<PAGE>   1

                                                                   EXHIBIT 10.1


                                PROMISSORY NOTE

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    PRINCIPAL         LOAN DATE        MATURITY       LOAN NO.     CALL      COLLATERAL     ACCOUNT     OFFICER     INITIALS
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<S>                   <C>              <C>            <C>          <C>       <C>            <C>         <C>         <C>
$4,000,000.00         12-05-1996       02-05-1997     1-3895-6      0400       AR, IN                      MHD
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        REFERENCES IN THE SHADED AREA ARE FOR LENDER'S USE ONLY AND DO NOT LIMIT THE APPLICABILITY OF THIS DOCUMENT TO
                                      ANY PARTICULAR LOAN OR ITEM.
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</TABLE>

BORROWER:     SEAMED CORPORATION             LENDER: PACIFIC NORTHWEST BANK
              (TIN: 91-1002092)                      BELLEVUE FINANCIAL CENTER
              14500 N.E. 87TH ST.                    11100 N.E. 8TH
              REDMOND, WA  98052-3431                BELLEVUE, WA  98004

================================================================================


PRINCIPAL AMOUNT:      INITIAL RATE: 8.500%    DATE OF NOTE:  DECEMBER 5, 1996
$4,000,000.00                  


PROMISE TO PAY.  SEAMED CORPORATION ("BORROWER") PROMISES TO PAY TO PACIFIC
NORTHWEST BANK ("LENDER"), OR ORDER, IN LAWFUL MONEY OF THE UNITED STATES OF
AMERICA, THE PRINCIPAL AMOUNT OF FOUR MILLION & 00/100 DOLLARS ($4,000,000.00)
OR SO MUCH AS MAY BE OUTSTANDING, TOGETHER WITH INTEREST ON THE UNPAID
OUTSTANDING PRINCIPAL BALANCE OF EACH ADVANCE.  INTEREST SHALL BE CALCULATED
FROM THE DATE OF EACH ADVANCE UNTIL REPAYMENT OF EACH ADVANCE.

PAYMENT.  BORROWER WILL PAY THIS LOAN ON DEMAND, OR IF NO DEMAND IS MADE, IN
ONE PAYMENT OF ALL OUTSTANDING PRINCIPAL PLUS ALL ACCRUED UNPAID INTEREST ON
DECEMBER 5, 1996.  IN ADDITION, BORROWER WILL PAY REGULAR MONTHLY PAYMENTS OF
ACCRUED UNPAID INTEREST BEGINNING JULY 5, 1996, AND ALL SUBSEQUENT INTEREST
PAYMENTS ARE DUE ON THE SAME DAY OF EACH MONTH AFTER THAT.  Interest on this
Note is computed on a 365/360 simple interest basis; that is, by applying the
ratio of the annual interest rate over a year of 360 days, multiplied by the
outstanding principal balance, multiplied by the actual number of days the
principal balance is outstanding.  Borrower will pay Lender at Lender's address
shown above or at such other place as Lender may designate in writing.  Unless
otherwise agreed or required by applicable law, payments will be applied first
to accrued unpaid interest, then to principal, and any remaining amount to any
unpaid collection costs and late charges.

VARIABLE INTEREST RATE.  The interest rate on this Note is subject to change
from time to time based on changes in an index which is Lender's Prime Rate
(the "Index").  This is the rate Lender charges, or would charge, on 90-day
unsecured loans to the most creditworthy corporate customers.  This rate may or
may not be the lowest rate available from Lender at any given time.  Lender
will tell Borrower the current Index rate upon Borrower's request.  Borrower
understands that Lender may make loans based on other rates as well.  The
interest rate change will not occur more often than each DAY.  THE INDEX
CURRENTLY IS 8.250% PER ANNUM.  THE INTEREST RATE TO BE APPLIED TO THE UNPAID
PRINCIPAL BALANCE OF THIS NOTE WILL BE AT A RATE OF 0.250 PERCENTAGE POINTS
OVER THE INDEX, RESULTING IN AN INITIAL RATE OF 8.500% PER ANNUM.  NOTICE:
Under no circumstances will the interest rate on this Note be more than the
maximum rate allowed by applicable law.

