Document:

<PAGE>

EXHIBIT 10.au

                           SECOND AMENDED AND RESTATED
                            REVOLVING PROMISSORY NOTE

$30,000,000.00             Albuquerque, New Mexico               March 31, 2000

         SBS TECHNOLOGIES, INC., a New Mexico corporation, having its principal
office located at 2400 Louisiana Blvd., NE, AFC Building 5, Suite 600,
Albuquerque, NM, 87110 ("BORROWER"), for value received, hereby promises to pay
to the order of BANK OF AMERICA, N.A., formerly NationsBank, N.A., a national
banking association ("LENDER"), at its Albuquerque, New Mexico office at 303
Roma, NW, Albuquerque, New Mexico 87102, or at such other address given to
Borrower by Lender, in immediately available funds and in lawful money of the
United States of America, the principal sum of THIRTY MILLION AND NO/100 DOLLARS
($30,000,000.00), or so much thereof as may be advanced and outstanding, on
March 31, 2001, or sooner as provided in the Credit Agreement (as defined
herein), together with interest on the unpaid principal balance of this Note
from time to time outstanding at the applicable interest rate. Unless prohibited
by Applicable Law and subject to the terms hereof and the Credit Agreement
limiting interest to the Maximum Lawful Rate, interest on this Note shall be
calculated on the basis of actual days elapsed, but as if each year consisted of
360 days.

         This Note is executed pursuant to that certain Second Modification of
Credit Agreement, Guaranty Agreements and Related Loan Documents (the
"MODIFICATION AGREEMENT") of even date herewith executed by and among Lender,
Borrower and the Guarantors, pertaining to that certain Credit Agreement dated
as of December 1, 1998, executed by and between Lender and Borrower, as
previously modified by (i) Note Modification Agreement dated as of November 30,
1999 and (ii) Modification of Credit Agreement, Guaranty Agreements and Related
Documents dated as of January 31, 2000 ("First Modification Agreement") (such
Credit Agreement, as amended by such Note Modification Agreement, the First
Modification Agreement and the Modification Agreement, and as it may hereafter
be amended, supplemented, renewed, extended, or restated or replaced from time
to time, the "CREDIT AGREEMENT"), and this Note is the "Second Restated Note"
defined and described in the Modification Agreement and the "Note" under and as
defined in the Credit Agreement, the terms and provisions of the Credit
Agreement and the Modification Agreement related to this Note being incorporated
herein by reference for all purposes. Each capitalized term used but not
expressly defined herein shall have the meaning given to such term in the Credit
Agreement as modified by the Modification Agreement. Reference is hereby
expressly made to the Credit Agreement for a statement of the rights and

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obligations of Lender and the duties and obligations of Borrower in relation
thereto; but neither this reference to the Credit Agreement nor any provision
thereof shall affect or impair the absolute and unconditional obligation of
Borrower to pay unpaid principal of and interest on this Note when due.

         This Note is secured by the Credit Agreement and the Security Agreement
dated the date hereof and all other Loan Documents, and all liens and security
interests created or evidenced thereby, and payment of this Note is guaranteed
by the Guaranty Agreements. Any holder hereof shall be entitled to all benefits
of and remedies set forth in the Credit Agreement, the Security Agreement and
all the other Loan Documents.

         This Note is given in modification, renewal, restatement and
replacement, but not in novation or extinguishment, of the Amended and Restated
Revolving Promissory Note dated January 31, 2000, evidencing the Advances under
the Available Commitment pursuant to the Credit Agreement. All rights and
interests of Lender under the Credit Agreement and such prior note are renewed
and extended hereby.

         Lender may disburse the principal of this Note to Borrower in one or
more advances from time to time, subject to and upon the terms and conditions
set forth in the Credit Agreement with respect to the Available Commitment, so
long as the outstanding principal balance hereof never exceeds the then
applicable amount of the Available Commitment, less any Letter of Credit
Exposure. Subject to and upon the terms and conditions of the Credit Agreement,
Borrower shall be entitled to prepay the principal of this Note from time to
time, in whole or in part, without premium or penalty, except for any prepayment
fee due upon prepayment of a LIBOR Rate Portion prior to the expiration of the
applicable Interest Period as provided in Section 3.5(g) of the Credit
Agreement, and thereafter, prior to the maturity date hereof (and provided that
no Default has occurred and is in existence), to request additional advances
hereunder, subject to and in accordance with the terms and conditions of the
Credit Agreement.

