Document:

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                                                                  EXHIBIT 10.5.1

                       AMENDMENT TO AMENDED AND RESTATED
                                CREDIT AGREEMENT

          THIS AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT (this
"Amendment"), dated as of February 20, 2001 by and among Safeguard Scientifics,
Inc., a Pennsylvania corporation ("SSI" or a "Borrower"), Safeguard Scientifics
(Delaware) Inc., a Delaware corporation ("SSD" or a "Borrower"), Safeguard
Delaware, Inc., a Delaware corporation ("SDI" or a "Borrower" and, collectively
with SSI and SSD, the "Borrowers") and PNC Bank, National Association ("PNC") as
agent for the "Lenders" under the Loan Agreement, and each of the "Lenders"
signatory hereto.

BACKGROUND

          A.   The parties entered into that certain Amended and Restated Credit
Agreement dated April 18, 2000 (as amended to date, the "Loan Agreement").

          B.   Lenders and the Borrowers desire to amend the Loan Agreement in
the manner hereinafter set forth.

          C.   Capitalized terms that are not defined herein shall have the
meanings ascribed to them in the Loan Agreement.

          D.   Subject to compliance with all conditions specified herein, all
amendments hereinafter set forth are effective as of the date hereof unless
otherwise expressly stated herein to the contrary.

          NOW, THEREFORE, intending to be legally bound, the parties agree as
follows:

          1.   Waiver of Covenant Violation.  Lenders hereby waive violations by
               ----------------------------
the Borrower of Section 6.8 of the Loan Agreement (Tangible Net Worth) for the
period (the "Waiver Period") 12/31/00 through and including 3/30/01, provided
that Borrowers agree to maintain Tangible Net Worth during the Waiver Period of
not less than $1,000,000,000.  Borrowers will be in compliance with Section 6.8
as of 3/31/01 and thereafter.

          2.   Rate of Interest.   Section 2.8(c)(i)(B) of the Loan Agreement
               ----------------
("LIBOR Rate") is, effective as of February 22, 2001, amended and restated in
its entirety as follows:

          "LIBOR Rate" means for any day during each Rate Period (a) the per
          ------------
     annum rate of interest (computed on a basis of a year of 360 days and
     actual days elapsed) determined by Agent as being the composite rate
     available to Agent at approximately 11:00 a.m., London time in the London
     Interbank Market, as referenced by Telerate (page 3750), in accordance with
     the usual practice in such market, for the Rate Period elected by
     Borrowers, in effect two (2) Good Business Days prior to the funding date
     for a requested LIBOR Rate advance for deposits of dollars in amounts equal
     (as nearly as may be estimated) to the amount of the LIBOR Rate advance
     which shall then be loaned by the Lenders to Borrowers as of the time of
     such determination, as such rate (the "Base Rate") may be adjusted by the
     reserve percentage applicable during the Rate Period in effect (or if more
     than one such percentage shall be applicable, the daily average of such
     percentages for those days in such Rate Period during which any such
     percentage shall be so applicable) under regulations issued from time to
     time by the Board of Governors of the Federal Reserve System (or any
     successor) for determining the maximum reserve requirement (including,
     without
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     limitation, any emergency, supplemental or other marginal reserve
     requirement) for the Agent with respect to liabilities or assets consisting
     of or including "Eurocurrency Liabilities" as such term is defined in
     Regulation D of the Board of Governors of the Federal Reserve System, as in
     effect from time to time, having a term equal to such Rate Period
     ("Eurocurrency Reserve Requirement"), plus (b) 2.25 percentage points. Such
                                           ----
     reserve adjustment shall be effectuated by calculating, and the LIBOR Rate
     shall be equal to, (a) the quotient of (i) the Base Rate divided by (ii)
     one minus the Eurocurrency Reserve Requirement, plus (b) 2.25 percentage
                                                     ----
     points."

          3.   Cross Collateralization.   Borrowers agree that, effective as of
               ------------------------
the date hereof, the "Collateral" will now secure both the Revolving Loan I and
the Revolving Loan II. Accordingly, the definition of "Secured Obligations" is
hereby amended to mean all "Obligations" as presently defined in the Loan
Agreement, including all liabilities and obligations of the Borrowers in
connection with both the Revolving Loan I and the Revolving Loan II. The Pledge
Agreement, as defined in the Loan Agreement, is deemed amended hereby to reflect
the foregoing.

