  Canadian Dollars,
     Dutch Guilders,  Spanish Pesetas,  Danish Kroners,  Belgium Francs, Finnish
     Marks,  Singapore Dollars,  Taiwanese Dollars,  Hong Kong Dollars,  Israeli
     Shekels, Mexican Pesos, Irish Punts, and European Union Euros.

                                     Page 25



          G.  Interest  Rate on  Foreign  Currency  Advances.  Foreign  Currency
     Advances shall bear interest at a fixed per annum rate equal to the Foreign
     Currency  Rate plus two  percent  (2%) per  annum,  but never to exceed the
     Maximum Lawful Rate.

          H. Repayment. Interest on the Note is payable quarter-annually, at the
     end of each calendar quarter, and the outstanding  principal balance of the
     Note is due and payable on the Maturity Date, except as follows:

               i. LIBOR  Advances.  Interest on each LIBOR  Advance with a LIBOR
          Interest  Period  of 30 or 60 days is due on the last day of the LIBOR
          Interest Period for such LIBOR Advance, without regard to whether such
          LIBOR  Advance is Continued or Converted,  and  otherwise  accrued and
          unpaid  interest on any LIBOR Advance is due and payable  quarterly on
          the  last  day of  each  calendar  quarter,  and  accrued  and  unpaid
          interest,  and  the  principal  amount  of the  LIBOR  Advance  if not
          Continued or Converted pursuant to this Agreement,  is due and payable
          in full on the last day of any LIBOR Interest Period; and

               ii. Foreign Currency Advances.  Interest on each Foreign Currency
          Advance with a term of less than 90 days is due on the last day of the
          term of such Foreign Currency Advance,  without regard to whether such
          term is  extended;  interest on each Foreign  Currency  Advance with a
          term  greater  than 90 days shall be due and payable  quarterly on the
          last day of each  calendar  quarter  during  the term of such  Foreign
          Currency  Advance;  and accrued and unpaid  interest and the principal
          amount of each Foreign  Currency Advance is due on the last day of the
          term of such Foreign  Currency Advance unless such term is extended in
          accordance with the terms of this Agreement.

Repayment of Advances made in Dollars shall be made at Bank's offices in Austin,
Travis  County,  Texas or such other address as may be  designated by Bank,  and
repayment of Foreign  Currency  Advances  shall be made in the foreign  currency
advanced  at a  depository  designated  by Bank in the  country  in  which  such
currency is legal tender during business hours of such designated depository.

          I.  Special  Provisions  Regarding  Foreign  Currency  Advances.  Each
     Foreign  Currency  Advance  requested  by  Borrower  shall be for an amount
     having  a  Dollar  Equivalent  of at least  $50,000.00  and  shall be for a
     limited  term of not less than  thirty  (30) days and not more than one (1)
     year.

          Bank may decline to make a requested  Foreign Currency Advance for any
     reason  which Bank in good faith deems  sound,  in Bank's sole  discretion,
     including  without  limitation  a  determination  by Bank that the Currency
     requested  by  Borrower  is   excessively   volatile,   or  is  not  freely
     transferrable and convertible into Dollars, or that it is impracticable for
     Bank to fund such advance or that the advance risks  illegality or involves
     significant costs not anticipated by Bank. Bank shall not decline to make a
     requested  Foreign  Currency  Advance simply because the requested  advance
     involves  incidental or minor inconvenience or expense. If Bank declines to
     extend  a  requested  Foreign  Currency  Advance,  Borrower  may  obtain  a
     substitute advance in Dollars or, subject to Bank's acceptance, a different
     foreign currency.

          If Bank shall determine that any adverse changes affecting any foreign
     currency  deposit  market or any  applicable  law (whether as a result of a
     change thereof or otherwise) make it  impracticable or unlawful for Bank to
     make  Foreign  Currency  Advances  generally  or  to  make  advances  in  a
     particular  foreign  currency,  then  Bank  may  notify  Borrower  of  such
     determination in writing and Borrower shall not request any further Foreign
     Currency Advances or advances in the particular  foreign  currency,  as the
     case may be,  until  and  unless  Borrower  is  notified  in  writing  of a
     determination by Bank that such advances are again feasible.

          In the event Borrower fails to repay any Foreign  Currency  Advance on
     the last day of the term of such Foreign Currency Advance,  Borrower shall,
     upon  demand by Bank,  pay to Bank,  for the  account of Bank,  all amounts
     reasonably  determined by Bank to be necessary to compensate  Bank for such
     failure,  including  without  limitation  any  losses  incurred  by Bank in
     converting  funds to and/or  from the  foreign  currency  involved,  wiring
     costs, loss of interest or additional interest costs incurred. In the event
     a Foreign  Currency  Advance  is not  repaid on the last day of the term of
     such Foreign Currency Advance and Bank pursues  collection of the same from
     Borrower,  Bank  may,  at its  option,  either  pursue  collection  of such
     delinquent  amount  denomination  in the  foreign  currency  which  was the
     subject of the advance or the Dollar Equivalent of the same,  determined as
     of the date on which Borrower repays the  indebtedness  incurred by Bank in
     order to make such Foreign Currency Advance.

                                     Page 26



          J.  Prepayment.  Advances  bearing  interest  at the Prime Rate may be
     repaid  in whole or in part at any time  without  penalty  or  premium.  No
     prepayment  of any LIBOR  Advance  or  Foreign  Currency  Advance  shall be
     permitted without the prior written consent of Bank, such consent not to be
     unreasonably  withheld.  Notwithstanding  such  prohibition,  if there is a
     prepayment  of any such LIBOR  Advance,  whether  by  consent  of Bank,  or
     because of acceleration or otherwise, Borrower shall, within 15 days of any
     request by Bank,  pay to Bank any loss or  expense  which Bank may incur or
     sustain as a result of such prepayment. For the purposes of calculating the
     amounts  owed  only,  it shall be  assumed  that  Bank  actually  funded or
     committed to fund the loan through the purchase of an underlying deposit in
     an amount and for a term comparable to the loan, and such  determination by
     Bank shall be conclusive, absent a manifest error in computation.

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

          A. Good Standing. Borrower is a corporation,  duly organized,  validly
     existing  and in good  standing  under  the  laws of  Delaware  and in good
     standing in the State of Texas and has the power and  authority  to own its
     property  and to  carry  on its  business  in each  jurisdiction  in  which
     Borrower does business.

          B. Authority and Compliance.  Borrower has full power and authority to
     execute  and  deliver  the Loan  Documents  and to incur  and  perform  the
     obligations provided for therein, all of which have been duly authorized by
     all  proper  and  necessary  action of the  appropriate  governing  body of
     Borrower.  No consent or  approval of any public  authority  or other third
     party is required as a condition to the validity of any Loan Document,  and
     Borrower is in  compliance  with all laws and  regulatory  requirements  to
     which it is subject.

          C. Binding  Agreement.  This  Agreement  and the other Loan  Documents
     executed by Borrower  constitute  valid and legally binding  obligations of
     Borrower, enforceable in accordance with their terms.

          D. Litigation.  There is no proceeding  involving Borrower pending or,
     to the knowledge of Borrower,  threatened  before any court or governmental
     authority,  agency or arbitration authority that would materially adversely
     affect  Borrower's  financial  condition,  except as  disclosed  to Bank in
     writing and acknowledged by Bank prior to the date of this Agreement.

          E. No  Conflicting  Agreements.  There  is no  charter,  bylaw,  stock
     provision,  partnership  agreement  or  other  document  pertaining  to the
     organization,  power or  authority  of  Borrower  and no  provision  of any
     existing agreement,  mortgage, indenture or contract binding on Borrower or
     affecting its property, which would conflict with or in any way prevent the
     execution,  delivery or carrying out of the terms of this Agreement and the
     other Loan Documents.

          F. Ownership of Assets. Borrower has good title to its assets, and its
     assets  are free and clear of liens,  except  those  granted to Bank and as
     disclosed to Bank in writing prior to the date of this Agreement.

          G. Taxes.  All taxes and  assessments due and payable by Borrower have
     been paid or are being  contested in good faith by appropriate  proceedings
     and the Borrower has filed all tax returns which it is required to file.

