EXHIBIT 4

                  DEBENTURE PURCHASE AGREEMENT W/ EXHIBITS




                       DATAMARINE INTERNATIONAL, INC.

               $2,000,000 Convertible Subordinated Debentures
                            due December __, 2000





                        DEBENTURE PURCHASE AGREEMENT



                          As of December ___, 1995

                       Datamarine International, Inc.

                        Debenture Purchase Agreement
                          As of December ___, 1995

                                  INDEX

<TABLE>
<CAPTION>
                                                                           Page

<S>                                                                        <C>
SECTION 1.   TERMS OF PURCHASE; PAYMENT TERMS                                1
      1.1    Sale and Purchase                                               1
      1.2    Terms of the Debentures                                         1 
      1.3    Closing                                                         3

SECTION 2.   REPRESENTATIONS AND WARRANTIES OF THE COMPANY, SEA AND 
             NARROWBAND                                                      3
      2.1    Organization, Existence and Authority                           3
      2.2    Authorization                                                   4
      2.3    Non-Contravention                                               4
      2.4    Capitalization                                                  4
      2.5    Subsidiaries; Investments                                       5
      2.6    SEC Reports and Financial Statements                            5
      2.7    Absence of Undisclosed Liabilities                              6
      2.8    Absence of Certain Developments                                 6
      2.9    Accounts Receivable                                             7
      2.10   Title to Properties                                             7
      2.11   Tax Matters                                                     7
      2.12   Contracts and Commitments                                       8
      2.13   Proprietary Rights; Employee Restrictions                       8
      2.14   Litigation and Compliance with Laws                             9
      2.15   Permits; FCC Approvals; Customer and Supplier Relations        10
      2.16   Employee Benefit Programs                                      12
      2.17   Labor Laws                                                     12
      2.18   Solvency                                                       13
      2.19   Environmental Matters                                          13
      2.20   Inventory                                                      14
      2.21   Product and Service Claims.                                    14
      2.22   Backlog.                                                       14
      2.23   Information Supplied to Lenders                                14
      2.24   Broker's Fee                                                   15

SECTION 3.   CLOSING CONDITIONS OF LENDERS                                  15
      3.1    Opinion of Company Counsel                                     15
      3.2    Authorization                                                  15
      3.3    Irrevocable Proxy                                              16
      3.4    Delivery of Documents                                          16
      3.5    Use of Proceeds                                                16
      3.6    No Violation or Injunction                                     16
      3.7    No Litigation                                                  16
      3.8    No Adverse Change                                              16
      3.9    All Proceedings Satisfactory                                   17

SECTION 4.   FINANCIAL COVENANTS                                            17
      4.1    Indebtedness                                                   17
      4.2    Liens                                                          18
      4.3    Distributions or Redemptions                                   19

SECTION 5.   OPERATING AND REPORTING COVENANTS                              19
      5.1    Financial Statements; Minutes                                  19
      5.2    Budget and Strategic Plan                                      20
      5.3    Conduct of Business                                            20
      5.4    Payment of Taxes, Compliance with Laws, Etc.                   20
      5.5    Adverse Changes                                                20
      5.6    Insurance                                                      20
      5.7    Maintenance of Properties                                      21
      5.8    Affiliated Transactions                                        21
      5.9    Management Compensation                                        21
      5.10   Board of Directors; Inspection                                 21
      5.11   Issuance of Capital Stock, Convertible Securities, Options, 
             Warrants or Rights                                             23
      5.12   Merger, Consolidation, Reorganization, Sale of Assets, 
             Acquisition                                                    23
      5.13   No Amendments to Charter Documents                             23
      5.14   Restrictions on Other Agreements                               24
      5.15   Stay, Extension and Usury Laws                                 24
      5.16   Right of Participation in Financings                           24
      5.17   [Intentionally Omitted]                                        25
      5.18   Dissolution of Data I.C., Inc.                                 25
      5.19   Transactions with Foreign Subsidiaries                         25

SECTION 6.   CONVERSION                                                     25

SECTION 7.   EVENTS OF DEFAULT; REMEDIES                                    26
      7.1    Events of Default                                              26
      7.2    Remedies on Default, Etc.                                      28

SECTION 8.   REPRESENTATIONS AND WARRANTIES OF THE LENDERS                  28
      8.1    Representation of Lenders                                      28

SECTION 9.   INTERCREDITOR MATTERS                                          29
      9.1    Subordination to Payment                                       29
      9.2    Bankruptcy or Liquidation                                      29
      9.3    Payment Default on Senior Debt                                 30
      9.4    Non-Payment Default on Senior Debt                             30
      9.5    Limitation on the Exercise of Certain Rights                   30
      9.6    Subrogation                                                    31
      9.7    Absolute Obligation                                            31
      9.8    Conversion                                                     31

SECTION 10.  INDEMNIFICATION                                                31

SECTION 11.  DEFINITIONS                                                    33

SECTION 12.  GENERAL                                                        36
      12.1   Amendments, Waivers and Consents                               36
      12.2   Survival of Covenants; Assignability of Rights                 37
      12.3   Governing Law; Jurisdiction; Venue                             37
      12.4   Section Headings                                               38
      12.5   Counterparts                                                   38
      12.6   Notices and Demands                                            38
      12.7   Severability                                                   39
      12.8   Expenses                                                       39
      12.9   Integration                                                    39
</TABLE>

EXHIBITS
Exhibit A   -   List of Lenders
Exhibit B   -   Form of Debenture
Exhibit C   -   Preferred Stock Terms
Exhibit D   -   Company Counsel Opinion
Exhibit E   -   Form of Irrevocable Proxy
Exhibit F   -   Form of SEA Management Agreement
Exhibit G   -   Form of SMR Operator Letter of Intent
Exhibit H   -   Form of Employee Invention and Non-Disclosure Agreement

SCHEDULES

Schedule 2.1(a)   -   Locations of Real Property and Employees
Schedule 2.1(b)   -   Locations of Real Property and Employees
Schedule 2.4      -   Capitalization of Company
Schedule 2.5      -   Subsidiaries; Investments
Schedule 2.6      -   Financial Statements
Schedule 2.7      -   Undisclosed Liabilities
Schedule 2.8      -   Absence of Certain Developments
Schedule 2.10     -   Title of Properties
Schedule 2.12     -   Contracts and Commitments
Schedule 2.13     -   Proprietary Rights
Schedule 2.14     -   Litigation and Compliance with Laws
Schedule 2.15(a)  -   Customer and Supplier Relations
Schedule 2.15(b)  -   FCC Licenses
Schedule 2.15(c)  -   Management Agreement
Schedule 2.16     -   Employee Benefit Programs
Schedule 2.17     -   Labor Laws
Schedule 2.21     -   Product and Service Claims
Schedule 2.22     -   Backlog
Schedule 4.1(b)   -   Indebtedness


                        DEBENTURE PURCHASE AGREEMENT


      AGREEMENT made as of the ____ day of December, 1995 by and among 
Datamarine International, Inc., a Massachusetts corporation (the 
"Company"), SEA Inc. of Delaware, a Delaware corporation ("SEA") and 
Narrowband Network Systems, Inc., a Washington corporation ("Narrowband") 
and the persons named in Exhibit A hereto (collectively the "Lenders," and 
each individually a "Lender").  Unless otherwise expressly stated herein 
or unless the context otherwise requires, all references to the Company 
shall include all Subsidiaries on a consolidated basis.

      WHEREAS, the Company, SEA and Narrowband have agreed to sell and the 
Lenders have agreed to purchase convertible debentures due December __, 
2000 of the Company, SEA and Narrowband in an aggregate principal amount 
of $2,000,000. 

      WHEREAS, the proceeds from the purchase and sale of such convertible 
debentures shall be used by the Company and its Subsidiaries for the 
production of FCC approved 220MHz radio equipment and for general working 
capital purposes.

      NOW, THEREFORE, for good and valuable consideration, the receipt and 
sufficiency of which are hereby acknowledged, the parties hereby agree as 
follows:


SECTION 1.  TERMS OF PURCHASE; PAYMENT TERMS

      1.1   Sale and Purchase.  Subject to the terms and conditions herein 
set forth, the Company, SEA and Narrowband shall issue and sell to each of 
the Lenders, and each Lender shall purchase from the Company, SEA and 
Narrowband, a convertible debenture due December __, 2000 in substantially 
the form attached hereto as Exhibit B (a "Debenture" and collectively, the 
"Debentures") in the principal amount set forth opposite the name of such 
Lender in Exhibit A hereto for a purchase price equal to 100% of the 
principal amount thereof (the "Purchase Price").  The Debentures, which 
will aggregate to $2,000,000 in principal amount, will be dated the date 
of issuance thereof, mature on December __, 2000 (the "Maturity Date"), 
bear interest and be payable as set forth in Section 1.2 hereof and be 
convertible as set forth in Section 6 hereof.

      1.2   Terms of the Debentures.

            (a)   Interest.  The Debentures shall bear interest on the 
unpaid principal amount thereof:  (i) from the date of issuance thereof 
through and until December 31, 1996 at the rate of ten (10%) per annum; 
(ii) from and after January 1, 1997 through and until December 31, 1997 at 
a rate of eleven percent (11%) per annum; (iii) from and after January 1, 
1998 through and until December 31, 1998 at a rate equal to twelve percent 
(12%) per annum; (iv) from and after January 1, 1999 through and until 
December 31, 1999 at a rate of fourteen percent (14%) per annum, and (v) 
from and after January 1, 2000 at a rate of fifteen percent (15%) per 
annum (the "Interest").  The Interest shall be computed on the basis of a 
365-day year and the actual number of days elapsed, and be payable on each 
March 31, June 30, September 30 and December 31 for the respective three-
month periods ending on each such date, commencing on March 31, 1997, and 
upon any other payment or conversion of any principal amount of the 
Debentures.

            (b)   Default Interest.  In the event that any amount payable 
in respect of the Debentures is not paid within fifteen (15) days of when 
due and payable (whether at stated maturity, by acceleration or 
otherwise), the Interest on that portion of such amount which has not been 
so paid shall, notwithstanding anything herein to the contrary and until 
that portion of such payment on the Debentures has been brought current, 
thereafter bear interest at a rate of twenty percent (20%) per annum.  

            (c)   Principal Payments.  Subject to prior conversion 
pursuant to the terms of this Agreement and prepayments authorized under 
Section 1.2(f), the Company shall pay the principal balance of the 
Debentures, without set-off, deduction or counterclaim, together in each 
case with all accrued interest thereon on December __, 2000.

            (d)   Conversion.  The Debentures shall be convertible at the 
option of a majority in interest of the Lenders into shares of Redeemable 
Convertible Participating Preferred Stock, $1.00 par value per share 
("Convertible Preferred Stock"), and Redeemable Preferred Stock, $1.00 par 
value per share ("Redeemable Preferred Stock"), of the Company, all in 
accordance with, on the terms and during the periods set forth in Section 
6 hereof.  No conversion of the Debentures shall be permitted except as 
provided in Section 6 hereof.

            (e)   Payments on the Debentures.  All payments of principal 
and interest on the Debentures shall be made by the Company in lawful 
money of the United States of America in immediately available funds not 
later than 12:00 p.m., Boston time, on the date such payment is due, or, 
if such date is not a Business Day, then on the next succeeding Business 
Day, at the address of the Lenders stated in Exhibit A hereto or, if not 
so stated, at such other addresses of which the Company shall have 
received written notice or, at the Company's or the Lender's election, by 
crediting the Lender's account at a bank designated by the Lender in 
writing to the Company.

            (f)   Prepayment.  Subject to the Lender's rights of 
conversion pursuant to the terms of Section 6 hereof, the outstanding 
principal amount of the Debentures may be prepaid, in whole but not in 
part, by the Company at any time upon sixty (60) days prior written 
notice.  The Debentures shall be subject to mandatory prepayment upon the 
consummation of: (i) the sale of all or substantially all of the assets of 
the Company or SEA; (ii) the sale or transfer of all or a majority of the 
outstanding common stock of the Company or SEA in any one transaction or 
series of related transactions; or (iii) the merger or consolidation of 
the Company or SEA with or into another corporation or entity (other than 
a wholly-owned subsidiary or in connection with an acquisition permitted 
under the terms of Section 5.12 hereof) (each of the foregoing, a 
"Liquidating Event").

      1.3   Closing.  A closing (the "Closing") of the sale and purchase 
of the Debentures shall take place at such location, date and time and in 
such manner as shall be mutually agreed upon by the Company and the 
Lenders (the "Closing Date").  At the Closing, the Company will deliver 
the Debentures being acquired by each Lender against payment of the full 
Purchase Price therefor by or on behalf of each Lender to the Company by 
certified or bank cashier's check or wire transfer of immediately 
available funds.


SECTION 2.  REPRESENTATIONS AND WARRANTIES OF THE COMPANY, SEA AND 
            NARROWBAND

      In order to induce the Lenders to enter into the Agreement, the 
Company, SEA and Narrowband hereby jointly and severally agrees with the 
Lenders and represents and warrants to the Lenders that, as of the date 
hereof:

      2.1   Organization, Existence and Authority.  

            (a)   The Company has been duly formed and is validly existing 
as a corporation in good standing under the laws of the Commonwealth of 
Massachusetts.  Except as set forth on Schedule 2.1(a), the Company does 
not own or lease any real property outside The Commonwealth of 
Massachusetts, and has no employees residing outside The Commonwealth of 
Massachusetts.  The Company has all requisite corporate power and 
authority, and all material and necessary authorization, approvals, 
orders, licenses, certificates and permits, to conduct its business as 
presently conducted and to enter into, execute, deliver and perform all of 
its duties and obligations under this Agreement and all related 
instruments and agreements executed in connection herewith.  A true and 
complete copy of the Company's Articles of Organization as amended to 
date, certified by The Commonwealth of Massachusetts, and of the Company's 
by-laws, as amended to date, certified by the Company's Secretary have 
previously been delivered to the Lenders, are complete and correct, and, 
with the exception of the amendment creating the Preferred Shares (as 
defined below), no amendments thereto are pending.  The Company is not in 
violation of any term of its charter or by-laws, or, in any material 
respect, of any term of any agreement, instrument, judgment, decree, 
order, statute, rule or government regulation applicable to the Company or 
to which the Company is a party, which would, in any individual instance, 
or in any series of related instances, have a material adverse effect on 
the Company.

