content: <PAGE>   1
  
  As filed with the Securities and Exchange Commission on November 13, 1996
  
                                                     Registration No. 333-
                                                                          ------
  ================================================================================
  
                         SECURITIES AND EXCHANGE COMMISSION
                               Washington, D.C. 20549
  
                                --------------------
                                      FORM S-8
                               REGISTRATION STATEMENT
                                        under
                             THE SECURITIES ACT OF 1933
  
                                   MATHSOFT, INC.
               (Exact name of registrant as specified in its charter)
  
  <TABLE>
  <S>                                                               <C>                    
                        Massachusetts                                          04-2842217
  (State or other jurisdiction of incorporation or organization)    (I.R.S. Employer Identification No.)
  
  
           101 Main Street, Cambridge, Massachusetts                              02142
              (Address of Principal Executive Offices)                          (Zip Code)
  </TABLE>
  
                                --------------------
  
                                   MATHSOFT, INC.
                        AMENDED AND RESTATED 1992 STOCK PLAN
                              (Full title of the plan)
  
                                  Charles J. Digate
                                   MATHSOFT, INC.
                                   101 Main Street
                                 Cambridge, MA 02142
                       (Name and address of agent for service)
  
                                   (617) 577-1017
            (Telephone number, including area code, of agent for service)
                                --------------------
  
                                      Copy to:
                                   Gordon H. Hayes
                           Testa, Hurwitz & Thibeault, LLP
                                  High Street Tower
                                   125 High Street
                             Boston, Massachusetts 02110
                                   (617) 248-7000
                                --------------------
  
  
  <TABLE>
                           Calculation of Registration Fee
  <CAPTION>
  
  =================================================================================================================================
    Title of Securities        Amount to be       Proposed maximum offering        Proposed maximum         Amount of registration
      to be registered          registered           price per share(1)           aggregate offering                fee(2)
                                                                                       price(1)
  ---------------------------------------------------------------------------------------------------------------------------------
  <S>                             <C>                       <C>                       <C>                           <C>    
  Common Stock,                   400,000                   $3.69                     $1,476,000                    $447.28
  par value $.01
  =================================================================================================================================
  
  <FN>
  (1)  Estimated solely for the purpose of calculating the registration fee
       pursuant to Rule 457 under the Securities Act of 1933.
  
  (2)  Pursuant to Rule 457(c) under the Securities Exchange Act of 1933, the
       registration fee has been calculated based upon the average of the high and
       low prices per share of Common Stock on the Nasdaq National Market on
       November 7, 1996.
  </TABLE>
  
  
  <PAGE>   2
                                       -2-
  
  
       This Registration Statement registers additional securities of the same
  class as other securities for which: (i) the Registration Statement No. 33-58560
  on Form S-8 as filed with the Securities and Exchange Commission on February 19,
  1993, relating to the MathSoft, Inc. Amended and Restated 1992 Stock Plan, (ii)
  the Registration Statement No. 33-72162 on Form S-8 as filed with the Securities
  and Exchange Commission on November 24, 1993, relating to the MathSoft, Inc.
  Amended and Restated 1992 Stock Plan, (iii) the Registration Statement No.
  33-87542 on Form S-8 as filed with the Securities and Exchange Commission on
  December 16, 1994, relating to the MathSoft, Inc. Amended and Restated 1992
  Stock Plan, and (iv) the Registration Statement No. 33-99618 on Form S-8 as
  filed with the Securities and Exchange Commission on November 20, 1995, relating
  to the MathSoft, Inc. Amended and Restated 1992 Stock Plan, are effective.
  Pursuant to General Instruction E, the contents of the above-listed Registration
  Statements are hereby incorporated by reference.
  
  
                                       PART II
                 INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
  
  <TABLE>
  
  Item 8. Exhibits
          --------
  
  <CAPTION>
  Exhibit No.   Description of Exhibit
  -----------   ----------------------
  
  <S>           <C>
  5.1           Opinion of Testa, Hurwitz & Thibeault, LLP.
  
  23.1          Consent of Arthur Andersen LLP.
  
  23.2          Consent of Testa, Hurwitz & Thibeault, LLP (included in Exhibit 5.1).
  
  24.1          Power of Attorney (contained in Page 3 of this Registration Statement).
  
  </TABLE>
  
  
  <PAGE>   3
                                       -3-
  
  
                                     SIGNATURES
  
  Pursuant to the requirements of the Securities Act of 1933, as amended, the
  Registrant certifies that it has reasonable grounds to believe that it meets all
  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 Cambridge, Commonwealth of Massachusetts, on the 13th
  day of November, 1996.
  
                                 MATHSOFT, INC.
  
