JOINDER AND AMENDMENT TO
                          REGISTRATION RIGHTS AGREEMENT


                  JOINDER AND AMENDMENT TO REGISTRATION  RIGHTS  AGREEMENT dated
September 29, 2000 (the "Joinder  Agreement")  by and among Tidel  Technologies,
Inc., a Delaware  corporation (the "Company"),  Acorn Investment Trust on behalf
of its series Acorn Fund (the "Subsequent  Purchaser") and Montrose  Investments
Ltd. (the "Existing Purchaser").

                               W I T N E S S E T H
                               -------------------

                  WHEREAS,  the Existing Purchaser has entered into that certain
Convertible Debenture Purchase Agreement (the "Montrose Purchase Agreement") and
a Registration Rights Agreement ("Registration Rights Agreement"), each dated as
of  September  8, 2000,  by and among the  Company and the  Existing  Purchaser,
pursuant to which the Existing Purchaser purchased from the Company an aggregate
principal  amount of $15,000,000 of the Company's 6% Convertible  Debentures due
September 8, 2004.

                  WHEREAS,  the  Subsequent  Purchaser  has  entered  into  that
certain Acorn Purchase Agreement (as defined below) of even date herewith by and
among the Company and the Subsequent Purchaser, pursuant to which the Subsequent
Purchaser purchased from the Company an aggregate principal amount of $3,000,000
of the Acorn Debenture.

                  NOW,  THEREFORE,  in  consideration of the premises and of the
mutual  covenants and  agreements of the parties herein  contained,  the parties
hereby agree as follows:

                  Section 1.  Joinder.  Effective  immediately,  the  Subsequent
Purchaser is joined as a party to the Registration  Rights Agreement as a Holder
(as  that  term  is  defined  in the  Registration  Rights  Agreement),  and the
Subsequent  Purchaser  hereby  expressly  assumes  all rights,  liabilities  and
obligations of a Holder under the Registration Rights Agreement.

                  Section 2.        Amendments.

                  (a) Section 1 of the  Registration  Rights Agreement is hereby
amended to restate the definitions listed below:

                      "Debentures"  means (i) the Convertible  Debentures issued
to the Purchasers in accordance  with the Purchase  Agreement and (ii) the Acorn
Debentures  issued to the  Subsequent  Purchaser  in  accordance  with the Acorn
Purchase Agreement.

                      "Warrants"  means  (i) the  Warrants  (as  defined  in the
Montrose  Purchase  Agreement)  and (ii) the  Warrants  (as defined in the Acorn
Purchase Agreement).

                  (b) Section 1 of the  Registration  Rights Agreement is hereby
amended by adding the definitions listed below:







                      "Acorn  Debenture" means the 6% Convertible  Debenture due
September 8, 2004 in principal  amount of  $3,000,000  issued to the  Subsequent
Purchaser.

                      "Acorn Purchase Agreement" means the Convertible Debenture
Purchase  Agreement  dated as of the date  hereof by and among the  Company  and
Acorn Investment Trust on behalf of its series Acorn Fund.

                  (c) Except as modified  and amended  herein,  all of the terms
and conditions of the  Registration  Rights Agreement shall remain in full force
and effect.

                  Section 3. Capitalized Terms. Unless otherwise defined herein,
all  capitalized  terms  shall have the  meanings  assigned to such terms in the
Registration Rights Agreement, as amended hereby.

                  Section 4. Non-Liability of Trustees and Shareholders.  A copy
of the  Declaration  of Trust of the  Subsequent  Purchaser  is on file with the
Secretary of The Commonwealth of Massachusetts,  and notice is hereby given that
this agreement is executed on behalf of the Subsequent  Purchaser by officers of
the Subsequent  Purchaser as officers and not  individually.  All obligations of
the Subsequent  Purchaser hereunder shall be binding only upon the assets of the
Subsequent  Purchaser  (or the  appropriate  series  thereof)  and  shall not be
binding  upon  any  trustee,  officer,  employee,  agent or  shareholder  of the
Subsequent Purchaser. Neither the authorization of any action by the Trustees of
the  Subsequent  Purchaser nor the execution of this  agreement on behalf of the
Subsequent  Purchaser  shall impose any liability  upon any trustee,  officer or
shareholder of the Subsequent Purchaser.