          H.  Financial   Statements.   The  financial  statements  of  Borrower
     heretofore  delivered to Bank have been  prepared in  accordance  with GAAP
     applied on a consistent  basis  throughout  the period  involved and fairly
     present Borrower's financial condition as of the date or dates thereof, and
     there has been no material adverse change in Borrower's financial condition
     or operations  since March 31, 1998. All factual  information  furnished by
     Borrower  to Bank in  connection  with this  Agreement  and the other  Loan
     Documents is and will be accurate and complete on the date as of which such
     information  is delivered to Bank and is not and will not be  incomplete by
     the omission of any material fact  necessary to make such  information  not
     misleading.

          I. Chief  Executive  Office.  Borrower's  chief  executive  office and
     principal place of business is located 11500 N. Mopac  Expressway,  Austin,
     Travis County, Texas, 78759.

                                     Page 27



          J. Environmental.  Except for Hazardous  Materials,  if any, which are
     used in Borrower's business and are stored,  handled and disposed of in all
     respects in compliance with applicable legal requirements, no real property
     owned by Borrower (i) is currently being used or is intended to be used for
     the storage, transportation,  processing or disposal of Hazardous Materials
     or, to the  knowledge  of Borrower,  has ever been used for such  purposes,
     (ii) is currently being used or is intended to be used or, to the knowledge
     of Borrower, has ever been used in such a way as to create an environmental
     condition that is actionable under applicable laws or regulations, (iii) to
     the  knowledge of Borrower,  contains any Hazardous  Materials,  or (iv) is
     currently  being  operated,  occupied  or used in a manner  which  fails to
     comply  with  all  applicable  health,   safety  and  environmental   laws,
     regulations and ordinances.

          K.  Year  2000.   Borrower   reasonably  believes  that  Borrower  and
     Borrower's  subsidiaries  and affiliates  will be Year 2000 compliant (that
     is, that computer applications, imbedded microchips, and other systems will
     be able to perform date-sensitive functions prior to and after December 31,
     1999) for the  operations  of  Borrower  and  Borrower's  subsidiaries  and
     affiliates on a timely basis except to the extent that a failure to be Year
     2000 compliant  could not  reasonably be expected to have material  adverse
     effect on Borrower's financial condition. Borrower reasonably believes that
     its suppliers and vendors will be Year 2000 compliant  except to the extent
     that  their  failure  to be Year 2000  compliant  could not  reasonably  be
     expected  to  have  a  material  adverse  effect  on  Borrower's  financial
     condition.
 
          L. Continuation of Representations and Warranties. All representations
     and warranties  made under this Agreement shall be deemed to be made at and
     as of the date  hereof and at and as of the date of any  advance  under any
     Loan.

     5.  Affirmative  Covenants.  Until  full  payment  and  performance  of all
obligations of Borrower  under the Loan  Documents,  Borrower will,  unless Bank
consents otherwise in writing (and without limiting any requirement of any other
Loan Document):

          A.  Financial  Condition.  Until  payment  in full of the  Term  Note,
     maintain  Borrower's   financial   condition  as  follows,   determined  in
     accordance  with GAAP applied on a consistent  basis  throughout the period
     involved except to the extent modified by the following definitions:

               i. Maintain Tangible Net Worth of not less than $154,000,000 (the
          "TNW  Requirement")  for each  calendar  quarter;  provided,  however,
          Borrower's  Tangible  Net Worth shall be  maintained  at not less than
          $114,000,000,  provided that any such decrease in the TNW  Requirement
          shall be allowed only if the decrease in Borrower's Tangible Net Worth
          results from intangible assets acquired,  assumed, created, or arising
          from Borrower's  permitted  acquisition of another company or business
          operation or the assets thereof.

          B. Financial  Statements and Other  Information.  Maintain a system of
     accounting  satisfactory  to Bank and in accordance  with GAAP applied on a
     consistent basis throughout the period involved,  permit Bank's officers or
     authorized representatives to visit and inspect Borrower's books of account
     and other records at such reasonable times and as often as Bank may desire,
     after  reasonable  prior  notice  to  Borrower.   Borrower  shall  pay  the
     reasonable  fees and  disbursements  of any  accountants or other agents of
     Bank selected by Bank for the foregoing purposes.  Unless written notice of
     another  location is given to Bank,  Borrower's  books and records  will be
     located at Borrower's chief executive office set forth above. All financial
     statements  called  for  below  shall  be  prepared  in  form  and  content
     acceptable  to  Bank  and  by  independent   certified  public  accountants
     acceptable to Bank. In addition, Borrower will:

               i. Furnish to Bank annual  consolidated  financial  statements of
          Borrower  for each fiscal year of  Borrower,  certified by Borrower as
          true and correct,  within 45 days after Borrower's  filing of its Form
          10-K with the Securities and Exchange Commission (the "SEC").

                                     Page 28



               ii. Furnish to Bank quarterly  consolidated  financial statements
          (including a balance sheet and profit and loss  statement) of Borrower
          for  each  quarter  of each  fiscal  year of  Borrower,  certified  by
          Borrower as true and correct,  within 45 days after Borrower's  filing
          of its Form 10-Q with the SEC.

               iii. Furnish to Bank a copy of each regular,  periodic or special
          report,  registration  statement, or prospectus filed by Borrower with
          any securities exchange or with the SEC or any successor agency to the
          SEC,  including  without  limitation all Forms 10-K, 10-Q, and 8-K and
          all other periodic  reports  required to be filed under the Securities
          Exchange  Act of  1934  and  the  rules  and  regulations  promulgated
          thereunder.

               iv. If at the end of any  fiscal  quarter  there is  indebtedness
          outstanding  under the Line of Credit (or if  Borrower  has  elected a
          Rate Option with respect to an Advance  under the Term Note),  furnish
          to Bank a compliance  certificate  for (and  executed by an authorized
          representative  of)  Borrower  containing  (a)  a  certification  that
          Borrower is not in default under the terms of this Agreement,  and (b)
          computations and conclusions, in such detail as Bank may request, with
          respect  to  compliance  with  this  Agreement,  and  the  other  Loan
          Documents, including computations of all quantitative covenants.

               v. Furnish to Bank promptly such additional information,  reports
          and  statements  respecting  the  business  operations  and  financial
          condition of Borrower and Borrower's affiliates and subsidiaries, from
          time to time, as Bank may reasonably request.

          C.   Insurance.   Maintain   insurance  for  Borrower  and  Borrower's
     subsidiaries   with  responsible   insurance   companies  on  such  of  its
     properties,  in such  amounts  and  against  such  risks as is  customarily
     maintained  by  similar   businesses   operating  in  the  same   vicinity,
     specifically to include fire and extended coverage  insurance  covering all
     assets, business interruption insurance, workers compensation insurance and
     liability  insurance,  all to be with such companies and in such amounts as
     are satisfactory to Bank and providing for at least 30 days prior notice to
     Bank of any cancellation  thereof.  Satisfactory evidence of such insurance
     will be  supplied  to Bank prior to funding  under the  Loan(s) and 30 days
     prior to each policy renewal.

          D. Existence and Compliance. Maintain its existence, good standing and
     qualification  to do  business,  where  required  and comply with all laws,
     regulations and governmental  requirements  including,  without limitation,
     environmental  laws, health and safety laws, and employment laws (including
     ERISA) which are applicable to Borrower or to any of its property, business
     operations and transactions.

          E. Adverse  Conditions or Events.  Promptly  advise Bank in writing of
     any  condition,  event or act which  comes to its  attention  that would or
     might  materially   adversely  affect  Borrower's  financial  condition  or
     operations or Bank's  rights under the Loan  Documents,  including  without
     limitation (i) any material  litigation filed by or against Borrower,  (ii)
     any material  event that has  occurred  that would  constitute  an event of
     default  under any Loan  Documents,  and (iii) any  uninsured  or partially
     uninsured loss through fire, theft,  liability or property damage in excess
     of an aggregate of $1,000,000.00.

