Document:

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                                                                     EXHIBIT 4.2

                            CERTIFICATE OF AMENDMENT
                                     TO THE
                      RESTATED CERTIFICATE OF INCORPORATION
                                       OF
                        INTEGRATED SECURITY SYSTEMS, INC.

         Integrated Security Systems, Inc., a corporation organized and existing
under and by virtue of the General Corporation Law of the State of Delaware (the
"Corporation"), does hereby certify that:

         FIRST: The name of the Corporation is Integrated Security Systems, Inc.

         SECOND: The Board of Directors of the Corporation, by the unanimous
written consent of its members, adopted a resolution proposing and declaring
advisable that (i) the number of authorized shares of the Corporation's Common
Stock, par value $.01 per share, be increased from 7,500,000 shares to
11,000,000 and (ii) 750,000 shares of the Corporation's Preferred Stock, par
value $.01 per share, be authorized by adopting the following amendment to the
Restated Certificate of Incorporation of the Corporation:

                  Articles FOURTH AND FIFTH shall be amended in their entirety
as follows:

         "FOURTH: The total number of shares of stock which the Corporation
         shall have authority to issue is 11,750,000 shares, of which 11,000,000
         shares shall be Common Stock, par value $.01 per share ("Common
         Stock"), and 750,000 shares shall be Preferred Stock, par value $.01
         per share ("Preferred Stock").

         FIFTH: From time to time the Corporation may issue its authorized
         shares for such consideration per share (with respect to shares having
         a par value, not less than the par value thereof), either in money or
         money's worth of property or services, and for such other
         consideration, whether greater or less, now or from time to time
         hereafter permitted by law, as may be fixed by the Board of Directors;
         and all shares so issued shall be fully paid and nonassessable.

         No holder of any shares of any class shall as such holder have any
         preemptive right to subscribe for or purchase any other shares or
         securities of any class, whether now of hereafter authorized, which at
         any time may be offered for sale or sold by the Corporation.

         The Corporation may issue Preferred Stock from time to time in one or
         more series as the Board of Directors may establish by the adoption of
         a resolution or resolutions relating thereto, each series to have such
         voting powers, full or limited, or no voting powers, and such
         designations, preferences and relative, participating, optional or
         other special rights, and qualifications, limitations or restrictions
         thereof, as shall be stated and expressed in the resolution or
         resolutions providing for the issue of such

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         series adopted by the Board of Directors pursuant to authority to do
         so, which authority is hereby granted to the Board of Directors."

         THIRD: The resolution adopted by the Board of Directors has been duly
adopted by vote of the holders of a majority of the outstanding Common Stock at
a Special Meeting of Stockholders called and held in accordance with the
provisions of Sections 211 and 222 of the General Corporation Law of the State
of Delaware, as an amendment to the Restated Certificate of Incorporation of the
Corporation.

         FOURTH: The aforesaid amendment was duly adopted in accordance with the
applicable provisions of Section 242 of the General Corporation Law of the State
of Delaware.

         IN WITNESS WHEREOF, Integrated Security Systems, Inc. has caused this
certificate to be signed by its Chief Executive Officer and President and
attested to by its Secretary, this 19th day of January, 1995.

                                    INTEGRATED SECURITY SYSTEMS, INC.

                                    By:    /s/ Ferdinand A. Hauslein, Jr.
                                          -------------------------------
                                          Ferdinand A. Hauslein, Jr.
                                          Chief Executive Officer and President

ATTEST:

 /s/ William S. Leftwich
---------------------------
     William S. Leftwich
---------------------------
Secretary

STATE OF TEXAS

COUNTY OF DALLAS

         Before me this 19th day of January, 1995, appeared Ferdinand A.
Hauslein, Jr., Chief Executive Officer and President of Integrated Security
Systems, Inc., who acknowledged that the foregoing instrument is the act and
deed of the Corporation and that the facts stated therein are true.

                                               /s/ Dianne Boysen
                                            -----------------------------------
                                            Notary Public in and for the
                                            State of Texas

                                            (Notary Seal)<PAGE>

                                                                     EXHIBIT 4.3

                            CERTIFICATE OF AMENDMENT
                                     TO THE
                      RESTATED CERTIFICATE OF INCORPORATION
                                       OF
                        INTEGRATED SECURITY SYSTEMS, INC.

