Document:

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                                                                   EXHIBIT 10.35
                                                                   -------------

July 28, 1999

Amphion Ventures, L.P.
c/o Amphion Capital Management, LLC
590 Madison Avenue
32nd Floor
New York, NY  10022

         Re:  Notice of Assignment

Gentlemen:

         AXCESS Inc. ("AXCESS") and Prism Video, Inc. ("Prism") have entered
into an Asset Purchase Agreement, dated as of July 15, 1999 (the "Asset Purchase
Agreement"). As part of this transaction, AXCESS delivered to Prism a Purchase
Note (the "Purchase Note"). To secure payment of the Purchase Note, AXCESS
granted Prism a security interest in that certain Subordinated Promissory Note,
dated as of April 30, 1999, by Amphion Ventures, L.P. ("Amphion"), as Maker, in
favor of AXCESS (the "Collateral Note").

         Pursuant to the Asset Purchase Agreement, AXCESS also assigned to Prism
all payments of principal to be made by Amphion under the Collateral Note until
the balance of the Collateral Note is paid in full or the balance due under the
Purchase Note is paid, whichever occurs first.

         Effective immediately, please pay to Prism directly all payments of
principal payable under the Collateral Note until such time as you are advised
in writing by joint notice from AXCESS and Prism that the Purchase Note has been
paid. The payments should be made payable to Prism Video, Inc. and sent to the
address to be provided by Prism.

         By executing this letter, you acknowledge and affirm to Prism as
follows:

         The Collateral Note has been duly and validly executed and delivered
by, and is the binding obligation of Amphion, and is in full force and effect.

         As of July 28, 1999, the balance due under the Collateral Note is
$3,902,375.

         No default or condition exists, which, with or without the passage of
time, the giving of notice, or both, would constitute a default under any
agreement which would give rise to a defense to a lawsuit to enforce payment of
the Collateral Note.

         The payment terms of the Collateral Note and the obligation it
memorializes are accurately
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set forth in the Collateral Note.

         There have been no amendments to the terms of the Collateral Note.

         Amphion consents to the assignment of the principal payments due under
the Collateral Note by AXCESS to Prism until the balance of the Collateral Note
is paid in full or the balance due under the Purchase Note is paid, whichever
occurs first and will remit and deliver all payments directly to Prism at the
address set forth above.

         Amphion will not enter into any agreement amending or modifying the
Collateral Note to (a) decrease the principal balance thereof to an amount which
is less than the difference between the balance of the Collateral Note as of the
date hereof and all principal payments received by the Company from Maker from
and after the date hereof or (b) extend the date on which the Maker shall make
any principal payment beyond the date such principal payment was originally due.
Nothing herein shall prohibit Maker and the Company from otherwise amending,
modifying or changing the Collateral Note. Amphion does not have, and will not
assert against Prism, any defense, counterclaim or offset to full and timely
payment of the Collateral Note.

         Please return this letter, when executed by an authorized signatory of
Amphion Ventures, L.P., to Prism at the address set forth herein.

                                 Very truly yours,

                                 AXCESS INC.

                                 By: /s/ Danny G. Hair
                                    --------------------------------------------
                                         Danny G. Hair, Chief Financial Officer

ACKNOWLEDGED BY:

AMPHION VENTURES, L.P.,
a Delaware limited partnership

By:      AMPHION PARTNERS LLC,
         its General Partner

By:/s/ Richard C.E. Morgan
   ------------------------------------
   Richard C.E. Morgan, Managing Member<PAGE>

                                                                   EXHIBIT 10.36
                                                                   -------------

                              SECURITY AGREEMENT

     This Security Agreement (the "Security Agreement") is made and dated this
28/th/ day of July, 1999, by and among AXCESS Inc., a Delaware corporation (the
"Company"), and Prism Video, Inc., a Delaware corporation ("Seller").

                                    RECITALS

     The Company has issued that certain Purchase Note dated as of the date
hereof in favor of Seller (as amended, renewed, extended and replaced from time
to time, the "Purchase Note") pursuant to the terms of that certain Asset
Purchase Agreement of even date herewith by and between the Company and Seller
(as amended from time to time, the "Asset Purchase Agreement," and with
capitalized terms used herein and not otherwise defined used with the meanings
given such terms in the Asset Purchase Agreement).

     As a condition precedent to the Asset Purchase Agreement, the Company is
required, among other things, to execute and deliver this Security Agreement to
Seller.

