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                                 EXHIBIT 10 (nn)

                       REVOLVING NOTE BETWEEN THE COMPANY
                         AND THE NORTHERN TRUST COMPANY
                               DATED JUNE 30, 1997



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$15,000,000.00                                      Chicago, Illinois
                                                    Note Date: June 30, 1997

                           LINE OF CREDIT DEMAND NOTE
                    (CORPORATION - FIXED AND FLOATING RATES)
                                  (UNCOMMITTED)

         ON DEMAND, for value received,  COMPUTER DISCOUNT  WAREHOUSE,  INC., an
Illinois  corporation  (the  "Borrower"),  promises  to pay to the  order of THE
NORTHERN TRUST COMPANY,  an Illinois  banking  corporation  (the "Lender"),  the
aggregate   unpaid   principal   balance  of  each  advance  (an  "Advance"  and
collectively the "Advances") made by the Lender to the Borrower  hereunder.  The
total principal  amount of Advances  outstanding at any one time hereunder shall
not exceed FIFTEEN MILLION and no/100ths UNITED STATES DOLLARS ($15,000,000.00).

         The unpaid  principal  balance of each Advance shall bear interest from
the date thereof until its interim maturity date, as reflected in the records of
the  Lender or on an  annexed  schedule  (the  "Interim  Maturity  Date") or the
occurrence of a demand for payment hereof, whichever is earlier, at the fixed or
floating  rate (as the  parties  may agree) set forth in an annexed  schedule or
otherwise in the Lender's  records.  The principal  amount of each Advance shall
mature and be payable on its  Interim  Maturity  Date,  unless the Lender  makes
prior demand for payment hereof, as provided below.
         Accrued  but unpaid  interest on each  Advance  shall be payable on the
earlier of (a) the last day of each month, (b) its Interim Maturity Date, or (c)
upon payment of such Advance in full (whether  pursuant to demand or otherwise).
Any  Advance  which is not paid in full on its  Interim  Maturity  Date or on or
before demand shall thereafter bear interest, payable upon demand, until paid at
a rate equal to two percent  (2%) in  addition  to the "Prime  Rate" (as defined
below).
         The Borrower hereby  authorizes the Lender to charge any account of the
Borrower  maintained  with the Lender for any amounts due or payable  hereunder;
unless the Borrower instructs otherwise, all Advances made to the Borrower under
this Note shall be credited to an account of the Borrower  with the Lender.  THE
LENDER AT ITS OPTION MAY MAKE ADVANCES  HEREUNDER AND IN SO DOING  SHALL BE
FULLY  ENTITLED  TO RELY  SOLELY  UPON  INSTRUCTIONS, INCLUDING  INSTRUCTIONS TO
MAKE TRANSFERS TO THIRD PARTIES,  REASONABLY BELIEVED BY THE LENDER TO HAVE BEEN
GIVEN BY AN AUTHORIZED  PERSON,  WITHOUT  INDEPENDENT INQUIRY OF ANY TYPE.
         For purposes  hereof,  "Prime Rate" means the rate of interest per year
announced  from time to time by the Lender called its prime rate,  which may not
at any time be the lowest rate  charged by the Lender.  Changes in the  interest
rate on any Advance  resulting from a change in the Prime Rate shall take effect
as set forth in each  announcement.  Interest  shall be computed  for the actual
number of days elapsed on the basis of a year consisting of 360 days,  including
the date an Advance  is made and  excluding  the date an Advance or any  portion
thereof is paid or prepaid.
         All payments  hereunder shall be payable at the principal office of the
Lender at 50 South LaSalle Street,  Chicago,  Illinois 60675, in lawful money of
the United States of America and in immediately available funds.
         The Borrower may prepay without  penalty or premium any Advance bearing
interest at a rate based on the Prime Rate. If the Borrower prepays, in whole or
in part,  any Advance  bearing any other interest rate or if the maturity of any
such fixed rate  Advance is  accelerated  upon  demand for payment  hereof,  the
Borrower shall also pay the Lender for all losses  (including but not limited to
interest  rate  margin) or  expenses  incurred by reason of the  liquidation  or
re-employment of deposits acquired by the Lender to make the Advance or maintain
principal  outstanding  at a fixed  rate.  Upon the  Lender's  demand in writing
specifying  such losses and expenses,  the Borrower shall promptly pay them; the
Lender's specification shall be deemed correct in the absence of manifest error.
Each Advance shall be conclusively deemed to have been funded by or on behalf of
the Lender by the purchase of a deposit  corresponding in amount to such Advance
and in maturity to such Advance's Interim Maturity Date.
         The Lender shall, and is hereby  authorized by the Borrower to, endorse
on a schedule  annexed to this Note or otherwise  record in its records the date
and principal amount of each Advance,  the Interim Maturity Date, the applicable
interest rate, and the date and amount of each payment of principal and interest
made by the Borrower with respect to each such Advance;  provided,  however, the
failure of the Lender to make any endorsement on any schedule shall not limit or
otherwise affect the right of the Lender to repayment of all Advances (including
interest thereon) made by the Lender to the Borrower.  The Lender's endorsements
as well as its  records  relating to Advances  shall be  rebuttably  presumptive
evidence of the outstanding principal and interest on the Advances.