          4.   Miscellaneous.
               -------------

          A.   Construction.   Except to the extent any provision of this
               ------------
Amendment restates or otherwise amends a provision of the Loan Agreement, the
provisions of this Amendment shall be in addition to those of the Loan
Agreement, the Notes and the Security Documents, all of which shall be construed
as integrated and complementary to each other. In the event of any express
inconsistency between the terms hereof and those contained in the Loan
Agreement, the terms hereof shall control. Except as modified by the terms
hereof, all terms and provisions of the Loan Agreement remain unchanged and in
full force and effect.

          B.   Binding Effect; Assignment and Entire Agreement. This Amendment
               -----------------------------------------------
shall inure to the benefit of, and shall be binding upon, the respective
successors and permitted assigns of the parties hereto. Borrowers have no right
to assign any of their rights or delegate any of their obligations hereunder
without the prior written consent of Lenders. This Amendment, together with the
Loan Agreement, the Notes and the Security Documents, constitute the entire
agreement among the parties relating to the subject matter thereof. All exhibits
referred to herein and attached hereto shall be deemed expressly incorporated
herein by reference and made a part hereof.

          C.   Waiver of Jury Trial. Borrowers and Lenders irrevocably waive
               --------------------
trial by jury and the right thereto in any litigation in any court with respect
to, in connection with, or arising out of, this Amendment, the Notes, Security
Documents, or any instrument or document delivered pursuant to this Amendment,
or the validity, protection, interpretation, collection or enforcement thereof.

          D.   Expenses. In addition to all other expense reimbursement
               --------
obligations of the Borrowers contained in the Loan Agreement and the Security
Documents, Borrowers will reimburse Lenders for all costs and expenses,
including reasonable attorneys' fees, incurred by Lenders in the negotiation,
preparation and consummation of this Amendment and the documents to be delivered
pursuant hereto.

          E.   Reaffirmation and Release. Borrowers ratify and reaffirm all of
               --------------------------
their Obligations to Lenders and agree that the same are owing without set-off,
counterclaim or other defense of any nature. Borrowers specifically ratify and
reaffirm all waiver of jury trial provisions set forth in the Loan Agreement,
the Notes and the Security Documents.

                                      -2-
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               IN WITNESS WHEREOF, the parties hereto have caused this Amendment
to be executed and delivered by their duly authorized officers as of the day and
year first above written.

                                             LENDERS:

                                             PNC BANK, NATIONAL ASSOCIATION
                                             By: /S/ Joseph G. Meterchick
                                                 -------------------------------
                                             Name: Joseph G. Meterchick
                                                   -----------------------------
                                             Title: Vice President
                                                    ----------------------------

                                             SUMMIT BANK
                                             By: /S/ Jeff Southworth
                                                 -------------------------------
                                             Name: Jeff Southworth
                                                   -----------------------------
                                             Title: Vice President
                                                    ----------------------------

                                             FIRST UNION NATIONAL BANK
                                             By: /S/ Richard Wolbach
                                                 -------------------------------
                                             Name: Richard Wolbach
                                                   -----------------------------
                                             Title: Vice President
                                                    ----------------------------

                                             U.S. BANK NATIONAL ASSOCIATION
                                             By: /S/ Mark R. Olmon
                                                 -------------------------------
                                             Name: Mark R. Olmon
                                                   -----------------------------
                                             Title: Senior Vice President
                                                    ----------------------------

                                             MELLON BANK, N.A.
                                             By: /S/ Donald G. Cassidy, Jr.
                                                 -------------------------------
                                             Name: Donald G. Cassidy, Jr.
                                                   -----------------------------
                                             Title: Senior Vice President
                                                    ----------------------------

                                             NATIONAL CITY BANK OF PENNSYLVANIA
                                             By: /S/ Charles P. Bugajski
                                                 -------------------------------
                                             Name: Charles P. Bugajski
                                                   -----------------------------
                                             Title: Vice President
                                                    ----------------------------

                                             COMERICA BANK
                                             By: /S/ Alan Jepsen
                                                 -------------------------------
                                             Name: Alan Jepsen
                                                   -----------------------------
                                             Title: Senior Vice President
                                                    ----------------------------

                                             BANK OF AMERICA, N.A.
                                             By: /S/ Jouni Korhonen
                                                 -------------------------------
                                             Name: Jouni Korhonen
                                                   -----------------------------
                                             Title: Managing Director
                                                    ----------------------------

                                      -3-
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               SIGNATURES CONTINUED.....