          F. Taxes and Other Obligations.  Pay all of its taxes, assessments and
     other  obligations,  including,  but not  limited to taxes,  costs or other
     expenses  arising  out of this  transaction,  as the  same  become  due and
     payable, except to the extent the same are being contested in good faith by
     appropriate proceedings in a diligent manner.

          G.  Maintenance.  Maintain  all  of  its  tangible  property  in  good
     condition  and  repair and make all  necessary  replacements  thereof,  and
     preserve  and  maintain  all  licenses,  trademarks,  privileges,  permits,
     franchises,  certificates  and the like  necessary for the operation of its
     business.

                                     Page 29



          H. Environmental.  Defend, indemnify and hold harmless Lender from any
     and  all  liabilities   (including  strict  liability)  actions,   demands,
     penalties,   losses,   costs  or  expenses  (including  without  limitation
     reasonable  attorneys'  fees  and  remedial  costs),  suits,  costs  of any
     settlement  or judgment and claims of any and every kind  whatsoever  which
     may now or in the  future be paid,  incurred  or  suffered  by or  asserted
     against  Lender by any person or entity or  governmental  agency for,  with
     respect  to, or as a direct or  indirect  result  of, the  placement  on or
     under, or the escape,  seepage,  leakage,  spillage,  discharge,  emission,
     release from any property of Borrower of any Hazardous Materials,  or arise
     out of or result from the environmental condition of any of such properties
     or the applicability of any governmental  requirement relating to Hazardous
     Materials (including,  without limitation, CERCLA or any so-called federal,
     state or local  "Superfund" or "Superlien" law, statute,  ordinance,  code,
     rule, regulation order or decree).

          I. Year 2000. Borrower will promptly notify Bank in the event Borrower
     determines  that  any  computer   application  which  is  material  to  the
     operations of Borrower and its subsidiaries will not be Year 2000 compliant
     on a timely  basis,  except to the extent  that non-  compliance  could not
     reasonably  be expected  to have a material  adverse  effect on  Borrower's
     financial condition.

     6.  Negative   Covenants.   Until  full  payment  and  performance  of  all
obligations  of Borrower  under the Note,  Borrower will not,  without the prior
written consent of Bank (and without  limiting any requirement of any other Loan
Documents):

          A. Transfer of Assets or Control. (i) Sell, transfer,  or lease all or
     substantially all of the assets of Borrower,  or (ii) enter into any merger
     or  consolidation  in  which  Borrower  is not the  surviving  entity  upon
     completion of such merger or consolidation.

          B. Liens.  Grant,  suffer or permit any contractual or  noncontractual
     lien on or  security  interest  in its 65.250  acre tract of land,  more or
     less,  out the James  Rogers  Headright  Survey No.  19, in Travis  County,
     Texas, including improvements thereon, except in favor of Bank.

          C.  Extensions of Credit.  Make or permit any  subsidiary to make, any
     loan or advance to any person or entity in excess of  $10,000,000.00 in the
     aggregate.

          D.  Investments.  Make  investments  except for "Permitted  Investment
     Securities."  "Permitted  Investment  Securities" shall mean investments in
     cash,  money market funds,  Government  and Government  Agency  Securities,
     including:  (1)  taxable  investments  in  (i)  U.S.  Government  and  U.S.
     Government   Obligations,   (ii)  Repurchase  Agreements,   (iii)  Domestic
     Certificates  of  Deposit,  Bankers  Acceptances  and Time  Deposits,  (iv)
     Eurodollar  Certificates  of  Deposit  and  Time  Deposits,  (v)  Corporate
     Obligations, Medium Term Notes and Deposit Notes, (vi) Commercial Paper and
     (vii) Auction Rate  Preferreds;  (2) tax-exempt  investments in the form of
     (i) Variable  Rate Demand  Notes,  (ii) Puttable  Bonds,  (iii)  Commercial
     Paper,  (iv)  General  Obligation  &  Revenue  Bonds and (v)  Auction  Rate
     Securities; and (3) foreign currency forward contracts and purchased option
     contracts  specifically  undertaken  for the  purpose  of  hedging  foreign
     currency receivable  exposure.  In order to qualify as Permitted Investment
     Securities,  Commercial Paper must be a2/P2 or better;  taxable instruments
     must be Aa/AA or better;  Municipal  Notes must be Mig2/A-2 or better;  and
     Municipal  Obligations  must be AA or better.  This Section shall in no way
     restrict Borrower's ability to make any acquisition.

          E. Borrowings.  Create,  incur,  assume or become liable in any manner
     for any indebtedness (for borrowed money, deferred payment for the purchase
     of assets, lease payments, as surety or guarantor for the debt for another,
     or otherwise) other than to Bank in excess of $20,000,000 in the aggregate,
     except for normal trade debts incurred in the ordinary course of Borrower's
     business, and except for existing indebtedness disclosed to Bank in writing
     and acknowledged by Bank prior to the date of this Agreement.

                                     Page 30



          F. Character of Business.  Change the general character of business as
     conducted  at the  date  hereof,  or  engage  in any type of  business  not
     reasonably related to its business as presently conducted.

     7. Default.  Borrower  shall be in default  under this  Agreement and under
each of the other Loan Documents, and an "Event of Default" shall exist, if:

          A. Borrower shall fail to pay any amounts due and owing under the Loan
     or any other Indebtedness  within five (5) business days following the date
     on which the same is due;

          B.  Borrower  should fail to timely and  properly  observe,  keep,  or
     perform any term, covenant,  agreement,  or condition in any Loan Document,
     other than a failure to comply with the  financial  covenants  set forth in
     Section 5.A.i.;

          C. Any  representation  or warranty herein  contained or any financial
     statement,  certificate, report, or opinion submitted to Bank in connection
     with the Loans,  or pursuant  to the  requirements  of the Loan  Documents,
     shall prove to have been  incorrect or misleading  in any material  respect
     when made;

          D.  Borrower  fails to be in compliance  with the  financial  covenant
     contained  in  Section  5 A.  i.,  as of the  end of  two  (2)  consecutive
     quarter-annual accounting periods;

          E. Any  material  judgment  against  Borrower  with respect to a claim
     remains unpaid, not superseded on appeal or unstayed on appeal by agreement
     with the judgment creditor, undischarged, not bonded or not dismissed for a
     period of thirty (30) days;

          F. Borrower makes an assignment for the benefit of creditors,  becomes
     insolvent,  fails generally to pay its debts as they become due,  petitions
     or applies to any tribunal  for the  appointment  of a trustee,  custodian,
     receiver,  (or  similar  official)  of, or for,  Borrower  or of all or any
     substantial part of the assets of Borrower or commences a voluntary case or
     any  other   proceedings   relating  to  Borrower  under  any   bankruptcy,
     reorganization,  compromise arrangement,  insolvency, readjustment of debt,
     dissolution or  liquidation  or similar law (herein called the  "bankruptcy
     law") of any jurisdiction;

          G. Any petition or  application is filed,  or any such  proceeding are
     commenced against Borrower under the bankrupt law of any jurisdiction,  and
     Borrower  by  any  act or  omission  indicates  its  approval,  consent  or
     acquiescence,  or an order for  relief is entered  in an  involuntary  case
     under the federal  bankruptcy laws as now or hereafter  constituted,  or an
     order,  judgment or decree is entered  appointing  any trustee,  custodian,
     receiver,  liquidator or similar  official for Borrower or any  substantial
     part of its assets or  adjudicating  Borrower  bankrupt  or  insolvent,  or
     approving the petition in any such proceedings, and such order, judgment or
     decree remains in effect for sixty (60) days; or

          H.  Borrower  conceals,  removes or permits to be concealed or removed
     any part of its  property,  with  intent to hinder,  delay or  defraud  its
     creditors,  or any of them,  or makes or suffers a  transfer  of any of its
     property  which  may  be  fraudulent   under  any  bankruptcy,   fraudulent
     conveyance  or similar law; or shall have made any transfer of its property
     to or for  the  benefit  of a  creditor  oat a time  when  other  creditors
     similarly situated have not been paid.

     8. Remedies upon  Default.  If an Event of Default shall occur,  Bank shall
have all rights,  powers and remedies available under each of the Loan Documents
as well as all rights and remedies available at law or in equity.

