EXHIBIT 10.21
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                                PLEDGE AGREEMENT

                                      among


                               SIMTEK CORPORATION

                                       and


                RENAISSANCE CAPITAL GROWTH & INCOME FUND III, INC

                                       and


                    RENAISSANCE US GROWTH & INCOME TRUST PLC

                                       and


                      BFSUS SPECIAL OPPORTUNITIES TRUST PLC



                            Dated as of June 28, 2002

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     THIS PLEDGE AGREEMENT,  dated as of June 28, 2002 among SIMTEK CORPORATION,
a Colorado  corporation  ("Pledgor"),  RENAISSANCE  CAPITAL GROWTH & INCOME FUND
III,  INC., a Texas  corporation  ("Renaissance  III"),  RENAISSANCE US GROWTH &
INCOME  TRUST PLC, a public  limited  company  registered  in England  and Wales
("RUSGIT"),  BFSUS SPECIAL  OPPORTUNITIES  TRUST PLC, a public  limited  company
registered in England and Wales  ("BFSUS")  (Renaissance  III,  RUSGIT and BFSUS
collectively  referred to as "Secured  Party"),  and RENAISSANCE  CAPITAL GROUP,
INC., a Texas corporation, as Agent for the Lender (the "Agent").

                                    RECITALS

     A. Pledgor,  Secured  Party and Agent have entered into a Convertible  Loan
Agreement of even date herewith (the "Convertible Loan Agreement").  Capitalized
terms  used but not  defined  herein  shall have the  meanings  set forth in the
Convertible Loan Agreement.

     B. Pursuant to the terms of the Convertible  Loan Agreement,  Secured Party
will lend to Pledgor the aggregate  principal  amount of Three  Million  Dollars
($3,000,000)  to be evidenced by the Pledgor's 7.50%  Convertible  Debentures of
even date herewith (the "Debentures").

     C. Pledgor is the owner of the shares of capital stock hereto issued by the
Subsidiary  described on Schedule A, and Pledgor has agreed to pledge and assign
to Secured Party a security interest in the Shares,  together with any shares of
capital stock of any Subsidiary subsequently acquired or formed by Pledgor or an
affiliate (collectively,  the "Shares"), to secure payment of the Obligations of
Pledgor under the  Convertible  Loan Agreement and  Debentures.  The Obligations
shall  also  consist  of  payment  of the  costs  and  expenses  of that sale or
realization, including compensation to Secured Party and its agents and counsel,
and all expenses, liabilities, and advances made or incurred by Secured Party in
connection therewith, all as set forth in the Convertible Loan Agreement.

     NOW,  THEREFORE,  in consideration of the foregoing recitals and the mutual
covenants, the parties agree as follows:

     1. PLEDGE OF SHARES.  Pledgor hereby  pledges and,  subject to the terms of
this Pledge  Agreement,  assigns to the Secured Party the Shares for the purpose
of  securing  the  full  and  prompt  payment,  when  due,  by  Pledgor  of  the
Obligations.

     2. DELIVERY OF SHARES. Upon execution of this Pledge, Pledgor shall deliver
to Agent  all the  certificates  representing  the  Shares,  together  with duly
executed  stock powers,  in blank.  Agent shall hold all such  certificates  and
stock powers subject to the terms of this Pledge Agreement.

     3. VOTING OF SHARES AND RECEIPT OF DIVIDENDS.  Pledgor shall have the right
to vote the  Shares,  except as  provided  herein  and in the  Convertible  Loan
Agreement  and  Debentures,  upon the  occurrence  of an Event of  Default  or a
Default.