                                        WILMINGTON TRUST
                                        By: /S/ Jerald C. Goodwin
                                            ------------------------------------
                                        Name: Jerald C. Goodwin
                                              ----------------------------------
                                        Title: Vice President
                                               ---------------------------------

                                        BORROWERS:

                                        SAFEGUARD SCIENTIFICS, INC.
                                        By: /S/ Gerald A. Blitstein
                                            ------------------------------------
                                        Name: Gerald A. Blitstein
                                              ----------------------------------
                                        Title: Executive Vice President and CFO
                                               ---------------------------------

                                        SAFEGUARD SCIENTIFICS (Delaware) INC.
                                        By: /S/ NJ Klauder
                                            ------------------------------------
                                        Name: NJ Klauder
                                              ----------------------------------
                                        Title: Vice President
                                               ---------------------------------

                                        SAFEGUARD DELAWARE, INC.
                                        By: /S/ NJ Klauder
                                            ------------------------------------
                                        Name: NJ Klauder
                                              ----------------------------------
                                        Title: Vice President
                                               ---------------------------------

                                      -4-<PAGE>

                                                                   EXHIBIT 10.20

                              GUARANTY OF ACCOUNT

                                                         Dated:  October 4, 2000

To:  Legg Mason Wood Walker, Incorporated

1.   In consideration of your continuing the extension of the margin loans in
     the principal amount existing on the date hereof (such margin loans, the
     "Guaranteed Loans") to the Warren V. Musser Foundation Inc Legg Mason
     Account (Number [INTENTIONALLY OMITTED]) (the "Foundation Account") and the
     Warren V. Musser Legg Mason Account (Number [INTENTIONALLY OMITTED]) (the
     "Musser Account") (including without limitation the margin loans extended
     to other accounts which are guaranteed on the date hereof by the Musser
     Account), (which separately or jointly, with any and all renewals thereof,
     are hereinafter referred to as the "guaranteed accounts") the undersigned
     (hereinafter referred to as the "Guarantor") hereby unconditionally agrees
     to pay you, on demand, any indebtedness (including interest) that may now
     or hereafter be owing you by Warren V. Musser or the Warren V. Musser
     Foundation (collectively, the "Clients") Clients in respect of the
     Guaranteed Loans to the guaranteed accounts, provided however that
     notwithstanding anything else in this guaranty to the contrary the
     Guarantor's obligations hereunder shall in no event exceed $35,000,000 in
     the aggregate.

2.   The Guarantor's obligations hereunder shall not be affected by the
     validity, regularity or enforceability of the indebtedness, or by the
     existence validity, enforceability, perfection, or extent of any collateral
     therefor or by any other circumstance relating to the indebtedness which
     might otherwise constitute a defense to this guaranty. You make no
     representation or warranty in respect to any such circumstance and have no
     duty or responsibility whatsoever to the Guarantor in respect of the
     management and maintenance of the indebtedness or any collateral therefor,
     provided however that you agree that you will not extend any further margin
     loans in respect of the Musser Account, the Foundation Account or any of
     the other guaranteed accounts. You shall not be obligated to file any claim
     relating to the indebtedness in the event that any of the Clients become
     subject to a bankruptcy, reorganization or similar proceeding, and the
     failure by you to so file shall not affect the Guarantor's obligations
     hereunder. In the event that any payment to you in respect of any
     indebtedness is rescinded or must otherwise be returned for any reason
     whatsoever, the Guarantor shall remain liable hereunder in respect of such
     indebtedness as if such payment had not been made.

     The Guarantor represents that it has made its own credit analysis with
     respect to the Clients and the indebtedness and has made such arrangements
     with the Clients not inconsistent with the provisions hereof as it has
     deemed appropriate. The Guarantor further represents that it has full power
     and authority to execute, deliver and perform this guaranty in accordance
     with its terms.
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3.   The Guarantor agrees that this guaranty is a continuing one and shall cover
     any present indebtedness plus interest thereon in the guaranteed accounts.
     The Guarantor agrees that the guaranteed accounts may be changed from time
     to time by the sale or exchange of securities or other property, or by
     payments by deliveries of securities or other property by or to or upon the
     order of the Clients; and that, in general, you may accept the orders of
     the Clients with respect to transactions in the guaranteed accounts
     provided, however, that any purchases in the guaranteed accounts or
     withdrawals of cash or securities from the guaranteed accounts require
     prior notice to and prior consent of Guarantor. The Guarantor also agrees
     that after prior notice to Guarantor the guaranteed accounts may be closed
     out by you at any time.