     NOW, THEREFORE, in consideration of the above Recitals and for other good
and valuable consideration, the receipt and adequacy of which are hereby
acknowledged, the parties hereto hereby agree as follows:

                                   AGREEMENT

     1.   Grant of Security Interest.  The Company hereby grants to Seller a
          --------------------------
first-priority security interest in that certain Subordinated Promissory Note,
dated as of April 30, 1999, by Amphion Ventures, L.P. ("Maker") in favor of the
Company (the "Collateral Note") and any proceeds thereof, to secure payment and
performance of the Company's obligations under the Purchase Note.

     2.   Representations and Warranties.  The Company represents and warrants
          ------------------------------
to Seller that (a) the Company is the true and lawful owner of the Collateral
Note, having good and marketable title thereto, free and clear of any and all
liens, (b) the Collateral Note is a valid and binding obligation of the Maker,
(c) Maker holds no defenses or offsets against any amounts due under the
Collateral Note, (d) the principal balance of the Collateral Note, as of the
date hereof, is $3,902,375, (e) the Collateral Note accurately reflects the
payment terms of the obligation memorialized therein, (f) there have been no
amendments to the terms of the Collateral Note, and (f) the Maker is current in
all payment due, and not in default of any of the terms of the Collateral Note.
The Company shall not create or assume or permit to exist any lien on or against
the Collateral Note except for liens subordinate to the lien granted to Seller
hereunder or as otherwise as created or permitted by this Security Agreement,
and the Company shall promptly notify Seller of any such other lien against the
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Collateral Note and shall defend the Collateral Note against, and take all such
action as may be necessary to remove or discharge, any lien.

     3.   Perfection of Security Interest.  Contemporaneously herewith, the
          -------------------------------
Company shall deliver possession of the Collateral Note to Seller to allow
Seller to perfect its security interest in the Collateral Note.  The Company
agrees to take all other actions requested by Seller reasonably necessary to
perfect, to continue the perfection of, and to otherwise give notice of the lien
granted hereunder, including, but not limited to, execution of financing
statements.

     4.   Covenants and Agreements of the Company.  In addition to all covenants
          ---------------------------------------
and agreements of the Company set forth in the Asset Purchase Agreement, which
are incorporated herein by this reference, the Company agrees:

          To do all acts that may be necessary to maintain, preserve and protect
the Collateral Note;

          Not to use or permit the Collateral Note to be used unlawfully or in
violation of any provision of this Security Agreement, any other agreement with
Seller related hereto, or any requirement of law or contractual obligation
affecting the Collateral Note;

          To pay promptly when due all taxes, assessments, charges, encumbrances
and liens now or hereafter imposed upon or affecting the Collateral Note;

          To appear in and defend any action or proceeding, at the Company's
sole expense, which may affect its title to or Seller's interest in the
Collateral Note;

          Not to sell, encumber or otherwise dispose of or transfer the
Collateral Note or right or interest therein except as expressly provided
herein, and to keep the Collateral Note free of all levies and security
interests or other liens or charges except as otherwise provided herein or as
approved in writing by Seller.

          To account fully for and promptly deliver to Seller, in the form
received, all documents, instruments and agreements constituting the Collateral
Note hereunder and all proceeds of principal payments received by the Company,
all endorsed to Seller or in blank, as requested by Seller, and accompanied by
such stock powers as appropriate and until so delivered all such documents,
instruments, agreements and proceeds shall be held by the Company in trust for
Seller separate from all other property of the Company;

          Not to amend, modify or change the Collateral Note to (a) decrease the
principal balance thereof to an amount which is less than the difference between
the balance of the Collateral Note as of the date hereof and all principal
payments received by the Company from Maker from and after the date hereof or
(b) extend the date on which the Maker shall make any principal payment beyond
the date such principal payment was originally due.  Nothing herein shall
prohibit Maker and the Company from otherwise amending, modifying or changing
the Collateral Note.

                                      -2-
<PAGE>

          To inform Seller immediately of any information obtained or learned by
the Company which may have an effect on the value or collectability of the
Collateral Note;

          To give Seller thirty (30) days prior written notice of any change in
the Company's chief place of business or legal name or trade name(s) or
style(s);

          To keep the records concerning the Collateral Note at the location(s)
referred to in Paragraph 8 below and not to remove such records from such
location(s) without the prior written consent of Seller.

