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[XYBERNAUT LOGO]                                                EXHIBIT 10.17


PURCHASE AGREEMENT BETWEEN ADAPTIVE SYSTEMS INC. AND XYBERNAUT CORPORATION
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XYBERNAUT Corporation desires to purchase Application Specific Integrated
Circuits (ASIC) chips from ADAPTIVE SYSTEMS INCORPORATED (ASI). This purchase
agreement replaces and supersedes in its entirety the Memorandum of
Understanding (MOU) signed by both companies on Oct. 9, 1996.

1.   Adaptive Systems will provide or have provided ASIC chips to Xybernaut's
     designee. Xybernaut will build and sell systems containing the ASIC chips
     to Xybernaut customers.

2.   The cost that Xybernaut's designee pays for the chips will be based on the
     following quantities:

               Order Quantity           Cost for 520001
               --------------           ---------------

               25,000 or less               $29.00

               25,001 - Plus                $15.00

     These fees are cumulative, that is, for an order of 75,000 ASIC chips the
fee allowed would be:

      25,000 x $29.00 = $725,000

      50,000 x $15.00 = $750,000
                        --------

                      $1,475,000

     3.   The cost for the next generation ASIC chip will not exceed the higher
          of: a.) the cost for the 520001 plus 25% or; b.) the actual cost of
          the ASIC from the manufacturer plus 10%. The cost for the next
          generation ASIC chips are not cumulative with quantities ordered for
          the 52001 or any other ASIC chips from ASI. Accordingly, ASI agrees to
          provide the next generation of the ASIC chips to Xybernaut, subject to
          the terms and conditions herein.

     4.   At Xybernaut's request, ASI will deposit the applicable intellectual
          Property into a mutually designated escrow for Xybernaut's use in
          case ASI becomes unwilling or unable to support the product with a
          maximum of three configuration releases during the base period of this
          agreement. Priority and content of required releases will be mutually
          determined. If Xybernaut uses the ASI Intellectual Property (IP) and
          funds a significant amount of additional development, then Xybernaut
          will pay a royalty to ASI in the amount of $25.00 for each system sold
          that uses the subject IP.

     5.   ASI hereby grants an exclusive license to Xybernaut under U.S.Patent
          Number 5,539,330 to use and sell the invention described in said
          patent or improvements therein whether or not described in ASI patents
          for computer equipment as protected by Xybernaut's Patent Number
          5.305.244 and subsequent Xybernaut patents. Both parties will notify
          the other in writing of all patents when issued.


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          ASI will not knowingly license anyone else to use the ASIC chip and
          related IP that may violate Xybernaut's patents.

     6.   Xybernaut's forecast for Mobile Assistant II (586) is as follows:
<TABLE>
               <S>           <C>       <C>           <C>        <C>           <C>
               March '97      -150     April '97      -200      May '97        -425

               June '97       -550     July '97       -650      August '97     -700

               September '97  -900     October '97    -900      November '97  -1025

               December '97  -1100     January '88   -1150      February '98  -1200

               March '98     -1200
</TABLE>

          The systems may be manufactured by Hi-Tech Manufacturing and Solectron
          Corporation, or other manufacturers designated by Xybernaut. The
          manufacturer will order the ASIC chips directly from ASI. Each system
          will require six (6) ASIC chips.

     7.   This Agreement is for a base period of one (1) year, plus a one (1)
          year option at the option of Xybernaut. Not withstanding the term of
          this agreement, the right to use and sell shall be in effect for as
          long as Xybernaut's patents are in effect.

     8.   ASI will provide updated quote packages to Xybernaut for transmittal
          to contract manufacturers selected by Xybernaut for the actual board
          production and component mounting.

     9.   This Agreement shall be governed by and construed in accordance with
          the laws of the state of Delaware.

     10.  If any claim arises out of this Agreement, the parties shall make a
          good faith attempt to resolve the matter. In the event that the claim
          cannot otherwise be settled after a good faith attempt, the claim
          shall be submitted to arbitration in accordance with the American
          Arbitration Association Arbitration Rules. Neither ASI nor Xybernaut
          shall unreasonably object to transfer or assignment of this agreement
          by the other party to a successor or assignee.

     11.  Either party shall have the right to terminate this Agreement upon
          written notice to the other, if it is determined that the other party
          is in material breach of any term, condition or covenant of this
          Agreement and fails to cure that breach within sixty (60) days of
          receipt of written notice of such alleged breach, provided such cure
          can reasonably be affected within 60 days. If such cure cannot be
          reasonably effected within 60 days, then one additional 30 day period
          will be allowed to effect such cure. If cure is not affected in such
          period, the party in breach shall be considered in default.


/s/ EDWARD G. NEWMAN                    /s/ WILLIAM J. MCDERMID
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Date:   12/28/96                        Date:  12/30/96
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Mr. Edward G. Newman                    Mr. William J. McDermid
President & CEO                         President & CEO
Xybernaut Corporation                   Adaptive Systems Inc.


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