         (b)   Each of SEA and Narrowband has been duly formed and is 
validly existing as a corporation in good standing under the laws of its 
state of incorporation.  Except as set forth on Schedule 2.1(b), neither 
SEA nor Narrowband owns or leases any real property outside its state of 
incorporation and has no employees residing outside its state of 
incorporation.  Each of SEA and Narrowband has all requisite corporate 
power and authority, and all material and necessary authorization, 
approvals, orders, licenses, certificates and permits, to conduct its 
business as presently conducted and to enter into, execute, deliver and 
perform all of its duties and obligations under this Agreement and all 
related instruments and agreements executed in connection herewith.  A 
true and complete copy of each Subsidiary's charter documents, except for 
those of Data I.C., Inc., have previously been delivered to the Lenders, 
are complete and correct, and no amendments thereto are pending.  Neither 
SEA nor Narrowband is in violation of any term of its charter or by-laws, 
or, in any material respect, of any term of any agreement, instrument, 
judgment, decree, order, statute, rule or government regulation applicable 
to it or to which it is a party, which would, in any individual instance, 
or in any series of related instances, have a material adverse effect on 
the Company on a consolidated basis.

      2.2   Authorization.  This Agreement and all documents and 
instruments executed by the Company, SEA and Narrowband pursuant hereto 
are valid and binding obligations of the Company, SEA and Narrowband, 
enforceable in accordance with their terms, except as the enforcement 
thereof may be limited by bankruptcy and other laws of general application 
relating to creditor's rights or general principles of equity.  The 
execution, delivery and performance of this Agreement and all documents 
and instruments contemplated hereby, the issuance of the Debentures and, 
if converted, the Convertible Preferred Stock and the Redeemable Preferred 
Stock (collectively, the "Preferred Shares") issuable upon such conversion 
and, if the Convertible Preferred Stock is converted into Common Stock, 
the Common Stock issuable upon such conversion (the "Conversion Shares"), 
have been duly authorized by all necessary corporate action of the 
Company.  No consent, approval or authorization of, or designation, 
declaration or filing with, any governmental authority is required to be 
obtained by the Company in connection with the execution and delivery of 
this Agreement or the issuance, delivery, payment, redemption or 
conversion of the Debentures in accordance with the terms of this 
Agreement or, if the Debentures are converted, the Preferred Shares, or, 
if the Convertible Preferred Stock is converted, the Conversion Shares, or 
the performance or consummation of any other transaction contemplated 
hereby or thereby.

      2.3   Non-Contravention.  The execution, delivery and performance by 
each of the Company, SEA and Narrowband of this Agreement and the other 
agreements executed pursuant hereto to which they are a party and the 
consummation of the transactions contemplated hereby does not and will 
not: (a) conflict with or result in any default under any material 
contract, obligation or commitment of the Company or any of the 
Subsidiaries or any charter provision, by-law or corporate restriction 
applicable to any of them; (b) result in the creation of any lien, charge 
or encumbrance of any nature upon any of the properties or assets of the 
Company or any of the Subsidiaries; or (c) violate any instrument, 
agreement, judgment, decree or order, or any statute, rule or regulation 
of any federal, state or local government or agency, applicable to the 
Company or any of the Subsidiaries or to which the Company or any of the 
Subsidiaries is a party.

      2.4   Capitalization.  The authorized capital stock of the Company 
consists of (a) 3,000,000 shares of common stock, $.01 par value per share 
(the "Common Stock"), of which 1,296,865 shares are, as of November 6, 
1995, duly and validly issued, outstanding, fully paid and non-assessable, 
and (b) 1,000,000 shares of preferred stock, $1.00 par value per share (i) 
of which 2,000 shares are, or as of the Closing Date will be, (upon the 
filing of the Amended Charter), designated as Convertible Preferred Stock, 
$1.00 par value per share and are duly and validly authorized and are 
reserved for issuance upon conversion of the Debentures, and (ii) of which 
2,000 shares are, or as of the Closing Date will be (upon the filing of 
the Amended Charter) designated as Redeemable Preferred Stock, $1.00 par 
value per share and are duly and validly authorized and are reserved for 
issuance upon conversion of the Debentures.  Except for the Debentures to 
be issued hereunder and outstanding options to purchase 178,838 shares of 
Common Stock which have been issued under the Company's 1991 Stock Option 
Plan and 1992 Stock Option Plan for Non-Employee Directors  (the "Option 
Plans"), there are no outstanding warrants, options, rights, commitments, 
pre-emptive rights or agreements of any kind for the issuance or sale of, 
or outstanding securities convertible into, any additional shares of 
capital stock of any class of the Company.  The Company has duly and 
validly authorized and reserved 2,000 shares of Convertible Preferred 
Stock and 2,000 shares of Redeemable Preferred Stock for issuance upon 
conversion of the Debentures and 163,967 Conversion Shares for issuance 
upon conversion of the Convertible Preferred Stock; and the shares of 
Convertible Preferred Stock, Redeemable Preferred Stock and Common Stock 
so issued will, upon such conversion, be validly issued, fully paid and 
non-assessable.  The relative rights, preferences, restrictions and other 
provisions relating to the Convertible Preferred Stock and Redeemable 
Preferred Stock are as set forth in Exhibit C attached hereto (the 
"Preferred Stock Terms").  Except as disclosed in Schedule 2.4 hereof or 
as set forth in the Company's charter documents, there are no restrictions 
on the transfer of the shares of capital stock of the Company other than 
those arising under federal and state securities laws or under this 
Agreement. There are no rights to have the Company's capital stock 
registered for sale to the public in connection with the laws of any 
jurisdiction, other than rights set forth in the Registration Rights 
Agreement. 

      2.5   Subsidiaries; Investments.  Except as disclosed in Schedule 
2.5, the Company does not own or have, nor has it previously owned or had, 
any direct or indirect interest in, control over or loan or advance to, 
any person, corporation, partnership, joint venture or other entity of any 
kind.  Schedule 2.5 accurately sets forth (i) the correct legal name of 
each Subsidiary owned, directly or indirectly, by the Company, (ii) the 
number of authorized, issued, and outstanding shares of capital stock of 
each such Subsidiary, (iii) the ownership of such shares of capital stock, 
and (iv) whether such shares are fully paid and nonassessable.  There are 
no outstanding warrants, options, rights, commitments, preemptive rights 
or agreements of any kind for the issuance or sale of, or outstanding 
securities convertible into, any additional shares of capital stock of any 
class of any Subsidiary.  The aggregate net worth of the Foreign 
Subsidiaries is not greater than $175,000.

      2.6   SEC Reports and Financial Statements.  The Company has 
previously furnished to the Lenders complete and correct copies, including 
exhibits of: (i) its Annual Report on Form 10-K for the fiscal year ended 
October 1, 1994; (ii) its Quarterly Reports on Form 10-Q for the three-
month period ended December 31, 1994, April 1, 1995 and July 1, 1995; 
(iii) its proxy statement relating to its February 7, 1995 meeting of 
shareholders; and (iv) all reports on forms other than 10-K or 10-Q filed 
by the Company with the Securities and Exchange Commission (the "SEC") or 
the NASDAQ since October 2, 1993.  The Company has heretofore made timely 
all filings, reports and registrations required under the Securities Act 
of 1993, as amended, and the rules and regulations thereunder (the 
"Securities Act") and the Securities Exchange Act of 1934, as amended, and 
the rules and regulations thereunder (the "Exchange Act") and all such 
filings conformed in all material respects to the requirements of the 
Securities Act and the Exchange Act, and did not at the time of filing 
contain an untrue statement of a material fact or omit to state a material 
fact necessary to make the statements therein not misleading.

      Except as set forth on Schedule 2.6, the audited financial 
statements and unaudited interim financial statements included in the 
reports or other filings referred to in this Section 2.6 were prepared in 
conformity with generally accepted accounting principles applied on a 
consistent basis (except as may be indicated therein or in the notes 
thereto and except that the notes to the unaudited interim financial 
statements have been condensed pursuant to the rules and regulations of 
the SEC) and fairly present the consolidated financial position of the 
Company as of the dates thereof and the results of operations and cash 
flows of the Company for the periods shown therein, subject, in the case 
of unaudited interim financial statements, to normal year-end audit 
adjustments which will not, in any event, be material.  Nothing has come 
to the attention of the senior management of the Company since such dates 
which would indicate that such financial statements were not true, 
accurate and complete in all material respects as of the dates thereof.  

      2.7   Absence of Undisclosed Liabilities.  Except as and to the 
extent disclosed in Schedule 2.7 or to the extent reflected or reserved 
against in the Base Balance Sheet included in Schedule 2.6, the Company 
does not have any material liability or liabilities arising out of any 
transaction or state of facts existing prior to the date hereof and 
required to be disclosed in a balance sheet prepared in accordance with 
general accepted accounting principals ("GAAP") and the Company has no 
other material contingent liability or liabilities arising out of any 
transaction or state of facts existing prior to the date hereof which are 
not specifically disclosed elsewhere in this Agreement or the Schedules 
hereto (other than contractual obligations to customers and vendors 
arising out of transactions entered into in the ordinary course of the 
Company's business).

      2.8   Absence of Certain Developments.  Except as disclosed on 
Schedule 2.8 or elsewhere in this Agreement (including the Schedules 
hereto), since the date of the Base Balance Sheet, there has been: (a) no 
material adverse change in the condition, financial or otherwise, of the 
Company, SEA, or the other Subsidiaries (on a consolidated basis with the 
Company and SEA) or in the assets, liabilities, properties or business of 
the Company, SEA, or the other Subsidiaries (on a consolidated basis with 
the Company and SEA); (b) no declaration, setting aside or payment of any 
dividend or other distribution with respect to, or any direct or indirect 
redemption or acquisition of, any capital stock in the Company or any 
Subsidiary; (c) no waiver of any valuable right of the Company or any 
Subsidiary or cancellation of any material debt or claim held by the 
Company or any Subsidiary; (d) no material loan by the Company or any 
Subsidiary to any officer, director, employee or shareholder of the 
Company or any Subsidiary, or any agreement or commitment therefor; (e) no 
increase, direct or indirect, in the compensation paid or payable to any 
officer, director, employee, agent or shareholder of the Company or any 
Subsidiary (other than salary increases in the ordinary course of business 
consistent with past practice); (f) no material loss, destruction or 
damage to any property of the Company or any Subsidiary, whether or not 
insured; (g) no labor trouble involving the Company or any Subsidiary and 
no material change in the senior management or other key personnel of the 
Company or any Subsidiary, or the terms and conditions of their 
employment; and (h) no acquisition or disposition of any assets (or any 
contract or arrangement therefor) nor any other material transaction by 
the Company or any Subsidiary otherwise than for fair value in the 
ordinary course of business.

      2.9   Accounts Receivable.  Except to the extent reserved against in 
the Base Balance Sheet or disclosed elsewhere in this Agreement (including 
the Schedules hereto), all of the accounts receivable of the Company 
represent bona fide completed sales made in the ordinary course of 
business, are valid and enforceable claims and are, to the best knowledge 
of the Company, subject to no set-off or counterclaim and collectible in 
the ordinary course. The Company has no accounts receivable from any 
person, firm or corporation which is affiliated with it or from any of its 
directors, officers, employees or, to its knowledge, shareholders.

      2.10  Title to Properties.  Except as disclosed in Schedule 2.10 or 
in the Base Balance Sheet, the Company and each Subsidiary has good and 
marketable title to all of its respective properties and assets, free and 
clear of any liens, restrictions or encumbrances which could materially 
and adversely affect the value of such properties or interfere with the 
Company's or such Subsidiary's use thereof.  All machinery and equipment 
included in such properties which is necessary to the business of the 
Company, SEA or Narrowband is in good condition and repair, reasonable 
wear and tear excepted, and none of the Company, SEA or Narrowband is in 
default under any material leases of real or personal property to which it 
is a party.  Neither the Company nor SEA is in violation, in any material 
respect, of any zoning, building or safety ordinance, regulation or 
requirement or other law or regulation applicable to the operation of its 
owned or leased properties, nor has it received any notice of violation 
with which it has not complied, which would, in any individual instance, 
or any series of related instances, have a material adverse effect on the 
Company or SEA, as applicable.

      2.11  Tax Matters.  The Company and each of the Subsidiaries have 
timely and properly filed or received timely and proper extensions for the 
filing of all Tax Returns required to be filed by them, and all such Tax 
Returns were correct and complete in all material respects.  The Company 
and each of the Subsidiaries has paid all Taxes owed by them (whether or 
not shown on any Tax Return), except Taxes which have not yet accrued or 
otherwise become due.  All Taxes and other assessments and levies which 
the Company and each of the Subsidiaries was or is required to withhold or 
collect from customers or employees have been withheld and collected and 
have been paid over or will be paid over when due to the proper 
governmental authorities.  Neither the Company nor any Subsidiary has ever 
received notice of any audit or of any proposed deficiencies from the 
Internal Revenue Service ("IRS") or any other taxing authority (other than 
routine audits undertaken in the ordinary course and which have been 
resolved on or prior to the date hereof without material adverse effect on 
the Company or any of the Subsidiaries or their respective financial 
condition).  There are in effect no waivers of applicable statutes of 
limitations with respect to any Taxes owed by the Company or any of the 
Subsidiaries for any year.  Neither the IRS nor any other taxing authority 
is now asserting or, to the best knowledge of the Company and each of the 
Subsidiaries, threatening to assert against the Company or any of the 
Subsidiaries any deficiency or claim for additional Taxes or interest 
thereon or penalties in connection therewith in respect of the income or 
sales of the Company.  None of the Company or any of the Subsidiaries is a 
party to any Tax allocation or sharing arrangement. 

