Document:

<PAGE>

THE WARRANTS REPRESENTED BY THIS CERTIFICATE AND THE OTHER SECURITIES ISSUABLE
UPON EXERCISE THEREOF MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO (i) AN
EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933, AS AMENDED,
(ii) TO THE EXTENT APPLICABLE, RULE 144 UNDER SUCH ACT (OR ANY SIMILAR RULE
UNDER SUCH ACT RELATING TO THE DISPOSITION OF SECURITIES), OR (iii) AN OPINION
OF COUNSEL, IF SUCH OPINION SHALL BE REASONABLY SATISFACTORY TO COUNSEL FOR THE
ISSUER, THAT AN EXEMPTION FROM REGISTRATION UNDER SUCH ACT IS AVAILABLE.

THE TRANSFER OR EXCHANGE OF THE WARRANTS REPRESENTED BY THIS CERTIFICATE IS
RESTRICTED IN ACCORDANCE WITH THE WARRANT AGREEMENT REFERRED TO HEREIN.

                            EXERCISABLE ON OR BEFORE
                    5:00 P.M., NEW YORK TIME, April 22, 2004

No. W-05                                                         18,461 Warrants

                              WARRANT CERTIFICATE

         This Warrant Certificate certifies that Ronald Heineman, or registered
assigns, is the registered holder of 18,461 Warrants to purchase initially, at
any time from March 15, 2000 until 5:00 p.m. New York time on April 22, 2004
("Expiration Date"), up to 18,461 Shares of common stock, $.01 par value
("Common Stock") of LOG ON AMERICA, INC., a Delaware corporation (the
"Company"), at the initial exercise price, subject to adjustment in certain
events (the "Exercise Price"), of $16.50 per Share upon surrender of this
Warrant Certificate and payment of the Exercise Price at an office or agency of
the Company, or by surrender of this Warrant Certificate in lieu of cash
payment, but subject to the conditions set forth herein and in the warrant
agreement dated as of April 22, 1999 between the Company and Dirks & Company,
Inc. (the "Warrant Agreement"). Payment of the Exercise Price shall be made by
certified or official bank check in New York Clearing House funds payable to the
order of the Company or by surrender of this Warrant Certificate.

         No Warrant may be exercised after 5:00 p.m., New York time, on the
Expiration Date, at which time all Warrants evidenced hereby, unless exercised
prior thereto, hereby shall thereafter be void.

         The Warrants evidenced by this Warrant Certificate are part of a duly
authorized issue of Warrants issued pursuant to the Warrant Agreement, which
Warrant Agreement is hereby incorporated by reference in and made a part of this
instrument and is hereby referred to for a description of the rights, limitation
of rights, obligations, duties and immunities thereunder of the Company and the
holders (the words "holders" or "holder" meaning the registered holders or
registered holder) of the Warrants.

<PAGE>

         The Warrant Agreement provides that upon the occurrence of certain
events the Exercise Price and the type and/or number of the Company's securities
issuable thereupon may, subject to certain conditions, be adjusted. In such
event, the Company will, at the request of the holder, issue a new Warrant
Certificate evidencing the adjustment in the Exercise Price and the number
and/or type of securities issuable upon the exercise of the Warrants; provided,
however, that the failure of the Company to issue such new Warrant Certificates
shall not in any way change, alter, or otherwise impair, the rights of the
holder as set forth in the Warrant Agreement.

         Upon due presentment for registration of transfer of this Warrant
Certificate at an office or agency of the Company, a new Warrant Certificate or
Warrant Certificates of like tenor and evidencing in the aggregate a like number
of Warrants shall be issued to the transferee(s) in exchange for this Warrant
Certificate, subject to the limitations provided herein and in the Warrant
Agreement, without any charge except for any tax or other governmental charge
imposed in connection with such transfer.

         Upon the exercise of less than all of the Warrants evidenced by this
Certificate, the Company shall forthwith issue to the holder a new Warrant
Certificate representing such Warrant.

         The Company may deem and treat the registered holder(s) hereof as the
absolute owner(s) of this Warrant Certificate (notwithstanding any notation of
ownership or other writing hereon made by anyone), for the purpose of any
exercise hereof, and of any distribution to the holder(s) hereof, and for all
other purposes, and the Company shall not be affected by any notice to the
contrary. All terms used in this Warrant Certificate which are defined in the
Warrant Agreement shall have the meanings assigned to them in the Warrant
Agreement.

                                       2

<PAGE>

         IN WITNESS WHEREOF, the Company has caused this Warrant Certificate to
be duly executed under its corporate seal.

Dated as of March __, 2000

                                        LOG ON AMERICA, INC.

[SEAL]                                  By: /s/ David R. Paolo
                                           -------------------------------------
                                           David R. Paolo
                                           President and Chief Executive Officer

Attest:

/s/ Raymond E. Paolo
---------------------
Raymond E. Paolo
Secretary

                                       3

<PAGE>

             [FORM OF ELECTION TO PURCHASE PURSUANT TO SECTION 3.11]

         The undersigned hereby irrevocably elects to exercise the right,
represented by this Warrant Certificate, to purchase ___________ Shares and
herewith tenders in payment for such securities a certified or official bank
check payable in New York Clearing House Funds to the order of Log On America,
Inc. in the amount of $___________, all in accordance with the terms of Section
3.1 of the Representative's Warrant Agreement, dated as of April 22, 1999,
between Log On America, Inc. and Dirks & Company, Inc. The undersigned requests
that certificates for such securities be registered in the name of
__________________ whose address is __________________________________ and that
such certificates be delivered to ______________________ whose address is
________________________________________________________________________________
________________________________________________________________________ .

Dated:

                                  Signature:____________________________________
                                  (Signature must conform in all respects to
                                  name of holder as specified on the face of the
                                  Warrant Certificate.)

                                  ______________________________________________
                                                (Insert Social Security or Other
                                                Identifying Number of Holder)

                                       4

<PAGE>
                              [FORM OF ASSIGNMENT]

            (To be executed by the registered holder if such holder
                 desires to transfer the Warrant Certificate.)

         FOR VALUE RECEIVED _______________ hereby sells, assigns and transfers
unto

________________________________________________________________________________
                 (Please print name and address of transferee)

this Warrant Certificate, together with all right, title and interest therein,
and does hereby irrevocably constitute and appoint _______________ Attorney, to
transfer the within Warrant Certificate on the books of the within-named
Company, with full power of substitution.

Dated:___________________         Signature:____________________________________
                                  (Signature must conform in all respects to
                                  name of holder as specified on the face of the
                                  Warrant Certificate.)

                                  ______________________________________________
                                                (Insert Social Security or Other
                                                Identifying Number of Holder)
<PAGE>

THE WARRANTS REPRESENTED BY THIS CERTIFICATE AND THE OTHER SECURITIES ISSUABLE
UPON EXERCISE THEREOF MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO (i) AN
EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933, AS AMENDED,
(ii) TO THE EXTENT APPLICABLE, RULE 144 UNDER SUCH ACT (OR ANY SIMILAR RULE
UNDER SUCH ACT RELATING TO THE DISPOSITION OF SECURITIES), OR (iii) AN OPINION
OF COUNSEL, IF SUCH OPINION SHALL BE REASONABLY SATISFACTORY TO COUNSEL FOR THE
ISSUER, THAT AN EXEMPTION FROM REGISTRATION UNDER SUCH ACT IS AVAILABLE.

THE TRANSFER OR EXCHANGE OF THE WARRANTS REPRESENTED BY THIS CERTIFICATE IS
RESTRICTED IN ACCORDANCE WITH THE WARRANT AGREEMENT REFERRED TO HEREIN.

                            EXERCISABLE ON OR BEFORE
                    5:00 P.M., NEW YORK TIME, April 22, 2004

No. W-04                                                          6,964 Warrants

                              WARRANT CERTIFICATE

         This Warrant Certificate certifies that Ronald Heineman, or registered
assigns, is the registered holder of 6,964 Warrants to purchase initially, at
any time from March 15, 2000 until 5:00 p.m. New York time on April 22, 2004
("Expiration Date"), up to 6,964 Shares of common stock, $.01 par value ("Common
Stock") of LOG ON AMERICA, INC., a Delaware corporation (the "Company"), at the
initial exercise price, subject to adjustment in certain events (the "Exercise
Price"), of $16.50 per Share upon surrender of this Warrant Certificate and
payment of the Exercise Price at an office or agency of the Company, or by
surrender of this Warrant Certificate in lieu of cash payment, but subject to
the conditions set forth herein and in the warrant agreement dated as of April
22, 1999 between the Company and Dirks & Company, Inc. (the "Warrant
Agreement"). Payment of the Exercise Price shall be made by certified or
official bank check in New York Clearing House funds payable to the order of the
Company or by surrender of this Warrant Certificate.

         No Warrant may be exercised after 5:00 p.m., New York time, on the
Expiration Date, at which time all Warrants evidenced hereby, unless exercised
prior thereto, hereby shall thereafter be void.

         The Warrants evidenced by this Warrant Certificate are part of a duly
authorized issue of Warrants issued pursuant to the Warrant Agreement, which
Warrant Agreement is hereby incorporated by reference in and made a part of this
instrument and is hereby referred to for a description of the rights, limitation
of rights, obligations, duties and immunities thereunder of the Company and the
holders (the words "holders" or "holder" meaning the registered holders or
registered holder) of the Warrants.

<PAGE>

         The Warrant Agreement provides that upon the occurrence of certain
events the Exercise Price and the type and/or number of the Company's securities
issuable thereupon may, subject to certain conditions, be adjusted. In such
event, the Company will, at the request of the holder, issue a new Warrant
Certificate evidencing the adjustment in the Exercise Price and the number
and/or type of securities issuable upon the exercise of the Warrants; provided,
however, that the failure of the Company to issue such new Warrant Certificates
shall not in any way change, alter, or otherwise impair, the rights of the
holder as set forth in the Warrant Agreement.

         Upon due presentment for registration of transfer of this Warrant
Certificate at an office or agency of the Company, a new Warrant Certificate or
Warrant Certificates of like tenor and evidencing in the aggregate a like number
of Warrants shall be issued to the transferee(s) in exchange for this Warrant
Certificate, subject to the limitations provided herein and in the Warrant
Agreement, without any charge except for any tax or other governmental charge
imposed in connection with such transfer.

         Upon the exercise of less than all of the Warrants evidenced by this
Certificate, the Company shall forthwith issue to the holder a new Warrant
Certificate representing such Warrant.

         The Company may deem and treat the registered holder(s) hereof as the
absolute owner(s) of this Warrant Certificate (notwithstanding any notation of
ownership or other writing hereon made by anyone), for the purpose of any
exercise hereof, and of any distribution to the holder(s) hereof, and for all
other purposes, and the Company shall not be affected by any notice to the
contrary. All terms used in this Warrant Certificate which are defined in the
Warrant Agreement shall have the meanings assigned to them in the Warrant
Agreement.

                                       2

<PAGE>

         IN WITNESS WHEREOF, the Company has caused this Warrant Certificate to
be duly executed under its corporate seal.

Dated as of March __, 2000

                                        LOG ON AMERICA, INC.

[SEAL]                                  By: /s/ David R. Paolo
                                           -------------------------------------
                                           David R. Paolo
                                           President and Chief Executive Officer

Attest:

/s/ Raymond E. Paolo
---------------------
Raymond E. Paolo
Secretary

                                       3

<PAGE>

             [FORM OF ELECTION TO PURCHASE PURSUANT TO SECTION 3.11]

         The undersigned hereby irrevocably elects to exercise the right,
represented by this Warrant Certificate, to purchase ___________ Shares and
herewith tenders in payment for such securities a certified or official bank
check payable in New York Clearing House Funds to the order of Log On America,
Inc. in the amount of $___________, all in accordance with the terms of Section
3.1 of the Representative's Warrant Agreement, dated as of April 22, 1999,
between Log On America, Inc. and Dirks & Company, Inc. The undersigned requests
that certificates for such securities be registered in the name of
__________________ whose address is __________________________________ and that
such certificates be delivered to ______________________ whose address is
________________________________________________________________________________
________________________________________________________________________ .

Dated:

                                  Signature:____________________________________
                                  (Signature must conform in all respects to
                                  name of holder as specified on the face of the
                                  Warrant Certificate.)

                                  ______________________________________________
                                                (Insert Social Security or Other
                                                Identifying Number of Holder)

                                       4

<PAGE>
                              [FORM OF ASSIGNMENT]

            (To be executed by the registered holder if such holder
                 desires to transfer the Warrant Certificate.)

         FOR VALUE RECEIVED _______________ hereby sells, assigns and transfers
unto

________________________________________________________________________________
                 (Please print name and address of transferee)

this Warrant Certificate, together with all right, title and interest therein,
and does hereby irrevocably constitute and appoint _______________ Attorney, to
transfer the within Warrant Certificate on the books of the within-named
Company, with full power of substitution.

Dated:___________________         Signature:____________________________________
                                  (Signature must conform in all respects to
                                  name of holder as specified on the face of the
                                  Warrant Certificate.)

                                  ______________________________________________
                                                (Insert Social Security or Other
                                                Identifying Number of Holder)

                                       5<PAGE>   1

                                                                     EXHIBIT 4.1

                                CREDIT AGREEMENT

                                     BETWEEN

                             INTERFACE SYSTEMS, INC.

                                       AND

                               BANK ONE, MICHIGAN

                                   DATED AS OF

                                  JUNE 1, 2000

                                      -1-
<PAGE>   2

                                CREDIT AGREEMENT

         This Credit Agreement ("Agreement") dated as of June 1, 2000
("Effective Date"), is made between INTERFACE SYSTEMS, INC., a Michigan
corporation (the "Borrower"), and BANK ONE, MICHIGAN, a Michigan banking
corporation (the "Bank"). The parties agree as follows:

         1. DEFINITIONS

         1.1. Under this Agreement, the following terms shall have the following
meanings:

         "Affiliate" means any Person which directly or indirectly controls or
is controlled by or under common control with any other Person, and as to the
Borrower, shall include its stockholders, directors, officers, employees, and
Subsidiaries.

         "Book Value" means the value of an applicable asset as reflected on the
Borrower's financial statements delivered to the Bank in connection with this
Agreement.

         "Borrower's Related Documents" means the Related Documents to which the
Borrower is a party.

         "Borrowing Base" means, at any date of determination, the sum of (a)
75% of the Eligible Accounts of the Borrower plus (b) the Premises' Loan Value.

         "Borrowing Base Certificate" means a certificate in the form of
attached Exhibit B or other form acceptable to the Bank.

         "Business Day" means a day other than Saturday or Sunday on which banks
are open for business in Detroit.

         "Collateral" means all of the Borrower's present and future accounts,
chattel paper, documents, instruments, equipment, goods, inventory, fixtures,
general intangibles, and the proceeds and products thereof, as such terms are
defined in the Michigan Uniform Commercial Code, the Premises, and all other
tangible and intangible personal property in all cases wherever located and
however existing, arising, evidenced or acquired, all as more fully set forth in
the Security Agreement.

         "Commitment" means the obligation of the Bank to make Loans not
exceeding in aggregate principal amount outstanding at any time FIVE MILLION
DOLLARS ($5,000,000.00), subject to the limitations set forth in Section 2.1.

         "Covenant Compliance Certificate" means a certificate in the form of
attached Exhibit C or other form acceptable to the Bank.

         "Current Assets" means, as of any date of determination, all cash,
non-affiliated customer receivables, United States Government securities, claims
against the United States Government, and inventory, less all sums receivable
from Affiliates.

         "Current Liabilities" means, as of any date of determination, all
liabilities that should be classified as current in accordance with GAAP plus,
but without duplication, all liabilities to any Affiliates whether or not
classified as current in accordance with GAAP, except Subordinated Debt.

                                      -2-
<PAGE>   3

         "Debt" means all obligations for borrowed money, unpaid purchase price
for goods and services received, obligations under any lease of goods,
obligations secured by any lien on any property and liabilities as a guarantor.

         "Default" means an event described in Article 7.

         "Default Rate" means at any date of determination for a Loan, the
Loan's per annum interest rate otherwise in effect plus 3% per annum.

         "Eligible Accounts" means accounts owing to a Person from an account
debtor arising in the ordinary course of the Person's business out of the sale
of goods or services delivered to and accepted by the account debtor, each of
which is represented by an invoice delivered to the account debtor and meets
each of the following requirements:

                  (a)   Is due and payable not more than 60 days after its
invoice date with not more than 90 days elapsed since such invoice date.

                  (b)   Owed by an account debtor which:

                        (i) is domiciled in the United States, Canada, or
Mexico;

                        (ii) is not, to the Borrower's knowledge, insolvent or
subject to a proceeding in bankruptcy or for reorganization;

                        (iii) is not an Affiliate of the Borrower;

                        (iv) does not have more than 50% of its accounts unpaid
over 90 days after invoice date; and

                        (v) is not unacceptable to the Bank, in its sole
discretion, any such determination to be effective only after 30 days written
notice from the Bank.

                  (c)   Represents an unconditional, valid, legal and
enforceable claim.

                  (d)   Is valued after reduction for offsets, credits and
adjustments for returned or damaged goods or inferior services.

                  (e)   Is not subject to (i) any defense or counterclaim, (ii)
any agreement for rebate, concession, discount or release of liability, or (iii)
the claim or interest of any other person (not permitted under this Agreement).

                  (f)   Is subject to a first priority, perfected security
interest in favor of the Bank.

                  (g)   Is not evidenced by a note, trade acceptance, draft or
other instrument that has not been endorsed or delivered to the Bank.

         "ERISA" means the Employee Retirement Income Security Act of 1974, as
amended, or any successor act or code.

         "GAAP" means, at any date of determination, generally accepted
accounting principles consistently applied.

                                      -3-
<PAGE>   4

         "Intangible Assets" means, at any date of determination, goodwill,
licenses, patents, copyrights, franchises, mailing lists, catalogs, trademarks,
bond discount, underwriting expense, organizational expense and other similar
intangible assets, and all sums receivable from The Lance Field Company arising
out of its purchase of the assets and name of I.G.K. Industries, Inc. or any
Affiliate.

         "Lien" means any security interest, mortgage, pledge, lien, claim,
charge, encumbrance, title retention agreement, lessor's interest under a
capitalized lease or analogous instrument, in, of or on any Person's assets or
properties in favor of any other Person, whether obtained under agreement, by
statute, pursuant to judgment, or otherwise.

         "Loan" means any loan made by the Bank to the Borrower pursuant to this
Agreement.

         "Maize" means Maize Acquisition Sub, Inc., a Delaware corporation.

         "Material Adverse Effect" means with respect to any matter that (i)
could reasonably be expected to materially and adversely affect the business,
properties, condition (financial or otherwise), or results of operations of the
Borrower and its Subsidiaries, if any, taken as a whole, or (ii) has been
brought by or before any court or arbitrator or any governmental body, agency or
official, and draws into question the validity or enforceability of any material
provision of this Agreement.

         "Merger Agreement" means the Agreement and Plan of Merger dated as of
June 28, 2000, among the Borrower, Tumbleweed, and Maize.

         "Mortgage" means the mortgage dated February 19, 1997, granted by the
Borrower to the Bank covering the Premises.

         "Note" means a promissory note in the form of Exhibit A (or any other
form of note acceptable to the Bank), duly executed and delivered to the Bank by
the Borrower, including any amendment, modification, renewal or replacement, to
evidence Loans made under this Agreement, and any amendment, modification,
renewal or replacement.

         "Obligations" means all unpaid principal of and accrued and unpaid
interest on the Loans, and all other obligations of the Borrower to the Bank
arising under this Agreement, any Note, and the Related Documents.

         "PBGC" means the Pension Benefit Guaranty Corporation or any Person
succeeding to the present powers and functions of the Pension Benefit Guaranty
Corporation.

         "Person" means any corporation, natural person, firm, joint venture,
partnership, limited liability company, trust, unincorporated organization,
enterprise, government or any department or agency of any government.

         "Premises" shall mean the Borrower's real property and improvements
located at 5855 Interface Drive, Ann Arbor, Michigan.

         "Premises' Loan Value" shall mean 80.00% of the appraised value of the
Premises, as determined by an appraiser satisfactory to the Bank.

         "Prime Rate" means a rate per annum equal to the prime rate of interest
announced

                                      -4-
<PAGE>   5

from time to time by the Bank or its parent (which is not necessarily the lowest
rate charged to any customer), changing when and as the prime rate changes.

         "Prime-based Rate" means a per annum rate of interest equal to the
Prime Rate plus One per cent (1.00%).

         "Registration Rights Agreement" means a Registration Rights Agreement
in the form of attached Exhibit G.

         "Related Documents" means the Security Agreement, the Mortgage, any
Subordination Agreements, all financing statements, and each other document,
instrument, and agreement evidencing, securing or relating to the Obligations,
and the Registration Rights Agreement.

         "Section" means a numbered section of this Agreement, unless another
document is specifically referenced.

         "Security Agreement" means the Security Agreement of even date in the
form of attached Exhibit E, made by the Borrower to the Bank pursuant to which
the Borrower granted the Bank a first priority security interest in the
Collateral that is personal property and any amendment, modification, renewal or
replacement.

         "Subsidiary" means any corporation more than 50% of the outstanding
voting securities of which are at the time owned or controlled, directly or
indirectly, by the Borrower or by one or more Subsidiaries or by the Borrower
and one or more Subsidiaries, or any similar business organization which is so
owned or controlled.

         "Subordinated Debt" means indebtedness, obligations or liabilities of
the Borrower which have been subordinated to the Obligations pursuant to a
Subordination Agreement.

         "Subordination Agreement" means a subordination agreement in form and
content satisfactory to the Bank which makes identified indebtedness,
obligations and liabilities of the Borrower subordinate to the Obligations, and
any amendment, modification, renewal or replacement.

         "Tangible Capital Funds" means, at any date of determination, for the
Borrower, total assets less the sum of Intangible Assets and Total Liabilities.

         "Termination Date" means (a) August 14, 2001, unless payment of the
Loans is accelerated, in which event it shall mean the date of acceleration, or,
if earlier, (b) the effective date of the Tumbleweed Merger.

         "Total Leverage" means, as of any date of determination, for any
Person, its ratio of (a) Total Liabilities less Subordinated Debt to (b)
Tangible Capital Funds plus Subordinated Debt.

         "Total Liabilities" means, as of any date of determination, all
liabilities as determined in accordance with GAAP.

         "Tumbleweed" means Tumbleweed Communications Corp., a Delaware
corporation.

         "Tumbleweed Merger" means the merger of the Borrower and Maize pursuant
to the Merger Agreement.

                                      -5-
<PAGE>   6

         "Unmatured Default" means an event or condition which but for the lapse
of time or the giving of notice, or both, would constitute a Default.

         "Warrant" means a warrant for the purchase of the Borrower's common
stock in the form of attached Exhibit F.

         "Working Capital" means, at any date of determination, Current Assets
minus Current Liabilities.

         1.2. The foregoing definitions are equally applicable to both the
singular and plural forms of the defined terms. Any accounting terms used, but
not otherwise defined, in this Agreement shall be given the meanings attributed
to them under GAAP.

         2. THE COMMITMENT AND THE LOANS

         2.1. The Commitment. Under the Commitment, from and including the
Effective Date and prior to the Termination Date, subject to the terms and
conditions of this Agreement, upon the Borrower's request the Bank will make
advances and re-advances of Loans to the Borrower from time to time in amounts
not to exceed in aggregate at any one time outstanding the lesser of (a) the
amount of the Commitment or (b) the Borrowing Base. The Borrower shall use the
proceeds of the Loans under the Commitment solely for its working capital and
general corporate purposes. The Loans under the Commitment shall be evidenced by
a Note in the form of Exhibit A, shall bear interest at the rate(s) and be
payable at the times set forth therein, and must be repaid in full without
notice or demand on the Termination Date. The Borrower shall immediately repay,
without notice or demand, any amount of the Loans under the Commitment which is
necessary to cause at all times the aggregate outstanding amount of such Loans
not exceed the lesser of the Borrowing Base or the maximum amount of the
Commitment.

         2.2. Notice of Borrowing under the Commitment. The Borrower may request
Loans under the Commitment from time to time by giving the Bank an irrevocable
borrowing notice signed by an authorized representative of the Borrower and a
Borrowing Base Certificate not later than 3:00 p.m. Detroit time on the
borrowing date of each Loan specifying: (a) the borrowing date of the Loan,
which must be a Business Day, and (b) the aggregate amount of the Loan.

         2.3. Reduction of Commitment. The Borrower may permanently reduce,
without penalty or premium, the amount of the Commitment in whole, or in
integral multiples of $100,000.00, upon 10 Business Days' written notice to the
Lender, but not below the then-outstanding amount of the Loans.

         2.4. Rates Applicable After Default. If the Loans are not paid when
due, whether by demand, maturity, acceleration or otherwise, their outstanding
principal balances will bear interest at their applicable Default Rates. During
the continuance of any other Default, the Bank may, at its option, by notice to
the Borrower, declare that the outstanding principal balance thereof will bear
interest at the Default Rate from and after the date the Default first occurred
or existed.

         2.5. Method of Payment. All payments of principal, interest, fees and
all other Obligations must be made in immediately available funds to the Bank at
the Bank's address specified at the end of this Agreement, or at any other
office of the Bank specified in writing by the Bank to the Borrower, by 3:00
p.m. (local time) on the date when due. The Bank is authorized to

                                      -6-
<PAGE>   7

charge the account of the Borrower maintained with it for each payment of
principal, interest, fees and any other Obligations as it becomes due.

         2.6.     Loan Records. The Bank is authorized to record on its books
the date and amount of each Loan, and the date and amount of each principal
payment made under the Note. These records govern absent manifest error,
provided that neither the failure to record nor any error in that record affects
the Borrower's obligations under the Note or this Agreement.

         2.7.     Commitment and Unused Portion Fees. The Borrower has paid the
Bank a $37,500.00 fee for the credit made available under this Agreement. The
Borrower shall pay to the Bank a unused portion fee for the period from the
Effective Date to and including the Termination Date equal to 15/100 percent
(0.15%) per annum on the average daily excess of the amount of the Commitment
over the principal balance of the Loans. The unused portion fee shall be payable
quarterly on the first Business Day of each September, December, March and June,
beginning September 1, 2000, and on the Termination Date, for the periods ending
on such dates.

         2.8.     Warrant. As further consideration for the credit made
available under this Agreement, the Borrower has (a) issued and delivered to the
Bank a Warrant for the purchase of 20,000 shares of the Borrower's common stock
("Warrant Shares") at $13.44 per share for a term of three (3) years and (b)
executed and delivered the Registration Rights Agreement.

         2.9.     Replacement of Prior Credit Authorization. The Commitment and
the Loans made under the Commitment replace the uncommitted $3,500,000.00 Credit
Authorization identified in the Credit Authorization Agreement dated August 31,
1997, made between the Borrower and the Bank, as amended. The Note shall replace
the $3,500,000 Master Demand Business Loan Note dated August 31, 1997, made by
the Borrower to the Bank.

         3. COLLATERAL.

         3.1.     Security. Full and timely payment and performance of the
Obligations shall be secured by a first priority security interest in or first
mortgage lien on the Collateral and any other property of the Borrower as to
which the Bank has been granted a Lien to secure payment of any debt, obligation
or liability of the Borrower or any other Person. As further security for the
Obligations, the Borrower pledges to and grants to the Bank a continuing
security interest in all securities and other property of the Borrower at any
time in the Bank's custody, possession or control (except property the Bank
holds solely as a fiduciary) and the balances of all of the Borrower's deposit
accounts with the Bank and all proceeds of any of the foregoing.

         4.       CONDITIONS PRECEDENT

         4.1. Initial Loan. Before it may obtain the first Loan under this
Agreement, the Borrower shall pay all required fees, and costs and expenses of
the Bank and furnish or cause to be furnished to the Bank:

         4.1.1. a Note in the amount of the Commitment;

         4.1.2. the Security Agreement, with such financing statements and other
documents and instruments the Bank deems necessary to assure that the Collateral
secures the Obligations and the first priority of the Bank's security interests;

         4.1.3. an amendment to the Mortgage confirming that it secures the
Obligations, together with a loan policy of title insurance insuring the
Mortgage's lien as a valid first

                                      -7-
<PAGE>   8

mortgage (with coverage at least equal to the Premises' Loan Value) subject to
no exception unacceptable to the Bank;

                  4.1.4. the Warrant and the Registration Rights Agreement;

                  4.1.5. a certificate of the Borrower's secretary (or other
authorized representative) certifying as true and correct, copies of the
Borrower's articles of incorporation, bylaws, and resolutions of its board of
directors authorizing all actions related to this Agreement, all borrowings of
Loans and issuance of the Warrant and the Warrant Shares, and certifying the
names, offices and specimen signatures of the Borrower's officers or
representatives authorized to take action under the resolutions;

                  4.1.6. a certificate of good standing for the Borrower from
the Michigan Department of Consumer and Industry Services dated not earlier than
30 days prior to the Effective Date;

                  4.1.7. an opinion of counsel to the Borrower addressed to the
Bank and opining as to the matters in Sections 5.1, 5.2, 5.3, 5.6, 5.11, and
5.12 and other matters as reasonably requested by the Bank;

                  4.1.8. an Environmental Certificate in the form of attached
Exhibit D;

                  4.1.9. such other documents, instruments, agreements,
certificates, and reports as the Bank may require to establish or verify the
Borrower's compliance with or satisfaction of the terms and conditions of this
Agreement and the Related Documents.

         4.2.     Each Loan. On the Effective Date and afterwards before any
Loan is made under this Agreement, the following shall be satisfied on the
applicable borrowing or closing date: (i) there shall exist no Default or
Unmatured Default, (ii) the representations and warranties contained in Article
5 shall be true and correct in all respects, (iii) this Agreement, the Note, the
Warrant, and the Related Documents remain in full force and effect and (iv) the
Bank shall have received such other documents, instruments, agreements,
certificates, and reports as the Bank may require to establish or verify the
Borrower's compliance with or satisfaction of the terms and conditions of this
Agreement and the Related Documents.

         5.       REPRESENTATIONS AND WARRANTIES. The Borrower represents and
warrants to the Bank that:

         5.1.     Existence and Standing. The Borrower is a corporation, duly
organized, validly existing and in good standing under the laws of the State of
Michigan and has all requisite authority to conduct its business in each
jurisdiction in which its business is conducted except where the failure to have
that authority would not have a Material Adverse Effect. The Borrower's only
Subsidiaries are Interface Systems International, Ltd., a United Kingdom
corporation, and Interface Holdings, Inc. (f/k/a I.G.K. Industries, Inc.) a
Michigan corporation. Neither Subsidiary has any material assets.

         5.2.     Authorization and Validity. The Borrower has the power and
authority and legal right to execute and deliver this Agreement, the Note, the
Warrant, and the Borrower's Related Documents and to perform its obligations
under them. The execution and delivery by the Borrower of this Agreement, the
Note, the Warrant, and the Borrower's Related Documents and the performance of
its obligations under them have been duly authorized by proper proceedings, and
this Agreement, the Note, the Warrant, and the Borrower's Related Documents each
constitute legal, valid and binding obligations of the Borrower enforceable

                                      -8-
<PAGE>   9

against the Borrower in accordance with their terms.

         5.3.     No Conflict; Government Consent. Neither the execution and
delivery by the Borrower of this Agreement, the Note, the Warrant, and the
Borrower's Related Documents, nor the consummation of the transactions they
describe, nor compliance with their provisions will (a) violate any law, rule,
regulation, order, writ, judgment, injunction, decree or award binding on the
Borrower, or (b) violate the Borrower's or any Subsidiary's governing documents,
or the provisions of any indenture, instrument or agreement to which the
Borrower or any Subsidiary is a party or is subject, or by which it or its
property is bound, or conflict with or constitute a default under them, or (c)
result in the creation or imposition of any Lien in, of or on the property of
the Borrower or a Subsidiary pursuant to the terms of any indenture, instrument
or agreement. No order, consent, approval, license, authorization, or validation
of, or filing, recording or registration with, or exemption by, or other action
in respect of, any governmental or public body or authority, or any subdivision
of them, is required to authorize, or is required in connection with the
execution, delivery and performance of, or the legality, validity, binding
effect or enforceability of, this Agreement, the Note, the Warrant, or the
Borrower's Related Documents.

         5.4.     Financial Statements. The financial statements of the Borrower
as of September 30, 1999 and March 31, 2000, previously delivered to the Bank
were prepared in accordance with GAAP and fairly present the financial condition
and results of operations of the Borrower at those dates. Since those dates
there has been no change in the Borrower's business, prospects or condition
(financial or otherwise) or results of operations that would have a Material
Adverse Effect.

         5.5.     Solvency. The Borrower is solvent and has adequate capital for
the continuation of its business and has not incurred debts beyond its ability
to pay as they mature.

         5.6.     Litigation and Contingent Obligations. There is no litigation,
arbitration, governmental investigation, proceeding or inquiry pending or, to
the knowledge of any of its officers, threatened against or affecting the
Borrower which might have a Material Adverse Effect. Schedule 5.6 sets forth all
currently pending (or known to be threatened) litigation, none of which the
Company believes will have a Material Adverse Effect. The Borrower has no
contingent obligations, including liability for obligations of any of its
Affiliates, except the endorsement of instruments for deposit in the ordinary
course of business, not provided for or disclosed in the financial statements
referred to in Section 5.4.

         5.7.     Title to Property; No Liens. The Borrower has good and
marketable title to all property (tangible and intangible) necessary for the
proper and efficient operations of the Borrower's business. Except as permitted
under Section 6.9, none of the Borrower's assets and properties, including
without limit the Collateral, are subject to any Lien of any kind or character.

         5.8.     Taxes. The Borrower has filed by the due date therefor all
federal, state and local tax returns and other reports it is required by law to
file, has paid or caused to be paid all taxes, assessments and other
governmental charges that are shown to be due and payable under such returns,
and has made adequate provision for the payment of such taxes, assessments or
other governmental charges which have accrued but are not yet payable. The
Borrower has no knowledge of any deficiency or assessment in connection with any
taxes, assessments or other governmental charges not adequately disclosed in the
financial statements referred to in Section 5.4, except for the matters set
forth on Schedule 5.8, none of which the Company believes will have a Material
Adverse Effect.

                                      -9-
<PAGE>   10

         5.9.     Margin Stock. The Borrower is not engaged principally, or as
one of its important activities, in the business of extending credit for the
purpose of purchasing or carrying any "margin stock" within the meaning of
Regulation U of the Board of Governors of the Federal Reserve System, and no
part of the proceeds of any loan hereunder will be used, directly or indirectly,
to purchase or carry any margin stock or to extend credit to others for the
purpose of purchasing or carrying any margin stock or for any other purpose
which might violate the provisions of Regulation G, T, U or X of the said Board
of Governors. The Borrower does not own any margin stock.

         5.10.    Pension Funding. The Borrower has not incurred any accumulated
funding deficiency within the meaning of ERISA or incurred any liability to the
PBGC in connection with any employee benefit plan established or maintained by
the Borrower and no reportable event or prohibited transaction, as defined in
ERISA, has occurred with respect to such plans.

         5.11.    Compliance With Laws and Agreements. The Borrower has complied
in all material respects with (a) all applicable statutes, rules, regulations,
orders and restrictions of any domestic or foreign government or any
instrumentality or agency of them, having jurisdiction over the conduct of its
businesses or the ownership of its properties and (b) all leases, contracts, and
commitments as to which non-compliance would have a Material Adverse Effect.

         5.12.    Shares and Shareholders. The Borrower's entire issued and
outstanding capital stock consists of 4,716,075 shares of common stock, no par
value, as of June 1, 2000. Except as set forth in Schedule 5.12, no Person owns
beneficially or of record more than 5% of such shares. There are no outstanding
options, warrants or rights to purchase, nor any agreement for the subscription,
purchase or acquisition of, any shares of the capital stock of the Borrower,
except as set forth on Schedule 5.12. All outstanding shares of the capital
stock of the Borrower were offered and sold in compliance with all applicable
federal and state securities laws. No Person is entitled to pre-emptive or
similar rights to purchase any capital stock of the Borrower.

         5.13.    Representations in Warrant. The representations and warranties
the Borrower makes in the Warrant are incorporated in this Agreement by this
reference.

         6.       COVENANTS. During the term of this Agreement, unless the Bank
otherwise consents in writing:

         6.1.     Financial Reporting. The Borrower will maintain a system of
accounting established and administered in accordance with GAAP, and furnish to
the Bank (in each case prepared in accordance with GAAP):

                  6.1.1.  Within ninety (90) days after and as of the end of
each of the Borrower's fiscal years, financial statements, including balance
sheet, income, expense, and cash flow and retained earnings statements,
accompanied by an unqualified audit opinion of certified public accountants
acceptable to the Bank.

                  6.1.2.  Within twenty (20) days after and as of the end of
each month, management prepared and certified financial statements, including
balance sheet and statements of income, expense, and cash flow and retained
earnings for the month then ended and the year-to-date.

                  6.1.3.  Within ten (10) days after and as of the end of each
month, agings and listings of its accounts receivable and accounts payable.

                                      -10-
<PAGE>   11

                  6.1.4.  Within ten (10) days after and as of the end of each
month, a Borrowing Base Certificate, certified by an officer of the Borrower.

                  6.1.5.  Within thirty (30) days after and as of the end of
each of the Borrower's fiscal quarters, a Covenant Compliance Certificate,
certified by an officer of the Borrower.

                  6.1.6.  Within fifteen (15) days after filing, copies of all
federal tax returns of the Borrower.

                  6.1.7.  Promptly upon becoming available, a copy of all
financial statements, reports, notices, proxy statements and other
communications sent by the Borrower or any of its Subsidiaries to their
stockholders, and all regular and periodic reports filed by the Borrower or any
of its Subsidiaries with any securities exchange, the Securities and Exchange
Commission, the Corporations, Securities and Land Development Bureau of the
Department of Consumer and Industry Services of the State of Michigan or any
governmental authorities succeeding to any or all of the functions of said
Commission or Bureau.

                  6.1.8.  All management letters and reports prepared by the
Borrower's independent accountants including financial statement audits. Any
other information (including non-financial information) the Bank from time to
time reasonably requests.

         6.2.     Inspections. The Borrower will permit the Bank, through its
authorized attorneys, accountants and representatives, to examine all of the
Borrower's books, accounts, records, ledgers, property and assets at all
reasonable times and upon the Bank's request, including without limitation field
audits of the Collateral. The Borrower shall pay the Bank's costs and expenses
for each such field audit.

         6.3.     Use of Proceeds. The Borrower will use the proceeds of the
Loans only for the purposes set forth in this Agreement. The Borrower may not
use any of the proceeds of the Loans to purchase or carry any "margin stock" (as
defined in Regulation U).

         6.4.     Conduct of Business. The Borrower will carry on and conduct
its business in substantially the same manner and in substantially the same
fields of enterprise as it is presently conducted, and maintain the validity and
enforceability of all licenses, franchises, and similar rights necessary
thereto, and do all things necessary to remain duly incorporated, validly
existing and in good standing as a domestic corporation in its jurisdiction of
incorporation and maintain all requisite authority to conduct its business in
each jurisdiction in which its business is conducted, and will not form any
Subsidiary or enter into any partnership, joint venture, or other enterprise.
The Borrower will not amend its articles of incorporation or bylaws. The
Borrower will not change its principal place of business or the location of the
Collateral without giving prior written notice to the Bank.

         6.5.     Taxes. The Borrower will timely file complete and correct
United States federal and applicable foreign, state and local tax returns
required by law, and pay when due all taxes, assessments and governmental
charges and levies on it or its income, profits or property, except those which
are being contested in good faith by appropriate proceedings and with respect to
which adequate reserves have been set aside.

         6.6.     Insurance. The Borrower will keep its insurable properties
(including but not limited to the Collateral) and the insurable properties of
its Subsidiaries adequately insured and maintain (a) insurance against fire and
other risks customarily insured against under an "all-risk" policy and such
additional risks customarily insured against by companies engaged in the same or
a

                                      -11-
<PAGE>   12

similar business to that of the Borrower or its Subsidiaries, as the case may
be, (b) necessary worker's compensation insurance, (c) public liability, and (d)
such other insurance as may be required by law or as may be reasonably required
in writing by the Bank, all of which insurance shall be in such amounts,
containing such terms, in such form, for such purposes, prepaid for such time
period, and written by such companies as may be satisfactory to the Bank. All
such policies shall contain a provision whereby they may not be canceled or
amended except upon thirty (30) days' prior written notice to the Bank.

         6.7.     Compliance with Laws and Agreements. The Borrower will comply
in all material respects with all laws, rules, regulations, orders, writs,
judgments, injunctions, decrees or awards to which it or any of its property or
assets may be subject and all leases, contracts and commitments as to which
non-compliance could have a Material Adverse Effect.

         6.8.     Merger. The Borrower will not merge, change its name, or
consolidate with or into any other Person, or enter into an agreement to merge,
consolidate or acquire all or substantially all of any other Person's assets, or
in any other manner combine with any other person, except for the Tumbleweed
Merger, or reorganize, re-capitalize or reclassify its capital stock. The
Borrower will not enter into any amendment or modification of the Merger
Agreement.

         6.9.     Liens. The Borrower will not create, incur, or suffer to exist
any Lien in, of or on its property or assets, except:

                  6.9.1.  Liens for taxes, assessments or governmental charges
or levies on its property if they are not at the time delinquent or if they can
be paid later without penalty, or are being contested in good faith and by
appropriate proceedings;

                  6.9.2.  Liens imposed by law, such as carriers',
warehousemen's and mechanics' liens and other similar liens arising in the
ordinary course of business which secure payment of obligations not more than 60
days past due or which are being contested in good faith by appropriate
proceedings and for which adequate reserves have been set aside on its books;

                  6.9.3.  Liens arising out of pledges or deposits under
worker's compensation laws, unemployment insurance, old age pensions, or other
social security or retirement benefits, or similar legislation;

                  6.9.4.  Utility easements, building restrictions and any other
encumbrances or charges against real property which are of a nature generally
existing with respect to properties of a similar character and which do not in
any material way affect their marketability or interfere with their use in the
business of the Borrower; and

                  6.9.5.  Liens in favor of the Bank or permitted under the
terms of the Security Agreement or the Mortgage.

         6.10.    Notice of Default. The Borrower will give prompt notice in
writing to the Bank of the occurrence of any Default or Unmatured Default and of
any other development, financial or otherwise, other than general economic
conditions, which might have a Material Adverse Effect or might materially
adversely affect the ability of the Borrower to repay the Obligations.

         6.11.    Stock Redemptions; Distributions. The Borrower will not (a)
redeem, acquire or retire any of its capital stock or (b) declare, pay or make
any dividends or distributions upon any of its capital stock.

                                      -12-
<PAGE>   13

         6.12.    Acquire New Capital. On or before December 31, 2000, the
Borrower shall procure $3,000,000.00 in additional capital in the form of
privately-placed Subordinated Debt or newly-issued common stock. Otherwise, the
Borrower will not issue, sell or otherwise dispose of any of capital stock, or
rights, warrants or options to purchase or acquire any such capital stock.

         6.13.    Property Transfer. The Borrower will not sell, lease, transfer
or otherwise dispose of properties and assets having an aggregate Book Value of
more than $200,000.00 in any fiscal year, (whether in one transaction or a
series) except for (a) sales of inventory in the ordinary course of business and
(b) dispositions of vehicles and equipment which are obsolete, not economically
useful or replaced by substantially similar vehicles or equipment.

         6.14.    Debt. The Borrower will not incur, or permit to remain
outstanding, debt for borrowed money or installment obligations, except (a) debt
reflected in the latest financial statement of the Borrower furnished to the
Bank prior to execution of this Agreement and not to be paid with proceeds of
the Loans and (b) debt to Affiliates which is Subordinated Debt. For purposes of
this covenant, the sale of any account receivable shall be deemed the incurring
of debt for borrowed money.

         6.15.    Guaranties. The Borrower will not guarantee or otherwise
become or remain secondarily liable on the undertaking of any other Person,
except for guaranties made in favor of the Bank or endorsement of drafts for
deposit or collection in the ordinary course of business.

         6.16.    Subordination. The Borrower will not subordinate any
obligation due to it from a Person to obligations to other creditors of such
Person.

         6.17.    Advances and Investments. The Borrower will not purchase or
acquire any securities of, or make any loans or advances to, or investments in,
any Person, except obligations of the United States government, open market
commercial paper rated one of the top two ratings by a rating agency of
recognized standing, or certificates of deposit in insured financial
institutions.

         6.18.    Current Ratio. The Borrower will not permit the ratio of its
Current Assets to its Current Liabilities to be less than 1.05:1.00 at any time.

         6.19.    Working Capital. The Borrower will not permit its Working
Capital to be less than $1,000,000.00 at any time.

         6.20.    Tangible Capital Funds. The Borrower will not permit its
Tangible Capital Funds plus Subordinated Debt to be less than the amount set
forth below at any time during the specified effective period:

<TABLE>
<CAPTION>
                      Minimum Amount                                   Effective Period
                      --------------                                   ----------------
<S>                                                           <C>
                       $2,600,000.00                          June 30, 2000 through September 29, 2000

                       $2,100,000.00                          September 30, 2000 through December 30, 2000

                       $4,000,000.00                          December 31, 2001 and afterwards
</TABLE>

                                      -13-
<PAGE>   14

         6.21.    Total Leverage. The Borrower will not permit its Total
Leverage to exceed 1.70:1.00 at any time.

         6.22.    Management. Until the Tumbleweed Merger is consummated, the
Borrower will not cause, permit or suffer the failure of Robert Nero to continue
to be the chief executive officer of the Borrower with primary responsibility
for its operations in the ordinary course of business.

         7.       DEFAULTS. The occurrence or existence of any one or more of
the following events or conditions constitutes a Default:

         7.1.     Any representation or warranty made or deemed made by or on
behalf of the Borrower to the Bank under or in connection with this Agreement,
any Loan, or any certificate or information delivered in connection with this
Agreement, the Note or any Related Document is materially false on the date as
of which it is made.

         7.2.     The principal of the Loans or any other Obligations are not
paid when due, or any interest or any fee or other obligations under this
Agreement, the Note, or any Related Document are not paid within five days after
they become due.

         7.3.     The Borrower breaches or fails to observe, perform or comply
with any of the terms of Article 6, or any of the terms and conditions of any of
the Related Documents, or the Borrower breaches or fails for more than 30 days
to observe, perform or comply with any of the other terms of this Agreement.

         7.4.     The Borrower fails to pay any debt for borrowed money
exceeding $25,000.00 within 10 days of its due date (whether by maturity,
acceleration or otherwise); or the Borrower defaults in the performance of any
term contained in any agreement under which that debt was created or is
governed, the effect of which is to cause that debt to become due prior to its
stated maturity; or any debt of the Borrower is declared to be due and payable
or required to be prepaid or repurchased (other than by a regularly scheduled
payment) prior to its stated maturity; or the Borrower does not pay, or admits
in writing its inability to pay, its debts generally as they become due.

         7.5.     The Borrower (i) has an order for relief entered with respect
to it under present or future Federal bankruptcy laws, (ii) makes an assignment
for the benefit of creditors, (iii) applies for, seeks, consents to, or
acquiesces in, the appointment of a receiver, custodian, trustee, examiner,
liquidator or similar official for it or any substantial part of its property,
(iv) institutes any proceeding seeking an order for relief under present or
future Federal bankruptcy laws, or seeking to adjudicate it a bankrupt or
insolvent, or seeking dissolution, winding up, liquidation, reorganization,
arrangement, adjustment or composition of it or its debts under any law relating
to bankruptcy, insolvency or reorganization or relief of debtors, or fails to
file an answer or other pleading denying the material allegations of any such
proceeding filed against it, (v) takes any corporate action to authorize or
effect any of the foregoing actions set forth in this Section or (vi) fails to
contest in good faith any appointment or proceeding described in Section 7.6.

         7.6.     Without the application, approval or consent of the Borrower,
a receiver, trustee, examiner, liquidator or similar official is appointed for
the Borrower or any substantial part of its property, or a proceeding described
in Section 7.5 is instituted against the Borrower and that appointment continues
undischarged or those proceedings continue undismissed or unstayed for a period
of 30 consecutive days.

                                      -14-
<PAGE>   15

         7.7.     A judgment is rendered against the Borrower and has not been,
and does not remain, satisfied, discharged or stayed within 21 days thereafter;
or a writ of attachment or garnishment is issued against any property of the
Borrower and is not released or appealed and bonded in an amount and manner
satisfactory to the Bank within 21 days thereafter.

         7.8.     The Borrower fails to meet its minimum funding requirements
under ERISA with respect to, or any reportable event (as defined in Section 4043
of ERISA) occurs in connection with, any employee benefit plan established or
maintained by the Borrower, or if any such plan is the subject of any
termination proceeding giving rise to a liability of the Borrower to the PBGC
which the Bank shall determine to have a Material Adverse Effect.

         8.       ACCELERATION; REMEDIES; AND AMENDMENTS.

         8.1.     Acceleration. If any Default described in Section 7.5 or 7.6
occurs with respect to the Borrower, the Commitment and any other obligations
the Bank may at any time have to make Loans under this Agreement shall
automatically terminate and the Obligations shall be immediately due and payable
without any election or action on the part of the Bank. If any other Default
occurs, the Bank may terminate or suspend the Commitment or any other obligation
it may at any time have to make Loans under this Agreement, or declare the
Obligations due and payable, or both, whereupon the Obligations are immediately
due and payable, without presentment, demand, protest or notice of any kind, all
of which the Borrower expressly waives. When the Obligations become due and
payable the Bank may then exercise each other right or remedy available to it
under this Agreement, the Note, and the Related Documents, or otherwise by law.

         8.2.     Preservation of Rights. No delay or omission of the Bank to
exercise any right under this Agreement, the Note or the Related Documents
impairs that right nor can it be construed to waive any Default or acquiesce in
any Default, and the making of a Loan notwithstanding the existence of a Default
or the inability of the Borrower to satisfy the conditions precedent to that
Loan does not constitute a waiver or acquiescence. Any single or partial
exercise of any right does not preclude any other or further exercise of it or
the exercise of any other right. No waiver, amendment or other variation of the
terms of this Agreement, the Note or any Related Document is valid unless in
writing signed by the Bank and then only to the extent that writing specifies.
All remedies contained in this Agreement, the Note and the Related Documents or
afforded by law are cumulative and all are available to the Bank until the
Obligations have been paid in full and all sums received by the Bank may be
applied by the Bank to the Obligations in such order as it determines in its
sole discretion.

         8.3.     Amendments. Subject to the provisions of this Article 8, the
Bank and the Borrower may enter into written agreements supplementing this
Agreement for the purpose of amending or modifying this Agreement, the Note or
any Related Documents or changing in any manner the rights of the Bank or the
Borrower or waiving any Default.

         8.4.     Setoff. In addition to and without limiting any rights of the
Bank under applicable law, if the Borrower becomes insolvent, howsoever
evidenced, or any Default or Unmatured Default occurs, any and all deposits
(including all account balances, whether provisional or final and whether or not
collected or available) and any other debt at any time held or owing by the Bank
to or for the credit or account of the Borrower may be offset and applied toward
the payment of the Obligations owing to the Bank, to the extent that such
Obligations are then due (whether by maturity, acceleration or otherwise).

                                      -15-
<PAGE>   16

         9.       GENERAL PROVISIONS.

         9.1.     Survival of Representations and Warranties. All
representations and warranties of the Borrower contained in this Agreement
survive the delivery of the Note and the Related Documents and the making of the
Loans.

         9.2.     Taxes. Any taxes (excluding income taxes) or other similar
assessments or charges payable or ruled payable by any governmental authority in
respect of this Agreement, the Note and the Related Documents must be paid by
the Borrower, together with interest and penalties, if any.

         9.3.     Expenses; Indemnification. The Borrower must reimburse the
Bank for any costs, internal charges and out-of-pocket expenses (including
attorneys' fees and time charges of attorneys for the Bank, who may be employees
of the Bank) paid or incurred by the Bank in connection with the preparation,
review, execution, delivery, amendment, modification, administration, collection
and enforcement of this Agreement, the Note, the Warrant, and the Related
Documents. The Borrower further indemnifies the Bank, its directors, officers,
employees and agents (collectively, "Bank Indemnitees") against all losses,
claims, damages, penalties, judgments, liabilities and expenses (including
without limitation all expenses of litigation or preparation for litigation
whether or not the Bank or any of the other Bank Indemnitees is a party)
(collectively, "Losses") which any of them pay or incur arising out of or
relating to this Agreement, the Note, the Warrant, and the Related Documents,
the transactions described in this Agreement or the direct or indirect
application or proposed application of the proceeds of any Loan, except for
Losses caused solely by the willful misconduct of the Bank or any other Bank
Indemnitees. The obligations of the Borrower under this Section survive the
termination of this Agreement.