         1.  INTEREST AND PAYMENT.

                  (a) MATURITY. The entire principal balance of this Note, and
all accrued but unpaid interest hereon, shall be due and payable in full on the
Termination Date.

                  (b) ACCRUAL OF INTEREST. Subject to Paragraph 1(f) below,
interest on this Note shall accrue at a rate per annum equal to the lesser of
(i) at Borrower's option exercised in accordance with the terms of the Credit
Agreement, the Variable Rate or the LIBOR Rate with respect to the Variable Rate
Portions and the LIBOR Rate Portions outstanding hereunder from

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time to time, subject, however, to the provisions of the Credit Agreement, or
(ii) the Maximum Lawful Rate; provided, however, that as to any portion of the
outstanding principal balance hereof that is not subject to an effective
election of or conversion to the LIBOR Rate in accordance with the terms of the
Credit Agreement, interest on such portion of this Note shall accrue interest at
the lesser of (i) the Variable Rate or (ii) the Maximum Lawful Rate. Interest on
this Note shall be calculated at a daily rate equal to 1/360 of the annual
percentage rate which this Note bears, subject to the provisions hereof limiting
interest to the Maximum Lawful Rate. Without notice to Borrower or any other
Person, the Variable Rate and the Maximum Lawful Rate shall each automatically
fluctuate upward and downward as and in the amount by which the Base Rate and
the Maximum Lawful Rate, respectively, fluctuate, subject always to limitations
contained in this Note and the Credit Agreement.

                  (c) AGREEMENTS CONCERNING PRICING ELECTION. Reference should
be made to the provisions of SECTION 3.5 of the Credit Agreement concerning the
terms, manner and agreements related to the interest rate elections available to
Borrower under this Note.

                  (d) PRINCIPAL AND INTEREST PAYMENTS. Principal and interest
hereon shall be due and payable as is provided in ARTICLE III of the Credit
Agreement, which provides, in part, for payments of accrued, unpaid interest on
the first (1st) day of each calendar quarter and, with respect to any LIBOR Rate
Portion, on the last day of the applicable Interest Period.

                  (e) COSTS DUE TO REGULATORY CHANGES. Borrower shall indemnify
Lender against and reimburse Lender for increased costs to Lender, as a result
of any Regulatory Change, in the maintaining of any LIBOR Rate Portion. All
payments made pursuant to this paragraph shall be made free and clear, without
reduction for, or account of, any present or future taxes or other levies of any
nature, excluding net income and franchise taxes.

                  (f) DEFAULT RATE. After maturity of this Note or the
occurrence of an Event of Default, the outstanding principal balance of this
Note shall, at the option of Lender, bear interest at the Default Rate. Any past
due principal and, to the extent permitted by law, past due interest on the Loan
shall bear interest, payable as it accrues on demand, for each day until paid at
the Default Rate. Such interest shall continue to accrue at the Default Rate
notwithstanding the entry of a judgment with respect to any of the Obligation or
the foreclosure of any of Lender's Liens.

                  (g) MAXIMUM LAWFUL RATE ADJUSTMENTS. If at any time a change
in the Variable Rate or the LIBOR Rate shall cause the rate of interest on this
Note to be limited to the Maximum Lawful Rate, any subsequent reductions in the
Variable Rate or the LIBOR Rate, as applicable, shall not reduce the rate of
interest on this Note below the Maximum Lawful Rate

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until the total amount of interest accrued equals the amount of interest which
would have accrued if the Variable Rate or the LIBOR Rate, as applicable, had at
all times been in effect. In the event that at maturity (stated or by
acceleration), or at the final payment of the Loan, the total amount of interest
paid or accrued on the Loan is less than the amount of interest which would have
accrued if the Variable Rate or the LIBOR Rate, as applicable, had at all times
been in effect with respect thereto, then at such time, to the extent permitted
by law, Borrower shall pay to Lender an amount equal to the difference between
(a) the lesser of the amount of interest which would have accrued if the
Variable Rate or the LIBOR Rate, as applicable, had at all times been in effect
and the amount of interest which would have accrued if the Maximum Lawful Rate
had at all times been in effect, and (b) the amount of interest actually paid on
the Loan.