  Date:  November 13, 1996       By: /s/  Charles J. Digate
                                     ----------------------
                                     Charles J. Digate
                                     President, Chief Executive Officer and 
                                     Chairman of the Board of Directors
  
  
  
                          POWER OF ATTORNEY AND SIGNATURES
  
  We, the undersigned officers and directors of MathSoft, Inc., hereby severally
  constitute and appoint Charles J. Digate, Robert P. Orlando and Gordon H. Hayes,
  and each of them singly, our true and lawful attorneys, with full power to them
  and each of them singly, to sign for us in our names in the capacities indicated
  below, all pre-effective and post-effective amendments to this registration
  statement and generally do all things in our names and on our behalf in such
  capacities to enable MathSoft, Inc., to comply with the provisions of the
  Securities Act of 1933, as amended and all requirements of the Securities and
  Exchange Commission.
  
  Pursuant to the requirements of the Securities Exchange Act of 1933, as amended,
  this registration statement has been signed below by the following persons in
  the capacities and on the dates indicated.
  
  
  SIGNATURE                    TITLE(S)                         DATE:
  ---------                    --------                         -----
  
  /s/ Richard A. D'Amore       Director                         November 13, 1996
  -------------------------
  Richard A. D'Amore
  
  /s/ Charles J. Digate        President, Chief Executive       November 13, 1996
  -------------------------    and Chairman of the Board
  Charles J. Digate            of Directors (Principal
                               Executive Officer)
  
  /s/ Charles H. Federman      Director                         November 13, 1996
  -------------------------
  Charles H. Federman
  
  /s/ Robert P. Orlando        Vice President, Finance and      November 13, 1996
  -------------------------    Administration, Chief Financial
  Robert P. Orlando            Officer, Treasurer and Clerk
                               (Principal Financial and
                               Accounting Officer)
  
  /s/ Steven R. Vana-Paxhia    Director                         November 13, 1996
  -------------------------
  Steven R. Vana-Paxhia
  
  /s/ June L. Rokoff           Director                         November 13, 1996
  -------------------------
  June L. Rokoff
  
  <PAGE>   4
  
  
  
  <TABLE>
  
  
                                    EXHIBIT INDEX
                                    -------------
  
  <CAPTION>
  
  Exhibit No.   Description of Exhibit
  -----------   ----------------------
  <S>           <C>
  5.1           Opinion of Testa, Hurwitz & Thibeault, LLP
  23.1          Consent of Arthur Andersen LLP
  23.2          Consent of Testa, Hurwitz & Thibeault, LLP (included in Exhibit 5.1)
  24.1          Power of Attorney (contained in Page 3 of this Registration Statement)
  
  </TABLE>
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metadata_filer: {"company-data": {"conformed-name": "MATHSOFT INC", "cik": "0000895095", "assigned-sic": "7372", "irs-number": "042842217", "state-of-incorporation": "MA", "fiscal-year-end": "0630"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-16005", "film-number": "96660906"}, "business-address": {"street1": "101 MAIN ST", "city": "CAMBRIDGE", "state": "MA", "zip": "02142-1017", "phone": "6175771017"}, "mail-address": {"street1": "101 MAIN STREET", "city": "CAMBRIDGE", "state": "MA", "zip": "02142-1521"}}
text: 1
  
  As filed with the Securities and Exchange Commission on November 13, 1996
  
                                                     Registration No. 333-
                                                                          ------
  ================================================================================
  
                         SECURITIES AND EXCHANGE COMMISSION
                               Washington, D.C. 20549
  
                                --------------------
                                      FORM S-8
                               REGISTRATION STATEMENT
                                        under
                             THE SECURITIES ACT OF 1933
  
                                   MATHSOFT, INC.
               (Exact name of registrant as specified in its charter)
  Massachusetts                                          04-2842217
  (State or other jurisdiction of incorporation or organization)    (I.R.S. Employer Identification No.)
  
           101 Main Street, Cambridge, Massachusetts                              02142
              (Address of Principal Executive Offices)                          (Zip Code)
  --------------------
  
                                   MATHSOFT, INC.
                        AMENDED AND RESTATED 1992 STOCK PLAN
                              (Full title of the plan)
  
                                  Charles J. Digate
                                   MATHSOFT, INC.
                                   101 Main Street
                                 Cambridge, MA 02142
                       (Name and address of agent for service)
  
                                   (617) 577-1017
            (Telephone number, including area code, of agent for service)
                                --------------------
  
                                      Copy to:
                                   Gordon H. Hayes
                           Testa, Hurwitz & Thibeault, LLP
                                  High Street Tower
                                   125 High Street
                             Boston, Massachusetts 02110
                                   (617) 248-7000
                                --------------------
  
                           Calculation of Registration Fee
  =================================================================================================================================
    Title of Securities        Amount to be       Proposed maximum offering        Proposed maximum         Amount of registration
      to be registered          registered           price per share(1)           aggregate offering                fee(2)
                                                                                       price(1)
  ---------------------------------------------------------------------------------------------------------------------------------
  Common Stock,                   400,000                   $3.69                     $1,476,000                    $447.28
  par value $.01
  =================================================================================================================================
  (1)  Estimated solely for the purpose of calculating the registration fee
       pursuant to Rule 457 under the Securities Act of 1933.
  