     5.   Assignment of Principal Payments Under Collateral Note.  The Company
          ------------------------------------------------------
shall provide instructions to Maker, in a form satisfactory to Seller, to timely
make all principal payments due under the Collateral Note ("Principal Payments")
when due directly to Seller at such address as Seller shall provide until the
balance of the Collateral Note is paid in full or the balance due under the
Purchase Note is paid, whichever occurs first.  The Company shall take all
actions reasonably necessary to ensure that all Principal Payments are timely
paid.  The Company agrees to exercise such rights and remedies as Seller may
reasonably request, at the Company's sole expense, including, without
limitation, the taking of such action with respect thereto as Seller may
reasonably request, or, in the absence of such request, as the Company may
reasonably deem advisable to enforce any defaults or otherwise reduce the risk
of nonpayment or delinquent payment of the Collateral Note or the Principal
Payments.

          The Company will, forthwith upon receipt, transmit and deliver to the
Seller, in the form received, all cash, checks, drafts and other instruments for
the payment of money (properly endorsed where required so that such items may be
collected by the Seller) which may be received by the Company at any time as
payment on account of any Principal Payments and, until delivery to the Seller,
such items will be held in trust for the Seller and will not be commingled by
the Company with any of its funds or property.  Thereafter, the Seller is hereby
authorized and empowered to endorse the name of the Company on any check, draft
or other instrument for the payment of money received by the Seller on account
of any Principal Payments if the Seller believes such endorsement is necessary
or desirable for purposes of collection.  The Company will indemnify and save
harmless Seller from and against all reasonable liabilities and expenses on
account of any adverse claim asserted against the Seller relating to any moneys
received by Seller on account of any Principal Payments and such obligation of
the Company shall continue in effect after and notwithstanding the discharge of
the obligations under the Asset Purchase Agreement and the release of the
security interest granted in Paragraph 1 above.

     6.   Authorized Action by Secured Party.  The Company hereby agrees that
          ----------------------------------
from time to time Seller may, but shall not be obligated to and shall incur no
liability to the Company, the Maker or any third party for failure to, take any
action which the Company is obligated by this Security Agreement to do and to
exercise such rights and powers as the Company might exercise with respect to
the Collateral Note or the Principal Payments, and the Company hereby appoints
the Seller as its attorney-in-fact to exercise such rights and powers, including
without limitation, to: (a) collect by legal proceedings or otherwise and
endorse, receive and receipt for all Principal Payments now or

                                      -3-
<PAGE>

hereafter payable on or on account of the Collateral Note; (b) enter into any
extension, reorganization, deposit, merger, consolidation or other agreement
pertaining to, or deposit, surrender, accept, hold or apply other property in
exchange for the Collateral Note; (c) to execute and file in the Company's name
any financing statements or amendments thereto required to perfect or to
continue to perfect Seller's security interest in the Collateral Note; (d)
insure, process and preserve the Collateral Note; (e) make any compromise or
settlement, and take any action it deems advisable, with respect to the
Collateral Note; and (f) notify the Maker to make payment directly to the
Seller. The Company hereby grants to the Seller an exclusive, irrevocable power
of attorney, coupled with interest, with full power and authority in the place
and stead of the Company to take all such action permitted under this Paragraph
6 until the balance of the Collateral Note is paid in full or the balance due
under the Purchase Note is paid, whichever occurs first; provided, however, that
notwithstanding the terms and conditions of this Paragraph 6, Seller may only
take an action permitted under this Paragraph 6 on behalf of the Company if the
Company shall fail to take any such action during the thirty (30) day period
following the Company's receipt of Seller's written notice requesting the
Company take any such action.

     7.   Remedies.  Upon the occurrence of an event of default under the
          --------
Purchase Note or this Security Agreement which remains uncured by the Company
for a period of ten (10) days following the Company's receipt of Seller's notice
of default, Seller shall and in addition to all rights and remedies available to
Seller under the Asset Purchase Agreement, at law, in equity or otherwise, do
any one or more of the following:

          Foreclose or otherwise enforce, Seller's security interest in any
manner permitted by law, or provided for in this Security Agreement or in the
Asset Purchase Agreement;

          Sell, lease or otherwise dispose of the Collateral Note at one or more
public or private sales at Seller's place of business or any other place or
places, including, without limitation, any broker's board or securities
exchange, on such terms and in such manner as Seller may determine; and

          Recover from the Company all costs and expenses, including, without
limitation, reasonable attorneys' fees, incurred or paid by Seller in exercising
any right, power or remedy provided by this Security Agreement.

The Company shall be given ten (10) business days' prior notice of the time and
place of any public sale or of the time after which any private sale or other
intended disposition of the Collateral Note is to be made, which notice the
Company hereby agrees shall be deemed reasonable notice thereof. Upon any sale
or other disposition pursuant to this Security Agreement, Seller shall have the
right to deliver, assign and transfer to the purchaser thereof the Collateral
Note so sold or disposed of.

