As filed with the Securities and Exchange Commission on January 10, 2001

                        Registration No. 333-____________


                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM S-8

                             Registration Statement
                                      Under
                           The Securities Act of 1933

                      TRANSACTION SYSTEMS ARCHITECTS, INC.
             (Exact name of registrant as specified in its charter)

                               Delaware 47-0772104
        (State or other jurisdiction (I.R.S. Employer Identification No.)
                        of incorporation or organization)

                             224 South 108th Avenue
                              Omaha, Nebraska 68154
               (Address of principal executive offices) (Zip Code)

      MessagingDirect Ltd. Amended and Restated Employee Share Option Plan
                            (Full title of the plan)

                              David P. Stokes, Esq.
                          General Counsel and Secretary
                      Transaction Systems Architects, Inc.
                             224 South 108th Avenue
                              Omaha, Nebraska 68514
                                 (402) 334-5101
(Name, address and telephone number, including area code, of agent for service)



                         CALCULATION OF REGISTRATION FEE

================================== ========================== ==================== =================== ==============
                                                                                           
                                                                Proposed Maximum       Proposed          Amount of
    Title of Securities to be       Amount to be Registered    Offering Price Per       Maximum         Registration
           Registered                         (1)                    Share             Aggregate           Fee (2)
                                                                                    Offering Price (2)
================================== ========================== ==================== =================== ==============
      Class A Common Stock,              370,000 shares              $0.01               $3,700              $1
        $0.005 par value


(1)  Pursuant  to  Rule  416,  this  registration   statement  also  covers  any
additional  shares of Class A Common  Stock  which may be offered or issued as a
result of stock splits, stock dividends or similar transactions.

(2)  Pursuant to Rule  457(h),  computed on the basis of the  exercise  price of
the  outstanding  options  granted under the  MessagingDirect  Ltd.  Amended and
Restated  Employee  Share  Option  Plan  and  assumed  by  Transaction   Systems
Architects,  Inc.  The  exercise  price of the  outstanding  options  assumed by
Transaction Systems Architects, Inc. is $0.01 per share.


                                     PART II
               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Certain Documents by Reference

         Transaction   Systems   Architects,   Inc.  (the   "Company"))   hereby
incorporates by reference in this  Registration  Statement the documents  listed
in (a) through  (b) below  previously  filed with the  Securities  and  Exchange
Commission  (the  "Commission")  under the  Securities  Exchange Act of 1934, as
amended (the "Exchange Act"):

            (a)   The Company's Annual  Report on Form 10-K for the  fiscal
                  year ended  September  30, 2000.

            (b)   The   description  of  the Company's  Class  A  Common
                  Stock  contained  in  the Company's registration  statement
                  on Form  8-A  that the Company  filed  on January 11, 1995,
                  including  any amendment or reports  that we file for the
                  purposes of updating  this description.

         All  documents  subsequently  filed with the  Commission by the Company
pursuant to Sections  13(a),  13(c),  14 and 15(d) of the  Exchange Act prior to
the filing of a  post-effective  amendment  which  indicates that all securities
offered  hereby  have  been  sold  or  which  deregisters  all  securities  then
remaining  unsold shall be deemed to be incorporated  herein by reference and to
be a part hereof from the dates of filing of such documents.


Item 6.  Indemnification of Directors and Officers.

         Section 145 of the Delaware  General  Corporation  Law provides for the
indemnification  of  officers  and  directors,  subject to certain  limitations.
The  Certificate  of  Incorporation  of the  registrant  expressly  provides for
indemnification  of an  officer or  director  made a party or  threatened  to be
made a party to  proceedings  by  reason of the fact  that  such  person  was an
officer or director.  The  Certificate  of  Incorporation  also  authorizes  the
registrant  to maintain  officer and director  liability  insurance,  and such a
policy is currently in effect.


Item 8.  Exhibits

     Exhibit
     Number
    --------

        5         Opinion of Baker & McKenzie
       23         Consent of Arthur Andersen LLP
       24         Power of Attorney (included in Signature Page)


Item 9.  Undertakings.