          A.  Notice  and  Opportunity  to Cure.  Prior to  acceleration  of the
     maturity of the Note,  Bank shall give Borrower  written  notice of certain
     Events of Default and provide  Borrower with the  opportunity  to cure such
     Event of Default as set forth in this Section 8.A.

                                    Page 31



               i. If the Event of Default  is  Borrower's  breach of  subsection
          7.A.  above,  then Bank  shall give  Borrower  notice of such Event of
          Default.  If Borrower  fails to cure such Event of Default  within ten
          (10) days after the day on which notice is actually  given,  then Bank
          may  accelerate  the  maturity  of  the  Note  and  declare  the  Note
          immediately due and payable in full.

               ii. If the Event of Default is  Borrower's  breach of  subsection
          7.B., 7.C.,  7.F., or 7.I above,  then Bank shall give Borrower notice
          of such  Event of  Default.  If  Borrower  fails to cure such Event of
          Default  within  thirty  (30) days  after  the day on which  notice is
          actually  given,   then  Bank  may  accelerate  the  maturity  of  the
          Indebtedness   and  declare  the  Note  and  all  other   Indebtedness
          immediately due and payable in full.

               iv.  As to any  other  Event of  Default  (that  is, a breach  of
          subsection 7.D.,  7.E., 7.G., or 7.H.),  then Bank may, without notice
          to Borrower or any other party now or  hereafter  obligated to pay the
          Indebtedness  or any part  thereof,  accelerate  the  maturity  of the
          Indebtedness   and  declare  the  Note  and  all  other   Indebtedness
          immediately due and payable in full.

Bank's  failure to give  notice of default  upon the  occurrence  of an Event of
Default shall not constitute a waiver of the Event of Default.

          B. Cessation of Advances.  Notwithstanding any other provision herein,
     upon the  occurrence  of an Event of Default,  Bank's  obligations  to make
     further  advances  under  the  Note and this  Agreement  shall  immediately
     terminate without notice of any kind. Bank shall not be obligated to resume
     making  advances under the Note and under this Agreement until such time as
     any such Event of Default is cured.

     9. Notices. All notices, requests or demands which any party is required or
may desire to give to any other party under any provision of this Agreement must
be in writing delivered to the other party at the following address:

            Borrower:               National Instruments Corporation
                                    11500 N. Mopac Expressway, Bldg. B
                                    Austin, Texas 78759
                                    Attn:  Alex Davern
                                    Fax. No. 512.683.6931

            With copy to:           Graves, Dougherty, Hearon & Moody
                                    Post Office Box 98
                                    Austin, Texas  78767
                                    Attn:  Clarke Heidrick, Esq.
                                    Fax:  512.478.1976

            Bank:                   NationsBank, N.A.
                                    501 Congress Avenue (78701)
                                    Post Office Box 908
                                    Austin, Texas 78781
                                    Attn:  Mr. Eric Kosmin
                                    Fax No.: 512.397.2052

or to such other  address as any party may  designate  by written  notice to the
other party. Each such notice,  request and demand shall be deemed given or made
as follows: (a) if sent by mail, upon the earlier of the date of receipt or five
(5) days after deposit in the U.S. Mail, first class postage prepaid;  or (b) if
sent by any other means, upon delivery.

     10.  Costs,  Expenses  and  Attorneys'  Fees.  Borrower  shall  pay to Bank
immediately  upon  demand the full amount of all costs and  expenses,  including
reasonable  attorneys' fees for any outside counsel),  actually incurred by Bank
in connection with (a) negotiation and preparation of this Agreement and each of
the Loan Documents  executed  concurrently  with this  Agreement,  not to exceed
$2,500.00,  and (b) all other  costs and  attorneys'  fees  incurred by Bank for
which  Borrower is obligated to reimburse  Bank in accordance  with the terms of
the Loan Documents.

     11. Miscellaneous. Borrower and Bank further covenant and agree as follows,
without limiting any requirement of any other Loan Document:

                                    Page 32



          A.  Cumulative  Rights and No Waiver.  Each and every right granted to
     Bank  under any Loan  Document,  or  allowed  it by law or equity  shall be
     cumulative  of each other and may be  exercised  in addition to any and all
     other rights of Bank, and no delay in exercising any right shall operate as
     a waiver thereof,  nor shall any single or partial  exercise by Bank of any
     right preclude any other or future exercise  thereof or the exercise of any
     other right. Borrower expressly waives any presentment,  demand, protest or
     other notice of any kind,  including but not limited to notice of intent to
     accelerate and notice of  acceleration.  No notice to or demand on Borrower
     in any case  shall,  of  itself,  entitle  Borrower  to any other or future
     notice or demand in similar or other circumstances.

          B.  Applicable Law. This Loan Agreement and the Rights and Obligations
     of the Parties  Hereunder Shall Be Deemed to Have Been Made in the State of
     Texas at Bank's  Address  Indicated at the Beginning of this  Agreement and
     Shall Be Governed By, and  Construed in  Accordance  With,  the Laws of the
     State of Texas,  and Is  Performable in the City and County of Texas at the
     Bank's Address Indicated at the Beginning of this Agreement.

          C. Amendment.  No  modification,  consent,  amendment or waiver of any
     provision  of this  Agreement,  nor  consent to any  departure  by Borrower
     therefrom,  shall be  effective  unless the same  shall be in  writing  and
     signed by an  officer  of Bank,  and then  shall be  effective  only in the
     specified  instance and for the purpose for which given.  This Agreement is
     binding  upon  Borrower,  its  successors  and  assigns,  and inures to the
     benefit of Bank,  its  successors  and assigns;  however,  no assignment or
     other transfer of Borrower's rights or obligations  hereunder shall be made
     or be effective without Bank's prior written consent,  nor shall it relieve
     Borrower of any obligations hereunder.  There is no third party beneficiary
     of this Agreement.

          D.  Documents.  All documents,  certificates  and other items required
     under this  Agreement to be executed  and/or  delivered to Bank shall be in
     form and content satisfactory to Bank and its counsel.

          E. Partial  Invalidity.  The  unenforceability  or  invalidity  of any
     provision of this Agreement shall not affect the enforceability or validity
     of any other provision herein and the invalidity or unenforceability of any
     provision  of any Loan  Document  to any person or  circumstance  shall not
     affect the  enforceability or validity of such provision as it may apply to
     other persons or circumstances.

          F. Indemnification. Notwithstanding anything to the contrary contained
     in Section 11(G),  Borrower shall  indemnify,  defend and hold Bank and its
     successors  and  assigns  harmless  from and  against  any and all  claims,
     demands, suits, losses, damages,  assessments,  fines, penalties,  costs or
     other  expenses  (including  reasonable  attorneys'  fees and court  costs)
     arising from or in any way related to any of the transactions  contemplated
     hereby,  including  but not limited to actual or  threatened  damage to the
     environment,  agency costs of  investigation,  personal injury or death, or
     property  damage,  due  to  a  release  or  alleged  release  of  Hazardous
     Materials,  arising from Borrower's business operations, any other property
     owned by Borrower or in the surface or ground water arising from Borrower's
     business operations,  or gaseous emissions arising from Borrower's business
     operations  or any other  condition  existing  or arising  from  Borrower's
     business  operations  resulting  from  the use or  existence  of  Hazardous
     Materials,  whether such claim proves to be true or false. Borrower further
     agrees that its indemnity  obligations  shall include,  but are not limited
     to, liability for damages resulting from the personal injury or death of an
     employee of the  Borrower,  regardless of whether the Borrower has paid the
     employee  under  the  workmen'  s  compensation  laws of any state or other
     similar federal or state  legislation for the protection of employees.  The
     term  "property  damage"  as used in this  paragraph  includes,  but is not
     limited to, damage to any real or personal  property of the  Borrower,  the
     Bank,  and of any third  parties.  The  Borrower's  obligations  under this
     paragraph  shall  survive the repayment of the Loan and any deed in lieu of
     foreclosure  or  foreclosure  of any Deed to  Secure  Debt,  Deed of Trust,
     Security Agreement or Mortgage securing the Loan.