         2.       DEFAULT. The occurrence of a Default or an Event of Default,
                  under and as defined in the Credit Agreement, shall
                  constitute, respectively, a Default or an Event of Default
                  under this Note.

         3.       REMEDIES.

                  (a) ALL REMEDIES AVAILABLE. Upon the occurrence of an Event of
         Default, the holder hereof shall have the right to declare the entire
         unpaid principal balance of, and all accrued unpaid interest on, this
         Note at once due and payable (and upon such declaration, the same shall
         be at once due and payable), to foreclose any and all liens and
         security interests securing payment hereof, to offset against this Note
         any sum or sums owed by it to Borrower, and to exercise any of its
         other rights, powers and remedies under this Note, under the Credit
         Agreement or any other Loan Document, or at law or in equity.

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                  (b) NO WAIVER. Neither the failure by the holder hereof to
exercise, nor delay by the holder hereof in exercising, the right to accelerate
the maturity of this Note or any other right, power or remedy upon any Default
or Event of Default shall be construed as a waiver of such Default or Event of
Default or as a waiver of the right to exercise any such right, power or remedy
at any time. No single or partial exercise by the holder hereof of any right,
power or remedy shall exhaust the same or shall preclude any other or further
exercise thereof, and every such right, power or remedy may be exercised at any
time and from time to time. All rights and remedies provided for in this Note
and in any other Loan Document are cumulative of each other and of any and all
other rights and remedies existing at law or in equity, and the holder hereof
shall, in addition to the rights and remedies provided herein or in any other
Loan Document, be entitled to avail itself of all such other rights and remedies
as may now or hereafter exist at law or in equity for the collection of the
indebtedness owing hereunder, and the resort to any right or remedy provided for
hereunder or under any such other Loan Document or provided for by law or in
equity shall not prevent the concurrent or subsequent employment of any other
appropriate rights or remedies. Without limiting the generality of the foregoing
provisions, the acceptance by the holder hereof from time to time of any payment
under this Note which is past due or which is less than the payment in full of
all amounts due and payable at the time of such payment, shall not (i)
constitute a waiver of or impair or extinguish the rights of the holder hereof
to accelerate the maturity of this Note or to exercise any other right, power or
remedy at the time or at any subsequent time, or nullify any prior exercise of
any such right, power or remedy, or (ii) constitute a waiver of the requirement
of punctual payment and performance, or a novation in any respect.

         4.       USURY SAVINGS PROVISIONS.

                  (a) GENERAL LIMITATION. Notwithstanding anything herein or in
any other Loan Documents, expressed or implied, to the contrary, in no event
shall any interest rate charged hereunder or under any of the other Loan
Documents, or any interest contracted for, collected or received by Lender or
any holder hereof, exceed the Maximum Lawful Rate.

                  (b) INTENT OF PARTIES. It is expressly stipulated and agreed
to be the intent of Borrower and Lender at all times to comply with the
applicable law governing the maximum rate or amount of interest payable on or in
connection with this Note. If the applicable law is ever judicially interpreted
so as to render usurious any amount called for under this Note or under any of
the other Loan Documents, or contracted for, charged, taken, reserved or
received with respect to this Note, or if acceleration of the maturity of this
Note, any prepayment by Borrower, or any