     4. REPRESENTATIONS AND WARRANTIES.  Pledgor hereby warrants, represents and
covenants as follows:


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             (i)  Pledgor  owns the  Shares,  free from any  adverse  claims and
Liens;

             (ii) All  Shares  pledged  in this  Pledge  Agreement  are  validly
authorized, issued, and outstanding, and are fully paid and nonassessable;

             (iii)  Pledgor  will notify  Secured  Party of, and will defend the
Shares  against,  all claims and demands of all persons at any time claiming the
Shares or any interest therein;

             (iv)  Pledgor  will pay all taxes and  assessments  upon the Shares
prior to the date of delinquency for payment of such taxes and assessments; and

     5. PLEDGOR HAS THE FULL  CORPORATE  POWER,  AUTHORITY AND CAPACITY TO GRANT
THE SECURITY  INTEREST  HEREUNDER.  When the Obligations have been paid in full,
Agent shall promptly deliver the certificates  representing the Shares then held
by it and all related stock powers to Pledgor.

     6.  OCCURRENCE  OF EVENT OF  DEFAULT.  If an Event of  Default or a Default
occurs,  Agent or Secured  Party shall have the right to exercise any rights and
remedies provided in the Convertible Loan Agreement,  as Secured Party or Agent,
in its or their sole  discretion,  may deem  necessary or  appropriate.  Secured
Party or Agent shall further have the right to exercise any remedies  afforded a
secured party under the Uniform Commercial Code of Texas or any other applicable
law with respect to the Shares.

     7. DURATION OF PLEDGE. This Pledge shall be terminated upon the earlier of:
(i) foreclosure by Secured Party of the security interest granted hereunder upon
the  occurrence of a Default or an Event of Default,  or (ii) the payment of the
Obligations.

     8.  APPLICATION  OF  PROCEEDS.  The  proceeds  of any  sale  of,  or  other
realization  upon,  all or any part of the Shares,  and any other monies held by
Secured  Party under this Pledge  Agreement,  shall be applied in the  following
order of priority:

         (a)  First,  to  payment  of the  costs  and  expenses  of that sale or
realization, including compensation to Secured Party and its agents and counsel,
and all expenses, liabilities, and advances made or incurred by Secured Party in
connection therewith;

         (b) Second, to payment of the interest in full on the Debentures;

         (c) Third, to payment of the Principal Amount; and

         (d)  Finally,  to  payment  of any  surplus  then  remaining  from such
proceeds and other monies to Pledgor or its successors or assigns, or as a court
of competent jurisdiction may direct.

     If the proceeds of the Shares shall not suffice to pay all items  specified
in clauses a. and b. above, Pledgor shall remain liable for the deficiency.



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     9.  MISCELLANEOUS.

         a. SECURED PARTY  APPOINTED  ATTORNEY-IN-FACT.  Upon the occurrence and
continuation  of  a  Default,   Secured  Party  is  hereby  appointed  Pledgor's
attorney-in-fact,  for the purpose of carrying out the provisions of this Pledge
Agreement  and taking any action and  executing  any  instruments  which Secured
Party may deem  necessary or advisable to accomplish the purposes  hereof.  This
appointment as  attorney-in-fact  is  irrevocable  and coupled with an interest.
Without  limiting  the  generality  of this  appointment,  upon such  Default(i)
Secured  Party shall have the right and power to receive,  endorse,  and collect
all checks made payable to the order of Pledgor  which  represent  any dividend,
interest,  or other  payment  or  distribution  in  respect of all or any of the
Obligations  and to give full  discharge  for the same,  and (ii) Secured  Party
shall have the right to exercise,  as Pledgor's  proxy, the powers of voting and
consent pertaining to the Obligations or any part thereof.

         b.  EXPENSES.  Pledgor  agrees to pay to  Secured  Party  all  expenses
(including expenses for legal service of every kind) relating to the enforcement
of any of the  provisions of this Pledge  Agreement,  or any actual or attempted
sale or any exchange,  enforcement,  compromise, or settlement respecting any of
the  Obligations,  and any defense or  assertion of Secured  Party's  rights and
claims, by litigation or otherwise,  including  expenses of insurance.  All such
expenses will be Obligations secured under this Pledge Agreement.