      2.12  Contracts and Commitments.  Except as set forth in this 
Agreement (including the Schedules hereto), none of the Company, SEA or 
Narrowband is a party to any contract, obligation or commitment: (a) which 
involves a potential commitment or payment in excess of $50,000 or which 
is otherwise material and not entered into in the ordinary course of 
business; (b) with any of its officers or key employees or persons or 
organizations related to or affiliated with any such persons; (c) which 
relate to the purchase, redemption, transfer or voting of its capital 
stock; or (d) relating to the licensing, distribution, development, 
purchase, manufacturing, sale or servicing of telecommunications 
equipment; except in each case as are described in Schedule 2.12, and 
copies of all such agreements have been delivered or made available to the 
Lenders, (all such contracts and commitments described on Schedule 2.12 
are collectively referred to as the "Material Agreements").  Other than 
termination or expiration in the ordinary course of business, none of the 
Company, SEA or Narrowband knows of any basis for the termination, 
expiration or modification of any of the Material Agreements within one 
year from the date hereof nor has it received any notice thereof, which 
termination, expiration or modification would not be at the Company's, 
SEA's or Narrowband's option, as the case may be, and would have a 
material adverse effect on the Company.  Except as set forth on Schedule 
2.7, none of the Company, SEA or Narrowband is in default in any material 
respect under any Material Agreement, and to the best knowledge of the 
Company, SEA and Narrowband there is no state of facts which upon notice 
or lapse of time or both would constitute such a default.  

      2.13  Proprietary Rights; Employee Restrictions.  Set forth in 
Schedule 2.13 is a list and brief description of all patents, patent 
rights, patent applications, trademarks, trademark applications, service 
marks, service mark applications, trade names and copyrights, and all 
applications for such which are in the process of being prepared, owned by 
or registered in the name of the Company, SEA or Narrowband, or of which 
the Company, SEA or Narrowband is a licensor or licensee or in which the 
Company, SEA or Narrowband has any right, and in each case a brief 
description of the nature of such right.  Each of the Company, SEA and 
Narrowband owns or possesses adequate licenses or other rights to use its 
respective patents, patent applications, trademarks, trademark 
applications, service marks, service mark applications, trade names, 
copyrights, manufacturing processes, programming processes, formulae, 
trade secrets and know how (collectively "Intellectual Property") 
necessary to the conduct of its business as presently conducted and as 
proposed to be conducted.  None of the Company, SEA or Narrowband is aware 
of any infringement by any other person of any of their respective rights 
under any Intellectual Property.  No claim is pending or, to the best 
knowledge each of the Company, SEA or Narrowband, threatened against the 
Company, SEA or Narrowband, respectively, to the effect that any 
Intellectual Property owned or licensed by the Company, SEA or Narrowband, 
respectively, or which the Company, SEA or Narrowband, respectively, 
otherwise has the right to use, or the operation or products or services 
of the Company, SEA or Narrowband, respectively, infringe upon or conflict 
with the asserted rights of any other person under any Intellectual 
Property, and, to the knowledge of the Company, SEA and Narrowband there 
is no basis for any such claim (whether or not pending or threatened).  
None of the Company, SEA or Narrowband has received any notice from any 
other person asserting that any of the Intellectual Property owned or 
licensed by the Company, SEA or Narrowband, respectively, or which the 
Company, SEA or Narrowband, respectively, otherwise has the right to use, 
or the operation or products or services of the Company, SEA or 
Narrowband, respectively, (a) infringe upon or conflict with the asserted 
rights of such person under any Intellectual Property, or (b) is invalid 
or unenforceable by the Company, SEA or Narrowband, respectively.  Except 
as set forth on Schedule 2.13, each of the Company, SEA and Narrowband has 
taken commercially reasonable actions to ensure the confidentiality of all 
non-patented technical information developed by or belonging to the 
Company, SEA or Narrowband, respectively, that is material to its 
business.  Except as disclosed in Schedule 2.13, none of the Company, SEA, 
Narrowband or any other Subsidiary, nor, to the best of the Company's and 
SEA's knowledge, any of the Company's or SEA's employees, has any 
agreements or arrangements with former employers of any past or present 
employees relating to any Intellectual Property of such employers, which 
interfere or conflict with the performance of such employee's duties for 
the Company or SEA or results in such employers having any rights in, or 
claims on, the Company's or SEA's Intellectual Property. 

      2.14  Litigation and Compliance with Laws.

            (a)   Except as set forth in Schedule 2.14, there is no 
investigation, action, suit or proceeding at law or in equity or by or 
before any governmental instrumentality or other agency now pending or, to 
the best knowledge of the Company, threatened against the Company or key 
employee of the Company, which calls or has a possibility of calling into 
question the validity, or hindering the enforceability or performance, of 
this Agreement or any action taken or to be taken pursuant hereto or by 
any of the other agreements and transactions contemplated hereby; nor to 
the best knowledge of the Company, has there occurred any event or does 
there exist any condition on the basis of which any such litigation, 
proceeding or investigation should reasonably be anticipated to be 
instituted and have a material adverse effect on the Company or the 
business prospects of the Company.

            (b)   Except as to subject matter more specifically addressed 
elsewhere in this Agreement and except as set forth in Schedule 2.14, the 
Company is, and at all times during its existence has been, in material 
compliance with all laws and governmental rules and regulations, domestic 
or foreign and all export control or similar laws or regulations, except 
where non-compliance therewith, in any individual instance or any series 
of related instances, would not have a material adverse effect on the 
Company.  Except as set forth in Schedule 2.14, the Company is not in 
default in any material respect with respect to any judgment, order, writ, 
injunction, decree, demand or assessment, that the Company or its assets 
are subject to or by which the Company is bound and which has been issued 
by any court or any federal, state, municipal or other governmental or 
self-regulatory agency, organization, board, commission, bureau, 
instrumentality or department, domestic or foreign, relating to any aspect 
of the business, affairs, properties or assets of the Company.  Except as 
set forth in Schedule 2.14, the Company has not been charged or, to the 
best knowledge of the Company, threatened with, or under investigation 
with respect to, any material violation of material federal, foreign, 
state, municipal or other law or any administrative rule or regulation, 
domestic or foreign in any matter directly relating to or affecting the 
business, affairs, properties or assets of the Company.

      2.15  Permits; FCC Approvals; Customer and Supplier Relations.  

            (a)    Each of the Company, SEA and Narrowband, respectively, 
has all necessary franchises, permits, licenses, authorizations and other 
rights and privileges (including without limitation all FCC approvals) to 
own its property and to conduct its business as it is presently or 
proposed to be conducted, except for those the absence of which could not 
have a material adverse effect on the Company.  SEA's line of land mobile 
radio products for the 220MHz narrowband spectrum has all necessary or 
appropriate approvals and endorsements from the FCC and all other 
governmental agencies with jurisdiction over such products, and, to the 
Company's best knowledge, only Uniden, E.F. Johnson and Securicore have 
received similar approvals and endorsements. No prior FCC consent is 
required in connection with the execution, delivery and performance of 
this Agreement (including, without limitation, the conversion of the 
Debentures).  Each of the Company, SEA and Narrowband, respectively, 
believes that its major customers and its suppliers are good commercial 
working relationships, and, except as set forth on Schedule 2.15(a), no 
major customer has terminated such relationship and none of the Company, 
SEA or Narrowband has received any notice within the last two years from 
any major customers or suppliers of their intention to terminate, or 
otherwise modify such relationships in a manner which could have a 
material adverse effect on the Company.

            (b)   Schedule 2.15(b) correctly sets forth all approvals, 
permits and licenses required to be issued by the FCC in connection with 
SEA's line of mobile radio products for the 220MHz narrowband spectrum 
(collectively, the "Company FCC Licenses") which are held by the Company, 
SEA and/or Narrowband and correctly sets forth the issuer and termination 
date of each Company FCC License.

            (c)   Schedule 2.15(c) correctly sets forth each management 
agreement entered into by each of the Company, SEA and/or Narrowband 
relating to voice and data mobile radio systems operating on channel 220-
222MHz narrowband spectrum (collectively, the "Management Agreements") and 
each letter of intent of the Company, SEA and/or Narrowband relating to 
the management of a 220MHz system and the construction of such system by a 
third party (collectively, "SMR Operator Letters"), and correctly sets 
forth the identity of the party that entered into such Management 
Agreement with SEA or Narrowband, as the case may be, and that entered 
into such SMR Operator Letter with Narrowband, and the material economic 
terms thereof.  Each Management Agreement was executed in 1992, 1993 or 
1994 and has a term of ten years which term may be extended in accordance 
with the terms thereof.  Each Management Agreement entered into by either 
SEA or Narrowband is in substantially the form of Exhibit F hereto and 
each SMR Operator Letter entered into by Narrowband is in the form of 
Exhibit G hereto.  None of the Company, SEA or Narrowband is in default in 
any material respect under any Management Agreement or SMR Operator 
Letter, and to the best knowledge of the Company, SEA and Narrowband, 
there is no state of facts which upon notice or lapse of time or both 
would constitute such a default.

            (d)   To the best knowledge of each of the Company, SEA and 
Narrowband, each Company FCC License and each FCC license referred to in 
the Management Agreements (collectively with the Company FCC Licenses, the 
"FCC Licenses") was duly and validly issued by the issuer thereof pursuant 
to procedures which complied with all requirements of applicable law.  The 
Company, SEA and/or Narrowband, as the case may be,  is the licensee of 
the FCC Company Licenses, free and clear of all liens and encumbrances and 
is in compliance with the terms thereof in all material respects with no 
known conflict with the valid rights of others which could affect or 
impair materially in any manner the business, assets or condition, 
financial or otherwise, of the Company, SEA and/or Narrowband.  No event 
has occurred which permits, or after notice or lapse of time or both would 
permit, the revocation or termination of any FCC License or other right so 
as to adversely affect in any material respect the business or assets or 
condition, financial or otherwise, of the Company, SEA and/or Narrowband. 
To the extent necessary, the Company has timely filed all applications for 
renewal or extension of all FCC Licenses, and, except as otherwise 
indicated in Schedule 2.15(b), all such applications have been granted 
without conditions.  Except as indicated on Schedule 2.15(b), and except 
for actions or proceedings affecting its industry generally, no petition, 
action, investigation, notice of violation or apparent liability, notice 
of forfeiture, orders to show cause, complaint or proceeding is pending 
or, to the best knowledge of the Company, threatened before the FCC or any 
other forum or agency with respect to the Company, SEA or Narrowband or 
seeking to revoke, cancel, suspend or modify any of the FCC Licenses.  
None of the Company, SEA or Narrowband knows of any fact (other than facts 
relating to pending or future FCC rule changes which are applicable to the 
220MHz SMR industry generally) that is likely to result in the denial of 
an application for renewal, or the revocation, modification, nonrenewal or 
suspension of any of the FCC Licenses, or the issuance of a cease-and-
desist order, or the imposition of any administrative or judicial sanction 
with respect to any of the Company, SEA or Narrowband, which may 
materially adversely affect the rights under any of the FCC Licenses or 
which may have a materially adverse effect on any of the Company, SEA or 
Narrowband.  The Company, SEA and/or Narrowband, as applicable, is in 
compliance with the terms of the FCC Licenses and all applicable filing 
and operating requirements related thereto and all other applicable 
regulations and policies of the FCC and the Communications Act of 1934, 47 
U.S.C. [SECTION]151, et seq. (the "Communications Act") and any other 
governmental entity.

      2.16  Employee Benefit Programs.  Except as set forth on Schedule 
2.16 hereto, neither the Company nor SEA maintains and has not in the past 
maintained any Employee Program (as defined herein).  For purposes of this 
Section 2.16, "Employee Program" means (a) all employee benefit plans 
within the meaning of Section 3(3) of the Employee Retirement Income 
Security Act of 1974, as amended ("ERISA"), including, but not limited to, 
multiple employer welfare arrangements (within the meaning of ERISA 
Section 3(4)), plans to which more than one unaffiliated employer 
contributes and employee benefit plans (such as foreign or excess benefit 
plans) which are not subject to ERISA; and (b) all stock option plans, 
bonus or incentive award plans, severance pay policies or plans, deferred 
compensation plans, supplemental income arrangements, vacation plans, and 
all other employee benefit plans, agreements, and arrangements not 
described in (a) above.  An entity "maintains" an Employee Program if such 
entity sponsors, contributes to, or provides benefits under such Employee 
Program, or has any obligation (by agreement or under applicable law) to 
contribute to or provide benefits under such Employee Program, or if such 
Employee Program provides benefits to or otherwise covers employees of 
such entity (or their spouses, dependents, or beneficiaries).  Neither the 
Company nor SEA has maintained any employee benefit plan to which more 
than one employer contributes pursuant to one or more collective 
bargaining agreements.  Schedule 2.16 sets forth a list of every Pension 
Plan (as hereinafter defined) that has been maintained by the Company at 
any time during the twelve-month period ending on the Closing Date.  
Neither the Company nor SEA has incurred (a) any material accumulated 
funding deficiency within the meaning of ERISA, or (b) any material 
liability to the Pension Benefit Guaranty Corporation established under 
ERISA (or any successor thereto under ERISA) in connection with any 
Pension Plan established or maintained by it.  Neither the Company nor SEA 
has had any tax assessed against it by the IRS for any alleged violation 
under Section 4975 of the Internal Revenue Code.  Neither the Company nor 
SEA has any unfunded liability under a Pension Plan or a contingent 
liability for withdrawal from a multi-employer Pension Plan except as 
disclosed in the financial statements.  "Pension Plan" shall mean an 
employee benefit plan or other plan maintained for the employees of the 
Company as described in Section 4021(a) of ERISA.

      2.17  Labor Laws.  The Company and the Subsidiaries employ 
collectively approximately 100 individual employees.  Each employee of the 
Company and SEA has, in connection with his/her employment, entered into 
an invention and non-disclosure agreement in the form of Exhibit H hereto.  
Narrowband has no employees.  Neither the Company nor SEA is subject to 
any collective bargaining agreement or other labor agreement.  Neither the 
Company nor SEA is delinquent in payments to any of its employees for any 
wages, salaries, commissions, bonuses or other direct compensation for any 
services performed for it to the date hereof or amounts required to be 
reimbursed to such employees.  Except as set forth on Schedule 2.17, upon 
termination of the employment of any of said employees, neither the 
Company nor SEA will by reason of anything done prior to the Closing be 
liable to any of said employees for so-called "severance pay."  Each of 
the Company and SEA is in material compliance with all applicable laws and 
regulations respecting labor, employment, fair employment practices, terms 
and conditions of employment, and wages and hours.  There are no charges 
of employment discrimination or unfair labor practices or strikes, 
slowdowns, stoppages of work, or any other concerted interference with 
normal operations existing, pending or, to the best knowledge of the 
Company and SEA, threatened against or involving the Company, or SEA and 
no union has demanded or requested to represent or, to the best knowledge 
of the Company and SEA, is currently attempting to represent, any of the 
Company's or SEA's employees.

      2.18  Solvency.  None of the Company, SEA or Narrowband has: (a) 
made a general assignment for the benefit of creditors; (b) filed any 
voluntary petition in bankruptcy or suffered the filing of any involuntary 
petition by its creditors; (c) suffered the appointment of a receiver to 
take possession of all, or substantially all, of its assets; (d) suffered 
the attachment or other judicial seizure of all, or substantially all, of 
its assets; (e) admitted in writing its inability to pay its debts as they 
come due; or (f) made an offer of settlement, extension or composition to 
its creditors generally.  After giving effect to the transactions provided 
for or contemplated herein, to the best knowledge of each of the Company, 
SEA and Narrowband:  (a) it will be able to pay its debts as they come due 
in the usual course of business and will have adequate capital to conduct 
its business; and (b) its total assets will be greater than its total 
liabilities (total assets for this purpose being determined on the basis 
of the "fair saleable value" thereof).  For purposes of this Section 2.18, 
the "fair saleable value" of assets means the gross amount (without 
deduction for costs of sale, taxes or other payments) of money that might 
be expected to be realized, as of the valuation date, from an interested 
purchaser in a not theoretical market aware of all relevant information 
and a seller, equally informed, who is interested in disposing of the 
entire operation as a going-concern, neither party being under a 
compulsion to act.

      2.19  Environmental Matters.

            (a)   Except for individual instances or any series of related 
instances which would not have a material adverse effect on the assets, 
business or financial condition of the Company:  (i) to the best knowledge 
of the Company, the Company has never generated, transported, used, 
stored, treated, disposed of, or managed any Hazardous Waste (as defined 
in Section 2.19(b) below), nor has the Company contracted with any party 
for the generation, transportation, use, storage, treatment, disposal or 
management of any Hazardous Waste; (ii) to the best knowledge of the 
Company, the Company does not presently own, operate, lease, or use, nor 
has it previously owned, operated, leased, or used any site on which 
underground storage tanks are or were located or which contain or 
contained any asbestos or asbestos-containing material, any 
polychlorinated byphenyls ("PCBs") or equipment containing PCBs, or any 
urea formaldehyde foam insulation; (iii) to the best knowledge of the 
Company, the Company has never violated any Environmental Law (as defined 
in Section 2.19(b)(iii) below); and (iv) the Company, the operations of 
its businesses, and any real property owned, operated, leased, or used by 
the Company, and any facilities and operations of the Company thereon, to 
the best of the Company's knowledge, are presently in compliance in all 
material respects with all applicable Environmental Laws and any and all 
orders or directives of any governmental authorities having jurisdiction 
under such Environmental Laws, including, without limitation, any orders 
or directives with respect to any clean-up or remediation of any release 
or threat of release of any Hazardous Material.

            (b)   For purposes of this Section 2.19, (i) "Hazardous 
Material" shall mean and include any hazardous waste, hazardous material, 
hazardous substance, petroleum product, oil, asbestos, polychlorinated 
byphenyls, urea formaldehyde, toxic substance, pollutant, contaminant, or 
other substance which may pose a threat to the environment or to human 
health or safety, as defined or regulated under any Environmental Law; 
(ii) "Hazardous Waste" shall mean and include any hazardous waste as 
defined or regulated under any Environmental Law; (iii) "Environmental 
Law" shall mean any environmental or health and safety-related law, 
regulation, rule, ordinance, or by-law at the federal, state, or local 
level existing as of the date hereof or previously enforced; and (iv) the 
"Company" shall mean and include the Company and all other entities for 
whose conduct the Company is or may be held responsible under any 
Environmental Law including, but not limited to, lessees.

      2.20  Inventory.  The Company's and each Subsidiary's inventory is 
of a quality and quantity which is salable in the ordinary course of 
conduct of its business and the Company maintains adequate reserves 
against the cost basis of its inventory based on the Company's historical 
and projected performance.  None of the Company's or any Subsidiary's net 
inventory is obsolete or unsalable in a material amount.

      2.21  Product and Service Claims.  Except as set forth on Schedule 
2.21, other than warranty claims substantially consistent with the 
Company's past experience and which are not, in the aggregate, material to 
the Company, there are no pending or, to the best of the Company's 
knowledge, threatened product or service claims with respect to any 
products manufactured or services provided by the Company prior to the 
Closing Date nor are there any facts upon which a claim of such nature 
should reasonably be anticipated to be based.  Except for on-going price 
renegotiation with customers in the ordinary course of business, no claim 
has been made against the Company for renegotiation or price 
redetermination of any business transaction resulting from or relating to 
defective products or services, and, to the best of the Company's 
knowledge, there are no facts upon which any such claim should reasonably 
be anticipated to be based.

      2.22  Backlog.  As of September 30, 1995, the Company and the 
Subsidiaries had a backlog of firm orders for the sale of products as set 
forth in Schedule 2.22.  All of the Company's and each Subsidiary's 
backlog represents and will, as of the Closing Date, represent orders for 
products with specifications that can be met in accordance with the terms 
of such orders and in the ordinary course of conduct of its business 
without undue delay or extraordinary expense.

      2.23  Information Supplied to Lenders.  Neither this Agreement, nor 
the Schedules referenced herein, nor any certificate or statement 
furnished to the Lenders by or on behalf of the Company or any Subsidiary 
pursuant to the terms hereof, when taken together, contains any untrue 
statement of a material fact, and none of this Agreement, the Schedules or 
such other documents, omits to state a material fact necessary in order to 
make the statements contained therein not misleading, in light of the 
circumstances in which they were made.  To the best of the Company's, 
SEA's and Narrowband's knowledge, respectively, there is no material fact 
directly relating to its business, operations or condition (other than 
facts which relate to general economic conditions) that materially 
adversely affects the same that has not been set forth in this Agreement 
or in the Schedules hereto. 

      2.24  Broker's Fee.  The Company agrees to indemnify the Lenders 
against any claims against the Lenders for brokerage fees or commissions 
payable to any broker or finder retained by or on behalf of the Company or 
the Subsidiaries in connection with the financing contemplated by this 
Agreement and to pay all expenses incurred by the Lenders in connection 
with the defense of any action brought to collect any brokerage fees or 
commissions by any such broker or finder.


SECTION 3.  CLOSING CONDITIONS OF LENDERS

      The Lenders' obligation to purchase and pay for the Debentures shall 
be subject to compliance by the Company with the following conditions: 

      3.1   Opinion of Company Counsel.  The Lenders shall have received 
from Perkins Coie, counsel for the Company, SEA and Narrowband, their 
favorable opinion, dated the Closing Date, substantially in the form 
attached hereto as Exhibit D.

      3.2   Authorization.  

            (a)   Each of the Company, SEA and Narrowband shall have duly 
adopted resolutions in form reasonably satisfactory to the Lenders 
authorizing each of them to consummate the transactions contemplated 
hereby in accordance with the terms hereof, including, without limitation, 
the issuance of the Debentures, the issuance of the Preferred Shares upon 
conversion of the Debentures and, upon conversion of the Convertible 
Preferred Stock, the issuance of the Conversion Shares, and the Lenders 
shall have received duly executed certificate(s) of an authorized officer 
of each of the Company, SEA and Narrowband setting forth a copy of such 
resolutions and such other matters as may be requested by the Lenders.  

            (b)   The Company shall have amended its Articles of 
Organization to include the provisions set forth in Exhibit C (such 
Articles of Organization as so amended, the "Amended Charter") and except 
as so amended and restated, such Amended Charter shall not have been 
further amended or modified.

      3.3   Irrevocable Proxy.  Each of David C. Thompson, Peter D. Brown, 
and David M. Brown shall have executed and delivered to the Lenders an 
irrevocable proxy in substantially the form attached hereto as Exhibit E 
(the "Irrevocable Proxy").

      3.4   Delivery of Documents.  Concurrently with the Closing of the 
transactions contemplated hereby, the Company shall have executed and 
delivered to the Lenders (or shall have caused to be executed and 
delivered to the Lenders, by the appropriate Persons), the following:

            (a)   The Debentures;

            (b)   Certified copies of resolutions of the Company, SEA and 
Narrowband authorizing the execution and delivery of this Agreement and 
the Debentures;

            (c)   A copy of the Company's Amended Charter, certified as of 
a recent date by the Secretary of State of the Commonwealth of 
Massachusetts and a copy of the Company's by-laws certified by an officer 
of the Company, as amended; 

            (d)   The Registration Rights Agreement; and

            (e)   Such other supporting documents and certificates as the 
Lenders may reasonably request and as may be required pursuant to this 
Agreement.

      3.5   Use of Proceeds.  All proceeds from the sale of the Debentures 
by the Company to the Lenders may be used for the production of 220MHz 
radio equipment and general working capital purposes.

      3.6   No Violation or Injunction.  The consummation of the 
transactions contemplated by this Agreement shall not be in violation of 
any law or regulation applicable to the Company or the Subsidiaries, shall 
not be subject to any injunction, stay or restraining order and shall not 
require any filings, approvals or consents which shall not have previously 
been made or obtained.  Without limiting the generality of the foregoing, 
(a) the Company shall have timely and properly filed any required Report 
on Form 10-C and shall have publicly disclosed the consummation of the 
transactions contemplated hereby, and (b) the Lenders shall not be subject 
to any restrictions or limitations under Chapter 110F of the Massachusetts 
General Laws or any other similar statute.

      3.7   No Litigation.  No litigation, suit, action, claim or 
investigation shall be pending, or threatened, which might impair or 
prevent the performance of the Company, SEA and Narrowband hereunder or 
the transactions contemplated herein.

      3.8   No Adverse Change.  Between the date of the Base Balance Sheet 
and the Closing Date, there shall have been no material adverse change in 
the financial conditions, prospects, properties, assets, liabilities, 
business or operations of the Company, whether or not in the ordinary 
course of business.

      3.9   All Proceedings Satisfactory.  All corporate and other 
proceedings taken by each of the Company, SEA and Narrowband prior to or 
at the Closing in connection with the transactions contemplated by this 
Agreement, and all documents and instruments related thereto, shall be 
reasonably satisfactory in form and substance to the Lenders, and the 
Lenders shall receive such copies thereof and other materials (certified, 
if requested) as they may reasonably request in connection therewith.  The 
issuance and sale of the Debentures to the Lenders shall be made in 
conformity with all applicable state and federal securities laws.


SECTION 4.  FINANCIAL COVENANTS

      The Company (which term includes the Subsidiaries and shall be 
deemed to include, for purposes of this Section 4, any subsidiary or 
subsidiaries of the Company formed after the date of this Agreement) shall 
comply with the following covenants, from the date hereof and for so long 
as any of the Debentures remains outstanding.

      4.1   Indebtedness.  The Company will not directly or indirectly, 
incur, create, assume, become or be liable in any manner with respect to, 
or permit to exist, any Indebtedness or liability, except:

            (a)   Indebtedness under the Debentures and any other 
Indebtedness owed by the Company to the Lenders;

            (b)   Indebtedness as described in Schedule 4.1(b);

            (c)   Indebtedness with respect to trade obligations 
(including trade payables) and other normal accruals, including Taxes, 
assessments and other governmental charges, arising in the ordinary course 
of business and not yet due and payable, or which are being contested in 
good faith by appropriate proceedings, and then only to the extent the 
amount thereof has been set aside on the Company's books;

            (d)   Indebtedness incurred for purchase money obligations and 
Capital Leases, so long as: (i) the pertinent assets are acquired for use 
in the ordinary course of the Company's business; and (ii) either the 
Indebtedness secured thereby does not exceed the fair market value of such 
assets or the purchase price thereof if such assets are acquired directly 
from the manufacturer or an authorized dealer thereof; 

            (e)   Indebtedness owed to a commercial bank on commercially 
reasonable terms and conditions and approved by a majority of the 
directors of the Company's Board of Directors; and

            (f)   Indebtedness in respect of guarantees by the Company to 
a third party, to the extent that any such guarantee secures Indebtedness 
of the Company which is specifically permitted to be incurred or to remain 
outstanding under the provisions of this Section 4.1.

      4.2   Liens.  The Company will not, directly or indirectly, create, 
incur, assume or suffer to exist any Lien (as defined below) of any nature 
whatsoever on any of its assets (including any leasehold interests in 
property used by the Company) or ownership interests now or hereafter 
owned, other than:

            (a)   Liens securing the payment of taxes and other government 
charges, either not yet due or the validity of which is being contested in 
good faith by appropriate proceedings, and as to which the Company shall 
have set aside on its books adequate reserves to the extent required by 
generally accepted accounting principles and provided that, in any event, 
payment of any such tax, assessment, charge, levy or claim shall be made 
before any of the Company's property shall be seized and sold in 
satisfaction thereof;

            (b)   Liens securing Indebtedness permitted under Sections 
4.1(b) and 4.1(d) above;

            (c)   Deposits under worker's compensation, unemployment 
insurance and social security laws;

            (d)   Restrictions, easements, and minor irregularities in 
title which do not and will not materially interfere with the occupation, 
use and enjoyment of the properties of the Company in the normal course of 
business as presently conducted or materially impair the value of such 
assets for the purpose of such business;

            (e)   Liens imposed by law, such as mechanics', materialmen's, 
landlords', warehousemen's, and carriers' Liens and other similar Liens, 
securing obligations incurred in the ordinary course of business which are 
not past due or which are being contested in good faith by appropriate 
proceedings and for which appropriate reserves have been established;

            (f)   Liens, deposits or pledges to secure the performance of 
bids, tenders, contracts (other than contracts for the payment of 
indebtedness), leases (to the extent permitted under the terms of this 
Agreement), public or statutory obligations, surety, stay, appeal, 
indemnity, performance or other similar bonds, or other similar 
obligations arising in the ordinary course of business;

            (g)   Judgment and other similar Liens arising in connection 
with court proceedings, provided that the execution or other enforcement 
of such Liens is effectively stayed and the claims secured thereby are 
being actively contested in good faith and by appropriate proceedings; and

            (h)   Liens against the fee interest in real property leased 
by the Company which are securing obligations of the owner of such 
property.