                                    Page 33



          G.  Survivability.  All  covenants,  agreements,  representations  and
     warranties  made herein or in the other Loan  Documents  shall  survive the
     making of the Loan and shall  continue  in full force and effect so long as
     the Loan is  outstanding or the obligation of the Bank to make any advances
     under the Line shall not have expired.

          H. Amendment,  Restatement,  and Replacement.  This Agreement  amends,
     restates,  and replaces the Amended and Restated Loan Agreement  dated June
     27, 1996, executed by Borrower and NationsBank of Texas, N.A.

     12. NOTICE OF FINAL  AGREEMENT.  This Written Loan  Agreement and the Other
Loan Documents  Represent the Final Agreement Between the Parties and May Not Be
Contradicted by Evidence of Prior, 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  by their duly  authorized  representatives  as of the date first
above written.

                                    Borrower:

                                    National Instruments Corporation

      [Corporate Seal]

                                    By: /s/ Alex Davern
                                        Alex Davern, Chief Financial Officer

Attest: /s/ David Hugley
        David Hugley, Secretary


                                    Bank:

                                    NationsBank, N.A.
                                    (a national banking association)


                                    By: /s/ Eric Kosmin
                                        Eric Kosmin, Vice President

                                     Page 34



                                  PROMISSORY NOTE

Date:  June 30, 1998                                                         New
Amount:  $20,000,000.00                         Maturity Date: December 31, 1999

 

Bank:                                     Borrower:

NationsBank, N.A.                         National Instruments Corporation
Banking Center: Austin                    11500 N. Mopac Expressway
11th Floor, NationsBank Tower             Austin, Texas 75759
515 Congress Avenue                       (Travis County)
Austin, Texas 78701
(Travis County)
                                          (Name and street address,
(Street address including county)         including  county)
========================================= ======================================


     For Value Received,  the undersigned Borrower  unconditionally (and jointly
and  severally,  if more than  one)  promises  to pay to the order of Bank,  its
successors  and  assigns,  without  setoff,  at  its  offices  indicated  at the
beginning of this Note, or at such other place as may be designated by Bank, the
principal  amount of Twenty Million and 00/100 Dollars  ($20,000,000.00),  or so
much  thereof  as may be  advanced  from time to time in  immediately  available
funds,  together  with  interest  computed  daily on the  outstanding  principal
balance  hereunder,  at an annual  interest  rate,  and in  accordance  with the
payment schedule, indicated below.

     This  Note is  executed  pursuant  to and  shall  be  governed  by the Loan
Agreement dated June 30, 1998, executed by Borrower and Bank (as the same may be
modified,  amended,  and  restated  from time to time,  the  "Loan  Agreement").
Defined terms used in this Note and otherwise not defined  herein shall have the
meaning given such terms in the Loan  Agreement.  The Loan  Agreement sets forth
certain rights and obligations of the parties and certain provisions  concerning
this Note, such as (without limitation) events of default, notice of default and
opportunity to cure default.  To the extent,  if any, that the Loan Agreement is
inconsistent with this Note, the Loan Agreement shall control.

     1. Rate.  This Note and all Advances under this Note and the Loan Agreement
shall bear  interest  at one or more  rates per annum,  as set forth in the Loan
Agreement,  reference  to which is hereby  made for all  purposes.  Each  Dollar
Advance shall bear interest at the applicable  Contract Rate for such Advance as
determined by a properly  exercised Rate Option.  Each Foreign  Currency Advance
shall bear  interest at the  applicable  Foreign  Currency Rate for such Foreign
Currency Advance.

     Notwithstanding any provision of this Note or the Loan Agreement, Bank does
not intend to charge and  Borrower  shall not be  required  to pay any amount of
interest or other charges in excess of the maximum  permitted by applicable  law
(the "Maximum  Lawful Rate").  Borrower agrees that during the full term hereof,
the maximum  lawful  interest rate for this Note as  determined  under Texas law
shall be the "Weekly  Ceiling"  (as defined in Chapter 303 of the Texas  Finance
Code [and/or  Articles 1D.002 and 1D.003 of the Texas Credit Title] and formerly
referred to as the  "Indicated  (Weekly)  Ceiling" in Article  1.04(a)(1) of the
Texas Credit Code [Article 5069-1.04 of VATS]).  Further, to the extent that any
other lawful rate ceiling exceeds the rate ceiling so determined then the higher
rate  ceiling  shall  apply.  Any  payment  in excess of such  maximum  shall be
refunded to Borrower or credited against principal, at the option of Bank.

     2. Accrual Method.  Unless  otherwise  indicated,  interest at the Rate set
forth  above and in the Loan  Agreement  will be  calculated  by the 365/360 day
method (a daily  amount of interest is computed for a  hypothetical  year of 360
days;  that  amount is  multiplied  by the  actual  number of days for which any
principal is outstanding hereunder).  Provided, however, interest at the Maximum
Lawful Rate shall be  calculated  based on the actual number of days in the year
(365 or 366, as the case may be).

                                    Page 35



     3. Rate Change  Date.  Any Rate based on a  fluctuating  index or base rate
will change,  unless otherwise  provided,  each time and as of the date that the
index or base rate changes.  In the event any index is discontinued,  Bank shall
substitute an index determined by Bank to be comparable, in its sole discretion.

     4. Payment Schedule. All payments received hereunder shall be applied first
to the payment of any expense or charges  payable  hereunder  or under any other
loan documents  executed in connection  with this Note, then to interest due and
payable,  with the balance applied to principal,  or in such other order as Bank
shall determine at its option.

          (a) Interest shall be due and payable quarterly as it accrues,  on the
     last day of each  calendar  quarter,  beginning  September  30,  1998,  and
     continuing  on the last calendar day of each  December,  March,  June,  and
     September of each year during the term of this Note,  through and including
     September 30, 1999.

          (b) The  outstanding  principal  balance  and all  accrued  and unpaid
     interest shall be due and payable in full on December 31, 1999.

The foregoing notwithstanding,  all LIBOR Advances and Foreign Currency Advances
shall be due and payable as set forth in the Loan Agreement.

     5. Revolving Feature.  Borrower may borrow, repay and reborrow hereunder at
any time, up to a maximum aggregate amount  outstanding at any one time equal to
the  principal  amount of this Note,  provided  that  Borrower is not in default
under any  provision of this Note,  any other  documents  executed in connection
with this  Note,  or any other  note or other loan  documents  now or  hereafter
executed in  connection  with any other  obligation  of  Borrower  to Bank,  and
provided that the borrowings hereunder do not exceed any borrowing base or other
limitation  on  borrowings  by Borrower.  Bank shall incur no liability  for its
refusal to advance  funds based upon its  determination  that any  conditions of
such further  advances have not been met.  Bank records of the amounts  borrowed
from  time  to time  and  kept in the  ordinary  course  of  business  shall  be
conclusive proof thereof.

     6.  Waivers,  Consents  and  Covenants.  Except  as  provided  in the  Loan
Agreement, Borrower, any indorser or guarantor hereof, or any other party hereto
(individually an "Obligor" and collectively "Obligors") and each of them jointly
and severally:  (a) waive all notices,  demands for payment,  presentations  for
payment,  notices of intention to accelerate  the maturity,  notice of maturity,
protest  and notice of  protest,  as to this Note and as to each,  every and all
installments  hereof; (b) consent to all delays,  extensions,  renewals or other
modifications of this Note or the Loan Documents,  or waivers of any term hereof
or of the Loan Documents, or release or discharge by Bank of any of Obligors, or
release, substitution or exchange of any security for the payment hereof, or the
failure to act on the part of Bank,  or any  indulgence  shown by Bank  (without
notice to or  further  assent  from any of  Obligors),  and  agree  that no such
action,  failure to act or failure to exercise any right or remedy by Bank shall
in any way affect or impair the obligations of any Obligors or be construed as a
waiver by Bank of, or otherwise  affect,  any of Bank's  rights under this Note,
under  any  indorsement  or  guaranty  of this  Note or  under  any of the  Loan
Documents; and (c) agree to pay, on demand, all costs and expenses of collection
or defense of this Note or of any  indorsement  or  guaranty  hereof  and/or the
enforcement or defense of Bank's rights with respect to, or the  administration,
supervision,  preservation,  or protection of, or realization upon, any property
securing payment hereof,  including,  without limitation,  reasonable attorney's
fees, including fees related to any suit,  mediation or arbitration  proceeding,
out of court payment agreement,  trial, appeal,  bankruptcy proceedings or other
proceeding,  in such amount as may be determined reasonable by any arbitrator or
court, whichever is applicable.