         c. ADDITIONAL COLLATERAL. In the event that any shares of capital stock
of any issuer shall  hereafter  be acquired by or  otherwise  issued to Pledgor,
Pledgor  shall  promptly  (and in any  event  within  ten (10) days  after  such
acquisition)  deliver the certificates  evidencing the same to Secured Party, to
be held as  additional  collateral  to secure the  payment  of the  Obligations,
together  with the stock  powers duly  executed by Pledgor  according to Secured
Party's  instructions,  at Secured  Party's office as stated herein,  or at such
other place as Secured Party may request.

         d.  GOVERNING  LAW.  This Pledge shall be governed by and construed and
enforced in accordance with the substantive laws of the State of Texas,  without
regard to the conflicts of laws provisions  thereof,  and the applicable laws of
the  United  States.  Venue and  jurisdiction  shall be in the state or  federal
courts in Dallas County, Texas.

         e.  BINDING  EFFECT.  All of  the  terms,  covenants,  representations,
warranties and conditions herein shall be binding upon, and inure to the benefit
of, and be  enforceable  by the  parties  and their  respective  successors  and
assignees.

         f.  WAIVER.  This Pledge may not be amended,  modified,  superseded  or
canceled, nor may any of the terms,  covenants,  representations,  warranties or
conditions  hereof be waived,  except by a written  instrument  executed  by the
party against whom such amendment,  modification,  supersedure,  cancellation or
waiver is  charged.  The  failure  of any party at any time or times to  require
performance  of any  provision  hereof shall in no manner  affect the right at a
later time to enforce the same. No waiver by any party of any  condition,  or of
any breach of any term,  covenant,  representation or warranty contained herein,
in any one or more instances, shall be deemed to be or construed as a further or


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continuing  waiver  of any such  condition  or  breach  or  waiver  of any other
condition  or of any  breach  of any other  term,  covenant,  representation  or
warranty.

         g.  ATTORNEYS'  FEES. If any party brings an action in connection  with
the  performance,  breach or  interpretation  of this  Pledge,  or in any action
related to the transaction  contemplated  hereby,  the prevailing  party in such
action  shall be  entitled to recover  from the losing  party in such action all
reasonable  costs and expenses of such  litigation,  including  attorneys' fees,
court  costs,  costs of  investigation,  accounting  and other costs  reasonably
incurred or related to such litigation.

         h. SEVERABILITY. If any provision hereof is determined to be illegal or
unenforceable,   such   determination   shall  not   affect  the   validity   or
enforceability of the remaining  provisions hereof, all of which shall remain in
full force and effect.

         i. FURTHER  DOCUMENTS.  Each party covenants and agrees that, from time
to time,  after the date hereof,  at the reasonable  request of any other party,
and without  further  consideration,  such party will  execute and deliver  such
other documents and take such other action reasonably  required to carry out, in
all respects, the transactions contemplated and intended by this Pledge.

         j. NOTICES. Any notices or other  communications  required or permitted
to be given by this Agreement or any other documents and instruments referred to
herein must be (i) given in writing and personally delivered,  mailed by prepaid
certified or registered  mail or sent by overnight  service,  such as FedEx,  or
(ii) made by telex or facsimile  transmission  delivered or  transmitted  to the
party to whom such  notice  or  communication  is  directed,  with  confirmation
thereupon  given in  writing  and  personally  delivered  or mailed  by  prepaid
certified or registered mail.

        If to Pledgor:        Simtek Corporation
                              450 Buckingham Dr., Suite 100
                              Colorado Springs, CO 80907
                              Attn:    Douglas M. Mitchell
                              Telephone:        (719) 531-9444
                              Telecopier:       (719) 531-9481

        With a copy to:       Holme Roberts & Owen LLP
                              1700 Lincoln, Suite 4100
                              Denver, CO 80203
                              Attn:    Garth B. Jensen
                              Telephone:        (303) 861-7000
                              Telecopier:       (303) 866-0200



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        If to Secured Party:  Renaissance Capital Growth & Income Fund III, Inc.
                              c/o Renaissance Capital Group, Inc.
                              8080 North Central Expressway, Suite 210-LB59
                              Dallas, TX 75206
                              Attn.:  Robert C. Pearson
                                      Senior Vice President
                              Telephone:       (214) 891-8294
                              Telecopier:      (214) 891-8291