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         The Borrower  hereby  represents and warrants to the Lender that (a) it
is a corporation  existing and in good  standing  under the laws of its state of
incorporation and duly qualified, in good standing and authorized to do business
in each  jurisdiction  where the failure to so qualify would have a material and
adverse effect on its financial condition;  (b) the borrowings hereunder and the
execution and delivery of this Note are within the Borrower's  corporate powers,
have been duly authorized by all necessary  corporate action,  have received any
necessary  governmental  approval  and do not  contravene  or conflict  with any
provision  of  law or of the  charter  or  by-laws  of  the  Borrower  or of any
agreement  binding upon it; and (c) there has been no material adverse change in
the business, financial condition,  properties,  assets, operations or prospects
of the Borrower since the date of the latest financial statements provided by or
on behalf of the Borrower to the Lender.
         The   Borrower   shall  be  deemed  to  have   remade   the   foregoing
representations  and  warranties  each time it  requests  an Advance  hereunder,
except  that (c)  shall be deemed  to refer to the then  most  recent  financial
statements furnished to the Lender.
         All sums  outstanding  under  this Note  shall be  immediately  due and
payable  without  further action of any kind on the part of the Lender,  and the
Lender shall have and may exercise any and all rights and remedies  available at
law or in equity,  when the Lender demands  payment  hereof.  Such sums shall be
deemed to have been so demanded,  and shall be immediately and automatically due
and payable  without  any action of any kind on the part of the Lender,  and the
Lender shall have and may exercise any and all rights and remedies  available at
law or in equity, if any bankruptcy,  insolvency,  reorganization,  arrangement,
readjustment,  liquidation,  dissolution,  or similar  proceeding,  domestic  or
foreign,  is instituted  by the Borrower (or is instituted  against the Borrower
and  remains  undismissed  for more  than 60  days);  or if the  Borrower  shall
authorize  such  a  proceeding;  or if  the  Borrower  shall  become  insolvent,
generally  shall fail or be unable to pay its debts as they mature,  shall admit
in writing its  inability to pay its debts as they mature,  shall make a general
assignment for the benefit of its creditors, shall enter into any composition or
similar  agreement,  or shall  suspend the  transaction  of all or a substantial
portion of its usual business.

         All  notices,  requests and demands  hereunder  shall be deemed to have
been given or made when delivered by messenger or express delivery  service,  or
five (5) days after  deposit in the U.S.  mail,  first  class  postage  prepaid,
addressed, in each case:

         (A) if to the  Lender  to 50 South  LaSalle  Street, Chicago,  Illinois
             60675  (Attention:  Division  Head,  Mets I Division)
         (B) if to the Borrower to its address set forth below,

or to such other address as may be hereafter designated in writing by the 
respective parties hereto.

         THIS  NOTE  AND ANY  DOCUMENT  OR  INSTRUMENT  EXECUTED  IN  CONNECTION
HEREWITH SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE  WITH THE INTERNAL LAW
OF THE STATE OF ILLINOIS AND SHALL BE DEEMED TO HAVE BEEN EXECUTED AND DELIVERED
IN ILLINOIS.  Unless the context  requires  otherwise,  wherever used herein the
singular  shall  include  the  plural and vice  versa.  This Note shall bind the
Borrower,  its  successors  and  assigns,  and shall inure to the benefit of the
Lender, its successors and assigns, except that the Borrower may not transfer or
assign any of its rights or interest hereunder without the prior written consent
of the Lender.  The Borrower agrees to pay upon demand all expenses  (including,
without limitation,  reasonable  attorneys' fees, legal costs and expenses,  and
time  charges of  attorneys  who may be  employees  of the Lender,  in each case
whether  in or  out  of  court,  in  original  or  appellate  proceedings  or in
bankruptcy)  incurred or paid by the Lender or any holder  hereof in  connection
with the  enforcement  or  preservation  of its  rights  hereunder  or under any
document or instrument executed in connection  herewith.  The Borrower expressly
and irrevocably waives  presentment,  protest,  demand and notice of any kind in
connection herewith.