         (a)      The undersigned registrant hereby undertakes:

              1.       To file,  during  any period in which offers or sales are
being made, a post-effective amendment to this registration statement:

                  (i)      To  include  any   prospectus   required  by  Section
10(a)(3) of the Act;

                  (ii)     To  reflect  in the  prospectus  any  facts or events
arising  after the  effective  date of the  registration  statement (or the most
recent  post-effective   amendment  thereof)  which,   individually  or  in  the
aggregate,  represent a fundamental  change in the  information set forth in the
registration   statement.   Notwithstanding  the  foregoing,   any  increase  or
decrease  in  volume  of  securities  offered  (if the  total  dollar  value  of
securities  offered  would  not  exceed  that  which  was  registered)  and  any
deviation from the low or high end of the estimated  maximum  offering range may
be reflected in the form of  prospectus  filed with the  Commission  pursuant to
Rule 424(b) if, in the aggregate,  the changes in volume and price  represent no
more than a 20%  change in the  maximum  aggregate  offering  price set forth in
the  "Calculation  of  Registration  Fee"  table in the  effective  registration
statement.

                  (iii)    To include any material  information  with respect to
the  plan  of  distribution   not  previously   disclosed  in  the  registration
statement  or any  material  change  to  such  information  in the  registration
statement;

         Provided,  however,  that  paragraphs  (a)(1)(i) and  (a)(1)(ii) do not
apply if the information  required to be included in a post-effective  amendment
by those  paragraphs is contained in periodic  reports  filed by the  registrant
pursuant  to  Section  13  or  Section  15(d)  of  the  Exchange  Act  that  are
incorporated by reference in this registration statement.

              2.       That, for the purpose of determining any liability  under
the Act, each such  post-effective  amendment  shall  be  deemed  to  be  a  new
registration  statement  relating to the  securities  offered  therein,  and the
offering  of such  securities  at that time  shall be  deemed to be the  initial
bona fide offering thereof.

              3.       To remove from registration  by  means of  post-effective
amendment  any of the  securities  being  registered  which remain unsold at the
termination of the offering.

         (b)      The  undersigned   registrant   hereby  undertakes  that,  for
purposes  of  determining  any  liability  under  the Act,  each  filing  of the
registrant's  annual  report  pursuant to Section  13(a) or Section 15(d) of the
Exchange Act (and, where  applicable,  each filing of an employee benefit plan's
annual  report   pursuant  to  Section  15(d)  of  the  Exchange  Act)  that  is
incorporated  by reference in the  registration  statement shall be deemed to be
a new registration  statement  relating to the securities  offered therein,  and
the offering of such  securities  at that time shall be deemed to be the initial
bona fide offering thereof.

         (c)      Insofar as indemnification  for liabilities  arising under the
Act may be  permitted to  directors,  officers  and  controlling  persons of the
registrant pursuant to the foregoing  provisions,  or otherwise,  the registrant
has been advised that in the opinion of the Securities  and Exchange  Commission
such  indemnification  is against  public policy as expressed in the Act and is,
therefore,  unenforceable.  In  the  event  that  a  claim  for  indemnification
against such  liabilities  (other than the payment by the registrant of expenses
incurred  or  paid  by  a  director,  officer,  or  controlling  person  of  the
registrant  in the  successful  defense of any action,  suit or  proceeding)  is
asserted by such  director,  officer or  controlling  person in connection  with
the securities being  registered,  the registrant will, unless in the opinion of
counsel  the  matter  has been  settled by  controlling  precedent,  submit to a
court of appropriate  jurisdiction the question whether such  indemnification by
it is against  public  policy as  expressed  in the Act and will be  governed by
the final adjudication of such issue.

SIGNATURES The Registrant. Pursuant to the requirements of the Securities Act of 1933, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Omaha, State of Nebraska, on this 10th day of January, 2001. TRANSACTION SYSTEMS ARCHITECTS, INC. By: /s/ William E. Fisher ------------------------------------- William E. Fisher, Chairman, Chief Executive Officer and Director POWER OF ATTORNEY We, the undersigned officers and directors of Transaction Systems Architects, Inc., hereby severally and individually constitute and appoint William E. Fisher, Dwight G. Hanson and David P. Stokes, and each of them, the true and lawful attorneys and agents of each of us to execute in the name, place and stead of each of us (individually and in any capacity stated below) any and all amendments to this Registration Statement on Form S-8, and all instruments necessary or advisable in connection therewith, and to file the same with the Securities and Exchange Commission, each of said attorneys and agents to have power to act with or without the other and to have full power and authority to do and perform in the name and on behalf of each of the undersigned every act whatsoever necessary or advisable to be done in the premises as fully and to all intents and purposes as any of the undersigned might or could do in person, and we hereby ratify and confirm our signatures as they may be signed by our said attorneys and agents and each of them to any and all such amendments and other instruments. Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons in the capacities and on the date indicated. /s/ William E. Fisher Chairman, Chief Executive January 10, 2001 - -------------------------- Officer and Director William E. Fisher /s/ Dwight G. Hanson Chief Financial Officer January 10, 2001 - -------------------------- and Senior Vice President Dwight G. Hanson /s/ Edward C. Fuxa Controller January 10, 2001 - -------------------------- Edward C. Fuxa /s/ Charles E. Noell, III Director January 10, 2001 - -------------------------- Charles E. Noell, III /s/ Jim D. Kever Director January 10, 2001 - -------------------------- Jim D. Kever /s/ Larry G. Fendley Director January 10, 2001 - -------------------------- Larry G. Fendley /s/ Roger K. Alexander Director January 10, 2001 - -------------------------- Roger K. Alexander /s/ Gregory J. Duman Director January 10, 2001 - -------------------------- Gregory J. Duman