      4.3   Distributions or Redemptions.  Except as otherwise expressly 
authorized or permitted by this Agreement, the Company will not: (i) make 
any distributions of cash, property or securities of the Company with 
respect to any of its capital stock; or (ii) directly or indirectly 
redeem, purchase, or otherwise acquire for consideration any shares of its 
capital stock; provided, however, that any Subsidiary may make 
distributions of cash, property or securities to the Company.


SECTION 5.  OPERATING AND REPORTING COVENANTS

      Without the prior written consent of the Lenders representing a 
majority in interest of the Debentures, the Redeemable Preferred Stock, or 
the Convertible Preferred Stock, as the case may be, the Company (which 
term shall include the Subsidiaries and shall be deemed to include, for 
purposes of this Section 6, any subsidiary or subsidiaries of the Company 
formed after the date of this Agreement) shall: (a) comply with the 
covenants set forth in Sections 5.1 through 5.19, for so long as any of 
the Debentures or any shares of Redeemable Preferred Stock remain 
outstanding; and (b) comply with the covenants set forth in Sections 5.10, 
5.11  and 5.16 for so long as any shares of the Convertible Preferred 
Stock remain outstanding.

      5.1   Financial Statements; Minutes.  The Company shall maintain a 
system of accounts from which financial statements prepared in accordance 
with generally accepted accounting principles consistently applied can be 
derived, keep full and complete financial records and furnish to each of 
the Lenders the following reports:  (a) within 90 days after the end of 
each fiscal year, a copy of the consolidated balance sheet of the Company 
as at the end of such year, together with statements of operations and 
cash flow of the Company for such year, audited by independent public 
accountants of recognized national standing reasonably satisfactory to the 
Lenders, prepared in accordance with generally accepted accounting 
principles consistently applied, and including in comparative form the 
corresponding figures for the prior fiscal period; (b) within 45 days 
after the end of each calendar quarter, an unaudited consolidated balance 
sheet of the Company as at the end of such quarter, and unaudited 
statements of operations and cash flow for the Company for such quarter 
and for the year to date, and including in comparative form the 
corresponding figures for the prior fiscal period; (c) commencing January 
1, 1996, within 30 days after the end of each month, an unaudited 
consolidated balance sheet of the Company as at the end of such month and 
unaudited statements of operations for the Company for such month and for 
the year to date; (d) promptly after the same are available, copies of any 
proxy statements, financial statements and reports that the Company shall 
send or make available generally to any of its securityholders or file 
with the Security and Exchange Commission or other regulatory authority; 
(e) as soon as reasonably practicable after any meetings of the Board of 
Directors of the Company, copies of the minutes of such meeting; (f) in 
connection with the annual and quarterly financial statements delivered 
pursuant to clauses (a) and (b) above, a certification from the Chief 
Financial Officer of the Company if there exists any default or Event of 
Default under this Agreement, or any set of facts or circumstances which, 
with the giving of notice and/or the passage of time, could constitute 
such a default or Event of Default and stating the relevant facts and the 
related consequences and what actions the Company proposes to remedy them; 
and (g) such other financial information as the Lenders may reasonably 
request.  The Lenders or their authorized representatives shall have the 
right to meet with the Company's independent auditors not less than once 
each year to discuss the financial condition and results of operation of 
the Company, its financial controls and the accounting principles applied 
in the preparation of its financial statements.

      5.2   Budget and Strategic Plan.  The Company shall prepare and 
submit to the Lenders a budget and strategic plan for the Company for each 
fiscal year of the Company at least 15 days prior to commencement of each 
fiscal year thereafter, commencing fiscal year 1996.  The Company shall 
review the budget and strategic plan periodically with the Lenders and 
shall promptly advise the Lenders of all material changes therein and all 
material deviations therefrom.

      5.3   Conduct of Business.  The Company will continue to engage 
principally in the business now conducted by the Company or a business or 
businesses similar thereto or reasonably compatible therewith.  The 
Company will use its best efforts, in its reasonable business judgment, to 
keep in full force and effect its corporate existence and all intellectual 
property rights owned by it and useful in its business (except such rights 
as the Company has reasonably determined are not material to the Company's 
continuing operations).

      5.4   Payment of Taxes, Compliance with Laws, Etc.  The Company 
shall pay and discharge all lawful taxes, assessments and governmental 
charges or levies imposed upon it or its property before the same shall 
become in default, as well as all lawful claims for labor, materials and 
supplies which, if not paid when due, might become a lien or charge upon 
its property or any part thereof; provided, however, that the Company 
shall not be required to pay and discharge any such tax, assessment, 
charge, levy or claim so long as the validity thereof is being contested 
by it in good faith by appropriate proceedings and an adequate reserve 
therefor has been established. 

      5.5   Adverse Changes.  To the extent not disclosed in the financial 
statements to be provided under Section 5.1, the Company will promptly 
advise the Lenders of any event which represents a material adverse change 
in the condition or business, financial or otherwise, of the Company, and 
of each suit or proceeding commenced or threatened against the Company 
which, if adversely determined, could result in such a material adverse 
change.  

      5.6   Insurance.  The Company will keep its insurable properties 
insured, upon reasonable business terms, against liability, errors and 
omissions, and the perils of casualty, fire, business interruption, and 
extended coverage in amounts of coverage substantially similar to those 
customarily maintained by companies in the same or similar business, and 
of similar size, as the Company.  The Company will also maintain with such 
insurers insurance against other hazards and risks and liability to 
persons and property to the extent and in the manner customary for 
companies engaged in the same or similar business, and of similar size.  
The Company will maintain directors' and officers' liability insurance 
providing coverage of at least $2,000,000 per annum and subject to 
commercially reasonable deductions and exclusions, and shall not limit, 
amend, alter, modify or waive any director indemnification or exculpation 
provisions in its Articles of Organization or By-Laws or fail to renew the 
foregoing directors and officers' liability insurance, without providing 
the Lenders with at least 30 days prior written notice of such action; 
provided, however, in the event that the Lenders shall at any time have a 
Designated Director serving on the Board of Directors of the Company, the 
Company shall use its best efforts to increase its directors' and 
officers' liability insurance coverage to at least $5,000,000.

      5.7   Maintenance of Properties.  The Company, in its reasonable 
discretion, will maintain all properties used or useful in the conduct of 
its business in good repair, working order and condition, ordinary wear 
and tear excepted.

      5.8   Affiliated Transactions.  Except as otherwise permitted under 
this Agreement, the Company will not engage in any transactions with, or 
make any payments or distributions (excluding management compensation 
permitted by Section 5.9) to or for the benefit of, any officer or key 
employee of the Company or persons or entities controlling, controlled by, 
under common control with or otherwise affiliated with the Company unless 
such transaction shall be conducted on an arm's-length basis, shall be on 
terms and conditions no less favorable to the Company than could be 
obtained from nonrelated persons and shall be approved by the independent 
directors of the Board of Directors after full disclosure of the terms 
thereof.

      5.9   Management Compensation.  Compensation paid by the Company to 
its management and other employees will be: (i) both reasonably comparable 
to compensation paid to similarly-situated employees in companies in the 
same or similar businesses of similar size and maturity and with 
comparable financial performance and reasonable in relation to the 
Company's overall compensation structure; or (ii) reasonably consistent 
with the past practice of the Company.

      5.10  Board of Directors; Inspection.  

            (a)   At the request of the Lenders, the Company shall use its 
reasonable best efforts to cause one person designated by the Lenders to 
be nominated, elected and continued in office as a Director of Datamarine 
International, Inc. after the Closing Date and the Board of Directors of 
the Company shall, at that time, be expanded correspondingly. The Lenders' 
Director designee shall be entitled to reimbursement of all reasonable 
travel expenses incurred in connection with his/her attendance at all 
Board meetings and the Lenders' Director designee shall be entitled to 
receive the same board fees and other compensation, if any, paid to any 
outside Directors.  

            (b)   At the request of the Lenders, the Company shall cause 
one person designated by the Lenders to be, nominated, elected and 
continued in office as a Director of SEA after the Closing Date and the 
Board of Directors of SEA shall, at that time, be expanded 
correspondingly.  The Lenders' Director designee shall be entitled to 
reimbursement of all reasonable travel expenses incurred in connection 
with his/her attendance at all Board meetings and the Lenders' Director 
designee shall be entitled to receive the same board fees and other 
compensation, if any, paid to any outside Directors.

            (c)   At the request of the Lenders, the Company shall cause 
one person designated by the Lenders to be, nominated, elected and 
continued in office as a Director of Narrowband after the Closing Date and 
the Board of Directors of Narrowband shall, at that time, be expanded 
correspondingly.  The Lenders' Director designee shall be entitled to 
reimbursement of all reasonable travel expenses incurred in connection 
with his/her attendance at all Board meetings and the Lenders' Director 
designee shall be entitled to receive the same board fees and other 
compensation, if any, paid to any outside Directors.

            (d)   If at any time the Lenders do not have a designee 
serving on the Board of Directors ("Designated Director") of each of the 
Company, SEA and Narrowband, the Lenders shall be entitled to send a 
representative (the "Lender Representative") to attend all meetings of the 
Board of Directors of such companies not having a Designated Director 
serving on its Board of Directors, but such Lender Representative shall 
not be considered an elected member of the Board of Directors of any such 
company. Each of the Company, SEA and Narrowband will ensure that meetings 
of its Board of Directors are held at least once each calendar quarter and 
provide the Lender Representative with at least twenty (20) days prior 
written notice of all Board of Director meetings as well as copies of all 
materials provided to the Directors.  The Company, SEA and Narrowband, as 
appropriate, will reimburse the Lender Representative for reasonable 
travel expenses, including the cost of air fare and any necessary meals 
and lodging, incurred in connection with attending such meetings or 
performing such other business on its behalf as may be approved by it in 
advance.  The Company, SEA and Narrowband, as appropriate, will notify the 
Lenders in writing three (3) business days prior to the effectiveness of 
any action to be taken by written consent of directors or stockholders, 
except with respect to ministerial matters, and will provide reasonable 
opportunity for consultation with the Lenders with regard to the matters 
covered thereby during such three-day period prior to the effectiveness of 
such consents.  

            (e)   At such time, if any, that the Lenders shall have 
nominated a Designated Director to serve on the Board of Directors of any 
of the Company, SEA and/or Narrowband, the Company, SEA and/or Narrowband, 
as applicable, shall enter into an indemnification agreement with such 
Designated Director on terms and conditions comparable to indemnification 
agreements offered to directors of companies of similar size and maturity 
and with comparable financial performance.

            (f)   The Company will, upon reasonable prior notice to the 
Company, permit authorized representatives of the Lenders to visit and 
inspect any of the properties of the Company, including its books of 
account, and to discuss its affairs, finances and accounts with its 
agents, officers and independent accountants, all at such reasonable times 
and as often as may be reasonably requested, in all cases so as not to 
interfere with the Company's operations or personnel.

            (g)   From and after the time that no Debenture and/or 
Convertible Preferred Stock is outstanding, the Lenders shall, at the 
request of the Company, cooperate to cause the resignation or removal of 
the Designated Director(s), if any, from the Board of Directors of each of 
the Company, SEA and/or Narrowband, as applicable.

      5.11  Issuance of Capital Stock, Convertible Securities, Options, 
Warrants or Rights.  The Company covenants and agrees that it will not 
sell or issue any shares of capital stock or bonds, certificates of 
indebtedness, debentures or other securities convertible into or 
exchangeable for shares of capital stock, or options, warrants or rights 
carrying any rights to purchase shares of capital stock or convertible or 
exchangeable securities of the Company, other than pursuant to or as 
referenced in this Agreement (including with respect to stock option plans 
referenced in this Agreement), for more than 10% of the common equity in 
the Company or $3,000,000 in proceeds, whichever is less.

      The Lenders may, in their sole discretion, condition any waiver of 
the provisions of this Section 5.11 upon the Company offering each of the 
Lenders (on a pro rata basis with an overallotment option as to any 
amounts thereof not taken up by any other Lender) the right to participate 
in all or any portion of such proposed financing, on the most favorable 
terms and conditions proposed to be extended by the Company.

      5.12  Merger, Consolidation, Reorganization, Sale of Assets, 
Acquisition.  Each of the Company, SEA and Narrowband will not without the 
prior written consent of the Lenders (which consent will not be 
unreasonably withheld): (a) sell, lease or otherwise dispose of (whether 
in one transaction or a series of related transactions) all or any 
substantial portion of its assets, other than sales of inventory in the 
ordinary course of business, sales of obsolete assets and sales of other 
assets in any one fiscal year which have a book value of less than 
$150,000; (b) merge with or into or consolidate with another corporation, 
partnership or other entity (other than a wholly-owned subsidiary or in 
connection with an acquisition permitted under clause (c) below); or (c) 
acquire any other corporation or business concern, whether by acquisition 
of assets, capital stock or otherwise, and whether in consideration of the 
payment of cash, the issuance of shares of capital stock or otherwise 
where the consideration of any individual acquisition exceeds $500,000 or 
the consideration for all such acquisitions in the aggregate exceeds 
$1,000,000 and subject to the other limitations contained herein.

      5.13  No Amendments to Charter Documents.  The Company will not make 
any material amendment or modification to, or waiver of any of the terms 
of, the Company's Amended and Restated Articles of Organization, including 
any amendment, modification or waiver which would conflict with or impair 
any of the rights or privileges granted to the Lenders.

      5.14  Restrictions on Other Agreements.  Other than as provided in 
or contemplated by Section 11 of this Agreement, the Company will not 
enter into any agreement with any party which by its express terms:  (a) 
restricts the payments due the holders of the Debentures; or (b) otherwise 
conflicts with or impairs any of the express rights or privileges granted 
to the Lenders hereunder.

      5.15  Stay, Extension and Usury Laws.  For so long as any of the 
Debentures remain outstanding, the Company covenants (to the extent that 
it may lawfully do so) that it will not at any time insist upon, plead, or 
in any manner whatsoever claim or take the benefit or advantage of, any 
stay, extension or usury law wherever enacted, now or at any time 
hereafter in force, which may affect the covenants or the performance of 
this Agreement; and the Company (to the extent that it may lawfully do so) 
hereby expressly waives all benefit or advantage of any such law, and 
covenants that it will not, by resort to any such law, hinder, delay or 
impede the execution of any power herein granted to the Lenders, but will 
suffer and permit the execution of every such power as though no such law 
has been enacted.