         BOTH  PARTIES HEREBY  IRREVOCABLY  AGREES THAT,  ALL SUITS,  ACTIONS OR
OTHER  PROCEEDINGS  WITH RESPECT TO, ARISING OUT OF OR IN  CONNECTION  WITH THIS
NOTE OR ANY  DOCUMENT  OR  INSTRUMENT  EXECUTED  IN CONNECTION HEREWITH SHALL BE
SUBJECT  TO  LITIGATION  IN  COURTS  HAVING SITUS WITHIN CHICAGO, ILLINOIS. BOTH
PARTIES  HEREBY CONSENTS AND SUBMITS TO THE JURISDICTION OF ANY LOCAL,  STATE OR
FEDERAL COURT LOCATED IN CHICAGO,  ILLINOIS,  AND HEREBY IRREVOCABLY  WAIVES ANY
RIGHT IT MAY HAVE TO REQUEST OR DEMAND TRIAL BY JURY, TO TRANSFER OR CHANGE  THE
VENUE  OF  ANY  SUIT,  ACTION  OR  OTHER  PROCEEDING  BROUGHT BY THE  LENDER  IN
ACCORDANCE  WITH  THIS  PARAGRAPH,  OR TO  CLAIM  THAT  ANY  SUCH PROCEEDING HAS
BEEN BROUGHT IN AN INCONVENIENT FORUM.

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         NO PROVISION OF THIS NOTE OR ANY RELATED  DOCUMENT OR INSTRUMENT  SHALL
BE  CONSTRUED TO REQUIRE THE LENDER TO EXTEND ANY CREDIT OR MAKE ANY LOAN TO THE
BORROWER,  OR TO  REQUIRE  THE  BORROWER  TO  BORROW,  WHETHER OR NOT ANY FEE IS
PAYABLE BY THE BORROWER IN CONNECTION HEREWITH. THE BORROWER CLEARLY UNDERSTANDS
AND  AGREES  THAT  THIS  NOTE IS A DEMAND  OBLIGATION  PAYMENT  OF WHICH IN FULL
(INCLUDING  PRINCIPAL,  INTEREST,  AND ANY OTHER AMOUNTS) MAY BE DEMANDED BY THE
LENDER AT ANY TIME IN ITS DISCRETION WITHOUT PRIOR ORAL OR WRITTEN NOTICE OF ANY
KIND, AND REGARDLESS OF WHETHER OR NOT AN ADVANCE HAS BEEN  OUTSTANDING  THROUGH
OR BEYOND ITS INTERIM MATURITY DATE.

                        COMPUTER DISCOUNT WAREHOUSE, INC.


                        By: /s/ Harry Harczak
                            -------------------------
                        Name: Harry Harczak
                        Title: Chief Financial Officer


                        By: /s/ Michael P. Krasny
                            --------------------------
                        Name: Michael P. Krasny
                        Title: Chairman and Chief Executive Officer


                        Address for notices:
                        CDW Computer Centers, Inc.
                        200 North Milwaukee Ave.
                        Vernon Hills, Illinois 60061
                        Attention:  Mr. Harry Harczak

FORM 9640-B LARGE CORPORATE BORROWERS, UNCOMMITTED DEMAND LINE

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                                                     June 10, 1997

Mr. Harry Harczak
Chief Financial Officer
CDW COMPUTER CENTERS, INC.
1020 E. Lake Cook Road
Buffalo Grove, IL 60089

Dear Harry:

The  interest  rate that The Northern  Trust  Company will offer you on Advances
made under the Line of Credit  Demand Note dated June 30,  1997  executed by CDW
Computer  Centers,  Inc.  are Prime - 2.5% (with a floor of NY Federal  funds +.
45%), NY Federal funds +. 45% or 30, 60, or 90 day LIBOR +. 45%.

YOU SHALL INCUR AND PAY A PREPAYMENT  PENALTY FOR ANY LOSS, IF ANY,  INCURRED BY
NORTHERN AS A RESULT OF THE PREPAYMENT OF ANY LIBOR ADVANCE, AND SUCH LOSS SHALL
BE CUSTOMARILY DETERMINED IN NORTHERN'S GOOD FAITH DISCRETION.

Please  indicate  your  acceptance  of the  above by  signing  this  letter  and
returning it to my attention at Northern by June 30, 1997.

                                                     Best regards,

                                                     /s/ BRIAN D, BEITZ
                                                     ------------------
                                                     Brian D. Beitz
                                                     Vice President

Accepted and Agreed
CDW Computer Centers, Inc.

