As filed with the Securities and Exchange Commission on November 25, 1998.

                                               Registration No. 333- _______


                                    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 of (I.R.S. Employer
               incorporation or organization) Identification No.)

                  224 South 108th Ave., Omaha, Nebraska 68154 
               (Address of Principal Executive Offices) (Zip Code)


                 Transaction Systems Architects, Inc. Deferred 
                               Compensation Plan 
                            (Full title of the plan)

                 David P. Stokes, General Counsel and Secretary
                      Transaction Systems Architects, Inc.
                          224 South 108th Ave., Omaha,
                                 Nebraska 68154
                     (Name and address of agent for service)

                                 (402) 334-5101 
                (Telephone number, including area code, of agent
                                  for service)

<TABLE>
<CAPTION>

                         Calculation of Registration Fee
------------------------ ---------------------- ---------------------- ---------------------- ----------------------
<S>                         <C>                  <C>                   <C>                     <C>         
  Title of securities        Amount to be             Proposed               Proposed               Amount of
   to be registered           registered          maximum offering            maximum           Registration fee
                                                   price per unit       aggregate offering
                                                                             price(1)
------------------------ ---------------------- ---------------------- ---------------------- ----------------------
Transaction Systems          $30,000,000                100%                $30,000,000              $8,340
Architects, Inc.
Deferred Compensation
Plan Obligations(2)

</TABLE>

(1)      Estimated solely for the purpose of determining the registration fee.

(2)      The Transaction  Systems  Architects,  Inc. Deferred  Compensation Plan
         obligations   are  unsecured   obligations   of   Transaction   Systems
         Architects,  Inc.  to  pay  deferred  compensation  in  the  future  in
         accordance  with the  Transaction  Systems  Architects,  Inc.  Deferred
         Compensation Plan.

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Incorporation of Documents by Reference

         The  documents  listed in (a)  through  (c) below are  incorporated  by
reference in this registration  statement and all documents  subsequently  filed
by the  registrant  pursuant  to  Sections  13(a),  13(c),  14 and  15(d) of the
Securities  Exchange Act of 1934, as amended (the "Exchange Act"),  prior to the
filing  of a  post-effective  amendment  which  indicates  that  all  securities
offered  have been  sold or which  deregisters  all  securities  then  remaining
unsold,  shall be deemed to be  incorporated  by reference  in the  registration
statement and to be part thereof from the date of filing of such documents.

         (a)      The  registrant's  latest  annual  report  filed  pursuant  to
section 13(a) or 15(d) of the Exchange Act.

         (b)      All other  reports  filed  pursuant to Section  13(a) or 15(d)
of the Exchange  Act since the end of the fiscal year covered by the  registrant
document referred to in (a) above.

         (c)      The  description  of the class of  securities  contained  in a
registration  statement  filed under the Exchange  Act,  including any amendment
or report filed for the purpose of updating such description.


Description of Securities

         Under the Transaction  Systems Architects,  Inc. Deferred  Compensation
Plan (the  "Plan"),  certain  management  and highly  compensated  employees  of
Transaction  Systems  Architects,  Inc.  (the  "Company")  and  certain  of  its
subsidiaries   may  defer  a  portion   of  their  base   salary  and   variable
compensation  (including without limitation bonus amounts,  management incentive
compensation and commissions).

         Amounts  deferred by a  participant  under the Plan will be credited by
book  entry  to  the  participant's  deferral  contribution  account.  The  Plan
permits  the  Company  to  make  discretionary   contributions  to  an  employer
contribution  account  maintained  for each  Plan  participant.  The  value of a
participant's   accounts  will  be  based  on  the   performance   of  benchmark
investment  funds  selected by the  participant  under the Plan for  purposes of
accounting  (as if the deferred  compensation  had been so invested) and not for
actual   investment.   Since   no   participant   deferrals   or   discretionary
contributions  by the Company  actually will be invested in any investment fund,
participants  will not have any  ownership  interest in any  investment  fund. A
Benefits  Committee  appointed  by the Board of Directors of the Company has the
sole  discretion  to  determine  the  alternative   benchmark  investment  funds
available under the Plan as the  measurement  mechanism to determine the rate of
return on amounts deemed invested in accordance with the terms of the Plan.