         9.4.     Successors and Assigns. The terms of this Agreement, the Note
and the Related Documents bind and benefit the Borrower and the Bank and their
respective successors and assigns, except that the Borrower has no right to
assign its rights or obligations under this Agreement, the Note, or the Related
Documents. The Bank may, in the ordinary course of its commercial banking
business and in accordance with applicable law, at any time sell to one or more
banks or other entities participating interests in any Loan or the Note. The
Bank may, with the prior written consent of the Borrower, which consent may not
be unreasonably withheld, assign to one or more banks or other entities all or
any part of its rights and obligations under this Agreement, the Note, or the
Related Documents and the Borrower releases the Bank for the amount so assigned.

         9.5.     Giving Notice. Except as otherwise permitted by Section 2.2
with respect to borrowing notices, all notices, requests and other
communications to any party relating to this Agreement must be in writing
(including bank wire, telex, facsimile transmission or similar writing) and must
be given to a party: (y) in the case of the Borrower or the Bank, at its
address, facsimile number or telex number set forth on the signature page below,
or (z) in the case of any party, whatever other address, facsimile number or
telex number that party specifies for the purpose, by notice to the other. Each
notice, request or other communication is effective (i) if given by telex, when
it is transmitted to the telex number specified in this Section and the
appropriate answer back is received, (ii) if given by facsimile transmission,
when transmitted to the facsimile number specified in this Section and
confirmation of receipt is received, (iii) if given by mail, 72 hours after that
communication is deposited in the mails with first class postage prepaid,
addressed as required, or (iv) if given by any other means, when delivered at
the address specified in this Section. However, notices to the Bank under
Article 2 are not effective until received.

         9.6.     Counterparts. This Agreement may be signed in any number of
counterparts with the

                                      -16-
<PAGE>   17

same effect as if the signatures were upon the same instrument.

         9.7.     Headings. Article and section headings in this Agreement are
included for the convenience of reference only and shall not constitute a part
of this Agreement for any purpose.

         10.      GOVERNING LAW; JURISDICTION; JURY TRIAL WAIVER.

         10.1.    Governing Law. This Agreement, the Note and the Related
Documents are to be construed in accordance with the internal laws (but not the
law of conflicts) of Michigan. If any provisions of this Agreement, the Note, or
any Related Document shall for any reason be held invalid or unenforceable, such
invalidity or unenforceability shall not affect any other provision hereof, but
this Agreement shall be construed as if such invalid or unenforceable provisions
had never been contained herein.

         10.2.    Consent to Jurisdiction. The Borrower irrevocably submits to
the non-exclusive jurisdiction of any United States federal or Michigan state
court sitting in Michigan in any action or proceeding arising out of or relating
to any Loan, and the Borrower irrevocably agrees that all such claims may be
heard and determined in any such court and irrevocably waives any present and
future objection it may have as to the venue of any action or proceeding brought
in that court, or that  court is an inconvenient forum. Nothing in this
Section limits the right of the Bank to bring any action or proceeding against
the Borrower in the courts of any other jurisdiction. Any judicial proceeding by
the Borrower against the Bank or any affiliate of the Bank involving, directly
or indirectly, any matter in any way arising out of, related to, or connected
with any Loan must be brought only in a court in Michigan.

         10.3.    WAIVER OF JURY TRIAL. THE BORROWER AND THE BANK WAIVE TRIAL BY
JURY IN ANY JUDICIAL PROCEEDING INVOLVING, DIRECTLY OR INDIRECTLY, ANY MATTER
(WHETHER SOUNDING IN TORT, CONTRACT OR OTHERWISE) IN ANY WAY ARISING OUT OF,
RELATED TO, OR CONNECTED WITH ANY LOAN OR THE RELATIONSHIP ESTABLISHED UNDER
THIS AGREEMENT.

         This Credit Agreement is executed as of the Effective Date.

BORROWER:                                         BANK:

INTERFACE SYSTEMS, INC.                           BANK ONE, MICHIGAN

By: /s/ Brian D. Brooks                           By: /s/ Satish B. Jasti
    -----------------------------------               -------------------
        Brian D. Brooks                                 Satish B. Jasti
     Its:  Chief Financial Officer                    Its: Vice President

T.I.N. 38-1857379

                                      -17-
<PAGE>   18

ADDRESSES FOR NOTICES:

5855 Interface Drive                             125 South Main
Ann Arbor, Michigan 48103                        Ann Arbor, Michigan 48104

Phone:  (734) 769-5900                           Phone: (734) 995-8150
Fax:                                             Fax: (734) 995-8000

Attention:  Chief Financial Officer              Attention:  Satish B. Jasti

                                      -18-
<PAGE>   19

                             SCHEDULES AND EXHIBITS
                                       TO
                                CREDIT AGREEMENT

<TABLE>
<S>                                           <C>
Schedule 5.6                                  Schedule of Litigation and Contingent Obligations
Schedule 5.8                                                                  Schedule of Taxes
Schedule 5.12                                               Schedule of Shares and Shareholders

Exhibit A                                                                           Master Note
Exhibit B                                                            Borrowing Base Certificate
Exhibit C                                                       Covenant Compliance Certificate
Exhibit D                                                             Environmental Certificate
Exhibit E                                                                    Security Agreement
Exhibit F                                                                               Warrant
Exhibit G                                                         Registration Rights Agreement
</TABLE>

                                      -19-
<PAGE>   20

                                  Schedule 5.6

                SCHEDULE OF LITIGATION AND CONTINGENT OBLIGATIONS

         On July 7, 2000, three complaints were filed by David H. Zimmer,
Congressional Securities, Inc. and other plaintiffs against the Borrower and
various additional defendants, including the Borrower's President and Chief
Executive Officer, Robert A. Nero and Fiserv Correspondent Services, Inc., in
the United States District Court for the Southern District of New York. The
three cases contain substantially similar allegations of false and misleading
representations by various defendants allegedly designed to inflate Interface's
stock price. The complaints seek relief under the federal securities laws on
behalf of purported classes of persons who purchased, held, or sold shares of
Interface stock, and under various other causes of action. Recently, all three
of the complaints were amended. The Borrower and Mr. Nero intend vigorously to
defend them and seek their dismissal. Although the Borrower and Mr. Nero believe
these actions to be without merit, no prediction of the ultimate outcome can be
made at this time.

                                      -20-
<PAGE>   21

                                  Schedule 5.8

                                SCHEDULE OF TAXES

1.       The Borrower received a Notice of Delinquency, dated March 10, 2000
from the State of New Jersey Department of the Treasury. The Notice states that
the Division of Taxation's records reflect that the Company is delinquent in
paying New Jersey Corporation Business Tax for the taxable year 1996, ending
September 30, 1996.

2.       The Borrower received a notice from the New York State Department of
Taxation and Finance. The Notice and Warrant state that the Tax Compliance
Division's records show an outstanding New York State assessed tax liability in
the amount of $13,332.36, being principally interest and penalties.

                                      -21-
<PAGE>   22

                                  Schedule 5.12

                       SCHEDULE OF SHARES AND SHAREHOLDERS

1.       939,215 shares of the Borrower's common stock are purchasable by
Tumbleweed Communications Corp. ("Tumbleweed") upon exercise of an option
granted to Tumbleweed on June 28, 2000, and an approximately 210,526 shares of
the Borrower's common stock are purchasable by Tumbleweed upon conversion of a
note sold to Tumbleweed on June 28, 2000.

2.       See attached schedule of outstanding employee stock options.

                                      -22-
<PAGE>   23

INTERFACE SYSTEMS, INC.
OPTIONS SUMMARY
06/27/00
<TABLE>
<CAPTION>
                                                            FISCAL YEAR      FISCAL YEAR      FISCAL YEAR          OUTSTANDING
                                           BALANCE AT          2000              2000            2000                   AT
                PLAN                        9/30/99*          GRANTS          EXERCISED        CANCELED              6/27/00
--------------------------------------  ----------------- ----------------  ---------------  --------------        -------------
<S>                                     <C>               <C>               <C>              <C>                   <C>
                1982                              12,700                -                -           6,500                6,200

            Non-Qualified                         33,900                -           23,950           1,600                8,350

                1992                             644,102          167,500           80,932          16,702              713,968

           1993 Directors                        127,500           12,000            2,000               -              137,500
                                        ---------------- ----------------  ---------------  --------------        -------------
                                                 818,202          179,500          106,882          24,802              866,018
                                        ================ ================  ===============  ==============        =============

AVAILABLE GRANTS UNDER THE 1992 PLAN

Balance at 9/30/99*                              105,567

Additional Shares Approved                       300,000

FY 2000 Grants                                 (167,500)

FY 2000 Cancellations                             16,702
                                        -----------------
Remaining at 6/27/00                             254,769
                                        =================

AVAILABLE GRANTS UNDER THE 1993 PLAN

Balance at 9/30/99*                               47,500

FY 2000 Grants                                  (12,000)
                                        -----------------
Remaining at 6/27/00                              35,500
                                        =================

</TABLE>

*Per Annual Form 10K

                                      -23-
<PAGE>   24

                                    EXHIBIT A

                                   MASTER NOTE

$5,000,000.00                                         Date:          , 2000
                                                        Ann Arbor, Michigan

For value received, INTERFACE SYSTEMS, INC., a Michigan corporation (the
"Borrower") promises to pay to the order of BANK ONE, MICHIGAN (the "Bank"), at
the Bank's principal office in the State of Michigan, on or before           ,
2001, in lawful money of the United States of America and in immediately
available funds, the principal sum of FIVE MILLION AND 00/100 DOLLARS
($5,000,000.00), or such lesser amount as is indicated on the Bank's records,
together with interest computed on the outstanding balance from time to time
unpaid on the basis of the actual number of days elapsed in a year of 360 days
at the Prime-based Rate as defined in and determined from time to time pursuant
to the "Credit Agreement" as defined below and reflected on the Bank's records.
Interest is payable monthly commencing             1, 2000, and on the first day
of each succeeding month. This Note is a note under which advances, repayments
and re-advances may be made from time to time, on the terms and conditions of
the Credit Agreement. All advances and re-advances shall be made at the Bank's
sole discretion.

Usury. In no event may the interest rate exceed the maximum rate allowed by law.
Any payment of interest which would for any reason be unlawful under applicable
law will be applied to principal.

Late Fee. If any payment is not received by the Bank within fifteen days after
its due date, the Bank may assess and the Borrower agrees to pay a late fee
equal to five percent of the past due amount.

Waiver: The Borrower and each endorser of this Note and any other party liable
for the debt evidenced by this note severally waives demand, presentment, notice
of dishonor and protest of this Note, and consents to any extension or
postponement of time of its payment without limit as to number or period, to any
substitution, exchange or release of all or any part of any collateral securing
this note, to the addition of any party, and to the release, discharge, or
suspension of any rights and remedies against any person who is liable for the
payment of this Note. No delay on the part of the holder in the exercise of any
right or remedy waives that right or remedy. No single or partial exercise by
the holder of any right or remedy precludes any future exercise of that right or
remedy or the exercise of any other right or remedy. No waiver or indulgence by
the holder of any default is effective unless it is in writing and signed by the
holder, and a waiver on one occasion does not bar or waive any right on any
future occasion.

Credit Agreement. This Note evidences a debt under the terms of the Credit
Agreement between the Bank and the Borrower dated as of June 1, 2000, and any
amendments, (the "Credit Agreement"), which is incorporated by reference for
additional terms, including default and acceleration provisions.

WAIVER OF JURY TRIAL. THE BORROWER AND THE BANK WAIVE TRIAL BY JURY IN ANY
JUDICIAL PROCEEDING INVOLVING, DIRECTLY OR INDIRECTLY, ANY MATTER (WHETHER
SOUNDING IN TORT, CONTRACT OR OTHERWISE) IN ANY WAY ARISING OUT OF, RELATED TO,
OR CONNECTED WITH THIS NOTE OR ANY LOAN OR OTHER OBLIGATION EVIDENCED BY IT.

                                     INTERFACE SYSTEMS, INC.

                                     By:
                                         ---------------------------------------

                                              Its:
                                                   -----------------------------

                                      -24-
<PAGE>   25

                                    EXHIBIT B

                           BORROWING BASE CERTIFICATE

         INTERFACE SYSTEMS, INC. ("Borrower") certifies to BANK ONE, MICHIGAN
("Bank") the following as of the close of business on                         :

<TABLE>
<CAPTION>

         --------------------------------------------------------------------------------------------
         BORROWING BASE
         --------------------------------------------------------------------------------------------

<S>                                                       <C>                 <C>
         a.  Eligible Accounts:                           $
                                                          -------------------
         b.  Multiplied by .75                            x.75 =              $
                                                                              -----------------------
         c.  Plus Premises' Loan Value                                        $
         ------------------------------------------------ ------------------- -----------------------
         d.  Total Accounts and Premises Reliance and
              Borrowing Base                                                  $
         ------------------------------------------------ ------------------- -----------------------
</TABLE>

This Borrowing Base Certificate is submitted pursuant to the Credit Agreement
dated as of June 1, 2000, between the Borrower and the Bank ("Agreement").
Capitalized terms used but not defined herein have the meanings given them under
the Agreement. The Borrower represents and warrants that the information
provided herein is true, complete and correct.

Dated on
         ---------------------------
                                             INTERFACE SYSTEMS, INC.

                                             By:
                                                 -------------------------------

                                                      Its
                                                          ----------------------

                                      -25-
<PAGE>   26

                                    EXHIBIT C

                         COVENANT COMPLIANCE CERTIFICATE

         INTERFACE SYSTEMS, INC. ("Borrower") certifies to BANK ONE, MICHIGAN
("Bank") the following as of the close of business on
                             ("Compliance Date"):

         a. Current Ratio. On the Compliance Date, the ratio of Current Assets
to Current Liabilities was        :1.00 (and is required under the Agreement to
be not less than 1.05:1.00).

         b. Working Capital. On the Compliance Date, Working Capital was
$               (and is required under the Agreement to be not less than
$1,000,000.00 at the Compliance Date).

         c. Tangible Capital Funds. On the Compliance Date, Tangible Capital
Funds and Subordinated Debt (on a combined basis) was $                 (and is
required under the Agreement to be not less than $               at the
Compliance Date).

         d. Total Leverage Ratio. On the Compliance Date, Total Leverage was
1.70:1.00 (and is required under the Agreement to not exceed 1.70:1.00 at the
Compliance Date).

         e. Default. No Unmatured Default or Default existed on the Compliance
Date or exists as of the date of this Certificate.

         This Covenant Compliance Certificate is given with respect to the
Credit Agreement dated as of June 1, 2000, made between the Borrower and the
Bank ("Agreement"). Capitalized terms used but not defined herein have the
meanings given them under the Agreement. The Borrower represents and warrants
that the information provided herein is true, complete and correct.

Dated on
         ---------------------------

                                          INTERFACE SYSTEMS, INC.

                                          By:
                                              ----------------------------------

                                                   Its
                                                       -------------------------

                                      -26-
<PAGE>   27

                                    EXHIBIT D

ENVIRONMENTAL CERTIFICATE

In consideration of and in order to induce BANK ONE, MICHIGAN ("Bank") to loan
money, extend credit, or enter into certain other transactions from time to time
to or with INTERFACE SYSTEMS, INC., a Michigan corporation ("Borrower"),
Borrower makes the representations, warranties and covenants set forth in this
Environmental Certificate (the "Certificate") to Bank with respect to all
property and activities of Borrower.

1.  DEFINITIONS.

     A. "Environmental Law(s)" means any law, regulation, rule, policy,
     ordinance or similar requirement which governs or protects the environment,
     including those governing the use, storage, treatment, transportation,
     manufacture, refinement, handling, production or disposal of Hazardous
     Materials enacted from time to time by the United States, any foreign
     government, any state, or any county, city or agency or subdivision of the
     United States or foreign country or its political subdivisions.

     B. "Hazardous Materials" means any material or substance: (1) which is or
     becomes defined as a hazardous substance, pollutant, or contaminant,
     pursuant to the Comprehensive Environmental Response Compensation and
     Liability Act ("CERCLA") (42 USC ss.9601 et. seq.) as amended and
     regulations promulgated under it; (2) containing gasoline, oil, diesel fuel
     or other petroleum products; (3) which is or becomes defined as hazardous
     waste pursuant to the Resource Conservation and Recovery Act ("RCRA") (42
     USC ss.6901 et. seq.) as amended and regulations promulgated under it; (4)
     containing polychlorinated biphenyls (PCBs); (5) containing asbestos; (6)
     which is radioactive; (7) the presence of which requires investigation or
     remediation under any Environmental Law; (8) which is or becomes defined or
     identified as a hazardous waste, hazardous substance, hazardous or toxic
     chemical, pollutant, contaminant, or biologically Hazardous Material under
     any Environmental Law.

     C. "Indebtedness" means all loans made or credit extended to Borrower by
     Bank at any time including without limit all credit extended under the
     Credit Agreement of even date made between Borrower and Bank.

     D. "Property" means all tangible property now or hereafter owned, operated,
     leased or used by Borrower, including but not limited to, land (including
     soil, groundwater and surface water located on, in or under the Property)
     and buildings located at 5855 Interface Drive, Ann Arbor, Michigan, and all
     equipment and inventory at any time located thereon.