EXHIBIT INDEX Exhibit Number Description 5 Opinion of Baker & McKenzie 23 Consent of Arthur Andersen LLP 24 Power of Attorney (included in Signature Page)


                                                                       Exhibit 5

                                BAKER & McKENZIE
                                Attorneys at Law

                            2300 Trammell Crow Center
                                2001 Ross Avenue
                               Dallas, Texas 75201


                                January 10, 2001


Board of Directors
Transaction Systems Architects, Inc.
224 South 108th Avenue
Omaha, Nebraska  68154

Re:      Transaction Systems Architects, Inc. (the "Company")

Gentlemen:

         We have acted as your counsel in connection with the  registration,  on
a Registration  Statement on Form S-8 (the  "Registration  Statement") under the
Securities Act of 1933, as amended,  of 370,000 shares of the Company's  Class A
Common  Stock,  $.005  par value per  share  (the  "Stock").  The Stock is to be
issued by the Company upon the exercise of  outstanding  options  granted  under
the  MessagingDirect  Ltd. Amended and Restated  Employee Share Option Plan (the
"Plan") and to be assumed by the Company  pursuant  to a  Combination  Agreement
dated as of October 24,  2000,  by and among the  Company,  Transaction  Systems
Architects  Nova Scotia  Company,  TSA  Exchangeco  Limited and  MessagingDirect
Ltd. (the  "Combination  Agreement")  and Plan of Arrangement  attached  thereto
(the "Plan of Arrangement").  We have reviewed the Registration  Statement,  the
Combination Agreement,  the Plan of Arrangement,  the charter and by-laws of the
Company,  corporate  proceedings  of the  Board  of  Directors  relating  to the
issuance of the shares of Stock,  and such other  documents,  corporate  records
and  questions  of laws as we have  deemed  necessary  to the  rendering  of the
opinions expressed below.

         In all  examinations  of documents,  instruments  and other papers,  we
have  assumed  the  genuineness  of all  signatures  on original  and  certified
documents and the  conformity to original and certified  documents of all copies
submitted to us as  conformed,  photostatic  or other  copies.  As to matters of
fact  which  have  not  been  independently  established,  we have  relied  upon
representations of officers of the Company.

         Based  upon the  foregoing,  we are of the  opinion  that  the  370,000
shares of Stock to be issued by the  Company,  as  described in the Plan and the
Plan of  Arrangement,  will be validly  issued,  fully  paid and  non-assessable
when  issued  and paid for in the  manner  contemplated  in the Plan and Plan of
Arrangement.

         The opinion  expressed above is limited to the General  Corporation Law
of the State of Delaware and the federal laws of the United States of America.

         This  opinion  letter may be filed as an  exhibit  to the  Registration
Statement.  In giving this  consent,  this firm does not  thereby  admit that it
comes within the category of persons whose  consent is required  under Section 7
of the Securities Act of 1933, as amended,  or the rules and  regulations of the
Securities and Exchange Commission promulgated thereunder.



                                            Very truly yours,



                                            Baker & McKenzie


                                                                      Exhibit 23






Consent of independent public accountants


As independent public accountants, we hereby consent to the incorporation by
reference in this Form S-8 Registration Statement of our report dated October
26, 2000, included in Transaction Systems Architects, Inc.'s Annual Report on
Form 10-K for the fiscal year ended September 30, 2000, and to all references
to our Firm included in this Registration Statement.




Omaha, Nebraska,
January 9, 2001