                  Section 5.        Miscellaneous.

                  (a) Successors and Assigns. This Joinder Agreement shall inure
to the benefit of and be binding upon the  successors  and permitted  assigns of
each of the parties  and shall  inure to the benefit of each party.  The Company
may not assign its rights or  obligations  hereunder  without the prior  written
consent of each party.  Each party may assign their respective  rights hereunder
in the  manner and to the  Persons  as  permitted  under the  Montrose  Purchase
Agreement or the Acorn Purchase Agreement, as the case may be.

                  (b)  Counterparts.  This Joinder  Agreement may be executed in
any number of counterparts, each of which when so executed shall be deemed to be
an original and, all of which taken together  shall  constitute one and the same
Agreement.   In  the  event  that  any   signature  is  delivered  by  facsimile
transmission,  such  signature  shall create a valid  binding  obligation of the
party  executing  (or on whose behalf such  signature is executed) the same with
the same  force and  effect as if such  facsimile  signature  were the  original
thereof.

                  (c) Governing Law. All questions  concerning the construction,
validity,  enforcement  and  interpretation  of this Joinder  Agreement shall be
governed by and construed  and enforced in accordance  with the internal laws of
the State of New York, without regard to the


                                       -2-




principles of conflicts of law thereof. Each party hereby irrevocably submits to
the exclusive  jurisdiction  of the state and federal courts sitting in the City
of New York, borough of Manhattan, for the adjudication of any dispute hereunder
or in  connection  herewith  or with  any  transaction  contemplated  hereby  or
discussed herein, and hereby irrevocably waives, and agrees not to assert in any
suit, action or proceeding,  any claim that it is not personally  subject to the
jurisdiction  of any such  court,  that  such  suit,  action  or  proceeding  is
improper.  Each party hereby  irrevocably waives personal service of process and
consents  to process  being  served in any such suit,  action or  proceeding  by
mailing a copy  thereof to such party at the address in effect for notices to it
under this Joinder  Agreement and agrees that such service shall constitute good
and sufficient  service of process and notice thereof.  Nothing contained herein
shall be  deemed to limit in any way any right to serve  process  in any  manner
permitted by law.

                  (d) Notices.  Any and all notices or other  communications  or
deliveries  required or permitted to be provided  hereunder  shall be in writing
and shall be deemed given and effective as provided in the  Registration  Rights
Agreement.  The address for such notices and communications shall be as provided
in the  Registration  Rights  Agreement  with  respect  to the  Company  and the
Existing  Purchaser,  and with respect to Acorn,  to the address set forth under
Acorn's name on the signature pages hereto.



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                  IN WITNESS  WHEREOF,  the parties  hereto have  executed  this
Joinder and Amendment to  Registration  Rights  Agreement as of the day and year
first above written.


                               TIDEL TECHNOLOGIES, INC.



                               By: _________________________________________
                                   Name: James T. Rash
                                   Title: President and Chief Executive Officer



                               THE SUBSEQUENT PURCHASER:

                               ACORN INVESTMENT TRUST
                               on behalf of its series Acorn Fund


                               By: ____________________________________________
                                   Name: Kenneth A. Kalina
                                   Title: Assistant Treasurer


                               Address for Notice:

                               Acorn Investment Trust
                               on behalf of its series Acorn Fund
                               227 W. Monroe St., #3000
                               Chicago, IL 60606
                               Facsimile: 312-634-1919
                               Attn: Treasurer

         With copies to:       Bell, Boyd & Lloyd LLC
                               Three First National Plaza, #3300
                               Chicago, IL 60602
                               Facsimile: 312-372-2098
                               Attn: Janet D. Olsen









                               THE EXISTING PURCHASERS:

                               MONTROSE INVESTMENTS LTD.


                               By: ____________________________________________
                                   Name:
                                   Title: