<PAGE>

EXHIBIT 10.at

                    SECOND MODIFICATION OF CREDIT AGREEMENT,
                 GUARANTY AGREEMENTS AND RELATED LOAN DOCUMENTS


         THIS SECOND MODIFICATION OF CREDIT AGREEMENT, GUARANTY AGREEMENTS AND
RELATED LOAN DOCUMENTS (this "MODIFICATION AGREEMENT") is entered into as of
March 31, 2000, by and between SBS TECHNOLOGIES, INC., a New Mexico corporation
("BORROWER"), BANK OF AMERICA, N.A., formerly NationsBank, N.A., a national
banking association ("LENDER"), and the Subsidiaries of Borrower listed as
Guarantors on the signature pages hereof (the "GUARANTORS").

                                R E C I T A L S:

         WHEREAS, Borrower and Lender (under its prior name, NationsBank, N.A.)
have previously executed that certain Credit Agreement (as modified, amended and
supplemented from time to time, the "CREDIT AGREEMENT") dated as of December 1,
1998, pursuant to which Lender has made available to Borrower a revolving credit
loan facility currently in the amount of $25,000,000, which Credit Agreement has
been amended by (i) that certain Note Modification Agreement dated as of
November 30, 1999 and (ii) Modification of Credit Agreement, Guaranty Agreements
and Related Loan Documents dated as of January 31, 2000 (the "FIRST
MODIFICATION")(any capitalized term used but not otherwise defined herein shall
have the meaning set forth in the Credit Agreement); and

         WHEREAS, the indebtedness under the Credit Agreement is evidenced by
that certain Amended and Restated Revolving Promissory Note (the "RESTATED
NOTE") dated January 31, 2000, in the principal face amount of $25,000,000.00,
executed by Borrower and payable to the order of Lender, which Restated Note
amended and restated that certain Revolving Promissory Note, dated December 1,
1998, in the principal face amount of $15,000,000.00, executed by Borrower and
payable to the order of Lender; and

         WHEREAS, Borrower and the Guarantors have requested an increase in the
revolving credit facility to $30,000,000, and certain other modifications to the
Credit Agreement, the Guaranty Agreements and the other Loan Documents; and

         WHEREAS, Lender has agreed to such modifications, subject to the terms
and conditions hereof, including without limitation that certain assets of
Borrower and Guarantors be pledged as collateral to secure all of the
Obligations under and as defined in the Credit Agreement, as modified and
increased hereby, pursuant to the Security Agreement (hereinafter defined), and
upon the terms and conditions contained herein.

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                               A G R E E M E N T:

         NOW, THEREFORE, KNOW ALL MEN BY THESE PRESENTS, that for and in
consideration of the terms, conditions and agreements contained herein and for
other good and valuable consideration, the receipt and sufficiency of which is
hereby acknowledged, Lender, Borrower and the Guarantors agree as follows:

         1. INCREASE IN AVAILABLE COMMITMENT. From and after the effective date
hereof, the maximum amount of the revolving credit facility under the Credit
Agreement shall be increased from $25,000,000.00, to $30,000,000.00.
Accordingly, the definition of "AVAILABLE COMMITMENT" set forth in Section 1.1
of the Credit Agreement shall be amended to read in its entirety as follows:

                  "AVAILABLE COMMITMENT" means the maximum amount available to
         be advanced under the Credit Facility, being $15,000,000.00 as of the
         Closing Date through January 30, 2000; $25,000,000.00 as of January 31,
         2000 through March 30, 2000; and $30,000,000.00 from and after March
         31, 2000, subject to reduction as provided in SECTION 3.6(C)."