     The  obligations  of the  Company  under the Plan (the  "Obligations")  are
unsecured  general  obligations  to pay in the  future  the value of the  vested
deferred  compensation  accounts  adjusted  to reflect  the  performance  of the
selected measurement  investment funds in accordance with the terms of the Plan.
The  Obligations   will  rank  without   preference  with  other  unsecured  and
unsubordinated  indebtedness  of the Company from time to time  outstanding  and
are, therefore, subject to the risks of the Company's insolvency.

         The Company is not  required to fund or otherwise  segregate  assets to
be used for the  payment  of the  Obligations.  Notwithstanding  the  foregoing,
the  Company  may  establish  a trust to hold  assets to be used for  payment of
Obligations.  The  assets  held by such  trust  will be subject to the claims of
the Company's general creditors.

         Obligations  are generally  payable under the Plan upon (i) termination
of  employment,  (ii) death,  (iii) a  determination  by the Benefits  Committee
that a  participant  has suffered a financial  hardship,  (iv) the election of a
participant  (subject to a 10% withdrawal  penalty),  and (v) at the election of
the  participant,  January of any year designated by the  participant  beginning
after the third anniversary of a participant's deferral.

         The   Obligations   cannot   be   assigned,   alienated,   pledged   or
encumbered.  The  Obligations  are not  convertible  into  any  security  of the
Company.

         The Company  may amend the Plan from time to time,  except that no such
amendment may reduce the value of a  participant's  vested  account  balances to
less than the amount (as  subsequently  adjusted  for  earnings  and  losses) he
would be entitled to receive if he had resigned on the day of the amendment.


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.


Exhibits

    4.1    Transaction Systems Architects, Inc. Deferred Compensation Plan

    4.2    Transaction  Systems  Architects,  Inc.  Deferred  Compensation  Plan
           Trust Agreement

    5      Opinion of Legal Counsel

   23      Consent of Arthur Andersen LLP

   24      Power of Attorney (contained in signature page)


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

         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
November 20, 1998.


                                            TRANSACTION SYSTEMS ARCHITECTS, INC.


                                            By:      /s/  William E. Fisher     
                                                ------------------------------- 
                                              William E. Fisher, Chief Executive
                                              Officer, President 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,  Gregory J. Duman,  and Dwight G.  Hanson,  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.

Name                              Title                          Date
-------------------------  -------------------------  --------------------------

/s/ William E. Fisher      Chief Executive Officer,           November  20, 1998
-------------------------  President and Director                               
    William E. Fisher      (Principal Executive Officer)                        


/s/ Gregory J. Duman       Chief Financial Officer            November  20, 1998
-------------------------  (Principal Financial Officer)
    Gregory J. Duman    


/s/ Dwight G. Hanson       Vice President                     November  20, 1998
-------------------------  (Principal Accounting Officer) 
    Dwight G. Hanson                           


/s/ David C. Russell       Director                           November  20, 1998
-------------------------
    David C. Russell


/s/ Promod Haque           Director                           November  20, 1998
-------------------------
    Promod Haque


/s/ Charles E. Noell, III  Director                           November  20, 1998
-------------------------
    Charles E. Noell, III


/s/ Jim D. Kever           Director                           November  20, 1998
-------------------------
    Jim D. Kever


/s/ Larry G. Fendley       Director                           November  20, 1998
-------------------------
    Larry G. Fendley


                                  EXHIBIT INDEX



Exhibit No.                Description
-----------                -----------
    4.1                    Transaction   Systems   Architects,   Inc.   Deferred
                           Compensation Plan

    4.2                    Transaction   Systems   Architects,   Inc.   Deferred
                           Compensation Plan Trust Agreement

    5                      Opinion of Legal Counsel

   23                      Consent of Arthur Andersen LLP

   24                      Power of Attorney (contained in signature page)
[{"type": "S-8", "sequence": "1", "description": "REGISTRATION STATEMENT", "secsgml_size_bytes": 17211}]
{"company-data": {"conformed-name": "TRANSACTION SYSTEMS ARCHITECTS INC", "cik": "0000935036", "assigned-sic": "7372", "irs-number": "470772104", "state-of-incorporation": "DE", "fiscal-year-end": "0930"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-67987", "film-number": "98759768"}, "business-address": {"street1": "224 SOUTH 108TH AVE", "city": "OMAHA", "state": "NE", "zip": "68154", "phone": "4023907600"}, "mail-address": {"street1": "224 SOUTH 108TH", "city": "OMAHA", "state": "NE", "zip": "68154"}}
As filed with the Securities and Exchange Commission on November 25, 1998.