PREPAYMENT.  Borrower agrees that all loan fees and other prepaid finance
charges are earned fully as of the date of the loan and will not be subject to
refund upon early payment (whether voluntary or as a result of default), except
as otherwise required by law.  Except for the foregoing, Borrower may pay
without penalty all or a portion of the amount owed earlier than it is due.
Early payments will not, unless agreed to by Lender in writing, relieve
Borrower of Borrower's obligation to continue to make payments of accrued
unpaid interest.  Rather, they will reduce the principal balance due.


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LATE CHARGE.  If a payment is 10 DAYS OR MORE LATE, Borrower will be charged
5.000% OF THE UNPAID PORTION OF THE REGULARLY SCHEDULED PAYMENT OR $50.00,
WHICHEVER IS LESS.

DEFAULT.  Borrower will be in default if any of the following happens:  (a)
Borrower fails to make any payment when due.  (b) Borrower breaks any promise
Borrower has made to Lender, or Borrower fails to comply with or to perform
when due any other term, obligation, covenant, or condition contained in this
Note or any agreement related to this Note, or in any other agreement or loan
Borrower has with Lender.  (c) Any representation or statement made or
furnished to Lender by Borrower or on Borrower's behalf is false or misleading
in any material respect either now or at the time made or furnished.  (d)
Borrower becomes insolvent, a receiver is appointed for any part of Borrower's
property, Borrower makes an assignment for the benefit of creditors, or any
proceeding is commenced either by Borrower or against Borrower under any
bankruptcy or insolvency laws.  (e) Any creditor tries to take any of
Borrower's property on or in which Lender has a lien or security interest.
This includes a garnishment of any of Borrower's accounts with Lender.  (f) Any
guarantor dies or any of the other events described in this default section
occurs with respect to any guarantor of this Note.  (g) A material adverse
change occurs in Borrowers financial condition, or Lender believes the prospect
of payment or performance of the indebtedness is impaired.  (h) Lender in good
faith deems itself insecure.

LENDER'S RIGHTS.  Upon default, Lender may declare the entire unpaid principal
balance on this Note and all accrued unpaid interest immediately due, without
notice, and then Borrower will pay that amount.  Upon default, including
failure to pay upon final maturity, Lender, at its option, may also, if
permitted under applicable law, increase the variable interest rate on this
Note to 5.250 percentage points over the Index.  The interest rate will not
exceed the maximum rate permitted by applicable law.  Lender may hire or pay
someone else to help collect this Note if Borrower does not pay.  Borrower also
will pay Lender that amount.  This includes, subject to any limits under
applicable law, Lender's attorneys' fees and Lender's legal expenses whether or
not there is a lawsuit, including attorneys' fees and legal expenses for
bankruptcy proceedings (including efforts to modify or vacate any automatic
stay or injunction), appeals, and any anticipated post-judgment collection
services.  If not prohibited by applicable law, Borrower also will pay any
court costs, in addition to all other sums provided by law.  THIS NOTE HAS BEEN
DELIVERED TO LENDER AND ACCEPTED BY LENDER IN THE SLATE OF WASHINGTON.  IF
THERE IS A LAWSUIT, BORROWER AGREES UPON LENDER'S REQUEST TO SUBMIT TO THE
JURISDICTION OF THE COURTS OF KING COUNTY, THE STATE OF WASHINGTON.  THIS NOTE
SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF
WASHINGTON.

DISHONORED ITEM FEE.  Borrower will pay a fee to Lender of $18.00 if Borrower
makes a payment on Borrower's loan and the check or preauthorized charge with
which Borrower pays is later dishonored.