         2. RESTATED NOTE. To evidence the increased Available Commitment,
Borrower shall execute and deliver to Lender contemporaneously with this
Modification Agreement, a Second Amended and Restated Revolving Promissory Note
(the "SECOND RESTATED NOTE") dated the date hereof, in the original principal
face amount of $30,000,000.00, payable to the order of Lender, in substantially
the same form as the Note, which Second Restated Note shall be in renewal,
extension, amendment, restatement and replacement of the Restated Note. From and
after the date hereof, all references to the term "Note" in the Credit
Agreement, each Guaranty Agreement, and all other Loan Documents shall mean and
refer to the Second Restated Note. Accordingly, the definition of "Note' in the
Credit Agreement is hereby amended to read in its entirety as follows:

                  "NOTE" means the Revolving Promissory Note dated the date
         hereof, in the maximum principal amount of $15,000,000.00, executed by
         Borrower and payable to the order of Lender, in the form of EXHIBIT A
         attached hereto, as amended, extended, restated and replaced by the
         Amended and Restated Revolving Promissory Note dated January 31, 2000,
         in the maximum principal amount of $25,000,000.00, as further amended,
         extended, restated and replaced by the Second Amended and Restated
         Revolving Promissory Note dated March 31, 2000, in the maximum
         principal amount of $30,000,000.00, and any and all renewals,
         supplements, extensions, modifications, amendments, restatements and
         replacements thereof."

         The Restated Note held by Lender shall be legended to show that it has
been amended, restated and replaced by the Second Restated Note, and then
returned to Borrower.

         3. TERMINATION DATE. The termination of the revolving credit facility
is changed to March 31, 2001, subject to the terms and conditions set forth in
the Credit Agreement. Accordingly, clause (i) of the definition of "Termination
Date" in Section 1.1 of the Credit Agreement (as amended by the First
Modification) is amended to insert the date "March 31,

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2001", in place of "November 30, 2001." Any reference to the "Termination Date"
in the Credit Agreement, the Second Restated Note, the Guaranty Agreements or
any other Loan Document shall mean and refer to such new Termination Date.

         4. ACQUISITION OF SDL. Borrower has requested use of the proceeds of an
Advance in an amount up to $25,000,000 in connection with its acquisition of
100% of the stock of SDL Communications, Inc., a Massachusetts corporation
("SDL"). Notwithstanding the definition of "Permitted Acquisition" in Section
1.1 of the Credit Agreement or the provisions of Section 6.7 of the Credit
Agreement, Lender hereby agrees that up to $25,000,000 of the Available
Commitment may be used for an Advance for the acquisition by Borrower of 100% of
SDL's stock, subject to all other terms and conditions of Section 6.7 of the
Credit Agreement.

         5. COLLATERAL. For and in consideration of the increase in the
Available Commitment and other modifications and consents herein, from and after
the date hereof, all accounts and inventory of Borrower and the Guarantors shall
be pledged as security for all of the Obligations. Accordingly, and as a
condition to the effectiveness hereof, Borrower and all the Guarantors shall
execute and deliver to, and in favor of, Lender, a Security Agreement (herein so
called) dated the date hereof, in form and content acceptable to Lender in all
respects. Upon consummation of Borrower's acquisition of SDL, the assets of that
subsidiary shall also be pledged, and, accordingly, SDL shall join in the
execution of the Security Agreement.

         6. GUARANTY AGREEMENTS. Each of the undersigned Guarantors expressly
acknowledges and agrees to the increase in the Available Commitment to
$30,000,000, and the change of the Termination Date to March 31, 2001, and
agrees to execute an amended and restated Guaranty Agreement as a condition to
increasing the available Commitment. In addition, immediately upon Borrower's
acquisition of the stock of SDL, SDL shall become a Guarantor for all purposes
under the Credit Agreement and other Loan Documents, and, accordingly, SDL shall
execute a Guaranty Agreement in substantially the same form as the Guaranty
Agreement executed by the existing Guarantors on the date hereof. All Guarantors
shall also execute a replacement Contribution and Indemnification Agreement.

         7. ACQUISITION OF SDL. If Borrower's acquisition of the stock of SDL is
consummated, then from and after the date of such acquisition, due to the change
in Tangible Net Worth that will result from the goodwill acquired in such
transaction, Section 6.10 of the Credit Agreement shall be amended such that
effective as of the date of the acquisition of SDL, (i) the number in clause (a)
thereof shall be reduced to $30,000,000. If the acquisition of SDL does not
occur for any reason, the foregoing amendment shall not become effective.