     7.  Prepayments.  Prepayments  may only be made subject to the terms of the
Loan  Agreement.  All  prepayments of principal  shall be applied in the inverse
order of  maturity,  or in such other order as Bank shall  determine in its sole
discretion.

                                    Page 36



     8. Remedies upon Default.  Whenever there is an Event of Default under this
Note,  subject to the provisions for notice and cure in the Loan Agreement,  (a)
Bank  shall  have all  rights  and  remedies  available  under  each of the Loan
Documents,  as well as all rights and  remedies  available  at law or in equity,
and/or (b) to the extent  permitted  by law,  the Rate of interest on the unpaid
principal shall be increased at Bank's discretion up to the Maximum Lawful Rate,
or if none,  25% per annum (the "Default  Rate").  The  provisions  herein for a
Default Rate shall not be deemed to extend the time for any payment hereunder or
to constitute a "grace  period"  giving  Obligors a right to cure any default if
the same is not provided under the Loan Agreement. At Bank's option, any accrued
and unpaid interest, fees or charges may, for purposes of computing and accruing
interest  on a daily  basis  after  the due date of the Note or any  installment
thereof,  be deemed to be a part of the principal  balance,  and interest  shall
accrue on a daily  compounded basis after such date at the Default Rate provided
in this Note until the entire  outstanding  balance of principal and interest is
paid in full. Upon a default under this Note,  Bank is hereby  authorized at any
time, at its option and without notice or demand,  to set off and charge against
any  deposit  accounts  of any  Obligor  (as  well  as any  money,  instruments,
securities,  documents,  chattel paper, credits, claims, demands, income and any
other  property,  rights and interests of any Obligor),  which at any time shall
come into the  possession  or custody or under the control of Bank or any of its
agents, affiliates or correspondents, any and all obligations due hereunder.

     9.  Non-Waiver.  The  failure  at any time of Bank to  exercise  any of its
options or any other rights hereunder shall not constitute a waiver thereof, nor
shall it be a bar to the  exercise  of any of its  options  or rights at a later
date.  All rights and  remedies of Bank shall be  cumulative  and may be pursued
singly,  successively or together, at the option of Bank. The acceptance by Bank
of any partial payment shall not constitute a waiver of any default or of any of
Bank's rights under this Note. No waiver of any of its rights hereunder,  and no
modification  or  amendment  of this  Note,  shall be  deemed to be made by Bank
unless the same shall be in writing,  duly  signed on behalf of Bank;  each such
waiver  shall apply only with  respect to the specific  instance  involved,  and
shall in no way impair the rights of Bank or the obligations of Obligors to Bank
in any other respect at any other time.

     10. Applicable Law, Venue and Jurisdiction.  Borrower Agrees That this Note
Shall Be  Deemed  to Have  Been  Made in the  State of Texas at  Bank's  Address
Indicated at the  Beginning of this Note and Shall Be Governed By, and Construed
in Accordance  With,  the Laws of the State of Texas and Is  Performable  in the
City and  County  of Texas  Indicated  at the  Beginning  of this  Note.  In any
litigation  in  connection  with or to enforce this Note or any  indorsement  or
guaranty  of this  Note or any  Loan  Documents,  Obligors,  and  each of  them,
irrevocably  consent to and confer  personal  jurisdiction  on the courts of the
State of Texas or the United  States courts  located  within the State of Texas.
Nothing contained herein shall,  however,  prevent Bank from bringing any action
or  exercising  any  rights  within  any  other  state or  jurisdiction  or from
obtaining  personal  jurisdiction by any other means available under  applicable
law.

     11. Partial Invalidity. The unenforceability or invalidity of any provision
of this Note  shall not  affect  the  enforceability  or  validity  of any other
provision herein and the invalidity or unenforceability of any provision of this
Note or of the Loan Documents to any person or circumstance shall not affect the
enforceability or validity of such provision as it may apply to other persons or
circumstances.

     12.  Binding  Effect.  This  Note  shall be  binding  upon and inure to the
benefit of Borrower, Obligors and Bank and their respective successors, assigns,
heirs and personal  representatives,  provided,  however, that no obligations of
Borrower or Obligors  hereunder can be assigned without prior written consent of
Bank.

                                    Page 37



Borrower  represents  to Bank  that  the  proceeds  of this  loan are to be used
primarily  for  business,   commercial  or   agricultural   purposes.   Borrower
acknowledges  having read and  understood,  and agrees to be bound by, all terms
and conditions of this Note.

NOTICE OF FINAL  AGREEMENT:  This Written  Promissory  Note Represents the Final
Agreement Between the Parties, and May Not Be Contradicted by Evidence of Prior,
Contemporaneous,  or Subsequent  Oral  Agreements  of the Parties.  There Are No
Unwritten Oral Agreements Between the Parties.

                                      Borrower:

                                      National Instruments Corporation
                                      (a Delaware corporation)



                                      By: /s/ Alex Davern
                                          Alex Davern, Chief Financial Officer

Bank:

NationsBank, N.A.



By: /s/ Eric Kosmin
    Eric Kosmin, Vice President

                                    Page 38



                             NEGATIVE PLEDGE AGREEMENT


     This Negative Pledge Agreement (this  "Agreement")  dated June 30, 1998, by
and between NationsBank, N.A. (the "Bank") and National Instruments Corporation,
a Delaware corporation (the "Borrower");

     Whereas,  Borrower  desires to obtain a loan  (together with all extensions
and  renewals  thereof  hereafter  referred  to as the  "Loan") in the amount of
$20,000,000.00  from  Bank,  which  Loan  shall be  governed  by the  terms  and
conditions of the Loan Agreement of even date herewith, executed by Borrower and
Bank (as the same may be modified,  amended,  and/or restated from time to time,
the "Loan Agreement"); and

     Whereas,  Bank is willing to grant the Loan provided Borrower agrees not to
encumber certain real property owned by Borrower;

     Now, Therefore,  for and in consideration of the Loan made or to be made by
Bank to Borrower, and for other good and valuable consideration, the receipt and
sufficiency  of which is hereby  acknowledged  by both  Borrower  and Bank,  the
parties hereto do agree as follows:

     1. Property  Borrower  hereby  agrees that,  for so long as any part of the
Loan (as defined in the Loan Agreement) remains  outstanding and/or Bank has any
obligation  to make  advances  under the Loan,  that it will not,  without first
obtaining  the prior  written  consent  of Bank,  grant,  suffer,  or permit any
contractual or noncontractual  lien on or security interest in the real property
owned by Borrower and described as follows:  65.250 acres of land, more or less,
out of the James Rogers  Headright  Survey No. 19, in Travis County,  Texas, and
being a portion of those two certain  tracts of land  conveyed to  International
Business Machines Corporation by deeds recorded in Volume 3235, Page 386, and in
Volume 3235, Page 393, of the Deed Records of Travis County,  Texas; said 65.250
acre tract being more particularly  described by metes and bounds in Exhibit "A"
attached hereto and  incorporated  herein (the "Real  Property"),  including any
improvements constructed thereon, except in favor of Bank.

     2.  Recording.  Bank is  hereby  authorized  and  permitted  to cause  this
instrument (or a copy hereof) to be recorded at such times and at such places as
Bank, at its option, may elect.

     3. Termination.  This Agreement shall remain in full force and effect until
the Loan  described  above  shall  have been paid in full and Bank shall have no
further commitment to lend thereunder.

     4. Conflicting  Provisions.  To the extent, if any, that the Loan Agreement
is inconsistent with this Agreement, the Loan Agreement shall control.

