AMENDMENT NO. 5
                                       TO
                           THIRD AMENDED AND RESTATED
                     REVOLVING CREDIT AND SECURITY AGREEMENT

         THIS  AMENDMENT  NO. 5  ("Amendment")  is entered into as of April,
1997, among GENERAL DATACOMM INDUSTRIES, INC., a corporation organized under the
laws of the State of Delaware,  GENERAL DATACOMM,  INC., a corporation organized
under  the laws of the  State of  Delaware,  GDC  REALTY,  INC.,  a  corporation
organized  under  the  laws of the  State  of  Texas,  GDC  NAUGATUCK,  INC.,  a
corporation organized under the laws of the State of Delaware,  GENERAL DATACOMM
INTERNATIONAL  CORP.,  a  corporation  organized  under the laws of the State of
Delaware, GDC FEDERAL SYSTEMS, INC. (formerly known as GENERAL DATACOMM SYSTEMS,
INC.), a corporation  organized  under the laws of the State of Delaware (each a
"Borrower"  and  jointly  and  severally,  the  "Borrowers"),   the  undersigned
financial  institutions  (each a "Lender" and  collectively,  "Lenders") and THE
BANK OF NEW YORK COMMERCIAL CORPORATION  ("BNYCC"),  a New York corporation,  as
agent for Lenders (BNYCC in such capacity, "Agent").

                                   BACKGROUND

         Borrowers,  Lenders  and  Agent  are  parties  to a Third  Amended  and
Restated  Revolving Credit and Security  Agreement dated as of November 30, 1995
(as amended,  supplemented  or otherwise  modified from time to time,  the "Loan
Agreement")  pursuant to which Lenders provide  Borrowers with certain financial
accommodations.

         Borrowers  have  requested  that Lenders amend certain of the financial
covenants  contained in the Loan  Agreement and Agent and Lenders are willing to
do so on the terms and conditions hereafter set forth.

         NOW,  THEREFORE,  in  consideration  of any loan or advance or grant of
credit  heretofore  or  hereafter  made to or for the  account of  Borrowers  by
Lenders or Agent, and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto hereby agree as
follows:

         1. Definitions.  All capitalized terms not otherwise defined herein
 shall have the meanings given to them in the Loan Agreement.

         2. Amendment to Loan Agreement.  Subject to satisfaction of the 
conditions precedent set forth in Section 3 below, the Loan Agreement is hereby
amended as follows:

        (a) Section 6.5 of the Loan Agreement is amended in its entirety 
to provide as follows:

<PAGE>

                  "6.5   Tangible Net Worth.  Cause to be maintained at the
end of each fiscal quarter a Tangible Net Worth in an amount not less than the 
amount set opposite such fiscal quarter end below:

     FISCAL QUARTER ENDING              MINIMUM TANGIBLE NET WORTH
     ---------------------              --------------------------
     March 31, 1997                     $70,044,000
     June 30, 1997                      $60,503,000
     September 30, 1997                 $55,119,000
          
     December 31, 1997 and at the       the sum of (i) (a) $77,566,000
     end of each fiscal quarter         if the minimum Tangible Net Worth at
     thereafter                         the end of the fiscal quarter ending
                                        June 30, 1997 is less than $80,566,000
                                        or (b) an amount equal to the actual    
                                        Tangible Net Worth at the end of the
                                        fiscal quarter ending June 30, 1997 
                                        less $3,000,000 if such actual Tangible
                                        Net Worth is equal to or greater than
                                        $80,566,000 plus (ii) the product of
                                        (x) 75% times (y) Net Income (if   
                                        positive) during the fiscal quarter
                                        then ended (excluding net additions to
                                        capitalized software) plus (iii) the
                                        product of (x) 75% times (y) the sum
                                        of additional equity contributed to GDC
                                        (excluding stock options and stock
                                        purchase plan payments) and the amount
                                        of subordinated debt proceeds received
                                        by GDC and its Subsidiaries on a
                                        consolidated basis during such fiscal
                                        quarter."