                                               Registration No. 333- _______

                                    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 of (I.R.S. Employer
               incorporation or organization) Identification No.)

                  224 South 108th Ave., Omaha, Nebraska 68154 
               (Address of Principal Executive Offices) (Zip Code)

                 Transaction Systems Architects, Inc. Deferred 
                               Compensation Plan 
                            (Full title of the plan)

                 David P. Stokes, General Counsel and Secretary
                      Transaction Systems Architects, Inc.
                          224 South 108th Ave., Omaha,
                                 Nebraska 68154
                     (Name and address of agent for service)

                                 (402) 334-5101 
                (Telephone number, including area code, of agent
                                  for service)
Calculation of Registration Fee
------------------------ ---------------------- ---------------------- ---------------------- ----------------------
Title of securities        Amount to be             Proposed               Proposed               Amount of
   to be registered           registered          maximum offering            maximum           Registration fee
                                                   price per unit       aggregate offering
                                                                             price(1)
------------------------ ---------------------- ---------------------- ---------------------- ----------------------
Transaction Systems          $30,000,000                100%                $30,000,000              $8,340
Architects, Inc.
Deferred Compensation
Plan Obligations(2)
(1)      Estimated solely for the purpose of determining the registration fee.

(2)      The Transaction  Systems  Architects,  Inc. Deferred  Compensation Plan
         obligations   are  unsecured   obligations   of   Transaction   Systems
         Architects,  Inc.  to  pay  deferred  compensation  in  the  future  in
         accordance  with the  Transaction  Systems  Architects,  Inc.  Deferred
         Compensation Plan.

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Incorporation of Documents by Reference

         The  documents  listed in (a)  through  (c) below are  incorporated  by
reference in this registration  statement and all documents  subsequently  filed
by the  registrant  pursuant  to  Sections  13(a),  13(c),  14 and  15(d) of the
Securities  Exchange Act of 1934, as amended (the "Exchange Act"),  prior to the
filing  of a  post-effective  amendment  which  indicates  that  all  securities
offered  have been  sold or which  deregisters  all  securities  then  remaining
unsold,  shall be deemed to be  incorporated  by reference  in the  registration
statement and to be part thereof from the date of filing of such documents.

         (a)      The  registrant's  latest  annual  report  filed  pursuant  to
section 13(a) or 15(d) of the Exchange Act.

         (b)      All other  reports  filed  pursuant to Section  13(a) or 15(d)
of the Exchange  Act since the end of the fiscal year covered by the  registrant
document referred to in (a) above.

         (c)      The  description  of the class of  securities  contained  in a
registration  statement  filed under the Exchange  Act,  including any amendment
or report filed for the purpose of updating such description.

Description of Securities

         Under the Transaction  Systems Architects,  Inc. Deferred  Compensation
Plan (the  "Plan"),  certain  management  and highly  compensated  employees  of
Transaction  Systems  Architects,  Inc.  (the  "Company")  and  certain  of  its
subsidiaries   may  defer  a  portion   of  their  base   salary  and   variable
compensation  (including without limitation bonus amounts,  management incentive
compensation and commissions).

         Amounts  deferred by a  participant  under the Plan will be credited by
book  entry  to  the  participant's  deferral  contribution  account.  The  Plan
permits  the  Company  to  make  discretionary   contributions  to  an  employer
contribution  account  maintained  for each  Plan  participant.  The  value of a
participant's   accounts  will  be  based  on  the   performance   of  benchmark
investment  funds  selected by the  participant  under the Plan for  purposes of
accounting  (as if the deferred  compensation  had been so invested) and not for
actual   investment.   Since   no   participant   deferrals   or   discretionary
contributions  by the Company  actually will be invested in any investment fund,
participants  will not have any  ownership  interest in any  investment  fund. A
Benefits  Committee  appointed  by the Board of Directors of the Company has the
sole  discretion  to  determine  the  alternative   benchmark  investment  funds
available under the Plan as the  measurement  mechanism to determine the rate of
return on amounts deemed invested in accordance with the terms of the Plan.