     5.  Miscellaneous.  This  Agreement  shall be binding upon and inure to the
benefit of  Borrower  and Bank and their  respective  successors  and  permitted
assigns.  This Agreement is not intended to confer on any person other than Bank
and Borrower and their successors and permitted assigns any rights, obligations,
remedies,  or liabilities.  This Agreement shall be governed by and construed in
accordance with the laws of the State of Texas and the laws of the United States
of America applicable to transactions in Texas. In case any of the provisions of
this  Agreement  shall  for  any  reason  be  held to be  invalid,  illegal,  or
unenforceable, such invalidity, illegality, or unenforceability shall not affect
any other  provision  hereof,  and this Agreement  shall be construed as if such
invalid,  illegal,  or unenforceable  provision had never been contained herein.
This  Agreement  may be  executed in any number of  counterparts,  each of which
shall be deemed an original,  but all of which taken together  shall  constitute
one and the same instrument.

                                    Page 39



Notice of Final Agreement: this Written Negative Pledge Agreement Represents the
Final  Agreement  Between the Parties and May Not Be Contradicted by Evidence of
Prior,  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
executed by their duly authorized representatives.

                                      Borrower:

                                      National Instruments Corporation
                                      (a Delaware corporation)


                                      By: /s/ Alex Davern
                                          Alex Davern, Chief Financial Officer

                                      Bank:

                                      NationsBank, N.A.
                                      (a national banking association)


                                      By: /s/ Eric Kosmin
                                          Eric Kosmin, Vice President


STATE OF TEXAS

COUNTY OF TRAVIS

     This instrument was acknowledged  before me this 23rd day of July, 1998, by
Alex Davern,  Chief Financial  Officer of National  Instruments  Corporation,  a
Delaware corporation, on behalf of said corporation.


                                      /s/ Debra L. Kirchner
                                      Notary Public - State of Texas

                                    Page 40


STATE OF TEXAS

COUNTY OF TRAVIS

     This instrument was acknowledged  before me this 23rd day of July, 1998, by
Eric  Kosmin,   Vice  President  of  NationsBank,   N.A.,  a  national   banking
association, on behalf of said association.


                                      /s/ Rose Marie Story
                                      Notary Public - State of Texas




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



     This  Agreement  is to be recorded in the Real  Property  Records of Travis
County, Texas.

Grantor:  National Instruments Corporation    Grantee:    NationsBank, N.A.
Address:  11500 N. Mopac Expressway           Address:    P.O. Box 908
          Austin, Texas 78759                             Austin, Texas 78781


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



     This  Agreement is to be recorded with the Texas  Secretary of State and in
the UCC Records of Travis County, Texas

Debtor:   National Instruments Corporation    Secured Party: NationsBank, N.A.
Address:  11500 N. Mopac Expressway           Address:       P.O. Box 908
          Austin, Texas 78759                                Austin, Texas 78781


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



After Recording, Please Return To:

Timothy C. Taylor, Esq.
Small, Craig & Werkenthin, P.C.
100 Congress Avenue, Suite 1100
Austin, Texas 78701-4099

                                    Page 41



                             Officer's Certificate


     This  Officer's  Certificate  (this  "Certificate")  is  executed  by David
Hugley,  Secretary of National Instruments  Corporation,  a Delaware corporation
(the  "Corporation"),  for the benefit of NationsBank,  N.A., a national banking
association ("Lender").

     I, David Hugley, Secretary of the Corporation,  do hereby certify to Lender
the following:

     1. The  Corporation  is a  Delaware  corporation  duly  organized,  validly
existing,  and in good  standing  under the laws of the State of  Delaware.  The
Corporation  has paid when due all  franchise  and all other  taxes  required to
maintain its corporate existence and no such taxes are delinquent.  There are no
proceedings  pending for the  forfeiture  of the  Corporation's  Certificate  of
Incorporation   or   for   the   Corporation's   dissolution,   voluntarily   or
involuntarily.  The Corporation is duly qualified to do business in the State of
Texas and is in good  standing in the State of Texas.  The  Corporation  is duly
qualified as a foreign  corporation  and in good standing in other all states in
which it is doing business and in which it is required to be qualified.

     2.  All  tax  returns  required  to be  filed  by  the  Corporation  in any
jurisdiction  have  been  filed  and all  taxes,  assessments,  fees,  and other
governmental  charges upon the Corporation or upon any of its property have been
paid  prior to the time that such  taxes  could  give rise to a lien on any such
property.  There is no tax assessment  against the  Corporation  and there is no
basis for any such assessment. There are no actions, suits, or legal, equitable,
arbitration,  or administrative proceedings pending, or to the best knowledge of
the Corporation and the undersigned  threatened,  against the Corporation which,
if adversely determined, would have a material adverse effect on the validity or
enforceability  of any obligation of the  Corporation to Lender or the financial
condition or business  operations of the Corporation or could  otherwise  impair
the  ability  of the  Corporation  to  perform  its  obligations  to  Lender  in
connection with the Loan.

     3. The  Corporation  has the power and authority to conduct its business as
it is now conducted and to own all of its property. All documents and agreements
executed or to be executed by the  Corporation  in connection  with the Loan (a)
are within its corporate powers,  (b) have been duly authorized by all necessary
corporate action, (c) do not and will not contravene its charter, bylaws, or any
other law or governmental regulation, and (d) do not and will not contravene any
contractual  restriction  binding on or affecting the  Corporation or any of its
property. To the best knowledge and belief of the undersigned, all documents and
agreements  executed or to be executed by the Corporation in connection with the
Loan are, or will be when  executed and  delivered,  legal,  valid,  and binding
obligations  of  the  Corporation,   enforceable   against  the  Corporation  in
accordance with their terms (except to the extent  enforceability may be limited
by applicable bankruptcy, insolvency, reorganization,  moratorium, or other laws
or equitable  principles from time to time in effect which generally  affect the
enforcement of creditors' rights and remedies).

     4.  The  Secretary  is  the  keeper  of  the  records  and  minutes  of the
proceedings of the Board of Directors of the Corporation.  There is no provision
of the Articles of Incorporation or Bylaws of the Corporation limiting the power
of the Board of Directors to pass the  resolutions  set forth below and the same
are in  conformity  with the  provisions of such  Articles of  Incorporation  or
Bylaws.

     5. The  following  is a true and correct  copy of the  resolutions  adopted
either (a) at a meeting of the Corporation's  Board of Directors,  which meeting
was duly  called  and  held in  accordance  with  the law and the  Corporation's
Bylaws,  and at which meeting the Board duly and legally  passed and adopted the
following  resolutions,  or  (b)  by a  unanimous  consent  in  writing  of  all
Directors,  which  unanimous  written consent was and is in the form required by
and in conformity  with the Bylaws of the Corporation and the law. The following
resolutions have never been modified, rescinded, or repealed and are now in full
force and effect:

                                    Page 42



     Resolved,  that the  Corporation  execute and deliver  all  agreements  and
     documents  requested by NationsBank,  N.A.  ("Lender"),  in connection with
     Lender's making of one or more loans (the "Loans") to the Corporation in an
     aggregate  principal  amount  not to  exceed  $28,480,000.00,  specifically
     including,  without limitation,  a revolving line of credit facility in the
     maximum  amount  of  $20,000,000.00  and  modification  of the terms of the
     existing   $8,840,000.00   note   payable  to  Lender  and  signed  by  the
     Corporation,  at such  rates of  interest  and upon  such  other  terms and
     conditions  as the  Corporation's  Chief  Financial  Officer shall agree to
     (subject to  approval by the  Corporation's  corporate  counsel);  that the
     Corporation can reasonably expect to derive certain  benefits,  directly or
     indirectly, from entering into such relationships with Lender; and that the
     Corporation enter into the Loans and all transactions  contemplated by said
     agreements  and  documents  pertaining  to  the  Loans,  including  without
     limitation,  renewal and extension of said  agreements  upon such terms and
     conditions  as the  Corporation's  Chief  Financial  Officer shall agree to
     (subject to approval by the Corporation's  corporate counsel),  and perform
     its obligations under said agreements; and