         8. DEFINITION OF DOCUMENTS. All references to the Credit Agreement
therein and in the other Loan Documents shall mean the Credit Agreement as
amended hereby. The definition of "Loan Documents", as defined in and as used in
the Credit Agreement, each Guaranty Agreement and all other Loan Documents,
shall be, and is hereby, modified to include this Modification Agreement and any
and all documents executed in connection herewith, including without limitation
the Second Restated Note.

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         9. CONDITIONS PRECEDENT TO THIS MODIFICATION AGREEMENT. As conditions
precedent to this Modification Agreement and the agreements herein and
modifications to the Credit Agreement pursuant hereto, all of the following
shall have been satisfied:

         (a) Borrower and the Guarantors shall have executed and delivered to
Lender this Modification Agreement;

         (b) Borrower shall have executed and delivered to Lender the original
Second Restated Note;

         (c) Borrower and Guarantors shall have executed and deliverd the
Security Agreement;

         (d) Each Guarantor shall have executed and delivered an amended and
restated Guaranty Agreement and an amended and restated Contribution and
Indemnification Agreement;

         (e) Borrower shall have delivered, or cause to be delivered, to Lender
all corporate resolutions, consents, certificates or documents as Lender may
request relating to (i) the existence of Borrower and the Guarantors, and (ii)
the corporate authority for the execution, enforceability and validity of the
Second Restated Note and this Modification Agreement, together with all other
documents, instruments and agreements and any other matters relevant hereto or
thereto, all in form and content satisfactory to Lender;

         (f) Borrower shall have paid to Lender the $1,000.00 commitment fee for
the increase of the Available Commitment as agreed to between Borrower and
Lender, the reasonable attorneys' fees and expenses of Lender's counsel, and any
other fees as agreed in connection with this Modification Agreement; and

         (g) No Default of Event of Default shall exist.

         10. REAFFIRMATION OF OBLIGATIONS. Borrower and the Guarantors
acknowledge and agree that they are well and truly indebted to Lender pursuant
to the Credit Agreement, the respective Guaranty Agreements, the Second Restated
Note and the other Loan Documents, as modified hereby. Except as expressly
modified hereby and by the amended and restated Guaranty Agreement, all terms,
provisions, representations, warranties, covenants and agreements of Borrower
and each Guarantor contained in the Credit Agreement, each Guaranty Agreement,
and the other Loan Documents shall remain unchanged are hereby ratified and
confirmed by Borrower and the Guarantors, and all such agreements shall be and
shall remain in full force and effect, enforceable in accordance with their
terms.

         11. NO IMPLIED WAIVERS. None of the amendments or modifications
provided for herein shall be deemed a consent to or waiver of any breach of the
same or any other covenant, condition or duty. Borrower and the Guarantors
acknowledge and understand that Lender has no obligation to further amend or
modify the Credit Agreement, the Note, the Second Restated Note or any of the
other Loan Documents, or any of the terms, provisions or covenants thereof, and
that Lender has made no representations regarding any such amendments or
modifications. No

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failure or delay on the part of Lender in exercising, and no course of dealing
with respect to, any right, power or privilege under this Modification
Agreement, the Credit Agreement, the Guaranty Agreements, or any other Loan
Document shall operate as a waiver thereof or of the exercise of any other
right, power or privilege.

         12. REPRESENTATIONS AND WARRANTIES. Borrower hereby represents and
warrants to Lender that (a) the execution, delivery, and performance by the
Borrower and the Guarantors of this Modification Agreement and compliance with
the terms and provisions hereof (i) have been duly authorized by all requisite
action on the part of each such Person and (ii) do not, and will not violate or
conflict with, or result in a breach of, or require any consent under (A) the
articles of incorporation, certificate of incorporation, bylaws, partnership
agreement or other organizational documents of any such Person, (B) any
applicable law, rule, or regulation or any order, writ, injunction, or decree of
any Tribunal or arbitrator, or (C) any material agreement or instrument to which
any such Person is a party or by which any of them or any of their property is
bound or subject; (b) the signatories below have been duly authorized by all
necessary corporate action to make and enter this Modification Agreement as the
duly authorized action and deed of Borrower and the Guarantors; (c) the
representations and warranties contained in the Credit Agreement, as amended
hereby, and the other Loan Documents are true and correct in all material
respects on and as of the date hereof as though made on and as of the date
hereof; and (d) upon execution and effectiveness hereof, no Default or Event of
Default has occurred and is continuing.