4.   The Guarantor agrees that you may, at any time, but only after notice to
     and consultation with Guarantor and a failure of the guaranteed accounts to
     repay any Guaranteed Loans, use, without restriction, or transfer to the
     guaranteed accounts, the moneys or securities or other property in the
     Guarantor's account specified in Annex A hereto., to secure the guaranteed
     accounts or to pay any indebtedness due therein.

     The Guarantor agrees that you may proceed at any time, in your uncontrolled
     discretion, and without prior demand or notice, to enforce this Guaranty in
     any manner and upon such terms as you may determine; that the enforcement
     by you of your right to transfer in any manner, in whole or in part, shall
     not in any way affect the continuing liability of the Guarantor for any
     indebtedness in the guaranteed accounts; that any demand on the Guarantor
     to perform the obligations of this guaranty, or any action or proceedings
     brought to enforce the liability of the Guarantor hereunder, shall not
     release or otherwise affect said right to transfer; and that you shall at
     all times have both the personal liability of the Guarantor and the right
     to transfer to secure to you payment of any indebtedness in the guaranteed
     accounts, enforcement of both of which may be pursued concurrently.

5.   The Guarantor has deposited cash in the amount of $35,000,000 in the
     Guarantor's account specified in Annex A hereto. The Guarantor has
     authorized you by a separate instrument to invest and reinvest such cash in
     money market instruments, none of which will have a maturity at issuance of
     more than 270 days, or to maintain such cash with you as a free credit
     balance at an interest rate satisfactory to the Guarantor. The Guarantor
     agrees that such cash will at no time be invested in any other manner...The
     Guarantor agrees that the assets in the Guarantor's account specified in
     Annex A may not be withdrawn during the term of this guaranty without your
     prior written approval.

6.   The Guarantor hereby waives any notices, or confirmations whatsoever of
     acceptance by you of this guaranty and as to the current condition of the
     guaranteed accounts or any changes therein from time to time and the manner
     of conducting or closing the same or otherwise. In the event of default by
     either of the Clients, the Guarantor hereby waives any demands or notices
     whatsoever in respect thereof and any requirement of legal or equitable
     proceedings or otherwise on your part against the Clients or any other
     guarantor of said guaranteed account or other securities in the guaranteed
     accounts as a condition precedent to enforcing the obligations of the
     Guarantor hereunder.

7.   The Guarantor agrees not to exercise any rights which it may acquire by way
     of subrogation or by any indemnity, reimbursement or other agreement until
     all the indebtedness to you

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     shall have been paid in full. If any amount shall be paid to the Guarantor
     in violation of the preceding sentence, such amount shall be held in trust
     for the benefit of you and shall forthwith be paid to you to be credited
     and applied to the indebtedness, whether matured or unmatured.

8.   This guaranty shall be binding upon the Guarantor and its successors and
     assigns and shall inure to your benefit and that of any successor firm or
     firms that may take over or continue your business and/or any of the
     guaranteed accounts, irrespective of any changes or changes at any time in
     the personnel thereof, for any cause whatsoever, and to the individual
     officers, directors, employees and agents of your present firm or any
     successor firm.

9.   The Guarantor's obligations hereunder will terminate, as to existing and
     future indebtedness, upon the earlier of (a) September 30, 2001 or (b) such
     day on which each of the guaranteed accounts shall have been in compliance
     for 20 consecutive trading days with all applicable Legg Mason margin
     requirements which will not be changes with respect to the guaranteed
     accounts except in connection with changes generally applicable to all Legg
     Mason margin accounts (assuming the absence of this guaranty). In addition,
     by written notice to you effective upon your receipt of such notice, the
     Guarantor may at any time terminate its obligations and your rights
     hereunder in respect of future transactions in the guaranteed accounts, but
     notwithstanding such termination as to future transactions the obligations
     of the Guarantor hereunder with respect to any indebtedness in the
     guaranteed accounts shall continue in full force and effect until such
     indebtedness with interest to the date of payment thereon has been paid to
     you.