             (b)  Section 6.6 of the Loan Agreement is amended in its entirety
 to provide as follows:

                  "6.6 Total  Liabilities  to  Tangible  Net Worth.  Cause to be
maintained as of the end of each fiscal quarter a ratio of Total  Liabilities to
Tangible  Net  Worth of not  greater  than the ratio set  opposite  such  fiscal
quarter end below:

                                                     RATIO OF TOTAL
                                                     LIABILITIES
         FISCAL QUARTER END                          TO TANGIBLE NET WORTH
         ------------------                          ---------------------
         March 31, 1997                              1.20 to 1.0
         June 30, 1997                               1.45 to 1.0
         September 30, 1997                          1.70 to 1.0
         December 31, 1997                           1.00 to 1.0
         March 31, 1998                              1.00 to 1.0
         June 30, 1998                               0.95 to 1.0

                                     - 2 -
<PAGE>

         September 30, 1998                          0.95 to 1.0"

         (c)   Section 6.7 of the Loan Agreement is amended in its entirety
to provide as follows:

                  "6.7 Fixed Charge Coverage Ratio. Cause to be maintained as of
the end of each fiscal quarter a Fixed Charge Coverage Ratio for the immediately
preceding  fiscal  quarter  equal to or greater than the ratio set opposite such
fiscal quarter end below:

                                                     FIXED CHARGE
         FISCAL QUARTER ENDING                       COVERAGE RATIO
         ---------------------                       --------------
         March 31, 1997                              (3.36) to 1.00
         June 30, 1997                               (2.31) to 1.00
         September 30, 1997                          (0.99) to 1.00
         December 31, 1997                            1.30  to 1.00
         March 31, 1998                               1.40 to 1.00
         June 30, 1998                                1.50 to 1.00
         September 30, 1998                           1.60 to 1.00"

         (d)   Section 6.8 of the Loan Agreement is amended in its entirety 
to provide as follows:

                  "6.8   Net Income.  Cause Net Income (loss) for each fiscal
period set forth below to be not less than (more than) the amount set opposite
such fiscal period below:

         FISCAL PERIOD                               NET INCOME (LOSS)
         -------------                               -----------------
         October 1, 1996 - March 31, 1997            ($18,700,000)
         January 1, 1997 - June 30, 1997             ($21,700,000)
         October 1, 1996 - September 30, 1997        ($33,651,000)

         April 1, 1997 - September 30, 1997          ($16,700,000)
         July 1, 1997 - December 31, 1997             $        -0-
         October 1, 1997 - March 31, 1998             $ 1,000,000
         January 1, 1998 - June 30, 1998              $ 2,000,000
         October 1, 1997 - September 30, 1998         $ 4,000,000

         April 1, 1998 - September 30, 1998           $ 3,000,000"


         (e)   Section 6.9 of the Loan Agreement is amended in its entirety 
to provide as follows:

                  "6.9   Working Capital.  Cause to be maintained as of the
end of each fiscal quarter, Working Capital in an amount not less than the 
amount set opposite such fiscal quarter end below.

         FISCAL QUARTER END                       WORKING CAPITAL
         ------------------                       ---------------
         March 31, 1997                           $45,059,000
         June 30, 1997                            $35,736,000
         September 30, 1997                       $30,695,000
         December 31, 1997                        $53,000,000

                                     - 3 -
<PAGE>

         March 31, 1998                           $55,000,000
         June 30, 1998                            $57,000,000
         September 30, 1998                       $60,000,000"

         3. Conditions of  Effectiveness.  This Amendment shall become effective
upon  satisfaction  of the  following  conditions  precedent:  Agent  shall have
received  (i) four (4)  copies  of this  Amendment  executed  by  Borrowers  and
consented and agreed to by  Guarantors,  (ii) an amendment  fee of $10,000,  and
(iii) such other certificates,  instruments,  documents, agreements and opinions
of counsel as may be required by Agent, Lenders or their counsel,  each of which
shall be in form and substance satisfactory to Agent, Lenders and their counsel.

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

                           (a) This Amendment and the Loan Agreement, as amended
                  hereby,  constitute  legal,  valid and binding  obligations of
                  Borrowers and are enforceable  against Borrowers in accordance
                  with their respective terms.