By: /s/ MICHAEL P. KRASNY
    ---------------------
       Michael P. Krasny
       Chairman and Chief Executive Officer

By: /s/ HARRY J. HARCZAK
    --------------------
       Harry J. Harczak
       Chief Financial Officer

Date:    6-27-97
         -------

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                                   CERTIFICATE
                        BORROWING RESOLUTION & INCUMBENCY
                                   CORPORATION

The undersigned  certifies that set forth below is a copy of a Resolution of the
Board of Directors of CDW Computer Centers,  Inc., an Illinois  corporation (the
"Corporation", or the "Borrower") which Resolution was properly adopted, has not
been modified or rescinded, and is still in effect:

Resolved that this Corporation  borrow from The Northern Trust Company an amount
not  to  exceed   Fifteen   Million  and   no/100ths   UNITED   STATES   DOLLARS
($15,000,000.00) at any one time outstanding pursuant to the terms of the Master
Note dated as of June 30, 1997 (the  foregoing  document(s),  together  with any
related   documents,    being   collectively    referred   to   as   the   "Loan
Document(s)")filed  with this resolution,  the form of which Loan Document(s) is
approved;  that the any two of the "Named" officers be designated to execute and
deliver the Loan  Documents  with such changes as (s)he may approve as evidenced
by his  (her)  execution  of the  Loan  Documents;  that  the  Secretary  or any
Assistant  Secretary be and each hereby is, acting alone,  authorized to, attest
the  execution;  that any two of the  "Named"  officers of this  Corporation  be
authorized  to request  borrowings  under the Loan  Documents,  to  execute  and
deliver  from  time to time any notes and other  documents  and  instruments  in
connection  therewith,  whether  or not  specifically  referenced  in  the  Loan
Documents,  and to take any actions  deemed  necessary  or  appropriate  by such
officer to carry out the  provisions  of the Loan  Documents  and such notes and
other  documents  and  instruments;  and that any  actions of the type set forth
above  previously  taken by any of the foregoing  officers are hereby  approved,
adopted and ratified.

The  undersigned  does hereby further  certify that the persons named below have
been duly elected or appointed, have duly qualified as, and on this day are, the
"Named"  officers  of the  Borrower,  as  indicated  below,  and that set  forth
opposite  the  respective  name of each is a  sample  of the  signature  of such
person:

     NAME                     OFFICE                     SIGNATURE

Michael P. Krasny         Chairman & CEO            /s/ MICHAEL P. KRASNY
- -----------------         --------------            ----------------------

Gregory Zeman               President               /s/ GREGORY ZEMAN
- -------------               ---------               ----------------------

Harry J. Harczak      Chief Financial Officer       /s/ HARRY J. HARCZAK
- ----------------      -----------------------       ----------------------

      Dated as of June 30,1997.


              Signature /s/ MICHAEL P. KRASNY
                       ----------------------

              Name: Michael P. Krasny
                   ------------------

              Title: Chairman, Chief Executive Officer, Secretary and Treasurer
                    -----------------------------------------------------------

              Name of Borrower: CDW Computer Centers, Inc.
                               ---------------------------

         The  undersigned  (MAY NOT BE THE SAME PERSON WHO SIGNS  ABOVE)  hereby
certifies that the person who executed the foregoing portion of this Certificate
on behalf of the  Borrower  have been duly  elected or appointed as Secretary of
the Borrower, and that set forth above is the signature of such person.

              Signature /s/ HARRY J. HARCZAK
                       ---------------------

              Type Name: Harry J. Harczak
                        -----------------

              Title: Chief Financial Officer
                    ------------------------

              Name of Borrower: CDW Computer Centers, Inc.
                               ---------------------------

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                                   CERTIFICATE
                       NO AMENDMENT TO ARTICLES AND BYLAWS


         The undersigned  does hereby certify that the Articles of Incorporation
and  Bylaws  of  CDW  COMPUTER  CENTERS,  INC.  , an  Illinois  corporation,  as
previously  furnished to The Northern Trust Company under  Certificate(s)  dated
June 30,  1995 , have not been  amended,  modified or  rescinded  in any respect
since such date, and remain in full force and effect.

      Date as of June 30, 1997.


               Signature /s/ MICHAEL P. KRASNY
                        ----------------------

               Type Name    Michael P. Krasny
                        ----------------------

               Title Chairman, Chief Executive Officer, Secretary and Treasurer
                    -----------------------------------------------------------

               Name of Borrower   CDW Computer Centers, Inc.
                               -------------------------------





FORM 9718 (R 11/91)

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