     8.   General Terms and Conditions.
          ----------------------------

          No Waiver.  The waiver of any default or event of default hereunder
          ---------
shall not be a waiver of any subsequent default or event of default.  Seller's
acceptance of partial or delinquent

                                      -4-
<PAGE>

payments or Seller's failure to exercise any rights it may have shall not waive
any obligation of the Company or any rights of Seller or otherwise modify this
Security Agreement, or waive any other similar matter.

          Amendments, Etc.  No amendment or waiver of any provision of this
          ----------------
Security Agreement nor consent to any departure by the Company herefrom shall in
any event be effective unless the same shall be in writing and signed by the
Seller, and then such waiver or consent shall be effective only in the specific
instance and for the specific purpose for which given.

     9.   Notices.  Any written notice or other communication under this
          -------
Security Agreement shall be treated as given when personally received by the
party notified or upon the expiration of two (2) days from the date placed in
the United States mail, certified or registered, postage prepaid, addressed to
the party to be notified at the address set out below or at any address
furnished to the notifying party with a written request for notice at that
address.  The addresses to which notice shall be given until change in
accordance with this section are as follows:

          The Company:        AXCESS Inc.
                              3208 Commander Drive
                              Dallas, TX 75006
                              Attention: Chief Financial Officer
                              Telecopy: 972.407.0814

          with a copy to:     Sayles & Lidji, A Professional Corporation
                              4400 Renaissance Tower
                              1201 Elm Street
                              Dallas, TX 75270
                              Attention: Michael R. Dorey
                              Telecopy: 214.939.8787

          To the Seller:      Prism Video, Inc.
                              15851 Dallas Parkway, Suite 1060
                              Dallas, TX 75001
                              Attention: President
                              Telecopy: 972.770.7991

          with a copy to:     Gray Cary Ware & Freidenrich LLP
                              401 "B" Street, Suite 1700
                              Attention: Robert W. Ayling
                              Telecopy: 619.677.1477

     10.  Attorneys' Fees.  Should either party hereto employ an attorney for
          ---------------
the purpose of enforcing or construing this Security Agreement, or any judgment
based upon this Security Agreement, in any legal proceeding whatsoever,
including insolvency, bankruptcy, arbitration, declaratory relief or other
litigation, the prevailing party shall be entitled to receive from the other

                                      -5-
<PAGE>

party or parties thereto reimbursement for all attorneys' fees and all costs,
including but not limited to service of process, filing fees, court and court
reporter costs, investigative costs, expert witness fees, and the costs of any
bonds, whether taxable or not, and that such reimbursement shall be included in
any judgment or final order issued in such proceeding.  As used herein,
"prevailing party" shall mean the party determined by the court to most nearly
prevail and not necessarily the one in whose favor a judgment is rendered.

     11.  Miscellaneous.  Time is of the essence of this Security Agreement and
          -------------
all its provisions.  Section 12.10 of the Asset Purchase Agreement is hereby
incorporated by reference in the Security Agreement for all purposes as if set
forth herein verbatim.  All rights of Seller hereunder shall inure to the
benefit of its successors and assigns; all obligations of the Company shall bind
successors and assigns.  Unless otherwise defined or provided herein, all words
used in this Security Agreement shall have the meaning given to them in the
Uniform Commercial Code as adopted by the State of Texas.  Titles preceding any
section of this Security Agreement are for convenience only.  The Company will
execute any additional agreements, assignments or documents that may be deemed
necessary or advisable by the Seller to effectuate the purposes of this Security
Agreement or to preserve and protect the Collateral Note and Seller's rights.
Any corporation which signs this Security Agreement expressly warrants that the
officer signing on behalf of the corporation has authority to so sign by
resolution of the corporation's board of directors.  Each term, covenant,
condition or provision of this Security Agreement shall be viewed as separate
and distinct, and in the event that any such term, covenant, condition or
provisions shall be held by a court of competent jurisdiction to be invalid, the
remaining provisions shall continue in full force and effect.  The construction
of this Security Agreement, and the rights and liabilities of the parties
hereto, shall be governed by the laws of the State of Texas, without regard to
choice of law provisions, statutes, regulations or principles of this or any
other jurisdiction.

                                      -6-
<PAGE>

EXECUTED this 28/th/ day of July, 1999.

                              AXCESS INC.,
                              a Delaware corporation

                              By: /s/ Danny G. Hair
                                  --------------------------------------
                                  Danny G. Hair, Chief Financial Officer

                              PRISM VIDEO, INC.,
                              a Delaware corporation

                              By: /s/ Allan Griebenow
                                  --------------------------------------
                                  Allan Griebenow, President

                                      -7-

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