      Notwithstanding anything herein or in the Debentures which may be to 
the contrary, in no event, contingency, or circumstances whatsoever shall 
the interest or any amount deemed to be interest payable by the Company 
hereunder with respect to the Debentures exceed the maximum amount 
permitted by applicable law and, to the extent that any payments in excess 
of such permitted amount are finally determined to have been received by 
the Lenders, such excess shall be considered payments in respect of the 
principal of the Debentures, and, if the principal of the Debentures has 
been paid in full, shall be refunded to the Company.  All sums paid or 
agreed to be paid to any Lender for the use, forbearance, or detention of 
the Debentures shall, to the extent permitted by law, be amortized, 
prorated, allocated, and spread throughout the entire term of the 
Debentures.

      5.16  Right of Participation in Financings.  The Company and SEA 
each covenants and agrees that it will not sell or issue any shares of its 
capital stock, or bonds, certificates of indebtedness, debentures or other 
securities convertible into or exchangeable for its capital stock, or 
options, warrants or rights carrying any rights to purchase its capital 
stock or convertible or exchangeable securities (other than pursuant to 
(a) bona fide registered public offerings which are generally available to 
any investors on non-negotiated terms, (b) stock or option grants to 
directors, officers, employees, consultants or agents of the Company 
pursuant to bona fide issuances under the Company's employee, director, 
consultant and agent stock purchase, stock option or other employee 
benefit plans, or (c) any transactions involving the acquisition by the 
Company of other corporations, businesses or products in which the holders 
of the Common Stock of the Company immediately prior to any such 
transaction shall continue to hold a majority of the outstanding Common 
Stock of the Company (after giving effect to the exercise of any options, 
warrants or other rights to acquire Common Stock or the conversion or 
exercise of any securities convertible into or exchangeable for Common 
Stock which are issued in such transaction) immediately after such 
transaction) unless a written offer is first submitted to the Lenders 
identifying the terms of the proposed sale, and offering to each of the 
Lenders the opportunity to purchase their proportionate share of such 
securities (subject to increase for overallotment if some Lenders do not 
fully exercise their rights) on terms and conditions, including price, not 
less favorable to the Lenders than those on which the Company or SEA 
proposes to sell such securities to a third party.  Each Lender's 
"proportionate share" of such securities shall be based on the ratio which 
the shares of the Common Stock of the Company owned or obtainable by such 
Lender upon conversion of any Debentures or Convertible Preferred Shares 
owned by it bears to all the issued and outstanding shares of the Common 
Stock of the Company, calculated in each case on a fully-diluted basis to 
include shares of the Common Stock issuable upon the exercise of any stock 
options or warrants then outstanding and upon conversion or exchange of 
any convertible or exchangeable securities then outstanding.  Any offer to 
the Lenders herewith shall remain open and irrevocable for a period of 30 
days.  Any securities so offered to the Lenders which are not purchased 
pursuant to such offer may be sold to a third party on terms and 
conditions, including price, not more favorable to the third party than 
those set forth in such offer at any time within 90 days following the 
date of such offer, but may not be sold to any other person or after such 
90-day period without renewed compliance with this Section 5.16.  In the 
event that subsequent to any offer to the Lenders hereunder, the Company 
or SEA proposes to amend the terms and conditions offered to any third 
parties during such 90-day period, it may do so provided that it first 
provides the Lenders with the opportunity to purchase their proportionate 
share of the offered securities on such amended terms and conditions on at 
least fifteen (15) business days written notice prior to the date on which 
the securities are to be offered on such amended terms and conditions to 
such third parties.

      5.17  [Intentionally Omitted]

      5.18  Dissolution of Data I.C., Inc.   The Company shall, on or 
before January 1, 1996, take, or cause to be taken, all such actions 
necessary to effect the dissolution and liquidation of Data I.C., Inc. and 
shall not at any time after the Closing Date permit Data I.C., Inc. to 
have or hold any assets or to engage in any transaction except to the 
extent necessary to carry out the dissolution and liquidation of Data, 
I.C., Inc.

      5.19  Transactions with Foreign Subsidiaries.  The Company will not 
engage in any transaction with, or transfer any assets, make any loans, 
advances, capital contributions, payments or distributions to, any Foreign 
Subsidiary.


SECTION 6.  CONVERSION

      At any time on or after the earliest to occur of (i) receipt of 
notice from the Company of its intention to prepay the Debentures in 
accordance with Section 1.2(f) hereof, (ii) a Liquidity Event, (iii) an 
Event of Default, or (iv) December ___, 1998, Lenders holding a majority 
in interest of the Debentures may, upon 30 days prior written notice to 
the Company, require that all of the Debentures be converted into 2,000 
shares of Convertible Preferred Stock and 2,000 shares of Redeemable 
Preferred Stock.  The Company and the Lenders agree that if for any reason 
any principal of the Debentures shall have been prepaid prior to 
conversion, such prepayment shall only reduce the amount of Redeemable 
Preferred Stock received upon conversion by one (1) share of Redeemable 
Preferred Stock for each $1,000 in principal amount of the Debentures that 
have been prepaid and shall not reduce the amount of Convertible Preferred 
Stock received upon such conversion. 

      In connection with the conversion of Debentures under this Section 
6, the Company shall pay to the Lenders, in cash, all accrued but unpaid 
Interest on the Debentures through the date of such conversion and each 
Lender shall surrender all of its Debentures, marked canceled, and 
acknowledged by the Lenders to be paid-in-full, to the Company at the 
Company's principal office in exchange for the shares of Convertible 
Preferred Stock and Redeemable Preferred Stock and interest payments 
described above.  Upon delivery of the Debentures to the Company, marked 
canceled, the Lenders shall be deemed to be shareholders in the Company 
holding their respective shares of Convertible Preferred Stock and 
Redeemable Preferred Stock.  The Company shall make such filings as are 
required and obtain all necessary consents and approvals necessary to 
consummate such conversion, including, if applicable, all necessary 
filings and approvals under Title II of the Hart-Scott-Rodino Antitrust 
Improvements Act of 1976, as amended.  The Company shall take all other 
action that the Lenders may reasonably request to evidence and effectuate 
the Lenders becoming shareholders holding shares of Convertible Preferred 
Stock and Redeemable Preferred Stock in the Company.  The Company will 
comply with all applicable state "blue sky" or securities laws in 
connection with the issuance and sale of the Debentures, any of the 
securities into which the Debentures may be converted and the other 
securities issued by the Company. 


SECTION 7.  EVENTS OF DEFAULT; REMEDIES

      7.1   Events of Default.

      In each case of the happening of the following events while any of 
the Debentures are outstanding (each of which is herein sometimes referred 
to as an "Event of Default"):

            (a)   if a default occurs in the payment of any premium, 
installment of the principal of, interest on, or other obligation with 
respect to, the Debentures, whether at the due date thereof or upon 
acceleration thereof, and, solely in the case of any such default in the 
payment of interest, charges, fees or expenses, such default continues for 
more than five (5) days after the due date thereof;

            (b)   if any material representation or warranty made herein 
or in any agreement executed in connection with, or in any schedule, 
certificate, financial statement or other instrument furnished in 
connection with, this Agreement shall prove to have been false or 
misleading when made in any material respect;

            (c)   if a default occurs in the due observance or performance 
of any covenant, condition or agreement on the part of the Company to be 
observed or performed pursuant to the provisions of Sections 4, 5.8, 5.11, 
5.12 or 5.19 of this Agreement and such default remains uncured for thirty 
(30) days after the occurrence thereof, or for such longer period if the 
default cannot reasonably be cured within such 30-day period and the 
Company is diligently pursuing cure of the default, but in no event for a 
period greater than 90 days after written notice thereof has been 
delivered by the Lenders to the Company, provided, however, that if such 
default cannot be remedied, then such default shall be deemed to be an 
Event of Default as of the date of the occurrence thereof;

            (d)   if a default occurs in the due observance or performance 
of any covenant, condition or agreement on the part of the Company to be 
observed or performed pursuant to any of the provisions of this Agreement 
not referenced in subsections (a), (b) or (c) above and such default 
remains uncured for forty-five (45) days after written notice thereof has 
been delivered by the Lenders to the Company, or for such longer period if 
the default cannot reasonably be cured within such 45-day period and the 
Company is diligently pursuing cure of the default, but in no event for a 
period greater than 90 days after written notice thereof has been 
delivered by the Lenders to the Company, provided, however, that if such 
default cannot be remedied, then such default shall be deemed to be an 
Event of Default as of the date of the occurrence thereof;

            (e)   if a default occurs with respect to any other 
Indebtedness of the Company for borrowed money in an aggregate amount in 
excess of $100,000 and such default is not remedied or waived within 
thirty (30) days of the date thereof;

            (f)   if the Company shall (i) discontinue its business, (ii) 
apply for or consent to the appointment of a receiver, trustee, custodian 
or liquidator of it or any of its property, (iii) admit in writing its 
inability to pay its debts as they mature, (iv) make a general assignment 
for the benefit of creditors, or (v) file a voluntary petition in 
bankruptcy, or a petition or an answer seeking reorganization or an 
arrangement with creditors, or to take advantage of any bankruptcy, 
reorganization, insolvency, readjustment of debt, dissolution or 
liquidation laws or statutes, or an answer admitting the material 
allegations of a petition filed against it in any proceeding under any 
such law, or if corporate action shall be taken for the purpose of 
effecting any of the foregoing;

            (g)   there shall be filed against the Company an involuntary 
petition seeking reorganization of the Company or the appointment of a 
receiver, trustee, custodian or liquidator of the Company or a substantial 
part of its assets, or an involuntary petition under any bankruptcy, 
reorganization or insolvency law of any jurisdiction, whether now or 
hereafter in effect (any of the foregoing petitions being hereinafter 
referred to as an "Involuntary Petition");

            (h)   if final judgment(s) from a court of competent 
jurisdiction for the payment of money in excess of an aggregate of 
$100,000 shall be rendered against the Company and the same shall remain 
unstayed or undischarged for a period of thirty (30) consecutive days, 
during which time execution shall not be effectively stayed; or

            (i)   if there occurs any attachment of any property of the 
Company in an amount exceeding $100,000, which shall not be discharged or 
bonded within thirty (30) days of the date of such attachment; then, and 
upon each and every such Event of Default thereafter, and during the 
continuance of any Event of Default, at the election of the Lenders, the 
Debentures shall immediately become due and payable, both as to principal 
and interest, without presentment, demand, or protest, all of which are 
hereby expressly waived, anything contained herein or in the Debentures to 
the contrary notwithstanding (except in the case of an Event of Default 
under subsections (f) or (g) of this Section, in which event such 
Debentures shall automatically become due and payable).  In the event of 
an acceleration of the Debentures as a result of the filing of an 
Involuntary Petition as specified in subsection (g) of this Section, such 
acceleration shall be rescinded, and the Company's rights hereunder 
reinstated, if, within sixty (60) days following the filing of such 
Involuntary Petition, such Involuntary Petition shall have been dismissed 
or stayed, and there shall exist no other Event of Default under this 
Agreement.

      7.2   Remedies on Default, Etc.  In case any one or more Events of 
Default shall occur and be continuing, the Lenders may proceed to protect 
and enforce their rights by an action at law, suit in equity or other 
appropriate proceeding, whether for the specific performance of any 
agreement contained in this Agreement or the Debentures, or for an 
injunction against a violation of any of the terms hereof or thereof or in 
and of the exercise of any power granted hereby or thereby or by law.  No 
right conferred upon the Lenders hereby or the Debentures shall be 
exclusive of any other right referred to herein or therein or now or 
hereafter available at law, in equity, by statute or otherwise.


SECTION 8.  REPRESENTATIONS AND WARRANTIES OF THE LENDERS

      8.1   Representation of Lenders.  In order to induce the Company and 
the Subsidiaries to enter into this Agreement, each Lender hereby 
severally represents and warrants to and agrees with the Company and each 
of the Subsidiaries with respect to such Lender's purchase of Debentures 
hereunder that as of the date hereof:

            (a)   The execution of the Agreement has been duly authorized 
by all necessary action on the part of the Lender, and this Agreement has 
been duly executed and delivered, and constitutes a valid, legal and 
binding agreement of the Lender enforceable in accordance with its terms, 
except as the enforcement thereof may be limited by bankruptcy and other 
laws of general application relating to creditor's rights or general 
principles of equity.

            (b)   The Lender is acquiring the Debentures for its own 
account, for investment, and not with a view to any "distribution" thereof 
within the meaning of the Securities Act.  The Lender has not been formed 
for the specific purpose of making the investment contemplated by this 
Agreement, the information concerning the state of residence of each 
Lender supplied to counsel for the Company is true and correct as of the 
date hereof and, the Lender is an "accredited investor" as defined under 
the Securities Act and the regulations promulgated thereunder.

            (c)   The Lender understands that because the Debentures (and 
the securities into which they are convertible) have not been registered 
under the Securities Act, it cannot dispose of any or all of the 
Debentures (or the securities into which they are convertible) unless such 
Debentures (or such securities, as the case may be) are subsequently 
registered under the Securities Act or exemptions from such registration 
are available.  The Lender acknowledges and understands that, except as 
provided in the Registration Rights Agreement, it has no independent right 
to require the Company to register the Debentures (or the securities into 
which they are convertible), that the Company has no intention to register 
the Debentures (or the securities into which they are convertible), and 
that the Company may not accomplish a public offering of the Debentures or 
the securities into which they are convertible.

            (d)   The Lender is knowledgeable and experienced in the 
making of investments in private enterprises, is able to bear the economic 
risk of loss of its investment in the Company, has been granted the 
opportunity to investigate the affairs of the Company, and has availed 
itself of such opportunity either directly or through its authorized 
representative.

            (e)   The Lender has been advised that the Debentures (and the 
securities into which they are convertible) have not been and are not 
being registered under the Securities Act or under the securities or "blue 
sky" laws of any jurisdiction and that the Company in issuing the 
Debentures is relying upon, among other things, the representations and 
warranties of each Lender contained in this Section 10 in concluding that 
each such issuance is a "private offering" and does not require compliance 
with the registration provisions of the Securities Act.