         13. RATIFICATION. Except as otherwise expressly modified by this
Modification Agreement and the Second Restated Note, all terms and provisions of
the Credit Agreement, the Guaranty Agreements and the other Loan Documents shall
remain unchanged and are ratified and confirmed and shall be and shall remain in
full force and effect, enforceable in accordance with their terms.

         14. FURTHER ASSURANCES. Borrower shall execute and deliver to Lender
such other documents as may be necessary or as may be required, in the opinion
of Lender and/or counsel to Lender to effect the transactions contemplated
hereby and to create and evidence the rights and remedies of the Lender under
the Loan Documents.

         15. INCONSISTENT PROVISIONS. This Modification Agreement shall control
in the case of any inconsistency between the terms and provisions hereof and
those contained in the other Loan Documents.

         16. BINDING AGREEMENT. This Modification Agreement shall be binding
upon, and shall inure to the benefit of, the parties hereto and their respective
legal representatives, successors and assigns.

         17. GOVERNING LAW. THIS MODIFICATION AGREEMENT SHALL BE CONSTRUED IN
ACCORDANCE WITH AND GOVERNED BY THE LAWS OF THE STATE OF NEW MEXICO, EXCEPT TO
THE EXTENT THAT UNITED STATES FEDERAL LAW APPLIES.

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         18. COUNTERPARTS; TELECOPIES. This Modification Agreement may be
executed in multiple counterparts, each of which shall be deemed an original for
all purposes, and all of which, collectively, shall constitute one agreement. In
addition, due execution of this Modification Agreement by any party may be
evidenced by a telecopy reflecting such party's signature. Any party to this
Modification Agreement shall be entitled to receive upon request, from any other
party that has previously forwarded an executed counterpart of any such document
by telecopy, a duplicate of such document bearing such other party's ink
original signature.

         19. ENTIRE AGREEMENT. This Modification Agreement, the Credit
Agreement, the Second Restated Note and the Guaranty Agreements together with
the other Loan Documents, contain the entire agreement between the parties
relating to the subject matter hereof and thereof.

         THIS MODIFICATION AGREEMENT, TOGETHER WITH THE CREDIT 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.


       [Remainder of Page Intentionally Left Bank -- Signatures to Follow]



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         IN WITNESS WHEREOF, this Modification Agreement is 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


                             LENDER:

                             BANK OF AMERICA, N.A., formerly NationsBank, N.A.,
                             a national banking association


                             By: /s/  John A. Sanchez
                                 -------------------------------
                             Name: John A. Sanchez
                                   -----------------------------
                             Title: Senior Vice President
                                    ----------------------------

                             GUARANTORS:

                             SBS TECHNOLOGIES, INC. CONNECTIVITY
                             PRODUCTS, f/k/a SBS Bit 3 Operations, Inc.

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

                             SBS TECHNOLOGIES, INC. TELEMETRY AND
                             COMMUNICATIONS PRODUCTS, f/k/a SBS Berg
                             Telemetry Systems, Inc.

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

                                  Page 7
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                             SBS TECHNOLOGIES INC. MODULAR I/O, f/k/a SBS
                             Greenspring Modular I/O, Inc.

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

                             SBS TECHNOLOGIES, INC. EMBEDDED
                             COMPUTERS, f/k/a SBS Embedded Computers, Inc.

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

                             SBS TECHNOLOGIES INC. INDUSTRIAL
                             COMPUTERS, f/k/a SBS Micro Alliance, Inc.

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

                             SBS TECHNOLOGIES INC. COMMUNICATIONS
                             PRODUCTS, f/k/a VI Computer

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


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