<PAGE>
                 AMENDMENT NO. 1 TO AGREEMENT AND PLAN OF MERGER

     This Amendment No. 1 to Merger Agreement dated as of May 24, 2006 (this
"AMENDMENT"), among Halo Technology Holdings, Inc., a Nevada corporation
("PARENT"), UCA Merger Sub, Inc., a Delaware corporation and wholly-owned
subsidiary of Parent ("MERGER SUB") and Unify Corporation, a Delaware
corporation (the "COMPANY").

                                   WITNESSETH:

     WHEREAS, Parent, Merger Sub and the Company are parties to that certain
Agreement and Plan of Merger, dated as of March 14, 2006 (the "MERGER
AGREEMENT"), and desire to amend the Merger Agreement as set forth herein.

     NOW, THEREFORE, in consideration of the premises and of the mutual
covenants and agreements herein contained, and intending to be legally bound
hereby, the parties hereto do hereby agree as follows (capitalized terms used
but not defined herein have the meanings ascribed to such terms in the Merger
Agreement):

1.   AMENDMENT TO SECTION 7.1. The following provision is added immediately
following Section 7.1 (d):

     (e) Opinion of Counsel to Company. The Parent shall have received from DLA
     Piper Rudnick Gray Cary US LLP, counsel to the Company, an opinion dated as
     of the date the Registration Statement is declared effective, in the form
     mutually agreed to by the parties to the effect that the Merger will
     constitute a reorganization under the provisions of Section 368(a) of the
     Code.

2.   AMENDMENT TO SECTION 7.1. The following provision is added immediately
following Section 7.1 (e):

     (f) Opinion of Tax Counsel to Parent. The Company shall have received from
     Day, Berry & Howard LLP, tax counsel to the Parent, an opinion dated as of
     the date the Registration Statement is declared effective, in the form
     mutually agreed to by the parties to the effect that the Merger will
     constitute a reorganization under the provisions of Section 368(a) of the
     Code.

3.   MISCELLANEOUS.

     (a) The validity, construction and performance of this Amendment, and any
action arising out of or relating to this Amendment shall be governed by the
laws of the State of Delaware, without regard to the laws of the State of
Delaware as to choice or conflict of laws.

     (b) Except as modified herein, all other terms and provisions of the Merger
Agreement are unchanged and remain in full force and effect.
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     (c) The captions contained in this Amendment are for convenience of
reference only, shall not be given meaning and do not form part of this
Amendment.

     (d) This Amendment may be executed in counterparts, each of which shall be
deemed an original, but all of which taken together shall constitute one and the
same instrument. This Amendment shall become effective when each party to this
Amendment shall have received a counterpart hereof signed by the other parties
to this Amendment.

     (e) This Amendment shall be binding upon any permitted assignee,
transferee, successor or assign to any of the parties hereto.

     IN WITNESS WHEREOF, each of the parties has executed this Amendment as of
the date first set forth above.

                                PARENT:

                                HALO TECHNOLOGY HOLDINGS, INC.

                                By: /s/ Ernest C. Mysogland
                                    --------------------------------------------
                                    Name:  Ernest C. Mysogland
                                    Title:  Executive Vice President


                                MERGER SUB:

                                UCA MERGER SUB, INC.

                                By: /s/ Ernest C. Mysogland
                                    --------------------------------------------
                                    Name:  Ernest C. Mysogland
                                    Title:  President and Sole Director


                                COMPANY:

                                UNIFY CORPORATION

                                By: /s/ Todd Wille
                                    --------------------------------------------
                                    Name:  Todd Wille
                                    Title: President and Chief Executive Officer


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