            (f)   The Lender has had access to or been supplied with all 
material information regarding the Company, its financial condition and 
historical results of operations, and all questions concerning the Company 
have been answered to its satisfaction.


SECTION 9.  INTERCREDITOR MATTERS

      9.1   Subordination to Payment.  Notwithstanding anything in this 
Agreement, in the Debentures or in any of the other documents and 
instruments executed and, or, delivered pursuant thereto or in connection 
therewith to the contrary, the Debentures shall be subordinate and junior 
in right of payment to the Senior Debt of the Company to the extent and in 
the manner set forth in this Section 9.  Except as specifically provided 
for otherwise in this Section 9, payments on account of the Debentures may 
be made by the Company and such payments may be received and retained by 
the Lenders as and when due. 

      9.2   Bankruptcy or Liquidation.  Upon the event of:  (a) any 
insolvency or bankruptcy proceedings, or any receivership, liquidation, 
reorganization or other similar proceedings with respect to the Company; 
(b) any proceedings for voluntary liquidation, dissolution or other 
winding up of the Company (whether or not involving insolvency or 
bankruptcy proceedings); or (c) any distribution, division or application, 
partial or complete, voluntary or involuntary, by operation of law or 
otherwise, of all or substantially all of the property, assets or business 
of the Company or the proceeds thereof to or for any creditor or creditors 
other than in the ordinary course of business (including without 
limitation any marshalling of assets), all Senior Debt shall be paid in 
full in cash (or other property acceptable to the holders of Senior Debt 
in their sole determination) before any payment or distribution, direct or 
indirect, whether in cash, securities, property or otherwise, shall 
thereafter be made on the Debentures; provided, however, that this 
provision shall not preclude the Lenders from (i) exercising their 
conversion rights under Section 6 hereof and receiving the Preferred 
Shares issuable upon such conversion, or (ii) exchanging the Debentures 
for other securities which are subordinated in right of payment to the 
Senior Debt on terms which are no more favorable to the Lenders than the 
terms of this Section 9.

      9.3   Payment Default on Senior Debt.  Except as specifically 
provided otherwise in Section 9.8 hereof, during the continuance of any 
default (without regard to any applicable grace or cure periods) in the 
payment of any sums (principal, interest or otherwise) due and payable on 
any Senior Debt (whether as a result of a periodic payment, maturity, 
acceleration or a mandatory prepayment), no payment on the Debentures, 
direct or indirect, whether in cash, securities, property or otherwise, 
shall be made after written notice of the foregoing default is given to 
the Company and the Lenders, unless and until the default under such 
Senior Debt shall have been cured in full or arrangements for such cure, 
which are accepted in writing by the holder of such Senior Debt, shall 
have been made.

      9.4   Non-Payment Default on Senior Debt.  Except as specifically 
provided otherwise in Section 9.8 hereof, upon the occurrence of a default 
on any Senior Debt (without regard to any applicable grace or cure 
periods), other than a default described in Section 9.2 or 9.3 above, no 
payment on Debentures, direct or indirect, whether in cash, property, 
securities or otherwise shall be made from the date that written notice of 
the foregoing default is given to the Company and the Lenders and for a 
period of 90 days thereafter, unless and until the default under such 
Senior Debt shall have been cured in full or arrangements for such cure, 
which are accepted in writing by the holder of such Senior Debt, shall 
have been made provided; however, that: (i) no more than two (2) payment 
blockage periods may be declared hereunder in any 365-day period; and (ii) 
no default may be cited as the basis for two (2) separate payment 
blockages in any 365-day period.

      9.5   Limitation on the Exercise of Certain Rights.  The Lenders 
agree that, upon written notice to it from any holder of Senior Debt 
specifying such holder's name and address, they will not thereafter, 
without at least one day's prior written notice to the holder of such 
Senior Debt, make any request or demand for, accelerate or bring any 
action with respect to, the payment of the Debentures.

      9.6   Subrogation.  Upon the payment in full of all Senior Debt, the 
Lenders shall be subrogated to the rights of the holders of Senior Debt to 
receive payments or distributions of assets of the Company made on the 
Senior Debt until all of the obligations or the Debentures shall be paid 
in full.  Except as may be otherwise ordered by a court with respect to 
the payments contemplated under Section 9.2 hereof, no payments or 
distributions to the holders of the Senior Debt of cash, property, 
securities or otherwise (including any amounts paid on account of the 
Debentures which are subsequently paid over to or held in trust for the 
benefit of the holders of any Senior Debt) shall, as between the Company, 
the Lenders and the Company's other creditors, be deemed to be a payment 
by the Company on account of the Debentures.  The provisions of this 
Section 9 are intended solely to define the relative rights of the 
Lenders, on the one hand, and the holders of Senior Debt, on the other 
hand, vis a vis the Company.  

      9.7   Absolute Obligation.  Nothing contained in this Section 9 is 
intended to or shall impair, as among the Company, its creditors other 
than holders of Senior Debt and the Lenders, the obligation of the 
Company, which is absolute and unconditional, to pay to the Lenders any 
and all sums outstanding under the Debentures as and when the same shall 
become due and payable in accordance with the terms thereof.  Nor is 
anything contained in this Section 9 intended to: (a) affect the relative 
rights of the Lenders and creditors of the Company other than the holders 
of Senior Debt; or (b) prevent the Lenders from exercising all remedies 
otherwise permitted by applicable law upon default, subject to the 
limitations set forth in Section 9.5 hereof and to the rights under this 
Section 9 of the holders of Senior Debt with respect to cash, property or 
securities of the Company received upon the exercise of any such remedy.  
The failure of the Company to make any payment on the Debentures by reason 
of any provision of this Section 9 shall not be construed as preventing 
the occurrence of an Event of Default under Section 7.

      9.8   Conversion.  Nothing contained in this Section 9 shall be 
deemed to prohibit the rights of the Lenders to convert the Debentures 
pursuant to Section 6 hereof and to receive the Preferred Shares issuable 
upon such conversion.


SECTION 10.  INDEMNIFICATION

      (a)   The Company shall, to the full extent permitted by law, and in 
addition to any such rights which any Indemnified Party (as defined 
herein) may have pursuant to statute, the Company's charter, the Company's 
by-laws, or otherwise, indemnify and hold harmless each Lender (including 
its respective directors, officers, partners, employees and agents, an 
"Indemnified Investor") and each person (a "Controlling Person" and 
collectively with Indemnified Investors, the "Indemnified Parties") who 
controls any of them within the meaning of Section 15 of the Securities 
Act of 1933, as amended (the "Securities Act"), or Section 20 of the 
Securities Exchange Act of 1934, as amended (the "Exchange Act"), from and 
against any and all losses, claims, damages, expenses and liabilities, 
joint or several, including any investigation, legal and other expenses 
incurred in connection with the investigation, defense, settlement or 
appeal of, and any amount paid in settlement of, any action, suit or 
proceeding or any claim asserted ("Losses" or "Loss"), to which they, or 
any of them, may become subject solely by reason of their status as, and 
not directly or indirectly by reason of their actions as, a securityholder 
or controlling person of the Company, (including, without limitation, any 
and all Losses under the Securities Act, the Exchange Act or other federal 
or state statutory law or regulation, at common law or otherwise, which 
relates directly or indirectly to the registration, purchase, sale or 
ownership of any securities from the Company, other than the Debentures, 
the Redeemable Preferred Stock, the Convertible Preferred Stock and the 
Conversion Shares (collectively, the "Lender Securities"), or to any 
fiduciary obligation owed by the Company with respect to securities of the 
Company (other than the Lender Securities); provided, however, that the 
Company will not be liable to the extent that such Loss arises from and is 
based on an untrue statement or omission or alleged untrue statement or 
omission in a registration statement or prospectus which is made in 
reliance on and in conformity with written information furnished to the 
Company in an instrument duly executed by or on behalf of such Indemnified 
Party specifically stating that it is for use in the preparation thereof.  
The indemnification and contribution provided for in this Section 10 will 
remain in full force and effect regardless of any investigation made by or 
on behalf of the Indemnified Parties or any officer, director, employee, 
agent or Controlling Person of the Indemnified Parties.  

      (b)   If the indemnification provided for in Section 10(a) above for 
any reason is held by a court of competent jurisdiction to be unavailable 
to an Indemnified Party in respect of any Losses referred to therein, then 
the Company, in lieu of indemnifying such Indemnified Party thereunder, 
shall contribute to the amount paid or payable by such Indemnified Party 
as a result of such Losses (i) in such proportion as is appropriate to 
reflect the relative benefits received by the Company and the Lenders, or 
(ii) if the allocation provided by clause (i) above is not permitted by 
applicable law, in such proportion as is appropriate to reflect not only 
the relative benefits referred to in clause (i) above but also the 
relative fault of the Company and the Lenders in connection with the 
action or inaction which resulted in such Losses, as well as any other 
relevant equitable considerations.  In connection with the registration of 
the Company's securities, the relative benefits received by the Company 
and the Lenders shall be deemed to be in the same respective proportions 
that the net proceeds from the offering (before deducting expenses) 
received by the Company and the Lenders, in each case as set forth in the 
table on the cover page of the applicable prospectus, bear to the 
aggregate public offering price of the securities so offered.  The 
relative fault of the Company and the Lenders shall be determined by 
reference to, among other things, whether the untrue or alleged untrue 
statement of a material fact or the omission or alleged omission to state 
a material fact relates to information supplied by the Company or the 
Lenders and the parties' relative intent, knowledge, access to information 
and opportunity to correct or prevent such statement or omission.

      The Company and the Lenders agree that it would not be just and 
equitable if contribution pursuant to this Section 10(b) were determined 
by pro rata or per capita allocation or by any other method of allocation 
which does not take account of the equitable considerations referred to in 
the immediately preceding paragraph.  In connection with the registration 
of the Company's securities, in no event shall any Lender be required to 
contribute any amount under this Section 10(b) in excess of the lesser of 
(i) that proportion of the total of such Losses indemnified against equal 
to the proportion of the total securities sold under such registration 
statement which is being sold by such Lender or (ii) the proceeds received 
by such Lender from its sale of securities under such registration 
statement.  No person found guilty of fraudulent misrepresentation (within 
the meaning of Section 11(f) of the Securities Act) shall be entitled to 
contribution from any person who was not found guilty of such fraudulent 
misrepresentation.

      (c)   Any Indemnified Party that proposes to assert the right to be 
indemnified under this Section 10 will, promptly after receipt of notice 
of commencement of any claim or action against such party in respect of 
which a claim is to be made against the Company under this Section 10, 
notify the Company of the commencement of such action, enclosing a copy of 
all papers served, but the omission so to notify the Company will not 
relieve the Company from any liability that the Company may have to any 
Indemnified Party under the foregoing provisions of this Section 10 
unless, and only to the extent that, such omission results in the 
forfeiture of substantive rights or defenses by the Company or is 
materially prejudicial to the Company's ability to defend such claim or 
action.  The Company shall have the right to participate in, and, to the 
extent the Company so desires, to assume the defense of any such claim or 
action 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 Company, if in the 
reasonable opinion of the Company, representation of such Indemnified 
Party by the counsel retained by the Company would be inappropriate due to 
the actual or potential differing interests between such Indemnified Party 
and any other party represented by such counsel in such proceeding.  If 
the Indemnified Party retains its own counsel in accordance with the 
foregoing sentence, all fees, disbursements and other charges incurred in 
the investigation, defense and/or settlement of such action shall be 
advanced and reimbursed by the Company promptly as they are incurred; 
provided, however, that the Indemnified Party shall agree to repay any 
expenses so advanced hereunder if it is ultimately determined by a court 
of competent jurisdiction that the Indemnified Party to whom such expenses 
are advanced is not entitled to be indemnified as a matter of law.  The 
Company shall not settle any action or claim for which indemnification is 
sought under this Section 10 without the prior written consent of the 
Indemnified Party, which consent shall not be unreasonably withheld.  The 
Company shall not be liable for any amounts paid in any settlement of any 
proceeding effected without its consent, which consent shall not be 
unreasonably withheld.


SECTION 11.  DEFINITIONS

      Unless the context specifically requires otherwise, capitalized 
terms used in this Agreement shall have the meaning specified below:

"Base Balance Sheet" shall mean the unaudited consolidated balance sheet 
of the Company dated July 1, 1995 which was filed with the SEC as a part 
of the Company's Quarterly Report on 10-Q for its fiscal quarter then-
ended.

"Capital Lease" means any lease of property (real, personal or mixed) 
which in accordance with generally accepted accounting principles 
consistently applied, would be capitalized on the lessee's balance sheet 
or for which the amount of the asset and liability thereunder should be 
disclosed in a note to such balance sheet as if so capitalized.

"FCC" means the Federal Communications Commission and any successor 
governmental agency performing functions similar to those performed by the 
Federal Communications Commission on the date hereof.

"Foreign Subsidiaries" shall mean Nautical Realty ApS, a Danish 
corporation, and Datamarine International Australia PTY, Limited, a 
corporation organized under the laws of New South Wales.

"Indebtedness" means with respect to any Person, (i) any liability, 
contingent or otherwise, of such Person (A) for borrowed money (whether or 
not recourse of the lender is to the whole of the assets of such Person or 
only to a portion thereof), (B) evidenced by a note, debenture or similar 
instrument (including a purchase money obligation) given in connection 
with the acquisition of any property or assets, (C) for any letter of 
credit or performance bond in favor of such Person, (D) for the payment of 
money relating to a capitalized lease obligation, or (E) any liability, 
contingent or otherwise, of such Person to any other Person for any 
purchase price associated with any acquisition of assets, business or 
otherwise (including any deferred purchase price, assumption of 
Indebtedness, noncompetition payments or other forms of consideration); 
(ii) any liability of others of the kind described in the preceding clause 
(i), which the Person has guaranteed or which is otherwise its legal 
liability, contingent or otherwise; (iii) any obligation secured by a Lien 
to which the property or assets of such Person are subject, whether or not 
the obligations secured thereby shall have been assumed by or shall 
otherwise be such Person's legal liability; (iv) all other items (except 
items of capital stock, capital or paid-in surplus or of retaining 
earnings) which in accordance with generally accepted accounting 
principles, would be included as a liability on the balance sheet of such 
Person on the date of determination; and (v) any and all deferrals, 
renewals, extensions or refinancing of, or amendments, modifications of 
supplements to, any liability of the kind described in any of the 
preceding clauses (i), (ii), (iii) or (iv).