2.  BORROWER'S REPRESENTATIONS AND WARRANTIES.

Except as set forth on the attached SCHEDULE A, Borrower represents and warrants
to Bank as follows:

     A. REGULATORY COMPLIANCE; ENFORCEMENT; LITIGATION. (1) It is in substantial
     compliance with all Environmental Laws; (2) it has never received any
     notice of any violations of any Environmental Law; (3) no demand, claim,
     suit, administrative action, or criminal action whether brought by any
     government authority or private party, arising under or relating to any
     Environmental Law is pending or threatened against the Borrower, or with
     respect to

                                      -27-

<PAGE>   28

     the Property; and (4) it has not used Hazardous Materials on or
     about the Property in any manner which violates any Environmental Law
     governing the use, storage, treatment, transportation, manufacture,
     refinement, handling, production or disposal of Hazardous Materials and no
     prior owner of the Property or any existing or prior tenant or occupant has
     used Hazardous Materials on or about the Property in any manner which
     violates any Environmental Law.

     B. PERMITS AND LICENSES. All federal, state and local permits, licenses or
     authorizations required by Environmental Law(s) for present use of the
     Property or activities of the Borrower have been obtained, are presently in
     effect and are listed on the attached SCHEDULE A. All federal, state and
     local permits, licenses or authorizations required by Environmental Law(s)
     for any permitted or licensed activities or uses that are anticipated at
     the Property and for which permits/licenses have been sought but not yet
     received are also listed on the attached SCHEDULE A. There is and has been
     substantial compliance with all such permits, licenses or authorizations.

     C. CONTAMINATION/RELEASE. There has not been in the past, nor are there
     currently, any releases, spills, discharges nor other form of contamination
     on the Property the aggregate cost of which to remediate exceeded or will
     exceed $100,000.00, nor is there any accumulation, storage or disposal as
     defined in RCRA, of Hazardous Materials on, under or about the Property
     which violates any Environmental Law. The Property appears neither on the
     National Priorities List (as defined under CERCLA) nor on any state listing
     which identifies sites for remedial clean-up or investigatory actions.
     There are no environmental liens on the Property.

     D. FACILITIES AND PROGRAMS. The Property has adequate water supply, sewage
     and waste disposal facilities or will have such facilities upon completion
     of contemplated improvements. The appropriate operations and maintenance
     programs, contingency and emergency plans for environmental hazards to
     assure compliance with Environmental Laws are in place.

     E. The answers set forth in the CUSTOMER  ENVIRONMENTAL  QUESTIONNAIRE (if
     required to be completed) as provided to Bank are incorporated by reference
     and such responses are accurate and complete.

3.   AFFIRMATIVE COVENANTS.  Borrower shall:

     A. Do all things necessary to assure that the representations, warranties
     and covenants set forth in this certificate are met and continue to be
     accurate and correct.

     B. Assure that all individuals or entities acting on its behalf comply
     with the obligations under this Certificate.

     C. Conduct periodic reviews of the use of the Property and the activities
     on it to assure compliance with the obligations under this Certificate.

     D. Promptly (i) notify Bank in writing of any occurrence, development or
     claim, suit, administrative action, permit revocation or denial filed by or
     against the Borrower or any owner of the Property that would cause any
     representation, warranty or covenant set forth in this Certificate to be
     incorrect, and (ii) take steps necessary to mitigate the effect of such
     occurrence, development or claim, suit or administrative action.

                                      -28-

<PAGE>   29

     E. Promptly provide Bank with all written information, questionnaires,
     copies of: environmental compliance reports, policies, handbooks,
     litigation audit letters, government inspection reports and environmental
     assessment reports, whenever prepared, that are requested by Bank in
     accordance with Bank's environmental due diligence procedures.

     F. Keep or cause the Property to be kept free of Hazardous Materials except
     to the extent that such Hazardous Materials are stored and/or used in
     compliance with all applicable Environmental Laws; and, without limiting
     the foregoing, will not cause or permit the Property to be used to
     generate, manufacture, refine, transport, treat, store, handle, dispose of,
     transfer, produce, or process Hazardous Materials, except in compliance
     with all applicable Environmental Laws; and will not cause or permit, as a
     result of any intentional or unintentional act or omission on the part of
     Borrower or any owner of the Property or any tenant, subtenant or occupant,
     a release, spill, leak or emission of Hazardous Materials on, under or
     about the Property or onto any other contiguous property in violation of
     Environmental Laws.

     G. Conduct and complete all investigations, environmental site assessments,
     sampling, and testing, and all remedial and removal actions necessary to
     clean up and remove all Hazardous Materials on, under, or about the
     Property as required by all applicable Environmental Laws and in accordance
     with the orders and directives of all federal, state and local governmental
     authorities. Such testing, remedial and removal actions shall include those
     required by federal and state regulations governing underground storage
     tank systems.

     Borrower shall demonstrate its compliance with this requirement to the
     satisfaction of Bank. To the extent that written documentation such as
     reports, studies, or sampling results from the investigation(s) has been or
     is produced, Borrower shall provide copies of such documentation to Bank.
     Borrower shall demonstrate to Bank to its satisfaction that the value of
     any Property pledged or mortgaged to Bank is not materially adversely
     affected by releases, spills or discharges occurring subsequent to the
     initial extension of credit. If Borrower fails to conduct an environmental
     assessment to the satisfaction of Bank as required under Section 3.G., or
     fails to provide Bank with copies of the written documentation referenced
     above, then Bank may at its option and at the expense of Borrower conduct
     such assessment, without waiver of its other rights and remedies. Any such
     assessment conducted by Bank shall be conducted solely for the benefit of
     and to protect the interests of Bank and shall not be relied upon by
     Borrower or any owner of the Property or any third party for any purpose
     whatsoever without the Bank's written consent, including but not limited to
     Borrower's or any third party's obligation, if any, to conduct an
     independent environmental investigation. By conducting any such assessment,
     Bank does not assume any control over the environmental affairs or
     operations of Borrower nor assume any obligation or liability to Borrower
     or any third party.

4.   NEGATIVE COVENANT. Borrower shall not take any action or allow the Property
to be used in such a manner that any representation, warranty or covenant set
forth in this Certificate becomes inaccurate, incorrect or results in
noncompliance with Environmental Laws or this Certificate.

5.   DEFAULT AND REMEDIES. The Borrower makes any materially incorrect or
misleading representation, warranty or certification to Bank or provides
materially incorrect information to Bank in connection with this Certificate or
if the Borrower defaults under the terms of this Certificate, then, except to
the extent this provision is expressly modified under the documents

                                      -29-

<PAGE>   30

     governing the Indebtedness, whether or not Bank has made demand, the
     underlying credit facilities shall terminate and all borrowings under them
     shall become due immediately at Bank's option upon thirty (30) days notice
     by Bank to the Borrower.

     6. RIGHT OF ENTRY. Borrower grants Bank, its employees, agents and
     contractors the right to enter the Property for the purpose of conducting
     at the expense of Borrower, an environmental site assessment, sampling and
     testing and remedial, removal and other actions necessary to investigate or
     clean up and remove Hazardous Materials on, under or about the Property in
     accordance with Section 3.G. above, prior to or during any loan workout,
     liquidation of collateral, mortgage foreclosure, expiration of a redemption
     period, abandonment of the Property or any environmental litigation brought
     against Bank regarding the Property. Bank shall notify Borrower prior to
     its entry and shall use its best efforts to not disturb any ongoing
     operations on the Property. Borrower at the request of Bank shall execute
     any consultant contracts, waste manifests or notices necessary to
     effectuate the terms of this section. Any expenditures by Bank for
     activities performed by Bank in accordance with this section shall be
     considered an additional advance under the loan or extension of credit.

     7. INDEMNIFICATION. Subject to the limitations set forth below, Borrower
     shall defend, indemnify and hold harmless Bank, its successors and assigns,
     employees, agents, officers and directors, from and against any claims,
     demands, penalties, fines, liabilities, settlements, damages, costs or
     expenses, including, without limitation, attorney's and consultant's fees,
     investigation and laboratory fees, court costs and litigation expenses,
     known or unknown, contingent or otherwise, arising out of or in any way
     related to (a) the presence, disposal, release or threatened release of any
     Hazardous Materials on, over, under, from or affecting the Property or the
     soil, water, vegetation, buildings, personal property, persons or animals;
     (b) any personal injury (including wrongful death) or property damage (real
     or personal) arising out of or related to such Hazardous Materials on the
     Property; (c) any claim, demand, notice or lawsuit brought or threatened,
     settlement reached or government order relating to such Hazardous Materials
     with respect to the Property or regulated wetlands on the Property; and/or
     (d) any violation of laws, orders, regulations, requirements or demands of
     government authorities, which are based upon or in any way related to such
     Hazardous Materials used on the Property or regulated wetlands on the
     Property. The indemnity obligations under this paragraph are specifically
     limited as follows:

         (i) Borrower shall have no indemnity obligations with respect to
         Hazardous Materials that are first introduced, as evidenced by reliable
         documentation, to the Property or any part of the Property subsequent
         to the date that Borrower's interest in and possession of the Property
         or any part of the Property shall have ended or have been fully
         terminated by foreclosure of any mortgage held by Bank or acceptance by
         Bank of a deed in lieu of foreclosure or other collateral liquidation
         procedure; and

          (ii) Borrower shall have no indemnity obligation with respect to
          Hazardous Materials that are first introduced, as evidenced by
          reliable documentation, to the Property solely by Bank, its successors
          or assigns.

     Borrower agrees that in the event any mortgage held by Bank is foreclosed
     or Borrower or any owner of the Property tender a deed in lieu of
     foreclosure, Borrower shall deliver the Property to Bank free of any and
     all Hazardous Materials which are then required to be removed (whether over
     time or immediately) pursuant to applicable Environmental Laws affecting
     the Property.

     Notwithstanding the provisions of Section 8 below, the provisions of this
     Section 7 shall be in

                                      -30-

<PAGE>   31

     addition to any and all other obligations and liabilities Borrower may have
     to Bank under the Indebtedness, any loan document, and in common law, and
     shall survive (a) the loan closing (b) the repayment of all sums due for
     the Indebtedness, (c) the satisfaction of all of the other obligations of
     Borrower under any loan document, (d) the discharge of any mortgage held by
     Bank, and (e) the foreclosure of any mortgage held by Bank or acceptance of
     a deed in lieu of foreclosure. The indemnity provisions of this Section
     shall only apply to any demand or action commenced against (a) any owner or
     operator of the Property, or (b) Bank in which any interest of Bank is
     threatened or any claim, demand, notice or action is made or filed against
     Bank.

     8. MISCELLANEOUS. Except as otherwise specifically provided in this
     certificate, all of the representations, warranties and covenants set forth
     in the certificate shall be continuing and shall survive the execution of
     the certificate until all of the Indebtedness is fully paid to Bank and
     Borrower's obligations to Bank in connection with the Indebtedness are
     fully performed.

     This Environmental Certificate is executed on __________________, 2000.

                                      INTERFACE SYSTEMS, INC.

                                       By:

                                            Its:

                                      -31-

<PAGE>   32

                                   SCHEDULE A

                       SCHEDULE OF EXCEPTIONS AND PERMITS

A.       EXCEPTIONS:

B.       PERMITS IN EFFECT:

C.       PERMITS SOUGHT:

INITIALS:                  Bank ____________________      Borrower
____________________

                                                           ____________________

                                      -32-

<PAGE>   33

                                    EXHIBIT E

                               SECURITY AGREEMENT

         THIS SECURITY AGREEMENT ("Agreement") is made as of June 1, 2000, by
INTERFACE SYSTEMS, INC., a Michigan corporation, ("Debtor") in favor of BANK
ONE, MICHIGAN, a Michigan banking corporation, of 611 Woodward Avenue, Detroit,
Michigan 4826-3947 ("Bank").

         1. THE SECURED INDEBTEDNESS. For valuable consideration, Debtor makes
this Agreement to secure the payment of all present and future indebtedness,
liabilities and obligations of Debtor to Bank however created or arising,
whether under (a) the Credit Agreement contemporaneously made between Debtor and
Bank ("Credit Agreement") and each note made pursuant to it and all of their
respective extensions, renewals, modifications, substitutions or replacements,
(b) any note, credit agreement, equipment lease, security agreement, mortgage,
guaranty or other agreement or evidence of indebtedness contemporaneously made
by Debtor to Bank and all of their respective extensions, renewals,
modifications, substitutions or replacements, or (c) any other present or future
instrument or agreement between Debtor and Bank, or otherwise, and whether
direct, indirect, primary, secondary, fixed, contingent, joint or several, due
or to become due, and including, without limit, all present and future
indebtedness or obligations of third parties to Bank which is guaranteed by
Debtor, and the present or future indebtedness originally owing by Debtor to
third parties and assigned by third parties to Bank, and any and all renewals,
extensions, modifications, substitutions or replacements of any of them, and the
performance of the covenants and obligations due or to become due to Bank,
including, without limit, those due under this Agreement, and the repayment of
all sums expended by Bank in connection with performance of those covenants and
obligations (individually and collectively, the "Indebtedness")

         2. GRANT OF SECURITY INTEREST IN COLLATERAL. To secure payment and
performance of the Indebtedness, Debtor grants Bank a continuing security
interest in all of the following assets and property of Debtor, wherever located
and whether now owned or existing or hereafter arising or acquired:

         All accounts, accounts receivable, contract rights and obligations
         owing to Debtor for the sale or lease of goods or services, whether or
         not earned by performance ("Accounts"); all guaranties and letters of
         credit (and related drawings) given in support of any Accounts; all
         chattel paper; all leases of any property, whether real, personal or
         mixed, and all rents, revenues, and other payments for its use and/or
         occupancy; all claims and rights under any contracts; all insurance
         policies; all general intangibles; all instruments, checks, drafts, and
         notes, whether negotiable or non-negotiable; all refunds and claims for
         refunds of any taxes, impositions, fees, charges or assessments at any
         time paid by Debtor to any governmental entity;

         All licenses to use the property or rights of any other person; all
         copyrights, patents, trademarks, trade names, and literary rights and
         all royalties and claims for or under any license or agreement for the
         use thereof;

         All machinery, equipment, apparatus, tools, appliances, furniture,
         furnishings, fixtures, computers and peripheral equipment, mobile
         goods, and vehicles, and all additions, substitutions, replacements,
         accessories, and accessions thereto ("Equipment");

         All inventory, supplies, merchandise, goods, raw materials, work in
         process, finished goods, returned and repossessed goods, and other
         property held for sale or lease or to

                                      -33-

<PAGE>   34

        be furnished under a contract of service or used in the operation,
        maintenance or management of any facilities owned or occupied by Debtor
        ("Inventory"); all documents evidencing title to any goods, whether
        negotiable or non-negotiable;

together with all of their replacements, substitutions, accessions, and
additions, all of their proceeds and products, including, without limit,
insurance proceeds and proceeds of any insurance, indemnity, warranty, or
guaranty payable to Debtor, or arising out of any condemnation or other
governmental actions, and all cash, deposit accounts, accounts, chattel paper
and general intangibles arising from any sale, rent, lease, casualty loss or
other disposition, all documents of title covering any of them, and all books,
records, reports, and correspondence concerning them and devices and software
programs for maintaining the same (collectively, "Collateral").

         3. WARRANTIES AND REPRESENTATIONS. Debtor represents and warrants to
Bank as follows:

         3.1. Authority. This Agreement is the valid and binding obligation of
Debtor, enforceable in accordance with its terms. Debtor is duly organized and
validly existing and in good standing under the laws of the State of Michigan,
and the execution, delivery and performance of this Agreement has been duly
authorized by all necessary action of Debtor's governing body and will not
violate Debtor's governing instruments or other agreements.

         3.2. Name; Address; Location of Collateral. Debtor's name and mailing
address, chief executive office address, and the location of the Collateral and
all records concerning the Collateral are accurately set forth on the signature
page of this Agreement. Debtor has not conducted business in any other name.

         3.3. Title to Collateral. Debtor has good and marketable title to the
Collateral, free and clear of any liens, encumbrances or security interests
whatsoever, other than the security interest granted by this Agreement and
existing liens, encumbrances or security interests disclosed to and accepted by
Bank in writing. Bank's security interest in the Collateral has first priority,
and Debtor will keep the Collateral free of all other liens, encumbrances and
security interests. No tangible Collateral is in the possession or control of
any other person. Debtor will defend the Collateral against all claims and
demands of all persons at any time claiming any interest in the Collateral.
Debtor will mark its records and the Collateral to clearly indicate the security
interest of Bank.

         3.4. Nature of Collateral. All of the Collateral is held by Debtor
solely for business purposes, and none of the Collateral constitutes consumer
goods. No part of the Collateral consists of equipment used in farming
operations or farm products or accounts or general intangibles arising from or
relating to the sale of farm products by a farmer. The Collateral was acquired
in the ordinary course of business of Debtor. There are no setoffs,
counterclaims or defenses against the Collateral.

         3.5. Financing Statements. Except as disclosed to and accepted by Bank
in writing, no financing statement covering all or any part of the Collateral is
on file in any public office. Debtor will execute financing statement(s) in form
acceptable to Bank and will pay the cost of filing financing statement(s) in all
public offices wherever filing is deemed desirable by Bank. A carbon,
photographic or other reproduction of this Agreement shall be sufficient as a
financing statement under the Michigan Uniform Commercial Code ("UCC") and may
be filed by Bank in any filing office. This Agreement shall be terminated only
by the filing of a termination statement in accordance with the applicable
provisions of the UCC. Debtor will do all other things, execute all documents,
and pay all related costs necessary or requested by Bank to establish, verify or
continue the validity and priority of Bank's security interest.

                                      -34-

<PAGE>   35

        4. COVENANTS. Debtor covenants and agrees to and with Bank as follows:

        4.1. Payment of Taxes. Debtor shall pay when due and before any
interest, collection fees or penalties accrue, all taxes, expenses, assessments,
liens or other charges which may now or hereafter be levied or assessed against
the Collateral. Debtor shall furnish proof of payment upon request of Bank.

        4.2. Insurance.

             4.2.1. Debtor shall keep the tangible Collateral (including,
without limit, the Equipment and Inventory) insured for the benefit of Bank
against fire and other hazards and risks, including, without limit, vandalism
and malicious mischief, as Bank may reasonably require and shall provide public
liability and product liability insurance and any other insurance as Bank may
reasonably require from time to time. All insurance shall be in amounts and in
forms and with companies satisfactory to Bank. Debtor shall deliver to Bank the
policies evidencing the required insurance with premiums fully paid for one year
in advance, and with loss payee clauses making all losses payable to Bank.
Renewals of the required insurance (together with evidence of premium prepayment
for one (1) year in advance) shall be delivered to Bank at least thirty (30)
days before the expiration of any existing policies. All policies and renewals
shall provide that they may not be canceled or amended without giving Bank
thirty (30) days prior written notice of cancellation or amendment.

             4.2.2. In the event of loss or damage, the proceeds of all required
insurance shall be paid to Bank. No loss or damage shall itself reduce the
Indebtedness. Bank or any of its employees is each irrevocably appointed
attorney-in-fact for Debtor and is authorized to adjust and compromise each loss
without the consent of Debtor, to collect, receive and receipt for the insurance
proceeds in the name of Bank and Debtor and to endorse Debtor's name upon any
check in payment of the loss. The proceeds shall be applied first to reimburse
Bank's costs and expenses in collecting the proceeds (including, without limit,
court costs and reasonable attorneys' fees), and then to payment of the
Indebtedness or any portion of it, whether or not then due or payable and in
whatever order of maturity as Bank may elect. Bank, at its option may apply the
insurance proceeds, or any part of them, to the replacement, repair or
restoration of the Collateral, subject to a written agreement with Debtor
satisfactory to Bank providing for the terms under which the insurance proceeds
shall be released.

        4.3. Maintenance of Collateral. Debtor will maintain the Collateral in
good condition and repair, and will replace any damaged or obsolete Collateral.
Debtor shall not use, or suffer or permit the use of, the Collateral for any
unlawful purpose, and shall use, operate and control the Collateral in
compliance with all applicable law and regulation, including without limitation
those governing protection of the environment and the use and disposal of
hazardous substances, and shall not cause, permit or suffer the presence, use,
storage, disposal, or release on or in any place where the Collateral is located
any toxic or hazardous substance as defined in any federal or state law,
regulation or rule relating to health, safety or environmental protection.
Debtor will promptly inform Bank of any loss or diminution in value of the
Collateral. Debtor shall make or permit no modification, compromise or
substitution for the Collateral without the prior written consent of Bank,
provided that in the ordinary course of business Debtor may (1) grant any person
obligated on any of the Collateral any credits, refunds and adjustments to which
they may be lawfully entitled, and (2) repair and replace Equipment.

        4.4. Leased Facilities. If the Collateral is located at a facility
leased by Debtor, Debtor will obtain from the lessor a consent to the granting
of a security interest in the Collateral and a disclaimer of any interest of the
lessor in the Collateral. The consent and disclaimer shall be in form acceptable
to Bank. Debtor will pay all rents and perform other obligations for any leased
facilities.

                                      -35-

<PAGE>   36

              4.5. Redelivered Collateral. If Bank redelivers any of the
        Collateral in Bank's possession to Debtor or Debtor's designee for the
        purpose of (1) the ultimate sale or exchange thereof, (2) presentation,
        collection, renewal, or registration of transfer thereof, or (3)
        loading, unloading, storing, shipping, transshipping, manufacturing,
        processing or otherwise dealing therewith preliminary to sale or
        exchange, such redelivery shall be in trust for the benefit of Bank and
        shall not constitute a release of Bank's security interest therein or in
        the proceeds or products thereof unless Bank specifically so agrees in
        writing. If Debtor requests any such redelivery, Debtor will deliver
        with such request a duly executed financing statement in form and
        substance satisfactory to Bank. Any proceeds of Collateral coming into
        Debtor's possession as a result of any such redelivery shall be held in
        trust for Bank and forthwith delivered to Bank for application on the
        Indebtedness. Bank may (if, in its sole discretion, it elects to do so)
        deliver the Collateral or any part of the Collateral to Debtor, and such
        delivery by Bank shall discharge Bank from any and all liability or
        responsibility for such Collateral.

              4.6. Prohibition on Transfer or Modification. Debtor shall not
        transfer, sell, assign, lease or modify the Collateral or any interest
        therein, any part thereof, or any substantial portion of Debtor's other
        assets or property without the prior written consent of Bank, except for
        sales of Inventory and replacements of Equipment and supplies in the
        ordinary course of Debtor's business.

              4.7. Prohibition on Change of Name, Organization or Location.
        Debtor shall not conduct Debtor's business under any name other than as
        appears in this Agreement nor change or reorganize the type of Debtor's
        business entity, nor change the location of any of the Collateral
        without the prior written consent of Bank.

              4.8. Right of Setoff. Debtor grants Bank the right, exercisable at
        any time, whether or not Debtor is then in default, to set off or apply
        against the Indebtedness any account or deposit with Bank in which
        Debtor has an interest or against any other amounts which may be in the
        possession of Bank and to the credit of Debtor.

              4.9. Examination of Records and Collateral. Debtor shall keep full
        and accurate records of Debtor's business, including, without limit,
        records related to the Collateral, and such records shall be open to
        audit, inspection and duplication by Bank at all times. Upon reasonable
        advance notice to Debtor, Bank may enter upon any property owned by or
        in the possession of Debtor to examine and inspect the Collateral.
        Debtor shall promptly provide Bank with any information concerning the
        Collateral as Bank may reasonably request at any time.

              4.10. Further Actions. Promptly upon the request of Bank, Debtor
        shall execute, acknowledge and deliver any and all further documents,
        security agreements, financing statements and assurances, and do or
        cause to be done all further acts as Bank may reasonably require to
        confirm and protect the lien of this Agreement or otherwise to
        accomplish the purposes of this Agreement.

              5. RECEIVABLES. Debtor covenants and agrees as follows:

              5.1. Collection. Debtor shall continue to collect and enforce all
        present and future payments due to Debtor pursuant to the Accounts or
        any of the other Collateral (collectively, the "Receivables") until Bank
        notifies Debtor and the obligors under the Receivables of Bank's
        interest under this Agreement, after which time Debtor shall hold any
        proceeds collected with respect to the Receivables in trust for Bank and
        shall cooperate and assist in collection and enforcement of the
        Receivables. Debtor shall not commingle the proceeds and shall turn the
        proceeds over to Bank immediately upon receipt.

              5.2. Updates. Debtor shall, immediately upon request from Bank,
        provide Bank with an updated list of the Receivables, stating the
        current name and address of each obligor, the

                                      -36-

<PAGE>   37

        balance due, the amount of any setoffs, defenses, contras or
        counterclaims, whether Debtor's performance is complete, and any other
        comments reasonably required by Bank. Each update list shall be Debtor's
        warranty that (i) the Receivables are valid and enforceable and owing,
        subject only to reported offsets, (ii) if evidenced by a note, chattel
        paper, or other instrument or document, it has been endorsed and
        delivered to Bank, or (iii) Debtor does not know of any death,
        dissolution, liquidation, insolvency, bankruptcy, appointment of
        receiver, or similar action by or against any obligor of the
        Receivables.

              5.3. Notice to Obligors. Bank may notify obligors under the
        Receivables of the existence of this Agreement, and Bank may instruct
        the obligors under the Receivables to make future payments to Bank
        (whether before or after default by Debtor).

              5.4. Actions of Bank. Debtor agrees that Bank shall be entitled,
        in its own name (or in the name of Debtor or otherwise) but at the sole
        expense of Debtor, to collect, demand, receive, sue for or compromise
        any and all of the Receivables, to give good and sufficient releases, to
        endorse any checks, drafts or other orders for the payment of money
        payable to Debtor in payment of the Receivables and, in Bank's
        discretion, to file any claims or take any other action or proceeding
        which Bank deems advisable. Upon Bank's request, Debtor agrees to
        establish a United States Post Office Box in the name of Debtor but
        under the exclusive custody and control of Bank, to direct all obligors
        on any Receivables or other intangibles to make all payments due and to
        become due thereon to the United States Post Office Box or to make said
        payments directly to Bank, to direct the Postmaster of the United States
        Post Office to forward to Bank all mail addressed to Debtor or to hold
        all mail addressed to Debtor at the Post Office until an officer or
        employee of Bank shall request possession of same, to open and dispose
        of all mail, howsoever received by Bank, addressed to Debtor, and to
        endorse any item howsoever received by Bank, representing any payment on
        or other proceeds or products of the Collateral.

              5.5. No Duty. Debtor acknowledges and agrees that Bank shall not
        be required or obligated to make any, demand or to make any inquiry as
        to the nature or sufficiency of any payment received by Bank with
        respect to the Receivables or to present to file any claim or take any
        other action to collect or enforce the payment of any amounts with
        respect to the Receivables assigned to Bank.

              6. REIMBURSEMENT OF EXPENSES. Debtor shall reimburse Bank for all
        costs and expenses, including attorneys' fees, incurred by Bank in
        enforcing the rights of Bank under this Agreement. All costs and
        expenses shall be included in the Indebtedness and shall be immediately
        due and payable together with interest at the maximum legal rate. Such
        costs and expenses shall include, without limitation, costs or expenses
        incurred by Bank in any bankruptcy, reorganization, insolvency or other
        similar proceeding. Any reference in this Agreement to attorneys' fees
        shall mean fees, charges, costs and expenses of both in-house and
        outside counsel and paralegals, whether or not a suit or proceeding is
        instituted, and whether incurred at the trial court level, on appeal, in
        a bankruptcy, administrative or probate proceeding, in a workout, in
        consultation with counsel, or otherwise. All costs, expenses and fees of
        any nature for which Debtor is obligated to reimburse or indemnify Bank
        are part of the Indebtedness secured by this Agreement and are payable
        upon demand, unless expressly provided otherwise, with interest at the
        highest rate charged by Bank on any of the Indebtedness (but not to
        exceed the maximum rate permitted by law).

              7. RIGHTS AND OBLIGATIONS OF BANK. In the event that Debtor fails
        to pay taxes, maintain insurance, discharge liens or encumbrances on any
        Collateral, or perform any other obligation arising under this
        Agreement, Bank may pay or perform such obligation(s) for the account of
        Debtor and the same shall be added to the Indebtedness and shall be
        immediately due and payable together with interest at the highest rate
        charged by Bank on any of the

                                      -37-

<PAGE>   38

        Indebtedness (but not to exceed the maximum rate permitted by law). Bank
        shall not be liable for any loss to the Collateral nor shall such loss
        reduce the amount of the Indebtedness. Bank will use reasonable care in
        the custody and preservation of any Collateral in Bank's possession, but
        Bank has no duty to preserve rights against prior parties.

              8. INDEMNIFICATION. Debtor shall indemnify, defend and save Bank
        harmless from all claims, liabilities, obligations, damages, fines,
        costs, and expenses, including attorneys' fees, incurred by Bank and
        causes of action or other rights asserted against Bank and relating to
        this Agreement or Debtor's obligations hereunder and/or the Collateral,
        its ownership, use, collection, disposition or compliance with
        applicable law.

              9. EVENTS OF DEFAULT AND REMEDIES.

              9.1. Events of Default. Any of the following events shall, for
        purposes of this Agreement, constitute an "Event of Default":

                   9.1.1. Failure by Debtor to pay any amount owing on the
        Indebtedness when due, whether by maturity, acceleration or otherwise.

                   9.1.2. Any failure by Debtor or any guarantor of all or any
        part of the Indebtedness to comply with, or breach by Debtor, any
        guarantor or any subordinator of any of the terms, provisions,
        warranties or covenants of this Agreement or any other agreement or
        commitment between Debtor, any guarantor or any subordinator and Bank
        after the lapse of any period such agreement or commitment affords for
        remedy of the breach.

                   9.1.3. Any Default as defined in the Credit Agreement.

              9.2. Remedies. Upon the occurrence of any Event of Default, Bank
        shall have the right to do the following:

                   9.2.1. Declare all or part of the Indebtedness immediately
        due and payable.

                   9.2.2. Institute legal proceedings to foreclose the lien and
        security interest granted by this Agreement, to recover judgment for all
        of the Indebtedness then due and owing, and to collect it out of any of
        the Collateral or the proceeds of its sale.

                   9.2.3. Institute legal proceedings for the sale, under the
        judgment or decree of any court of competent jurisdiction, of any or all
        of the Collateral.

                   9.2.4. Take possession of the Collateral (and any other
        property then in or on the Collateral) and all related records, and/or
        render any of it unusable, with or without demand, and with or without
        process of law; sell and dispose of the Collateral at one or more public
        or private sales or other dispositions, at places and times and on terms
        and conditions as Lender may deem fit, in any amount or order and to
        distribute the proceeds according to this Agreement and applicable law.
        Any statutory requirement for notice shall be met if Bank shall send
        notice to Debtor at least ten (10) days prior to the date of sale,
        disposition or other applicable event. Debtor shall be liable for any
        deficiency remaining after disposition of the Collateral.

                   9.2.5. Notify all persons obligated under any of the
        Collateral to make all payments to Bank and demand, collect, sue for,
        receive, receipt for, settle and compromise, extend or postpone the time
        for payment of, forbear from enforcing, and otherwise do all things
        Debtor could do in connection therewith.

                   9.2.6. Exercise any one or more of the rights and remedies of
        a secured party under the UCC or at law or equity to enforce the payment
        of the Indebtedness.

              9.3. Remedies Generally.

                                      -38-

<PAGE>   39

                   9.3.1. At any sale pursuant to this Agreement, physical or
        constructive possession of the Collateral is not required and any
        purchaser may conclusively rely on the recitals in any evidence of
        conveyance and shall not have any obligation to see to the application
        of the purchase money. Any sale of any of the Collateral under this
        Agreement shall be a perpetual bar against Debtor with respect to that
        Collateral.

                   9.3.2. Debtor agrees, upon request of Bank, to assemble the
        Collateral and all related records and make it available to Bank at any
        place which is reasonably convenient for Bank. Debtor grants Bank
        permission to enter upon any premises owned or occupied by Debtor for
        the purpose of taking possession of the Collateral. Debtor agrees to
        notify all persons obligated under any of the Collateral to make all
        payments to Bank and Debtor waives any right to recover from Borrower
        (by subrogation, indemnity, or otherwise) any amount Debtor pays or Bank
        recovers under this Agreement.

                   9.3.3. All remedies provided for under this Agreement shall
        be available to the extent not prohibited by law. Each remedy shall be
        cumulative and additional to any other remedy of Bank at law, in equity
        or by statute. No delay or omission to exercise any right or power
        accruing upon any default or Event of Default shall impair any such
        right or power or shall be construed to be a waiver of, or acquiescence
        in, any such default or Event of Default.

              9.4. Application of Proceeds. Any proceeds received by Bank from
        the exercise of its remedies shall be applied as follows:

                   9.4.1. First, to pay all costs and expenses incidental to
        disposition of the Collateral, including, without limit, reasonable
        attorneys fees, any taxes, assessments, liens and encumbrances prior to
        the lien of this Agreement.

                   9.4.2. Second, to the payment of the Indebtedness in the
        following order: (i) Bank's expenses made to perform Debtor's
        obligations, (ii) late charges and interest accrued and unpaid, (iii)
        any prepayment premiums, (v) unpaid fees and other charges, and (v) the
        outstanding principal balance.

                   9.4.3. Third, any surplus remaining shall be paid to Debtor
        or to whomsoever may be lawfully entitled.

        10. MISCELLANEOUS.

              10.1. Governing Law. This Agreement shall be construed according
        to the laws of the State of Michigan.

              10.2. Successors and Assigns. Subject to the terms and conditions
        set forth in the Credit Agreement, Bank shall have the right to assign
        any of the Indebtedness and deliver all or any part of the Collateral.
        This Agreement shall be binding upon the successors and assigns of
        Debtor including, without limit, any debtor in possession or trustee in
        bankruptcy for Debtor, and the rights and privileges of Bank under this
        Agreement shall inure to the benefit of its successors and assigns. This
        shall not be deemed a consent by Bank to a conveyance by Debtor of all
        or any part of the Collateral or of any ownership interest in Debtor.

              10.3. Notices. Notice from one party to another relating to this
        Agreement, if required, shall be deemed effective if made in writing
        (including telecommunications) and delivered to the recipient's address,
        telex number or telecopier number set forth by any of the following
        means: hand delivery, registered or certified mail, postage prepaid,
        express mail or other overnight courier service or telecopy, telex or
        other wire transmission with request for assurance of receipt in a
        manner typical with respect to communications of that type. Notice made
        in accordance with these provisions shall be deemed delivered on receipt
        if delivered by hand or wire transmission, on the third business day
        after mailing if mailed by registered or certified

                                      -39-

<PAGE>   40

        mail, or on the next business day after mailing or deposit with the
        postal service or an overnight courier service if delivered by express
        mail or overnight courier. Debtor's telecopier number, if any, is set
        forth below and Bank's telecopier number is (734) 995-8000.

              10.4. Entire Agreement; Waivers; Amendments. This Agreement and
        any agreement to which it refers state all rights and obligations of the
        parties and supersede all other agreements (oral or written) with
        respect to the security interests granted by this Agreement. Any waiver
        by Bank of any default or Event of Default shall be in writing and shall
        be limited to the particular default waived and shall not be deemed to
        waive any other default. Any amendment of this Agreement shall be in
        writing and shall require the signature of Debtor and Bank.

              10.5. Partial Invalidity. The invalidity or unenforceability of
        any provision of this Agreement shall not affect the validity or
        enforceability of the remaining provisions of this Agreement.

              10.6. Inspections. Any inspection, audit, appraisal or examination
        by Bank or its agents of the Collateral or of information or documents
        pertaining to the Collateral is for the sole purpose of protecting
        Bank's interests under this Agreement and is not for the benefit or
        protection of Debtor or any third party.

              10.7. Automatic Reinstatement. Notwithstanding any prior
        revocation, termination, surrender or discharge of this Agreement, the
        effectiveness of this Agreement shall automatically continue or be
        reinstated, as the case may be, in the event that any payment received
        or credit given by Bank in respect of the Indebtedness is returned,
        disgorged or rescinded as a preference, impermissible setoff, fraudulent
        conveyance, diversion of trust funds, or otherwise under any applicable
        state or federal law, including, without limit, laws pertaining to
        bankruptcy or insolvency, in which case this Agreement shall be
        enforceable as if the returned, disgorged or rescinded payment or credit
        had not been received or given, whether or not Bank relied upon this
        payment or credit or changed its position as a consequence of it. In the
        event of continuation or reinstatement of this Agreement, Debtor agrees
        upon demand by Bank to execute and deliver to Bank those documents which
        Bank determines are appropriate to further evidence (in the public
        records or otherwise) this continuation or reinstatement, although the
        failure of Debtor to do so shall not affect in any way the reinstatement
        or continuation. If Debtor does not execute and deliver to Bank such
        documents upon demand, Bank and each officer of Bank is irrevocably
        appointed (which appointment is coupled with an interest) the true and
        lawful attorney of Debtor (with full power of substitution) to execute
        and deliver such documents in the name and on behalf of Debtor.

              10.8. WAIVER OF JURY TRIAL. DEBTOR AND BANK ACKNOWLEDGE THAT THE
        RIGHT TO TRIAL BY JURY IS A CONSTITUTIONAL ONE, BUT THAT IT MAY BE
        WAIVED. EACH PARTY, AFTER CONSULTING (OR HAVING HAD THE OPPORTUNITY TO
        CONSULT) WITH COUNSEL OF THEIR CHOICE, KNOWINGLY AND VOLUNTARILY, AND
        FOR THEIR MUTUAL BENEFIT, WAIVES ANY RIGHT TO TRIAL BY JURY IN THE EVENT
        OF LITIGATION REGARDING THE PERFORMANCE OR ENFORCEMENT OF, OR IN ANY WAY
        RELATED TO, THIS AGREEMENT OR THE INDEBTEDNESS.

              This Security Agreement is dated and effective on the date first
above written.

                                      -40-

<PAGE>   41

Debtor's Mailing Address and Chief Executive Office:   Debtor:

5855 Interface Drive
Ann Arbor, Michigan 48104                           INTERFACE SYSTEMS, INC.

Location of the Collateral and all
records:
                                                    By:

                                                         Its:

Debtor's Telecopier No.

Debtor's Tax Identification No. 38-1857379

                                      -41-

<PAGE>   42

                                    EXHIBIT F

                                [FORM OF WARRANT]

         THE WARRANT REPRESENTED BY THIS CERTIFICATE AND ANY SHARES THAT MAY BE
         ISSUED UPON THE EXERCISE OF THIS WARRANT HAVE NOT BEEN REGISTERED
         PURSUANT TO THE SECURITIES ACT OF 1933 OR ANY STATE SECURITIES LAW.
         NEITHER THIS SECURITY NOR ANY PORTION HEREOF OR INTEREST HEREIN MAY BE
         SOLD, ASSIGNED, PLEDGED OR OTHERWISE DISPOSED OF UNLESS THE SAME IS
         REGISTERED UNDER SAID ACT AND ANY APPLICABLE STATE SECURITIES LAW, OR
         UNLESS AN EXEMPTION FROM SUCH REGISTRATION IS AVAILABLE AND THE COMPANY
         SHALL HAVE RECEIVED, AT THE EXPENSE OF THE HOLDER HEREOF, EVIDENCE OF
         SUCH EXEMPTION REASONABLY SATISFACTORY TO THE COMPANY (WHICH MAY
         INCLUDE, AMONG OTHER THINGS, AN OPINION OF COUNSEL SATISFACTORY TO THE
         COMPANY).

                             INTERFACE SYSTEMS, INC.

                     WARRANT FOR COMMON STOCK, NO PAR VALUE

20,000 Shares                                       Dated: _______________, 2000

        1. Warrant Grant. FOR VALUE RECEIVED, INTERFACE SYSTEMS, INC. (the
"Company"), a Michigan corporation, hereby certifies that BANK ONE, MICHIGAN
(and any successor holder hereof, the "Purchaser") is entitled to purchase from
the Company up to 20,000 shares of the Company's common stock, no par value,
(the "Warrant Shares") at a price of $[EXERCISE PRICE] (the "Per Share Warrant
Price"). The Purchaser may exercise such right from and after the date hereof
until the date three (3) years after the date hereof (the "Termination Date").

        2. Exercise of Warrant. At any time prior to the Termination Date, the
Purchaser may exercise this Warrant, in whole or in part, by surrendering this
Warrant, together with a Notice of Exercise in the form attached hereto,
together with payment of an amount equal to the Per Share Warrant Price
multiplied by the number of Warrant Shares being purchased (the "Aggregate
Warrant Price"), which payment may be made in the manner prescribed by Section 3
hereof. Upon such surrender of this Warrant and payment of the Aggregate Warrant
Price, the Company will issue a certificate or certificates in the name of the
Purchaser for the number of Warrant Shares for which such exercise has been
made. In the event that the Purchaser shall exercise this Warrant only in part,
the Company shall also then re-issue this Warrant to the Purchaser for a number
of Warrant Shares equal to difference between the number of Warrant Shares noted
above and the number for which such exercise has been made.

        3. Payment of Aggregate Warrant Price. The Purchaser may pay the
Aggregate Warrant Price in the form of (a) immediately available funds, (b)
surrender to the Company of any promissory notes or other debt obligations
issued by the Company, with all the principal of, and accrued but unpaid
interest on, such notes and obligations so surrendered being credited against
the Aggregate Warrant Price through the date of surrender, (c) delivery to the
Company of other securities issued by the Company, with the value of such
securities, as determined in good faith by a disinterested majority of the Board
of Directors of the Company, being credited against the Aggregate Warrant Price,
or (d) any combination of the foregoing. In the event that the Purchaser shall
elect to pay all or any portion of the Aggregate Purchaser Price in the

                                      -42-

<PAGE>   43

        manner prescribed by the foregoing clause (c), such Purchaser shall, not
        less than thirty (30) days prior to exercise of this Warrant, request
        that the Board of Directors make a determination of the fair market
        value of the securities of the Company to be surrendered by the
        Purchaser and promptly provide such value to the Purchaser, and the
        Company shall cause such determination to be made.

              4. Reservation of Warrant Shares. The Company will at all times
        reserve and keep available, solely for issuance or delivery upon the
        exercise of this Warrant, the Warrant Shares receivable upon the
        exercise of this Warrant, free and clear of all restrictions on sale or
        transfer and free and clear of all preemptive rights.

              5. Fully Paid Stock; Taxes. The Company agrees that the Warrant
        Shares represented by each and every certificate delivered on the
        exercise of this Warrant and payment of the Aggregate Warrant Price
        shall, at the time of such delivery, be validly issued and outstanding,
        fully paid and non-assessable. The Company further covenants and agrees
        that it will pay, when due and payable, all federal and state stamp,
        original issue or similar taxes, if any, which are payable in respect of
        the issue of this Warrant and/or any Warrant Shares or certificates
        therefor, but excluding any federal, state or local taxes based on the
        income of the Purchaser.

              6. Adjustment of Per Share Warrant Price. If at any time after the
        date hereof the Company's outstanding common stock, no par value, (the
        "Shares") shall be subdivided into a greater number of shares or be
        combined into a smaller number of shares, the Per Share Warrant Price in
        effect as of the day first following the day upon which such subdivision
        or combination becomes effective shall be decreased or increased, as the
        case may be, to the Per Share Warrant Price determined by multiplying
        the Per Share Warrant Price then in effect by a fraction, the numerator
        of which shall be the number of Shares outstanding immediately before
        such subdivision or combination becomes effective and the denominator of
        which shall be the number of Shares outstanding immediately following
        such subdivision or combination. Upon each adjustment of the Per Share
        Warrant Price pursuant to this subsection, the Purchaser shall
        thereafter (until another such adjustment) be entitled to receive
        Warrant Shares based upon the so adjusted Per Share Warrant Price. For
        purposes of this Section, all calculations shall be made to the nearest
        one-hundredth of a cent or to the nearest one thousandth of a share, as
        the case may be. Notwithstanding anything contained in this Section to
        the contrary, no adjustment in the Per Share Warrant Price shall be
        required unless such adjustment would result in an increase or decrease
        of at least one (1%) percent of the Per Share Warrant Price.

              7. Reclassification, Merger, Sale or Dissolution. In the event of
        (a) any reclassification of Shares of the Company other than by a
        subdivision or combination of the outstanding Shares, (b) any
        consolidation or merger to which the Company is a party and for which
        approval of shareholders of the Company is required, (c) the sale or
        transfer of all or substantially all of the assets of the Company, or
        (d) the voluntary or involuntary dissolution, liquidation or winding up
        of the Company, the Company shall cause to be mailed to the Purchaser,
        at least ten (10) days prior to the applicable date hereinafter
        specified, a notice stating the date on which such reclassification,
        consolidation, merger, sale, transfer, dissolution, liquidation or
        winding up is expected to become effective, and the date as of which it
        is expected that holders of Shares (or the any capital stock into which
        Shares may then be converted) of record shall be entitled to exchange
        their shares for securities or other property deliverable upon such
        reclassification, consolidation, merger, sale, transfer, dissolution,
        liquidation or winding up.

              8. Merger or Consolidation. If while this Warrant is outstanding,
        the Company shall consolidate with or merge into another corporation, or
        another corporation shall merge into the Company in a merger in which
        Shares (or any capital stock into which Shares may then be converted)
        are converted into a right to receive cash, property or other
        securities, or the Company shall sell or transfer all or substantially
        all of the assets of the Company, the Company shall take such action so
        that the Purchaser will thereafter receive

                                      -43-

<PAGE>   44

        upon the exercise hereof the securities or property to which a holder of
        the number of Warrant Shares then deliverable upon the exercise of this
        Warrant would have been entitled to receive upon such consolidation,
        merger, sale or transfer if this Warrant had been exercised in full
        immediately prior to such transaction.

              9. Dividends. Upon any conversion of this Warrant at a time when
        there are dividends or distributions unpaid as to Warrant Shares and as
        to which the dividend date or other date fixed for payment has passed,
        then, (a) to the fullest extent permitted by law, such unpaid dividends
        or distributions shall be paid by the Company contemporaneously with the
        exercise of this Warrant as to the Warrant Shares issued upon such
        exercise, and (b) to the extent payment of such unpaid dividends or
        distributions is not legally permitted, then the Per Share Warrant Price
        shall be further adjusted by increasing the number of Warrant Shares
        issuable upon conversion of this Warrant to take into account the value
        of such unpaid dividends or other distributions in determining the
        amount of Warrant Shares to be issued upon exercise of this Warrant.

              10. Limited Transferability. Neither this Warrant nor the Warrant
        Shares have been registered under the Securities Act of 1933, as amended
        (the "Securities Act"), and may be transferred only pursuant to an
        effective registration thereunder or an exemption from the registration
        requirements of the Securities Act, and otherwise in compliance with
        applicable state securities laws. This Warrant may not be transferred if
        such transfer would require any registration or qualification under, or
        cause the loss of exemption from registration or qualification under,
        the Securities Act or any applicable state securities law with respect
        to the Warrant or the Warrant Shares. This Warrant and any Warrant
        Shares shall bear an appropriate legend with respect to such
        restrictions on transfer. This Warrant is transferable only upon the
        books which the Company shall cause to be maintained for such purpose.
        Any assignment or transfer may be made by surrendering this Warrant to
        the Company together with the attached assignment form properly executed
        by the assignor or transferor. Upon such surrender the Company will
        execute and deliver, in the case of an assignment or transfer in whole,
        a new Warrant in the name of the assignee or transferee or, in the case
        of an assignment or transfer in part, a new Warrant in the name of the
        assignee or transferee named in such instrument of assignment or
        transfer and a new Warrant in the name of the assignor or transferor
        covering the portion of this Warrant not assigned or transferred to the
        assignee or transferee. The Purchaser may not assign or transfer this
        Warrant without the prior written consent of the Company.

              11. Replacement of Warrant. Upon receipt of evidence satisfactory
        to the Company of the loss, theft, destruction or mutilation of this
        Warrant, and of indemnity in form and amount reasonably satisfactory to
        the Company, if lost, stolen or destroyed, and upon surrender and
        cancellation of this Warrant, if mutilated, and upon reimbursement of
        the Company's reasonable incidental expenses, the Company shall execute
        and deliver to the Purchaser a new Warrant of like date, tenor and
        denomination.

              12. Warrant Holder Not Shareholder. This Warrant does not confer
        upon the Purchaser any right to vote or to consent or to receive notice
        as a shareholder of the Company, as such, in respect of any matters
        whatsoever, or any other rights or liabilities as a shareholder, prior
        to the exercise hereof.

              13. Communication. No notice or other communication under this
        Warrant shall be effective unless, but any notice or other communication
        shall be effective and shall be deemed to have been given if, the same
        is in writing and is mailed by first-class mail, postage prepaid,
        addressed to the Company at its principal place of business, or such
        other address as the Company has designated in writing to the Purchaser,
        or to the Purchaser at the address shown on the Company's books as
        described above.

              14. Headings. The headings of this Warrant have been inserted as a
        matter of convenience, and shall not affect the construction hereof.

              15. Amendments. This Warrant may be amended only by written
        agreement of the Company and the Purchaser.

                                      -44-

<PAGE>   45

              16. No Limitation on Corporate Action. No provisions of this
        Warrant and no right granted hereunder shall in any way limit, affect or
        abridge the exercise by the Company of any of its corporate rights or
        powers to recapitalize, amend its Articles of Incorporation, reorganize,
        consolidate or merge with or into another corporation, or to transfer
        all or any part of its property or assets, or the exercise of any other
        of its corporate rights and powers.

              17. Applicable Law. This Warrant shall be governed by and
        construed in accordance with the laws of the State of Michigan
        applicable to agreements made and to be performed therein, without
        giving effect to principles of conflicts of law.

                                      INTERFACE SYSTEMS, INC.

                                      By

                                         Name:

                                         Title:

                                      -45-

<PAGE>   46

                               NOTICE OF EXERCISE

                     TO BE EXECUTED BY THE REGISTERED HOLDER
                            TO EXERCISE THIS WARRANT

                             INTERFACE SYSTEMS, INC.

         The undersigned hereby exercises the right to purchase _______ shares
of the common stock, no par value, covered by this Warrant according to the
conditions thereof, and herewith makes payment in full of $[EXERCISE PRICE] for
each such share.

                                     BANK ONE, MICHIGAN

                                     By

                                              Its

Dated:

                                      -46-

<PAGE>   47

                                   ASSIGNMENT

         FOR VALUE RECEIVED __________________________________hereby sells,
assigns and transfers unto _____________________________the foregoing Warrant
and all rights evidenced thereby, and does irrevocably constitute and appoint
_______________________, attorney, to transfer said Warrant on the books of
INTERFACE SYSTEMS, INC. hereby agrees to be bound by the terms of the Warrant as
defined therein.

                                   BANK ONE, MICHIGAN

                                   By

                                            Its

Dated:

                                      -47-

<PAGE>   48

                                    EXHIBIT G

                     [FORM OF REGISTRATION RIGHTS AGREEMENT]

                          REGISTRATION RIGHTS AGREEMENT

       This Registration Rights Agreement ("Agreement") dated June __, 2000
("Effective Date"), is made between INTERFACE SYSTEMS, INC., a Michigan
corporation ("Company") and BANK ONE, MICHIGAN, a Michigan banking corporation
("Holder").

                                    RECITALS

       D. On the Effective Date, Company has issued to Holder Company's Warrant
("Warrant") for the purchase of up to 20,000 shares of Company's common stock,
no par value ("Warrant Shares"). The Warrant is further consideration for
certain financial accommodations that Holder has agreed to provide Company.

       E. In order to induce Holder to accept the Warrant as such consideration,
Company is willing to grant these registration rights.

                                    AGREEMENT

       Accordingly, for valuable consideration, Company and Holder agree as
follows:

SECTION 1.        DEFINITIONS.  As used in this Agreement, the following terms
have the following meanings:

       "Commission" means the Securities and Exchange Commission, or any other
federal agency administering the Securities Act during the term of this
Agreement.

       "Common Stock" means the common stock, no par value, of Company.

       "Exchange Act" means the Securities Exchange Act of 1934, as amended, any
similar federal statute, and the rules and regulations of the Commission that
are in effect during the term of this Agreement.

       "Registration Request" means a written notice from Holder to Company
under Section 2 of this Agreement.

       "Securities Act" means the Securities Act of 1933, as amended, similar
federal statute, and the related rules and regulations of the Commission that
are in effect during the term of this Agreement.

       "Securities Laws" means the Securities Act, the Exchange Act, any State
securities law or any rule or regulation promulgated under the Securities Act,
the Exchange Act or any State securities law.

       "Underwritten Offering" means a firmly underwritten offering of Common
Stock to the public pursuant to an effective registration statement under the
Securities Act.

SECTION 2.        DEMAND REGISTRATION.

       2.1        REGISTRATION REQUESTS. At any time after the Effective Date
upon or after exercise of all or any of

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<PAGE>   49

the Warrant, Holder may deliver a Registration Request, requesting that Company
register under the Securities Act all or any portion of the Warrant Shares in
the manner specified in the Registration Request. In any Underwritten Offering
contemplated by this Section or Section 3, Holder may sell the Warrant Shares to
the underwriters.