         Integrated Security Systems, Inc., a corporation organized and existing
under and by virtue of the General Corporation Law of the State of Delaware (the
"Corporation"), does hereby certify that:

         FIRST: The name of the Corporation is Integrated Security Systems, Inc.

         SECOND: The Board of Directors of the Corporation, by the unanimous
written consent of its members, adopted a resolution proposing and declaring
advisable that the number of authorized shares of the Corporation's Common
Stock, par value $.01 per share, be increased from 11,00,000 shares to
18,000,000 by adopting the following amendment to the Restated Certificate of
Incorporation of the Corporation:

                  Article FOURTH shall be amended in its entirety as follows:

         "FOURTH: The total number of shares of stock which the Corporation
         shall have authority to issue is 18,750,000 shares, of which 18,000,000
         shares shall be Common Stock, par value $.01 per share ("Common
         Stock"), and 750,000 shares shall be Preferred Stock, par value $.01
         per share ("Preferred Stock")."

         THIRD: The resolution adopted by the Board of Directors has been duly
adopted by vote of the holders of a majority of the outstanding Common Stock at
a Special Meeting of Stockholders called and held in accordance with the
provisions of Sections 211 and 222 of the General Corporation Law of the State
of Delaware, as an amendment to the Restated Certificate of Incorporation of the
Corporation.

<PAGE>

         FOURTH: The aforesaid amendment was duly adopted in accordance with the
applicable provisions of Section 242 of the General Corporation Law of the State
of Delaware.

         IN WITNESS WHEREOF, Integrated Security Systems, Inc. has caused this
certificate to be signed by its President and attested to by its Secretary, as
of May 7, 1996.

                                     INTEGRATED SECURITY SYSTEMS, INC.

                                     By:       /s/ Gerald K. Beckmann
                                              ----------------------------------
                                              Gerald K. Beckmann
                                              President<PAGE>

                                                                     EXHIBIT 4.4

                            CERTIFICATE OF AMENDMENT
                                     TO THE
                      RESTATED CERTIFICATE OF INCORPORATION
                                       OF
                        INTEGRATED SECURITY SYSTEMS, INC.

         Integrated Security Systems, Inc., a corporation organized and existing
under and by virtue of the General Corporation Law of the State of Delaware (the
"Corporation"), does hereby certify that:

         FIRST: The name of the Corporation is Integrated Security Systems, Inc.

         SECOND: The Board of Directors of the Corporation, by the unanimous
written consent of its members, adopted a resolution proposing and declaring
advisable that the number of authorized shares of the Corporation's Common
Stock, par value $.01 per share, be increased from 18,000,000 shares to
30,000,000 by adopting the following amendment to the Restated Certificate of
Incorporation of the Corporation:

                  Article FOURTH shall be amended in its entirety as follows:

                  "FOURTH: The total number of shares of stock which the
         Corporation shall have authority to issue is 30,750,000 shares, of
         which 30,000,000 shares shall be Common Stock, par value $.01 per share
         ("Common Stock"), and 750,000 shares shall be Preferred Stock, par
         value $.01 per share ("Preferred Stock")."

         THIRD: The resolution adopted by the Board of Directors has been duly
adopted by vote of the holders of a majority of the outstanding Common Stock at
a Special Meeting of Stockholders called and held in accordance with the
provisions of Sections 211 and 222 of the General Corporation Law of the State
of Delaware, as an amendment to the Restated Certificate of Incorporation of the
Corporation.

         FOURTH: The aforesaid amendment was duly adopted in accordance with the
applicable provisions of Section 242 of the General Corporation Law of the State
of Delaware.

         IN WITNESS WHEREOF, Integrated Security Systems, Inc. has caused this
certificate to be signed by its President, as of May 1, 1997.

                                 INTEGRATED SECURITY SYSTEMS, INC.

                                 By:  /s/ Gerald K. Beckmann
                                      ------------------------------------------
                                      Gerald K. Beckmann
                                      President

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