     Resolved  Further,  that  the  President,   Chief  Financial  Officer,  and
     Controller,  or any one of them, are hereby authorized and directed to take
     all  actions,  including  without  limitation  the making and  executing on
     behalf of the Corporation of any and all notes,  loan agreements,  negative
     pledge  agreements,  interest rate exchange  agreements,  advance requests,
     certifications,  and other agreements and/or documents  requested by Lender
     and  deemed  appropriate  by them,  or any one of them,  pertaining  to the
     Loans,  upon such terms and  conditions as the  Corporation,  acting by and
     through any one or more of said officers, shall agree to; and that all such
     instruments which may be executed by any of said officers,  executed in the
     accomplishment of any action or actions so authorized, be and they shall be
     considered as being the act of the Corporation,  irrespective of whether or
     not  there  is  affixed  to  such   instrument   the   attestation  of  the
     Corporation's Secretary or the Corporation's seal;

     Resolved  Further,  that advance requests and the exercise of interest rate
     options shall be made in accordance with the terms of the Loan Agreement to
     be  executed  by the  Corporation  and  Lender  (and  such  may be  made by
     telephone,  provided that all such  advances  under the line of credit loan
     shall be deposited into the Corporation's  demand deposit account held with
     Lender),  and the  above-named  persons are authorized to make such advance
     requests and to exercise such interest rate options and in otherwise acting
     in the name of and on  behalf of the  Corporation  in  connection  with any
     matters authorized under these Resolutions;

     Resolved  Further,   that  Lender  is  authorized  and  directed,   without
     limitation  or inquiry,  irrespective  of the  circumstances,  to honor and
     carry out all  orders,  directions,  or  instructions  of the  above  named
     persons as to the disposition of any amounts borrowed or credit obtained on
     behalf  of  the  Corporation  hereunder,  and  Lender  shall  be  under  no
     obligation or liability for the use or disposition of any amounts  borrowed
     or credit  obtained,  and further that the Corporation  shall indemnify and
     hold harmless Lender from any claim,  loss,  cost,  damage,  liability,  or
     expense arising out of Lender acting in reliance upon these Resolutions;

     Resolved Further, that all acts, transactions, and/or agreements undertaken
     prior  to  the   adoption  of  these   Resolutions   by  any   officers  or
     representatives  of the  Corporation  in its name and for its accounts with
     Lender in  connection  with the  foregoing  matters  are  hereby  ratified,
     confirmed, and adopted by the Corporation;

     Resolved  Further,   that  the  Secretary  of  the  Corporation  is  hereby
     authorized and directed to certify these Resolutions to Lender; and

     Resolved  Further,  that  Lender be  promptly  notified  in  writing by the
     Secretary or any other  officer of the  Corporation  of any change in these
     Resolutions, and until Lender has actually received such notice in writing,
     Lender is authorized to act in reliance on these Resolutions.

                                    Page 43



     6. The  officers  of the  Corporation  as set  forth  below  have been duly
elected  and  qualified  and as of the date  hereof  hold the  offices  with the
Corporation  specified below. The signatures set forth beside each such person's
name is the true signature of such person.


         Title                   Typed Name                   Signature
======================== =========================== ===========================
        President              James Truchard        /s/ James Truchard
 Chief Financial Officer         Alex Davern         /s/ Alex Davern
       Controller                John Roiko          /s/ John Roiko
        Secretary               David Hugley         /s/ David Hugley

     7.  The  undersigned,   David  Hugley,  is  also  General  Counsel  of  the
Corporation.  The undersigned  certifies that the approvals of the Corporation's
corporate legal counsel required by the above resolutions have been obtained.

     8.  Attached  hereto  as  Exhibit  "A" is a true  and  correct  copy of the
Corporation's  Articles of  Incorporation.  Attached  hereto as Exhibit "B" is a
true and correct copy of the Corporation's Bylaws.

     EXECUTED  this 31 day of July,  1998,  by David  Hugley,  Secretary  of the
Corporation.




                                 /s/ David Hugley
                                 David Hugley, Secretary of National Instruments
                                 Corporation




     Subscribed To and Sworn before me, the undersigned  authority,  this 31 day
of July, 1998, by David Hugley, Secretary of National Instruments Corporation.


                                  /s/ Melanie J. Clevenger
                                  Notary Public - State of Texas

                                    Page 44



                                                                June 30, 1998
                                                                Date of Notice

               N O T I C E   O F   F I N A L   A G R E E M E N T


TO: Borrower and All Other Obligors with Respect to the Loan Which is Identified
Below.

1.   THE WRITTEN  LOAN  AGREEMENT  REPRESENTS  THE FINAL  AGREEMENT  BETWEEN THE
     PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR,  CONTEMPORANEOUS,
     OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES.

     THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

2.   As used in this Notice:

     "Borrower" means National Instruments Corporation, a Delaware corporation.

     "Lender" means NationsBank, N.A., a national banking association.

     "Other  Obligor" means any entity or individual who (i) is obligated to pay
     the Loan,  or (ii)  otherwise is or becomes  obligated to pay the Loan (for
     example,  as  cosigner  or  guarantor),  or (iii) has  pledged  property as
     security for the Loan.

     "Loan" means the loan by Lender which is to be evidenced by the  promissory
     notes,  loan agreement,  or other evidence of  indebtedness  dated June 30,
     1998, executed by Borrower,  payable to the order of Lender, in the maximum
     principal amount of $20,000,000.00.

     "Loan Agreement" means one or more promises,  promissory notes, agreements,
     undertakings,  security agreements,  deeds of trust or other documents,  or
     commitments, or any combination of those actions or documents,  relating to
     the Loan.

3.   This  Notice is given by Lender  with  respect  to the  Loan,  pursuant  to
     Section 26.02 of the Texas  Business and Commerce  Code.  Borrower and each
     other  obligor  with  respect  to the Loan who  signs  below  acknowledges,
     represents, and warrants to Lender that Lender has given and such party has
     received and retained a copy of this Notice.

Lender:                                Borrower:

NationsBank, N.A.                      National Instruments Corporation
(a national banking association)       (a Delaware corporation)

 
By: /s/ Eric Kosmin                    By: /s/ Alex Davern
    Eric Kosmin, Vice President            Alex Davern, Chief Financial Officer

                                    Page 45



                   NOTICE BY LENDER'S ATTORNEY TO BORROWER


Date:  June 30, 1998

Borrower:  National Instruments Corporation, a Delaware corporation

Lender:  NationsBank, N.A., a national banking association

Loan:  Loan evidenced by a promissory  note of even date herewith in the maximum
principal amount of $20,000,000.00, executed by Borrower, payable to Lender

This notice  discloses the relationship  between the law firm of Small,  Craig &
Werkenthin, P.C. ("scw"), Borrower, and Lender.

     1. Lender has engaged scw to prepare  the note,  loan  agreement,  security
agreements, and other documents relating to the Loan.

     2.  scw  represents  only  Lender  and no  other  party  involved  in  this
transaction, although scw's legal fees may be paid by Borrower.

     3. scw's legal fees in this transaction are based on the hourly rate of the
lawyer(s) and  paralegal(s)  working on this matter.  The sums to be paid to scw
may also include  reimbursement to scw for expenses  incurred in connection with
scw's  representation  of Lender,  including  without  limitation  as  photocopy
charges,  long distance  telephone,  UCC searches,  obtaining  certificates  and
documents from public authorities, and local and overnight courier charges.
 
     4. Borrower has the right to be represented by its own attorney and to have
its attorney  review the loan documents and closing  documents and be present at
the closing of the loan.

     5. If any documents to be used are prepared by someone other than scw, then
Lender  reserves  the right to have scw  review and  approve  the  documents  so
prepared in order to ensure they properly protect the interests of Lender.

Please sign below to indicate that you have been notified of and understand your
right to independent  legal counsel and that the firm of scw represents only the
interests of Lender, and not those of any other party.

                                    Borrower:

                                    National Instruments Corporation
                                    (a Delaware corporation)


                                    By: /s/ Alex Davern
                                        Alex Davern, Chief Financial Officer

                                    Page 46