  (2)  Pursuant to Rule 457(c) under the Securities Exchange Act of 1933, the
       registration fee has been calculated based upon the average of the high and
       low prices per share of Common Stock on the Nasdaq National Market on
       November 7, 1996.
  2
                                       -2-
  
       This Registration Statement registers additional securities of the same
  class as other securities for which: (i) the Registration Statement No. 33-58560
  on Form S-8 as filed with the Securities and Exchange Commission on February 19,
  1993, relating to the MathSoft, Inc. Amended and Restated 1992 Stock Plan, (ii)
  the Registration Statement No. 33-72162 on Form S-8 as filed with the Securities
  and Exchange Commission on November 24, 1993, relating to the MathSoft, Inc.
  Amended and Restated 1992 Stock Plan, (iii) the Registration Statement No.
  33-87542 on Form S-8 as filed with the Securities and Exchange Commission on
  December 16, 1994, relating to the MathSoft, Inc. Amended and Restated 1992
  Stock Plan, and (iv) the Registration Statement No. 33-99618 on Form S-8 as
  filed with the Securities and Exchange Commission on November 20, 1995, relating
  to the MathSoft, Inc. Amended and Restated 1992 Stock Plan, are effective.
  Pursuant to General Instruction E, the contents of the above-listed Registration
  Statements are hereby incorporated by reference.
  
                                       PART II
                 INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
  
  Item 8. Exhibits
          --------
  Exhibit No.   Description of Exhibit
  -----------   ----------------------
  5.1           Opinion of Testa, Hurwitz & Thibeault, LLP.
  
  23.1          Consent of Arthur Andersen LLP.
  
  23.2          Consent of Testa, Hurwitz & Thibeault, LLP (included in Exhibit 5.1).
  
  24.1          Power of Attorney (contained in Page 3 of this Registration Statement).
  3
                                       -3-
  
                                     SIGNATURES
  
  Pursuant to the requirements of the Securities Act of 1933, as amended, the
  Registrant certifies that it has reasonable grounds to believe that it meets all
  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 Cambridge, Commonwealth of Massachusetts, on the 13th
  day of November, 1996.
  
                                 MATHSOFT, INC.
  
  Date:  November 13, 1996       By: /s/  Charles J. Digate
                                     ----------------------
                                     Charles J. Digate
                                     President, Chief Executive Officer and 
                                     Chairman of the Board of Directors
  
                          POWER OF ATTORNEY AND SIGNATURES
  
  We, the undersigned officers and directors of MathSoft, Inc., hereby severally
  constitute and appoint Charles J. Digate, Robert P. Orlando and Gordon H. Hayes,
  and each of them singly, our true and lawful attorneys, with full power to them
  and each of them singly, to sign for us in our names in the capacities indicated
  below, all pre-effective and post-effective amendments to this registration
  statement and generally do all things in our names and on our behalf in such
  capacities to enable MathSoft, Inc., to comply with the provisions of the
  Securities Act of 1933, as amended and all requirements of the Securities and
  Exchange Commission.
  
  Pursuant to the requirements of the Securities Exchange Act of 1933, as amended,
  this registration statement has been signed below by the following persons in
  the capacities and on the dates indicated.
  
  SIGNATURE                    TITLE(S)                         DATE:
  ---------                    --------                         -----
  
  /s/ Richard A. D'Amore       Director                         November 13, 1996
  -------------------------
  Richard A. D'Amore
  
  /s/ Charles J. Digate        President, Chief Executive       November 13, 1996
  -------------------------    and Chairman of the Board
  Charles J. Digate            of Directors (Principal
                               Executive Officer)
  
  /s/ Charles H. Federman      Director                         November 13, 1996
  -------------------------
  Charles H. Federman
  
  /s/ Robert P. Orlando        Vice President, Finance and      November 13, 1996
  -------------------------    Administration, Chief Financial
  Robert P. Orlando            Officer, Treasurer and Clerk
                               (Principal Financial and
                               Accounting Officer)
  
  /s/ Steven R. Vana-Paxhia    Director                         November 13, 1996
  -------------------------
  Steven R. Vana-Paxhia
  
  /s/ June L. Rokoff           Director                         November 13, 1996
  -------------------------
  June L. Rokoff
  4
  
                                    EXHIBIT INDEX
                                    -------------
  Exhibit No.   Description of Exhibit
  -----------   ----------------------
  5.1           Opinion of Testa, Hurwitz & Thibeault, LLP
  23.1          Consent of Arthur Andersen LLP
  23.2          Consent of Testa, Hurwitz & Thibeault, LLP (included in Exhibit 5.1)
  24.1          Power of Attorney (contained in Page 3 of this Registration Statement)