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other circumstance whatsoever, results in Lender having been paid any interest
in excess of that permitted by applicable law, then it is the express intent of
Borrower and Lender that all excess amounts theretofore collected by Lender be
credited on the principal balance of this Note (or, if this Note has been or
would thereby be paid in full, refunded to Borrower), and the provisions of this
Note and the other applicable Loan Documents immediately be deemed reformed and
the amounts thereafter collectible hereunder and thereunder reduced, without the
necessity of the execution of any new document, so as to comply with the
applicable law, but so as to permit the recovery of the fullest amount otherwise
called for hereunder and thereunder. The right to accelerate the maturity of
this Note does not include the right to accelerate any interest which has not
otherwise accrued on the date of such acceleration, and Lender does not intend
to collect any unearned interest in the event of acceleration. All sums paid or
agreed to be paid to Lender for the use, forbearance or detention of the
indebtedness evidenced hereby or by any other Loan Document shall, to the extent
permitted by applicable law, be amortized, prorated, allocated and spread
throughout the full term of such indebtedness until payment in full so that the
rate or amount of interest on account of such indebtedness does not exceed the
Maximum Lawful Rate. The term "APPLICABLE LAW" as used herein shall mean the
laws of the State of New Mexico, or any applicable United States federal law to
the extent that it permits Lender to contract for, charge, take, reserve or
receive a greater amount of interest than under New Mexico law. The provisions
of this paragraph shall control all agreements between Borrower and Lender.

         5.       GENERAL PROVISIONS.

                  (a) BUSINESS DAY. Whenever any payment shall be due under this
Note on a day which is not a Business Day, the date on which such payment is due
shall be extended to the next succeeding Business Day, and such extension of
time shall be included in the computation of the amount of interest then
payable.

                  (b) MANNER OF PAYMENT. The manner in which payments are to be
made on this Note shall be governed by the provisions hereof and the Credit
Agreement, including, without limitation, SECTION 3.10 of the Credit Agreement.

                  (c) PREPAYMENTS. Prepayments may be made on this Note subject
to and in accordance with SECTIONS 3.5(g) and 3.6 of the Credit Agreement.

                  (d) APPLICATION OF PAYMENTS. All payments made on this Note
shall be applied in accordance with SECTIONS 3.11 and 8.8 of the Credit
Agreement, as applicable. Nothing herein shall limit or impair any rights of any
holder hereof to apply as provided in the Loan Documents any past due payments,
any proceeds from the disposition of any collateral by

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foreclosure or other collections after default. Except to the extent specific
provisions are set forth in this Note or another Loan Document with respect to
application of payments, all payments received by the holder hereof shall be
applied, to the extent thereof, to the indebtedness owing by Borrower to the
holder hereof in such order and manner as the holder hereof shall deem
appropriate, any instructions from Borrower or anyone else to the contrary
notwithstanding.

                  (e) COSTS OF COLLECTION. If any holder of this Note retains an
attorney in connection with any default or at maturity or to collect, enforce or
defend this Note or any other Loan Document in any lawsuit or in any probate,
reorganization, bankruptcy or other proceeding, or if Borrower sues any holder
of this Note in connection with this Note or any other Loan Document and does
not prevail, then Borrower agrees to pay to each such holder, in addition to
principal and interest, all costs and expenses incurred by such holder in trying
to collect this Note or in any such suit or proceeding, including reasonable
attorneys' fees.

                  (f) WAIVERS AND ACKNOWLEDGMENTS. Borrower and all sureties,
endorsers, guarantors and any other party now or hereafter liable for the
payment of this Note in whole or in part, hereby severally (i) waive demand,
presentment for payment, notice of dishonor and of nonpayment, protest, notice
of protest, notice of intent to accelerate, notice of acceleration and all other
notice (except only for any notice that is specifically required by the terms of
the Credit Agreement or any other Loan Document), filing of suit and diligence
in collecting this Note or enforcing any of the security herefor; (ii) agree to
any substitution, subordination, exchange or release of any such security or the
release of any party primarily or secondarily liable hereon; (iii) agree that
the holder hereof shall not be required first to institute suit or exhaust its
remedies against Borrower or others liable or to become liable hereon or to
enforce its rights against them or any security herefor; (iv) consent to any
extension or postponement of time of payment of this Note for any period or
periods of time and to any partial payments, before or after maturity, and to
any other indulgences with respect hereto, without notice thereof to any of
them; and (v) submit (and waive all rights to object) to personal jurisdiction
in the State of New Mexico, and venue in Bernalillo County, New Mexico, for the
enforcement of any and all obligations under the Loan Documents.