                              Renaissance US Growth & Income Trust PLC
                              c/o Renaissance Capital Group, Inc.
                              8080 North Central Expressway, Suite 210-LB59
                              Dallas, TX 75206
                              Attn.:  Robert C. Pearson
                                      Senior Vice President
                              Telephone:       (214) 891-8294
                              Telecopier:      (214)  891-8291

                              BFSUS Special Opportunities Trust PLC
                              c/o Renaissance Capital Group, Inc.
                              8080 North Central Expressway, Suite 210-LB59
                              Dallas, TX 75206
                              Attn.:  Robert C. Pearson
                                      Senior Vice President
                              Telephone:       (214) 891-8294
                              Telecopier:      (214) 891-8291

         with a copy to:      Kirkpatrick & Lockhart LLP
                              2828 N. Harwood, Suite 1800
                              Dallas, TX 75201
                              Attn:   Norman R. Miller
                              Telephone:       (214) 939-4906
                              Telecopier:       (214) 939-4949

         If to Agent:         Renaissance Capital Group, Inc.
                              8080 N. Central Expressway, Suite 210-LB 59
                              Dallas, TX 75206
                              Attn.:  Robert C. Pearson
                                      Senior Vice President
                              Telephone:        (214) 891-8294
                              Telecopier:       (214) 891-8291


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        with a copy to:       Kirkpatrick & Lockhart LLP
                              2828 N. Harwood, Suite 1800
                              Dallas, TX 75201
                              Attn:   Norman R. Miller
                              Telephone:       (214) 939-4906
                              Telecopier:      (214) 939-4949


         Any notice  delivered  personally in the manner provided herein will be
deemed  given to the  party to whom it is  directed  upon  the  party's  (or its
agent's) actual receipt.  Any notice addressed and mailed in the manner provided
herein will be deemed given to the party to whom it is addressed at the close of
business,  local time of the recipient, on the fourth business day after the day
it is placed in the mail, or, if earlier, the time of actual receipt.

         (v) Parties in  Interest.  Nothing in this Pledge,  whether  express or
implied, is intended to confer any rights or remedies under or by reason of this
Pledge on any persons other than the parties and their respective successors and
assigns,  nor is anything in this Pledge  intended to relieve or  discharge  the
obligation  or liability of any third  persons to any party to this Pledge,  nor
shall any provision  give any third persons any right of  subrogation  or action
over or against any party to this Pledge.

         (vi) Defined Terms. All capitalized terms, unless otherwise  specified,
have the same meanings  assigned to them in the  Convertible  Loan Agreement and
Debentures.


                            [Signature page follows.]















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     IN WITNESS  WHEREOF,  this  Agreement has been duly executed as of the date
and year written above.

                              PLEDGOR:

                              SIMTEK CORPORATION

                              By:  /s/Douglas Mitchell
                                  ----------------------------------------------
                                   Chief Executive Officer and President
                                  ----------------------------------------------


                              LENDER:

                              BFSUS SPECIAL OPPORTUNITIES TRUST PLC

                              By:  /s/Russell Cleveland
                                  ----------------------------------------------
                                  Russell Cleveland,
                                  President and CEO

                              RENAISSANCE US GROWTH & INCOME TRUST PLC

                              By:  /s/Russell Cleveland
                                 -----------------------------------------------
                                  Russell Cleveland,
                                  President and CEO


                              RENAISSANCE CAPITAL GROWTH & INCOME FUND III, INC.

                              By:    Renaissance Capital Group, Inc.,
                                     Investment Adviser

                                     By:  /s/Russell Cleveland
                                        ----------------------------------------
                                        Russell Cleveland
                                        President and CEO


                              AGENT:

                              RENAISSANCE CAPITAL GROUP, INC.

                              By:  /s/Russell Cleveland
                                 -----------------------------------------------
                                 Russell Cleveland,
                                 President and CEO


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                                   SCHEDULE A



                       Subsidiaries            No. of Shares
                       ------------            -------------

                       Q-DOT, Inc.                216,515