                           (b) Upon the  effectiveness  of this Amendment,  each
                  Borrower hereby reaffirms all covenants,  representations  and
                  warranties  made in the Loan  Agreement to the extent the same
                  are not  amended  hereby  and agree  that all such  covenants,
                  representations  and  warranties  shall be deemed to have been
                  remade as of the effective date of this Amendment.

                           (c) No Event of Default or Default has  occurred  and
                  is  continuing  or would  exist  after  giving  effect to this
                  Amendment.

                           (d) Borrowers have no defense, counterclaim or 
                  offset with respect to the Loan Agreement.

         5.       Effect on the Loan Agreement.

         (a) Upon the  effectiveness of Section 2 hereof,  each reference in the
Loan Agreement to "this Agreement,"  "hereunder," "hereof," "herein" or words of
like  import  shall mean and be a  reference  to the Loan  Agreement  as amended
hereby.

         (b) Except as specifically amended herein, the Loan Agreement,  and all
other  documents,  instruments  and  agreements  executed  and/or  delivered  in
connection  therewith,  shall  remain in full force and  effect,  and are hereby
ratified and confirmed.

         (c) The execution,  delivery and  effectiveness of this Amendment shall
not operate as a waiver of any right,  power or remedy of Agent or Lenders,  nor
constitute  a waiver  of any  provision  of the  Loan  Agreement,  or any  other
documents,  instruments  or agreements  executed  and/or  delivered  under or in
connection therewith.

                                     - 4 -
<PAGE>

         6.       Governing Law.  This Amendment shall be binding upon and 
inure to the benefit of the parties hereto and their respective successors and 
assigns and shall be governed by and construed in accordance with the laws of 
the State of New York.

         7.       Headings.  Section headings in this Amendment are included
herein for convenience of reference only and shall not constitute a part of 
this Amendment for any other purpose.

         8.       Counterparts.  This Amendment may be executed by the parties 
hereto in one or more counterparts, each of which shall be deemed an original 
and all of which when taken together shall constitute one and the same 
agreement.

        IN WITNESS WHEREOF, this Amendment has been duly executed as of the day
and year first written above.
                                            GENERAL DATACOMM INDUSTRIES, INC.
                                            GENERAL DATACOMM, INC.
                                            GDC REALTY, INC.
                                            GDC NAUGATUCK, INC.
                                            GENERAL DATACOMM INTERNATIONAL CORP.
                                            GDC FEDERAL SYSTEMS, INC.

                                            By:  /s/ DENNIS J. NESLER
                                            --------------------------
                                            Dennis J. Nesler, the Vice-
                                            President of each of the foregoing
                                            corporations


                                             THE BANK OF NEW YORK COMMERCIAL
                                             CORPORATION, as Agent and Lender

                                             By:  /s/ RYAN PEAK
                                             -------------------------------
                                             Name:  Ryan Peak
                                             Its:  Vice President

CONSENTED AND AGREED TO:

DATACOMM RENTAL CORPORATION

By:  /s/ DENNIS J. NESLER
-------------------------
Name: Dennis J. Nesler
Its:  Vice President & Treasurer



GENERAL DATACOMM LTD.

By:  /s/ DENNIS J. NESLER
--------------------------
Name: Dennis J. Nesler
Its:  Vice President & Treasurer

                                     - 5 -

<PAGE>

GENERAL DATACOMM FRANCE S.A.R.L.

By:  /s/ DENNIS J. NESLER
--------------------------
Name: Dennis J. Nesler
Its:  Vice President & Treasurer



GENERAL DATACOMM DE MEXICO S.A. DE C.V.

By:  /s/ DENNIS J. NESLER
--------------------------
Name: Dennis J. Nesler
Its:  Vice President & Treasurer



GENERAL DATACOMM PTY LIMITED

By:  /s/ DENNIS J. NESLER
--------------------------
Name: Dennis J. Nesler
Its:  Vice President & Treasurer



GENERAL DATACOMM S.A.R.L.

By:  /s/ DENNIS J. NESLER
--------------------------
Name: Dennis J. Nesler
Its:  Vice President & Treasurer

                                          - 6 -