     The  obligations  of the  Company  under the Plan (the  "Obligations")  are
unsecured  general  obligations  to pay in the  future  the value of the  vested
deferred  compensation  accounts  adjusted  to reflect  the  performance  of the
selected measurement  investment funds in accordance with the terms of the Plan.
The  Obligations   will  rank  without   preference  with  other  unsecured  and
unsubordinated  indebtedness  of the Company from time to time  outstanding  and
are, therefore, subject to the risks of the Company's insolvency.

         The Company is not  required to fund or otherwise  segregate  assets to
be used for the  payment  of the  Obligations.  Notwithstanding  the  foregoing,
the  Company  may  establish  a trust to hold  assets to be used for  payment of
Obligations.  The  assets  held by such  trust  will be subject to the claims of
the Company's general creditors.

         Obligations  are generally  payable under the Plan upon (i) termination
of  employment,  (ii) death,  (iii) a  determination  by the Benefits  Committee
that a  participant  has suffered a financial  hardship,  (iv) the election of a
participant  (subject to a 10% withdrawal  penalty),  and (v) at the election of
the  participant,  January of any year designated by the  participant  beginning
after the third anniversary of a participant's deferral.

         The   Obligations   cannot   be   assigned,   alienated,   pledged   or
encumbered.  The  Obligations  are not  convertible  into  any  security  of the
Company.

         The Company  may amend the Plan from time to time,  except that no such
amendment may reduce the value of a  participant's  vested  account  balances to
less than the amount (as  subsequently  adjusted  for  earnings  and  losses) he
would be entitled to receive if he had resigned on the day of the amendment.

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.

Exhibits

    4.1    Transaction Systems Architects, Inc. Deferred Compensation Plan

    4.2    Transaction  Systems  Architects,  Inc.  Deferred  Compensation  Plan
           Trust Agreement

    5      Opinion of Legal Counsel

   23      Consent of Arthur Andersen LLP

   24      Power of Attorney (contained in signature page)

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

         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
November 20, 1998.

                                            TRANSACTION SYSTEMS ARCHITECTS, INC.

                                            By:      /s/  William E. Fisher     
                                                ------------------------------- 
                                              William E. Fisher, Chief Executive
                                              Officer, President 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,  Gregory J. Duman,  and Dwight G.  Hanson,  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.

Name                              Title                          Date
-------------------------  -------------------------  --------------------------

/s/ William E. Fisher      Chief Executive Officer,           November  20, 1998
-------------------------  President and Director                               
    William E. Fisher      (Principal Executive Officer)                        

/s/ Gregory J. Duman       Chief Financial Officer            November  20, 1998
-------------------------  (Principal Financial Officer)
    Gregory J. Duman    

/s/ Dwight G. Hanson       Vice President                     November  20, 1998
-------------------------  (Principal Accounting Officer) 
    Dwight G. Hanson                           

/s/ David C. Russell       Director                           November  20, 1998
-------------------------
    David C. Russell

/s/ Promod Haque           Director                           November  20, 1998
-------------------------
    Promod Haque

/s/ Charles E. Noell, III  Director                           November  20, 1998
-------------------------
    Charles E. Noell, III

/s/ Jim D. Kever           Director                           November  20, 1998
-------------------------
    Jim D. Kever

/s/ Larry G. Fendley       Director                           November  20, 1998
-------------------------
    Larry G. Fendley

                                  EXHIBIT INDEX

Exhibit No.                Description
-----------                -----------
    4.1                    Transaction   Systems   Architects,   Inc.   Deferred
                           Compensation Plan

    4.2                    Transaction   Systems   Architects,   Inc.   Deferred
                           Compensation Plan Trust Agreement

    5                      Opinion of Legal Counsel

   23                      Consent of Arthur Andersen LLP

   24                      Power of Attorney (contained in signature page)