                  (g) AMENDMENTS IN WRITING. This Note may not be changed,
amended or modified except in a writing expressly intended for such purpose and
executed by the party against whom enforcement of the change, amendment or
modification is sought.

                  (h) PURPOSE OF PROCEEDS. The proceeds of this Note will be
used solely for business purposes and not for personal, family, household or
agricultural purposes.

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                  (i) NOTICES. Any notice required or which any party desires to
give under this Note shall be given and effective as provided in SECTION 9.2 of
the Credit Agreement.

                  (j) ASSIGNMENTS/PARTICIPATIONS. Borrower acknowledges and
agrees that the holder of this Note may, at any time and from time to time,
assign all or a portion of its interest in the Credit Facility or transfer to
any Person a participation interest in the Credit Facility.

                  (k) SUCCESSORS AND ASSIGNS. All of the covenants,
stipulations, promises and agreements contained in this Note by or on behalf of
Borrower shall bind its successors and assigns and shall be for the benefit of
Lender and any holder hereof, and their successors and assigns, whether so
expressed or not.

                  (l) TIME OF THE ESSENCE. Time shall be of the essence in this
Note with respect to all of Borrower's obligations hereunder.

                  (m) JURY TRIAL WAIVER. TO THE MAXIMUM EXTENT PERMITTED BY LAW,
EACH OF BORROWER AND LENDER HEREBY WAIVES ANY RIGHT THAT IT MAY HAVE TO A TRIAL
BY JURY OF ANY DISPUTE (WHETHER A CLAIM IN TORT, CONTRACT, EQUITY OR OTHERWISE)
ARISING UNDER OR RELATING TO THIS NOTE, THE OTHER LOAN DOCUMENTS OR ANY RELATED
MATTERS, AND AGREES THAT ANY SUCH DISPUTE SHALL BE TRIED BEFORE A JUDGE SITTING
WITHOUT A JURY.

                  (n) GOVERNING LAW. THIS NOTE SHALL BE CONSTRUED IN ACCORDANCE
WITH AND GOVERNED BY NEW MEXICO LAW, EXCEPT TO THE EXTENT THAT UNITED STATES
FEDERAL LAW APPLIES PURSUANT TO SECTION 9.8 OF THE CREDIT AGREEMENT OR
OTHERWISE. THE BOOKS AND RECORDS OF LENDER SHALL CONSTITUTE PRIMA FACIE EVIDENCE
OF ALL SUMS DUE LENDER HEREUNDER.

                  (o) INTEGRATION. THIS NOTE AND THE OTHER LOAN DOCUMENTS
REPRESENT THE FINAL AGREEMENT BETWEEN LENDER AND BORROWER AND MAY NOT BE
CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS
OF LENDER AND BORROWER. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE
PARTIES.

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         IN WITNESS WHEREOF, Borrower has duly executed this Note as of the date
first above written.

                                BORROWER:

                                SBS TECHNOLOGIES, INC., a New Mexico corporation

                                By: /s/ James E. Dixon Jr.
                                    ------------------------
                                    James E. Dixon, Jr.
                                    Vice President, Finance and Administration

                                     Page 9<PAGE>

EXHIBIT 10.av

                         SUPPLEMENT I TO LOAN DOCUMENTS

         This SUPPLEMENT I TO LOAN DOCUMENTS (this "SUPPLEMENT") is made and
executed as of April 14, 2000, by SBS TECHNOLOGIES, INC., a New Mexico
corporation ("BORROWER"), and SDL COMMUNICATIONS, INC., a Massachusetts
Corporation (the "ADDITIONAL GUARANTOR"), pursuant to the Credit Agreement
(hereinafter defined) and in connection with the Second Modification
(hereinafter defined). All terms used but not defined herein shall have the
meanings set forth in the Credit Agreement.