RIGHT OF SETOFF.  Borrower grants to Lender a contractual possessory security
interest in, and hereby assigns, conveys, delivers, pledges, and transfers to
Lender all Borrower's right, title and interest in and to, Borrower's accounts
with Lender (whether checking, savings, or some other account), including
without limitation all accounts held jointly with someone else and all accounts
Borrower may open in the future, excluding however all IRA and Keogh accounts,
and all trust accounts for which the grant of a security interest would be
prohibited by law.  Borrower authorizes Lender, to the extent permitted by
applicable law, to charge or setoff all sums owing on this Note against any and
all such accounts.

COLLATERAL.  This Note is secured by A SECURITY AGREEMENT DATED DECEMBER 5,
1996 FROM SEAMED CORPORATION TO LENDER CONVERING ALL ACCOUNTS, INVENTORY AND
GENERAL INTANGIBLES.



                                      -2-
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LINE OF CREDIT.  This Note evidences a revolving line of credit.  Advances
under this Note, as well as directions for payment from Borrower's accounts,
may be requested orally or in writing by Borrower or by an authorized person.
Lender may, but need not, require that all oral requests be confirmed in
writing.  The following party or parties are authorized to request advances
under the line of credit until Lender receives from Borrower at Lender's
address shown above written notice of revocation of their authority:  W. ROBERT
BERG, PRESIDENT; and EDGAR F. RAMPY, V.P. - FINANCE.  Borrower agrees to be
liable for all sums either: (a) advanced in accordance with the instructions of
an authorized person or (b) credited to any of Borrower's accounts with Lender.
The unpaid principal balance owing on this Note at any time may be evidenced by
endorsements on this Note or by Lender's internal records, including daily
computer print-outs.  Lender will have no obligation to advance funds under
this Note if:  (a) Borrower or any guarantor is in default under the terms of
this Note or any agreement that Borrower or any guarantor has with Lender,
including any agreement made in connection with the signing of this Note; (b)
Borrower or any guarantor ceases doing business or is insolvent; (c) any
guarantor seeks, claims or otherwise attempts to limit, modify or revoke such
guarantor's guarantee of this Note or any other loan with Lender; (d) Borrower
has applied funds provided pursuant to this Note for purposes other than those
authorized by Lender; or (e) Lender in good faith deems itself insecure under
this Note or any other agreement between Lender and Borrower.

GENERAL PROVISIONS.  This Note is payable on demand.  The inclusion of specific
default provisions or rights of Lender shall not preclude Lender's right to
declare payment of this Note on its demand.  Lender may delay or forgo
enforcing any of its rights or remedies under this Note without losing them.
Borrower and any other person who signs, guarantees or endorses this Note, to
the extent allowed by law, waive presentment, demand for payment, protest and
notice of dishonor.  Upon any change in the terms of this Note, and unless
otherwise expressly stated in writing, no party who signs this Note, whether as
maker, guarantor, accommodation maker or endorser, shall be released from
liability.  All such parties agree that Lender may renew or extend (repeatedly
and for any length of time) this loan, or release any party or guarantor or
collateral; or impair, fail to realize upon or perfect Lender's security
interest in the collateral; and take any other action deemed necessary by
Lender without the consent of or notice to anyone.  All such parties also agree
that Lender may modify this loan without the consent of or notice to anyone
other than the party with whom the modification is made.

PRIOR TO SIGNING THIS NOTE, BORROWER READ AND UNDERSTOOD ALL THE PROVISIONS OF
THIS NOTE, INCLUDING THE VARIABLE INTEREST RATE PROVISIONS.  BORROWER AGREES TO
THE TERMS OF THE NOTE AND ACKNOWLEDGES RECEIPT OF A COMPLETE COPY OF THE NOTE.

BORROWER:

SEAMED CORPORATION


BY                                             BY  /S/ EDGAR F. RAMPY
  ----------------------------                   ----------------------------
  W. ROBERT BERG, PRESIDENT                      EDGAR F. RAMPY, V.P. - FINANCE








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