       2.2        REGISTRATION OBLIGATION. Following receipt of a Registration
Request under this Section, Company shall register under the Securities Act for
public sale by the method of disposition specified by Holder, the number of
Warrant Shares specified in the Registration Request. Company shall be obligated
to register Warrant Shares pursuant to this Section on only one (1) occasion.
Company's obligation shall be satisfied only when a registration statement (with
the method of disposition reasonably agreed to by Holder) covering the Warrant
Shares specified in the Registration Request has become effective.

       2.3        ADDITIONAL COMPANY SHARES. Company may include in any
registration statement, for sale by the method of disposition specified by
Holder, shares of Common Stock to be sold by Company for its own account,
unless, in the opinion of the managing underwriter (if the method of disposition
is an Underwritten Offering) including Company shares would adversely affect the
marketing of the Warrant Shares to be sold.

SECTION 3.        PIGGYBACK REGISTRATIONS.

       3.1        NOTICE OF REGISTRATION. Company shall notify Holder, in
writing, at least fifteen (15) days prior to the filing of any registration
statement under the Securities Act (including but not limited to registration
statements relating to secondary offerings of Company's securities, but
excluding registration statements relating to employee benefit plans or with
respect to corporate reorganizations or other transactions under Rule 145 of the
Securities Act) and will afford Holder an opportunity to include in such
registration statement all or part of the Warrant Shares, regardless of whether
such registration is part of an Underwritten Offering. If Holder desires to
include in any such registration statement all or any part of the Warrant
Shares, Holder shall so notify Company within fifteen (15) days after receipt of
such notice from Company. Such notice shall state the intended method of
disposition of the Warrant Shares by Holder. If Holder decides not to include
all Warrant Shares in any registration statement thereafter filed by Company,
Holder shall nevertheless continue to have the right to include any Warrant
Shares in any subsequent registration statement or registration statements as
may be filed by Company with respect to offerings of its securities upon all the
terms and conditions set forth herein.

       3.2        CONDITIONS. Holder's right to have Warrant Shares included in
a registration upon exercising its rights in this Section 3 shall be conditioned
upon Holder's participation in the related Underwritten Offering and the
inclusion of Holder's Warrant Shares in such underwriting to the extent provided
herein. If Holder proposes to distribute Warrant Shares through an underwriting
pursuant to this Section 3, Holder shall enter into an underwriting agreement in
customary form with the underwriter or underwriters selected by Company for such
underwriting.

       3.3        CUTBACKS. If the managing underwriter for an Underwritten
Offering dictates that the number of shares to be underwritten must be limited
for marketing reasons and, as a result, the number of Warrant Shares to be
included is reduced, the number of shares that may be included in the
Underwritten Offering shall be allocated first to the Company and then among
Holder and any other selling shareholders participating in the Underwritten
Offering in proportion to their respective numbers of shares of Common Stock to
be included in the Underwritten Offering.

       3.4        WITHDRAWAL BY HOLDER. If Holder disapproves of the terms of
any Underwritten Offering, Holder may elect to withdraw by written notice to
Company and the underwriter delivered at least ten (10) business days prior to
the effective date of the registration statement. Any Warrant Shares excluded or

                                      -49-

<PAGE>   50

withdrawn from the Underwritten Offering shall be excluded and withdrawn from
the related registration.

SECTION 4.        EXPENSES OF REGISTRATION.

       4.1        COMPANY'S EXPENSES. Except as this Agreement specifically
provides, Company shall bear all expenses in complying with Sections 2 and 3,
including, without limitation, all registration and filing fees, printing
expenses, fees and disbursements of counsel for Company, "Blue Sky" fees and
expenses, and the expense of any special audits incident to or required by any
such registration (collectively, "Registration Expenses").

       4.2        HOLDER'S EXPENSES. If Holder exercises its rights under
Section 3, Holder shall bear all resulting underwriting discounts and selling
commissions in proportion to the number of Warrant Shares so registered as
compared to all Common Stock included in any such registration. Holder shall
also pay the fees and expenses of any counsel it may engage in connection with
any such registration.

SECTION 5.        OBLIGATIONS OF COMPANY.  Whenever required to effect the
registration  of any  Warrant  Shares, Company shall, as expeditiously as
reasonably possible:

       5.1        REGISTRATION STATEMENT. Prepare and file with the Commission a
registration statement with respect to the Warrant Shares and use all reasonable
efforts to cause such registration statement to become effective, and upon
Holder's request, keep such registration statement effective for up to one
hundred twenty (120) days (which period shall be tolled during suspension of the
effectiveness of any such registration statement by reason of its amendment) or,
if earlier, until Holder has completed the related distribution. Company shall
not be required to file, cause to become effective or maintain the effectiveness
of any registration statement that contemplates a distribution of securities on
a delayed or continuous basis pursuant to Rule 415 under the Securities Act.

       5.2        AMENDMENTS. Prepare and file with the Commission such
amendments and supplements to such registration statement and the prospectus
used in connection with such registration statement as may be necessary to
comply with the provisions of the Securities Act with respect to the disposition
of all securities covered by such registration statement for the period set
forth in subsection 5.1.

       5.3        COPIES. Furnish Holder such number of copies of a prospectus,
including a preliminary prospectus, in conformity with the requirements of the
Securities Act and such other documents as Holder may reasonably request in
order to facilitate the disposition of the Warrant Shares.

       5.4        STATE QUALIFICATIONS. Use commercially reasonable efforts to
register and qualify the securities covered by such registration statement under
State securities laws in such jurisdictions as Holder reasonably requests;
provided, however, that Company shall not be required in connection therewith or
as a condition thereto to qualify to do business or to file a general consent to
service of process in any such states or jurisdictions.

       5.5        EXCHANGE LISTINGS. If any of the Warrant Shares that are part
of a registration are to be qualified on any public stock exchange or Company's
shares are then listed on any public stock exchange, cause the Warrant Shares to
be included in such registration to be coincidentally qualified for listing on
such exchange.

       5.6        UNDERWRITING AGREEMENTS. Enter into and perform its
obligations under an underwriting agreement, in usual and customary form, with
the managing underwriter of such offering. Holder shall also enter into and
perform its obligations under any such agreement.

                                      -50-

<PAGE>   51

       5.7        NOTICE OF CHANGE OF FACTS. Notify Holder, at any time when a
prospectus relating to a registration statement is required to be delivered
under the Securities Act, of the happening of any event as a result of which the
prospectus included in such registration statement, as then in effect, includes
an untrue statement of a material fact or omits to state a material fact
required to be stated therein or necessary to make the statements therein not
misleading in the light of the circumstances then existing.

       5.8        PROFESSIONAL OPINIONS. In the case of an Underwritten
Offering, use commercially reasonable efforts to furnish Holder on the date the
Warrant Shares are delivered to the underwriters for sale (a) an opinion, dated
as of such date, of counsel representing Company for purposes of such
registration, in form and substance as is customarily given to underwriters in
an underwritten public offering, addressed to the underwriters, if any, and
Holder and (b) a letter, dated as of such date, from the independent certified
public accountants of Company, in form and substance as is customarily given by
independent certified public accountants to underwriters in an underwritten
public offering addressed to the underwriters and Holder.

SECTION 6.        TERMINATION OF REGISTRATION RIGHTS. All registration rights
granted under this Agreement shall terminate and be of no further force and
effect four (4) years after the Effective Date or, if earlier, whenever all the
Warrant Shares may be sold under Rule 144 during any ninety (90) day period.

SECTION 7.        DELAY OF REGISTRATION; REQUIRED INFORMATION.

       7.1        Holder shall not have any right to obtain or seek an
injunction restraining or otherwise delaying any registration as a result of any
controversy that might arise with respect to the interpretation or
implementation of this Agreement.

       7.2        Company's obligations under this Agreement shall be
conditioned upon Holder's furnishing to Company such information regarding
Holder, the Warrant Shares, and the intended method of disposition of the
Warrant Shares as shall be required to effect the registration of the Warrant
Shares.

SECTION 8.        INDEMNIFICATION.  In the event any Warrant Shares are included
in a registration statement filed  with the Commission pursuant to this
Agreement:

       8.1        INDEMNIFICATION BY COMPANY. To the extent permitted by law,
Company will indemnify and hold harmless Holder, its employees, officers and
directors, any underwriter (as defined in the Securities Act) for Holder and
each person, if any, who controls Holder or underwriter within the meaning of
the Securities Act or the Exchange Act, against any losses, claims, damages, or
liabilities (joint or several) to which they may become subject under any
Securities Laws or other federal or state law ("Losses"), insofar as such Losses
(or actions in respect thereof) arise out of or are based upon any of the
following statements, omissions or violations (each a "Violation") by Company:
(i) any untrue statement or alleged untrue statement of a material fact
contained in such registration statement, including any preliminary prospectus
or final prospectus contained therein or any amendments or supplements thereto,
(ii) the omission or alleged omission to state therein a material fact required
to be stated therein, or necessary to make the statements therein not
misleading, or (iii) any violation or alleged violation by Company of any
Securities Laws in connection with the offering covered by such registration
statement; and Company will pay as incurred to Holder, its employees, officer,
or director, underwriter or controlling person for any legal or other expenses
reasonably incurred by them in connection with investigating or defending any
such Losses or action; provided however, that the obligation of indemnity
contained in this Section 8.1(iii) shall not apply to amounts paid in settlement
of any such Losses or action if such settlement is effected without the consent
of Company, which consent shall not be unreasonably withheld; nor shall Company
be liable in any such case for any such Losses or action to the extent that it
arises out of, or is based upon, a Violation which occurs in reliance upon, and
in conformity with, written information furnished expressly for use in
connection with

                                      -51-

<PAGE>   52

such registration by Holder, its employees, officer, director, underwriter or
controlling person of Holder.

       8.2        INDEMNIFICATION BY HOLDER. To the extent permitted by law,
Holder will, if Warrant Shares are included in the securities as to which such
registration or qualification is being effected, indemnify and hold harmless
Company, each of its directors, its officers and each person, if any, who
controls Company within the meaning of the Securities Act or the Exchange Act
and any underwriter, against any Losses to which Company or any such director,
officer, controlling person or underwriter may become subject under any
Securities Laws, insofar as such Losses (or actions in respect thereto) arise
out of or are based upon any Violation, in each case to the extent (and only to
the extent) that such Violation occurs in reliance upon and in conformity with
written information furnished by Holder under an instrument duly executed by
Holder and stated to be specifically for use in connection with such
registration; and Holder will pay as incurred any legal or other expenses
reasonably incurred by Company or any such director, officer, controlling person
or underwriter in connection with investigating or defending any such Losses or
action if it is judicially determined that there was such a Violation; provided,
however, that the obligation of indemnity contained in this Section 8.2 shall
not apply to amounts paid in settlement of any such Losses or action if such
settlement is effected without the consent of Holder, which consent shall not be
unreasonably withheld; and provided further, that in no event shall any
indemnity under this Section 8.2 exceed the net proceeds from the offering
received by Holder.

       8.3        NOTICE OF CLAIM. Promptly after receipt by an indemnified
party under this Section 8.3 of notice of the commencement of any action
(including any governmental action), such indemnified party will, if a claim in
respect thereof is to be made against any indemnifying party under this Section
8.3, deliver to the indemnifying party a written notice of the commencement
thereof and the indemnifying party shall have the right to participate in, and,
to the extent the indemnifying party so desires, jointly with any other
indemnifying party similarly noticed, to assume the defense thereof with counsel
mutually satisfactory to the parties; provided, however, that an indemnified
party shall have the right to retain its own counsel, with the fees and expenses
to be paid by the indemnifying party, if representation of such indemnified
party by the counsel retained by the indemnifying party would be inappropriate
due to actual or potential differing interests between such indemnified party
and any other party represented by such counsel in such proceeding. The failure
to deliver written notice to the indemnifying party within a reasonable time of
the commencement of any such action, if materially prejudicial to its ability to
defend such action, shall relieve such indemnifying party of any liability to
the indemnified party under this Section 8.3, but the omission so to deliver
written notice to the indemnifying party will not relieve it of any liability
that it may have to any indemnified party otherwise than under this Section 8.3.

       8.4        CONTRIBUTION. If the indemnification provided for in this
Section 8.4 is held by a court of competent jurisdiction to be unavailable to an
indemnified party with respect to any Losses, the indemnifying party, in lieu of
indemnifying such indemnified party thereunder, shall to the extent permitted by
applicable law contribute to the amount paid or payable by such indemnified
party as a result of such Losses in such proportion as is appropriate to reflect
the relative fault of the indemnifying party on the one hand and of the
indemnified party on the other in connection with the Violation(s) that resulted
in such Losses, as well as any other relevant equitable considerations. The
relative fault of the indemnifying party and of the indemnified party shall be
determined by a court of law by reference to, among other things, whether the
untrue or alleged untrue statement of a material fact or the omission to state a
material fact relates to information supplied by the indemnifying party or by
the indemnified party and the parties' relative intent, knowledge, access to
information and opportunity to correct or prevent such statement or omission;
provided, however, that in no event shall any contribution by Holder hereunder
exceed the net proceeds from the offering received by Holder.

       8.5        SURVIVAL. The obligations of Company and the Holder under this
Section 8.5 shall survive completion of any offering of Registrable Securities
in a registration statement and the termination of this

                                      -52-

<PAGE>   53

Agreement. No indemnifying party, in the defense of any such claim or
litigation, shall, except with the consent of each indemnified party, consent to
entry of any judgment or enter into any settlement which does not include as an
unconditional term thereof the giving by the claimant or plaintiff to such
indemnified party of a release from all liability in respect to such claim or
litigation.

SECTION 9.        ASSIGNMENT OF REGISTRATION RIGHTS. Holder's rights to cause
Company to register Warrant Shares pursuant to this Agreement may be assigned by
Holder to any transferee or assignee of the Warrant; provided, however, that no
such assignment shall be effective unless Holder gives Company notice of the
name and address of such assignee, the effective date of such assignment, and
the number of Warrant Shares with respect to which such right is being assigned
and a writing executed by an authorized representative of such assignee pursuant
to which such assignee acknowledges the existence of and agrees to be subject to
and bound by the terms of this Agreement.

SECTION 10.       AGREEMENT TO FURNISH INFORMATION. Holder agrees to execute and
deliver such other agreements as may be reasonably requested by Company or an
underwriter which are consistent with this Agreement or which are necessary to
give it further effect. In addition, if requested by Company or an underwriter
in any Underwritten Offering, Holder shall provide, within ten (10) days of the
request, such information as may be required by Company or the underwriter in
connection with completion of any public offering of Company's securities
pursuant to a registration statement filed under the Securities Act. The
obligations described in this Section shall not apply to a registration relating
solely to employee benefit plans or registration relating solely to a Rule 144
transaction.

SECTION 11.       RULE 144 REPORTING. With a view to making available to Holder
the benefits of certain rules and regulations of the Commission which may permit
the sale of the Warrant Shares to the public without registration, Company
agrees to use commercially reasonable efforts to (a) make and keep public
information available, as those terms are understood and defined in Rule 144 or
any similar or analogous rule promulgated under the Securities Act, at all times
and (b) file with the Commission, in a timely manner, all reports and other
documents required of the Company under the Exchange Act. As long as Holder owns
the Warrant or any Warrant Shares, Company shall furnish Holder upon its request
(x) a written statement by Company as to its compliance with the reporting
requirements of Rule 144 and of the Exchange Act, (y) a copy of the most recent
annual or quarterly report of Company in the form required by the Exchange Act,
and (z) such other reports and documents as Holder may reasonably request in
availing itself of any rule or regulation of the Commission allowing Holder to
sell any such shares without registration.

SECTION 12.       MISCELLANEOUS.

       12.1       BINDING EFFECT. The covenants and agreements in this Agreement
shall bind and inure to the benefit of the respective successors and assigns of
Company and Holder.

       12.2       AMENDMENTS. This Agreement may be amended and its observance
may be waived only by a written agreement between Company and Holder.

       12.3       NOTICES. All notices and other communications required or
permitted hereunder shall be in writing and shall be deemed effectively given:
(a) upon personal delivery to the party to be notified, (b) when sent by
confirmed facsimile or electronic mail if sent during normal business hours of
the recipient, if not, then on the next business day, (c) five (5) days after
having been sent by United States first-class registered or certified mail,
return receipt requested, postage prepaid, or (d) one (1) day after deposit with
a nationally recognized overnight courier, special next day delivery, with
verification of receipt addressed to the address set forth below such party's
signature to this Agreement.

                                      -53-

<PAGE>   54

       12.4       GOVERNING LAW. This Agreement shall be governed by and
construed under the laws of the State of Michigan.

       12.5       COUNTERPARTS. This Agreement may be executed in two (2) or
more counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same agreement.

       12.6       SEVERABILITY. If any provision of this Agreement shall be held
to be illegal, invalid or unenforceable, the illegality, invalidity or
unenforceability shall attach only to that provision and shall not in any manner
affect or render illegal, invalid or unenforceable any other provision of this
Agreement, and this Agreement shall be carried out as if any illegal, invalid or
unenforceable provision were not in this Agreement.

       This Registration Rights Agreement is executed and delivered as of the
Effective Date.

COMPANY:                               HOLDER:

INTERFACE SYSTEMS, INC.                BANK ONE, MICHIGAN

By:                                    By:

     Its:                                    Its:

Address for notices:                   Address for notices:

5855 Interface Drive                   125 South Main
Ann Arbor, Michigan 48103              Ann Arbor, Michigan 48104

Phone:  (734) 769-5900                 Phone: (734) 995-8150
Fax:                                   Fax: (734) 995-8000

Attention:  Chief Financial Officer    Attention:  Satish B. Jasti

                                      -54-

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