                              W I T N E S S E T H:

         WHEREAS, Borrower and Bank of America, N.A., formerly NationsBank,
N.A., a national banking association ("LENDER") have entered into that certain
Credit Agreement dated as of December 1, 1998, as modified and extended by (i)
Note Modification Agreement dated as of November 30, 1999, (ii) Modification of
Credit Agreement, Guaranty Agreements and Related Loan Documents dated as of
January 31, 2000 (the "FIRST MODIFICATION"), and (ii) Second Modification of
Credit Agreement, Guaranty Agreements and Related Loan Documents (the "SECOND
MODIFICATION") dated as of March 31, 2000, executed by and among Lender,
Borrower, and the Existing Guarantors (hereinafter defined) (such Credit
Agreement as so modified and as it may hereafter be modified, supplemented,
extended, renewed or restated, and as in effect from time to time, the "CREDIT
AGREEMENT"), which Credit Agreement sets forth the terms and conditions of a
revolving credit facility to Borrower;

         WHEREAS, in connection with the Credit Agreement, (a) certain
Subsidiaries of Borrower named as Guarantors in the Second Modification (the
"EXISTING GUARANTORS") each executed and delivered a Guaranty Agreement (herein
so called) dated as of March 31, 2000, (b) the Borrower, the Existing Guarantors
and Lender executed that certain Contribution and Indemnification Agreement (the
"CONTRIBUTION AGREEMENT") pertaining to the Guaranty Agreements dated as of
March 31, 2000, and (c) the Borrower, the Existing Guarantors and Lender
executed that certain Security Agreement (herein so called) dated as of March
31, 2000;

         WHEREAS, the Additional Guarantor is a Subsidiary of Borrower that is
required by the terms of the Credit Agreement to become a "Guarantor" for all
purposes under the Credit Agreement, subject to the terms of the Credit
Agreement and each of the other Loan Documents; and

         WHEREAS, Additional Guarantor desires to execute this Supplement
because of the direct and/or indirect benefits to be obtained by Additional
Guarantor by virtue of the Credit Agreement.

         NOW, THEREFORE, KNOW ALL MEN BY THESE PRESENTS, that for and in
consideration of the mutual promises contained herein and in the Credit
Agreement, and other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the undersigned parties hereby
agree as follows:

         1. GUARANTY AGREEMENT. Additional Guarantor acknowledges and
understands that Additional Guarantor is a domestic Subsidiary of Borrower and,
as such, is required to be a Guarantor under the Credit Agreement. Accordingly,
Additional Guarantor is executing a Guaranty Agreement of even date herewith
simultaneously with execution hereof, and from and after this date Additional
Guarantor shall be a "Guarantor" for all purposes under the Credit Agreement and
all the other Loan Documents, and expressly assumes and makes all of the
representations, agreements and obligations of a Guarantor therein. By executing
and delivering this Supplement, Additional Guarantor becomes a signatory to the
Contribution Agreement and

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hereby expressly assumes all the obligations and liabilities of a "Guarantor"
thereunder as if it originally signed the Contribution Agreement.

         2. SECURITY AGREEMENT. By executing and delivering this Supplement,
Additional Guarantor hereby (i) becomes a party to the Security Agreement as an
"Assignor" thereunder as if Additional Guarantor had originally signed the
Security Agreement, (ii) expressly assumes all obligations and liabilities for
an "Assignor" thereunder, and (iii) pledges and assigns to Lender (as defined
therein), and grants to Lender a security interest in and to, all of the
Collateral (as defined in the Security Agreement) of Additional Guarantor, and
all right, title and interest of Additional Guarantor therein, wherever located,
and now owned or hereafter acquired, as collateral security for the prompt
payment in full when due (whether at stated maturity, by acceleration or
otherwise) of the Obligations, subject to and on the terms of the Security
Agreement. Schedules A, B, and C to the Security Agreement are each hereby
amended by supplementing such Schedules with the information contained in
Schedules A, B and C, attached as ANNEX I to this Supplement. Additional
Guarantor hereby makes each of the representations, warranties and agreements
contained in the Security Agreement on the date hereof, after giving effect to
this Supplement.