10.  The Guarantor agrees that no agreement on your behalf to waive or modify
     this guaranty or any provision thereof shall be valid or binding unless
     evidenced by a writing signed by an authorized officer of your firm. No
     failure on your part to exercise and no delay in exercising any right,
     remedy or power hereunder shall operate as a waiver thereof, nor shall any
     single or partial exercise by you of any right, remedy or power hereunder
     preclude any other or future exercise of any other right, remedy or power.
     Each and every right, remedy and power hereby granted to you or allowed you
     by law or other agreement shall be cumulative and not exclusive the one of
     any other, and may be exercised by you from time to time.

11.  The Guarantor agrees to pay on demand all out-of-pocket expenses (including
     the reasonable fees and expenses of your counsel) in any way relating to
     the enforcement or protection of your rights hereunder and further agrees
     that the aforementioned collateral secures such payment.

12.  The obligations of the Guarantor under the guaranty shall extend, upon the
     same terms and conditions, to each of your affiliates.

13.  This Agreement and its enforcement shall be governed by, and construed in
     accordance with, the laws of the State of Maryland.

14.  (a) Arbitration is final and binding on the parties.

                                       3
<PAGE>

     (b) The parties are waiving the right to seek remedies in court, including
     the right to a jury trial.

     (c) Pre-arbitration discovery is generally more limited than and different
     from court proceedings.

     (d) The arbitrators' award is not required to include factual findings or
     legal reasoning and any party's right to appeal or to seek modification of
     rulings by the arbitrators is strictly limited.

     (e) The panel of arbitrators will typically include a minority of
     arbitrators who were or are affiliated with the securities industry.

     Any controversy between you (together with any of your affiliates also
     involved in such controversy) or any of your or their officers, directors,
     employees or agents on the one hand and the Guarantor or Guarantor's
     officers, directors, employees or agents on the other hand, arising out of
     or relating to this agreement, the transactions contemplated hereby, the
     accounts established hereunder or the guaranteed accounts shall be settled
     by arbitration, in accordance with the rules then obtaining of The New York
     Stock Exchange, Inc., or any other exchange of which you are a member, or
     the National Association of Securities Dealers, Inc. If the Guarantor does
     not make such election by registered mail addressed to you at your main
     office within ten (10) days after receipt of notification from you
     requesting such election, then the Guarantor authorizes you to make such
     election on the Guarantor's behalf.. The award of the arbitrator shall be
     final, and judgment upon the award rendered may be entered in any court,
     state or federal, having jurisdiction.

     No person shall bring a putative or certified class action to arbitration,
     nor seek to enforce any pre-dispute arbitration agreement against any
     person who has initiated in court a putative class action or who is a
     member of a putative class who has not opted out of the class with respect
     to any claims encompassed by the putative class action until (i) the class
     certification is denied; (ii) the class is decertified; or (iii) the
     Guarantor is excluded from the class by the court.

     Such forbearance to enforce an agreement to arbitrate shall not constitute
     a waiver of any rights under this agreement except to the extent stated
     herein.

15.  Any notice given by the Guarantor to you under this Guaranty of Account
     shall be effective only when received by the General Counsel of Legg Mason
     Wood Walker, Incorporated, 100 Light Street, Baltimore, MD 21202. Any
     notice given by you to the Guarantor under this Guaranty of Account shall
     be effective only when received by the Chief Financial Officer of Safeguard
     Scientifics, Inc., 435 Devon Park Drive, Building 800, Wayne, Pennsylvania
     19087.

     This Guaranty of Account is effective from and after the date on which you
     accept it by signing and returning to the Guarantor, on or after the date
     of this Guaranty of Account set forth above, a copy hereof. By signing this
     Guaranty of Account, the Guarantor acknowledges receipt of a copy hereof. A
     predispute arbitration clause is contained in Paragraph 15 hereof.

                                       4
<PAGE>

                                             SAFEGUARD SCIENTIFICS, INC.

                                             By ...............................

Witnessed:

 ................................

Accepted by Legg Mason Wood Walker, Incorporated

By..............................

Witnessed:

 ................................

Annexes:

A                   Guarantor's Account

                                       5

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