         3. GENERAL MODIFICATIONS. All of the Loan Documents, including without
limitation the Credit Agreement, each Guaranty Agreement, the Contribution
Agreement and the Security Agreement, are hereby modified and amended to include
Additional Guarantor as a "Guarantor" or "Assignor," or any other defined term
used for the Guarantors thereunder to the same extent as the other Guarantors
that are parties thereto, without any further action being taken or further
documents required to be executed by any party.

         4. COLLATERAL DOCUMENTATION. Borrower and Additional Guarantor agree to
execute and/or deliver to Lender any and all other documents and agreements
reasonably requested by Lender to further evidence the agreements contained in
this Supplement, including without limitation all financing statements necessary
or advisable in order to perfect or evidence the Lender's security interests in
the Collateral.

         5. AUTHORITY DOCUMENTATION. Additional Guarantor agrees to deliver to
Lender all corporate authority and organizational documents required under
Section 4.1 of the Credit Agreement and represents and warrants to Lender that
(a) it is a corporation, duly created, presently existing and in good standing
under the laws of the state under which it is organized, (b) it has all
corporate powers and all governmental licenses, authorizations, consents and
approvals required to carry on its business as now conducted and as contemplated
to be conducted, except where the failure to have any such item would not have a
material adverse effect on Additional Guarantor's business and financial
condition, (c) the execution, delivery and performance of this Supplement and
any other documents executed in connection herewith or with the Credit Agreement
have been duly authorized by all necessary corporate action, require no action
by or in respect of, or filing with, any governmental body, agency or office,
and do not contravene, or constitute a default under, any provision of
applicable law or regulations or of certificate of incorporation or bylaws,
articles of organization or regulations, as applicable, of Additional Guarantor,
or any other agreement binding on Additional Guarantor, (d) this Supplement, and
as a result of the execution hereof, each of the Loan Documents to which the
Additional Guarantor is a party, constitute the valid and binding agreement of
Additional Guarantor, enforceable in accordance with the terms thereof, except
as (i) the enforceability thereof may be limited by bankruptcy, insolvency,
fraudulent transfer or similar laws affecting creditor rights generally, and
(ii) the availability of equitable principles of general applicability, and (e)
Additional Guarantor is executing this Supplement for its direct or indirect
benefit, Additional Guarantor has reviewed and is satisfied with the rights of
contribution or subrogation to which it may be entitled with respect to all
other Guarantors (and such other Guarantors' ability to perform thereon), and
such Additional Guarantor has determined that entering into the Credit Agreement
and the other Loan Documents enables it to obtain substantial benefits which it
would not otherwise have.

                                     Page 2
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         6. ADDITIONAL DOCUMENTATION. Additional Guarantor shall execute and
deliver to Lender such other agreements, assignments, financing statements,
certificates and other documents and instruments as Lender may reasonably
request to effect the transactions contemplated hereby and to establish and
perfect the liens and security interests intended to be created by the Loan
Documents.

         9. SUCCESSORS AND ASSIGNS. This Agreement shall inure to the benefit of
and be binding upon the parties hereto and their respective successors and
assigns.

         10. COUNTERPARTS. This Supplement may be executed in any number of
original counterparts, each of which when so executed and delivered shall be
deemed an original, and all of which, collectively, shall constitute one
agreement, it being understood and agreed that the signature pages may be
detached from one or more of such counterparts and combined with the signature
pages from any other counterpart in order that one or more fully executed
originals may be assembled.

         11. BINDING. This Supplement shall be binding upon, and inure to the
benefit of, the parties hereto and their successors and assigns, subject to the
provisions of the Credit Agreement.

         12. GOVERNING LAW. THIS SUPPLEMENT SHALL BE GOVERNED BY AND CONSTRUED
IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW MEXICO AND APPLICABLE FEDERAL
LAWS.

         13. ENTIRE AGREEMENT. THIS WRITTEN AGREEMENT AND THE OTHER LOAN
DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES HERETO AND MAY NOT
BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL
AGREEMENTS BETWEEN THE PARTIES HERETO. THERE ARE NO UNWRITTEN ORAL AGREEMENTS
BETWEEN THE PARTIES.

         Executed effective as of the date first above written.

                             BORROWER:

                             SBS TECHNOLOGIES, INC., a New Mexico corporation

                             By: /s/ James E. Dixon Jr.
                                 ----------------------------------
                                     James E. Dixon, Jr.
                                     Vice President, Finance and Administration

                             ADDITIONAL GUARANTOR :

                             SDL COMMUNICATIONS INC., a Massachusetts
                             corporation

                             By: /s/  James E. Dixon Jr.
                                 ----------------------------------
                             Name: James E. Dixon, Jr.
                                   --------------------------------
                             Title: Secretary
                                    -------------------------------

                                     Page 3
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                                     ANNEX I
                                       TO
                                  SUPPLEMENT I

                 SUPPLEMENTS TO SCHEDULES TO SECURITY AGREEMENT

Attached are replacement Schedules A, B and C to the Security Agreement.

Schedule A is also the replacement Schedule A to the Contribution Agreement.

                                     Page 2
<PAGE>

                                   SCHEDULE A

                          List of Subsidiary Assignors

SBS TECHNOLOGIES, INC. CONNECTIVITY PRODUCTS, f/k/a SBS Bit 3 Operations, Inc.
SBS TECHNOLOGIES, INC. TELEMETRY AND COMMUNICATIONS PRODUCTS, f/k/a SBS
     Berg Telemetry Systems, Inc.
SBS TECHNOLOGIES INC. MODULAR I/O, f/k/a SBS Greenspring Modular I/O, Inc.
SBS TECHNOLOGIES, INC. EMBEDDED COMPUTERS, f/k/a SBS Embedded Computers, Inc.
SBS TECHNOLOGIES INC. INDUSTRIAL COMPUTERS, f/k/a SBS Micro Alliance, Inc.
SBS TECHNOLOGIES INC. COMMUNICATIONS PRODUCTS, f/k/a VI Computer
SDL COMMUNICATIONS, INC.

                                     Page 1
<PAGE>

                                   SCHEDULE B

                           Principal Place of Business
                                       and
                 Location of Inventory, Equipment and Furniture

[LOGO]

                             SBS Technologies, Inc.
                             2400 Louisiana Boulevard, N.E.
                             AFC Building 5, Suite 600
                             Albuquerque, NM  87110-4316

                             SBS Technologies, Inc. Telemetry and Communications
                             Products
                             5791 Van Allen Way
                             Carlsbad, CA  92008

                             SBS Technologies Inc. Industrial Computers
                             5791 Van Allen Way
                             Carlsbad, CA  92008

                             SBS Technologies Inc. Communications Products
                             5791 Van Allen Way
                             Carlsbad, CA  92008

                             SBS Technologies Inc. Modular I/O
                             8371 Central Avenue, Suite C
                             Newark, CA  94560

                             SBS Technologies, Inc. Embedded Computers
                             6301 Chapel Hill Road
                             Raleigh, NC  27607

                             SBS Technologies, Inc. Connectivity Products
                             1284 Corporate Center Drive
                             St. Paul, MN  55121-1245

                             SDL Communications, Inc.
                             46 Eastman Street
                             Easton, MA  02375

                                     Page 1
<PAGE>

                                   SCHEDULE C

                                   Trade Names

<TABLE>
<CAPTION>
            NAME                                                    TRADE NAME(S)
            ----                                                    -------------
<S>                                                         <C>
SBS Technologies, Inc.                                      None

SBS Technologies, Inc. Telemetry and                        SBS Berg Telemetry Systems, Inc.
Communications Products

SBS Technologies Inc. Industrial Computers                  SBS Micro Alliance, Inc.

SBS Technologies Inc. Communications Products               VI Computer

SBS Technologies Inc. Modular I/O                           SBS Greenspring Modular I/O, Inc.

SBS Technologies, Inc. Embedded Computers                   SBS Embedded Computers, Inc.

SBS Technologies, Inc. Connectivity Products                SBS Bit 3 Operations, Inc.

SDL Communications, Inc.                                    None
</TABLE>

                                     Page 2

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