"Lien" means any interest in, or claim against, property relating to an 
obligation owed to, or claim by, a Person other than the owner of the 
property, whether such interest is based on the common law, statute or 
contract, and including but not limited to any security interest lien 
arising from a mortgage, encumbrance, pledge, conditional sale or trust 
receipt or a lease, consignment or bailment for security purposes, any 
rights of first refusal, charges, claims, liabilities,  limitations, 
conditions, restrictions or other adverse claims; provided, however, that 
"Lien" shall not include the interest retained by the lessor under a lease 
which is not a Capital Lease.  For the purposes of this Agreement, the 
Company shall be deemed to be the owner of any property which it has 
acquired or holds subject to a conditional sale agreement, financing lease 
or other arrangement pursuant to which title to the property has been 
retained by or vested in some other person or entity for security purposes 
and such retention or vesting shall be deemed to be a Lien.

"Person" means any individual, corporation, partnership, joint venture, 
trust or unincorporated organization or any government or any agency or 
political subdivision thereof.

"Registration Rights Agreement" means the Registration Rights Agreement, 
dated as of the date hereof, by and among the Company and the Lenders, as 
amended, supplemented or modified from time to time.

"Securities Act" means the Securities Act of 1933 and the rules and 
regulations promulgated thereunder, each as amended from time to time.

"Senior Debt" means the aggregate principal amount of any indebtedness for 
money borrowed in accordance with the provisions of Section 4.1(b) and 
Section 4.1(e) hereof from a bank, insurance company or other financial 
institution unaffiliated with the Company.

"Subsidiary" of any Person means (a) a corporation, a majority of whose 
capital stock with voting power, under ordinary circumstances, to elect 
directors is at a time, directly or indirectly owned by such Person, by 
one or more subsidiaries of such Person or by such Person in one or more 
subsidiaries of such Person, or (b) any other Person (other than a 
corporation) in which such Person, a subsidiary of such Person, or such 
Person and one or more subsidiaries of such Person, directly or 
indirectly, individually or with another Person, at the date of 
determination thereof, has (i) at least a majority ownership interest, or 
(ii) the power to elect or direct the election of a majority of the 
directors or other governing body of such Person.

"Tax" means any federal, state, local, or foreign income, gross receipts, 
capital stock, franchise, profits, windfall profits, withholding, payroll, 
social security (or similar), unemployment, disability, real property, 
personal property, excise, occupation, sales, use, transfer, value added, 
alternative minimum, environmental, customs, duties, estimated or other 
tax, including any interest, penalty or addition thereto, whether disputed 
or not.

"Tax Returns" means any return, declaration, report, claim for refund, or 
information return or statement relating to Taxes, including any schedule 
or attachment thereto and including any amendment thereof.

      The following terms shall have the meanings assigned to them in the 
provisions of this Agreement referred to below:

Amended Charter - Section 3.2(b)
Closing - Section 1.3
Closing Date - Section 1.3
Common Stock - Section 2.4
Communications Act - Section 2.15
Company - preamble
Company FCC Licenses - Section 2.15(b)
Conversion Shares - Section 2.2 
Convertible Preferred Stock - Section 1.2(d)
Debentures - Section 1.1
Designated Director - Section 5.10(d)
Employee Program - Section 2.16
Environmental Law - Section 2.19(b)
ERISA - Section 2.16
Event of Default - Section 7.1
FCC Licenses - Section 2.15(d)
GAAP - Section 2.7
Hazardous Material - Section 2.19(b)
Hazardous Waste - Section 2.19(b)
Intellectual Property - Section 2.12
Interest - Section 1.2(a)
Involuntary Petition - Section 7.1(g)
IRS - Section 2.11
Lender Representative - Section 5.10(c)
Lender Securities - Section 10(a)
Lenders - preamble
Liquidity Event - Section 1.2(f)
Management Agreements - Section 2.15(c)
Material Agreements - Section 2.12
Maturity Date - Section 1.1
Option Plan - Section 2.4
PCBs - Section 2.19(a)
Pension Plan - Section 2.16
Preferred Shares - Section 2.2
Preferred Stock Terms - Section 2.4
Purchase Price - Section 1.1
Redeemable Preferred Stock - Section 1.2(d)
SEC - Section 2.6
SMR Operator Letter - Section 2.15(c)


SECTION 12.  GENERAL

      12.1   Amendments, Waivers and Consents.  For the purposes of this 
Agreement and all agreements, documents and instruments executed pursuant 
hereto, except as otherwise specifically set forth herein or therein, no 
course of dealing between the Company and any Lender and no delay on the 
part of any party hereto in exercising any rights hereunder or thereunder 
shall operate as a waiver of the rights hereof and thereof.  No covenant 
or other provision hereof or thereof may be waived otherwise than by a 
written instrument signed by the party so waiving such covenant or other 
provision; provided, however, that except as otherwise provided herein or 
therein, changes in or additions to, and any consents required by, or 
requests or demands made pursuant to, this Agreement may be made, and 
compliance with any term, covenant, condition or provision set forth 
herein may be omitted or waived (either generally or in a particular 
instance and either retroactively or prospectively) by a written 
instrument or instruments signed by a majority in interest of the Lenders 
and the Company.  Any amendment or waiver effected in accordance with this 
Section 12.1 shall be binding upon each holder of any Debentures purchased 
under this Agreement at the time outstanding (including securities into 
which such Debentures have been converted), each future holder of all such 
securities and the Company.

      12.2   Survival of Covenants; Assignability of Rights.  All 
covenants, agreements, representations and warranties of the Company made 
herein and to be performed prior to or at the Closing and in the 
certificates, lists, exhibits, schedules or other written information 
delivered or furnished to any Lender pursuant to the terms of this 
Agreement shall be presumed to have been material and to have been relied 
upon by such Lender, and, except as otherwise provided in this Agreement, 
shall survive the delivery of the Debentures and shall bind the Company's 
successors and assigns, whether so expressed or not, and, except as 
otherwise provided in this Agreement, all such covenants, agreements, 
representations and warranties shall inure to the benefit of the Lenders' 
successors and assigns and to transferees of the Debentures or any 
securities received upon conversion thereof, whether so expressed or not.  
Notwithstanding the foregoing or anything to the contrary contained in 
this Agreement:  (a) the Lenders may not transfer or assign their rights 
hereunder unless (i) the Lenders have provided to the Company at least 
five (5) days prior written notice of such transfer or assignment, and 
(ii) the successor or assignee, as a condition to such transfer or 
assignment, agrees in writing with the Company and the Subsidiaries to be 
bound by all of the provisions hereof; (b) all representations and 
warranties of the Company or the Subsidiaries contained or referenced in 
Section 2 hereof shall survive only for a period of two (2) years from the 
date of this Agreement, and any claim based upon any misrepresentations or 
breach of warranty by the Company or the Subsidiaries under Section 2 must 
be made within such period.

      12.3   Governing Law; Jurisdiction; Venue.  THIS AGREEMENT SHALL BE 
DEEMED TO BE A CONTRACT MADE UNDER, AND SHALL BE CONSTRUED IN ACCORDANCE 
WITH, THE LAWS OF THE COMMONWEALTH OF MASSACHUSETTS.  The Company and each 
Subsidiary hereby agree that the state and federal court of The 
Commonwealth of Massachusetts shall have non-exclusive jurisdiction to 
hear and determine any claims or disputes between the Lenders and the 
Company and the Subsidiaries pertaining directly or indirectly to this 
Agreement and all documents, instruments and agreements executed pursuant 
hereto, or to any matter arising therefrom (unless otherwise expressly 
provided for therein).  To the extent permitted by law, the Company and 
each of the Subsidiaries hereby expressly submit and consent in advance to 
such jurisdiction in any action or proceeding commenced by the Lenders in 
any of such courts, and agrees that service of such summons and complaint 
or other process or papers may be made by registered or certified mail 
addressed to the Company and to each of the Subsidiaries at the address to 
which notices are to be sent pursuant to this Agreement.  The Company and 
each of the Subsidiaries waive any claim that Boston, Massachusetts is an 
inconvenient forum or an improper forum based on lack of venue.  The 
choice of forum set forth in this section 12.3 shall not be deemed to 
preclude the enforcement of any judgment obtained in such forum or the 
taking of any action to enforce the same in any other appropriate 
jurisdiction.

      12.4   Section Headings.  The descriptive headings in this Agreement 
have been inserted for convenience only and shall not be deemed to limit 
or otherwise affect the construction of any provision thereof or hereof.

      12.5   Counterparts.  This Agreement may be executed simultaneously 
in any number of counterparts, each of which when so executed and 
delivered shall be taken to be an original; but such counterparts shall 
together constitute but one and the same document.

      12.6   Notices and Demands.  Any notice or demand which, by any 
provision of this Agreement or any agreement, document or instrument 
executed pursuant hereto or thereto, except as otherwise provided therein, 
is required or provided to be given shall be deemed to have been 
sufficiently given or served and received for all purposes when delivered 
in hand, by facsimile transmission with receipt acknowledged or by express 
delivery providing receipt of delivery, to the following addresses and 
numbers: 

if to the Company, SEA or Narrowband:

         c/o SEA Inc. of Delaware
         7030 220th Street
         Mountlake Terrace, WA 98043
         Attn:  President
         Tel:  (206) 771-2182
         Fax:  (206) 771-2650

         with a copy to:

         Perkins Coie
         1201 Third Avenue, 40th Floor
         Seattle, WA 98101-3099
         Attn:  Stewart M. Landefeld, Esq.
         Tel:  (206) 583-8888
         Fax:  (206) 583-8500

or at such other address designated by the Company, SEA or Narrowband, as 
the case may be, to the Lenders in writing; if to a Lender, at its mailing 
address and facsimile number, if applicable, as shown on Exhibit A hereto, 
or at any other address or facsimile number designated by such Lender to 
the Company and the other Lenders in writing; and if to an assignee of a 
Lender, at its address or facsimile number as designated to the Company 
and the other Lenders in writing.

      12.7   Severability.  Whenever possible, each provision of this 
Agreement shall be interpreted in such a manner as to be effective and 
valid under applicable law, but if any provision of this Agreement shall 
be deemed prohibited or invalid under such applicable law, such provision 
shall be ineffective to the extent of such prohibition or invalidity, and 
such prohibition or invalidity shall not invalidate the remainder of such 
provision or the other provisions of this Agreement.

      12.8   Expenses.  The Company shall pay the reasonable legal fees 
and disbursements for professional services of Goodwin, Procter & Hoar, 
special counsel to the Lenders, incurred in connection with the 
negotiation, execution, delivery and performance of this Agreement and the 
agreements, documents and instruments contemplated hereby or executed 
pursuant hereto. 

      12.9   Integration.  This Agreement, including the exhibits, 
documents and instruments referred to herein or therein and executed in 
connection herewith or therewith, constitutes the entire agreement, and 
supersedes all other prior agreements and understandings, both written and 
oral, among the parties with respect to the subject matter hereof.

[END OF TEXT]



      IN WITNESS WHEREOF, the undersigned have executed this Debenture 
Purchase Agreement as of the day and year first above written.

      DATAMARINE INTERNATIONAL, INC.


      By:
      Name:
      Title:


      SEA INC. OF DELAWARE


      By: 
      Name:
      Title:


      NARROWBAND NETWORK SYSTEMS, INC.


      By:   
      Name:
      Title:


      LENDERS:


      ALTA SUBORDINATED DEBT PARTNERS III, L.P.

      By:   Alta Subordinated Debt Management III, L.P., its General Partner

      By:
            Robert F. Benbow
            General Partner

EXHIBIT A


List of Lenders

                                                     Aggregate Amount
      Name                                           of Debentures Purchased
      ----------------------------------------------------------------------

      Alta Subordinated Debt Partners III, L.P.      $2,000,000


THIS SECURITY AND THE SECURITIES ISSUABLE UPON CONVERSION OF THIS SECURITY 
HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, 
(THE "ACT") OR ANY APPLICABLE STATE LAW, AND MAY NOT BE SOLD, DISTRIBUTED, 
ASSIGNED, OFFERED, PLEDGED OR OTHERWISE TRANSFERRED UNLESS (a) THERE IS AN 
EFFECTIVE REGISTRATION STATEMENT UNDER SUCH ACT AND APPLICABLE STATE 
SECURITIES LAWS COVERING ANY SUCH TRANSACTION OR (b) SUCH TRANSACTION IS 
EXEMPT FROM REGISTRATION.

THIS SECURITY IS SUBJECT TO THE TERMS OF THE SUBORDINATION AGREEMENT DATED 
AS OF DECEMBER 19, 1995 BETWEEN SILICON VALLEY BANK AND ALTA SUBORDINATED 
DEBT PARTNERS III, L.P.


CONVERTIBLE DEBENTURE
DUE DECEMBER 19, 2000

$2,000,000   December 19, 1995
Boston, Massachusetts

      FOR VALUE RECEIVED, DATAMARINE INTERNATIONAL, INC., a Massachusetts 
corporation, SEA INC. OF DELAWARE, a Delaware corporation, and NARROWBAND 
NETWORK SYSTEMS, INC., a Washington corporation, (collectively, the 
"Maker"), jointly and severally promise to pay to ALTA SUBORDINATED DEBT 
PARTNERS III, L.P. (hereinafter called the "Payee"), or to its order, at 
its address c/o Burr, Egan, Deleage & Co., One Embarcadero Center, Suite 
4050, San Francisco, CA 94111, the principal sum of Two Million Dollars 
($2,000,000), together with interest in arrears on the unpaid principal 
balance from time to time outstanding from the date hereof until the 
entire principal amount due hereunder is paid in full at the rates 
provided in that certain Debenture Purchase Agreement of even date 
herewith by and between the Payee, certain other entities and the Maker 
(the "Agreement").  Principal shall be paid, and interest shall accrue and 
be paid, as provided in the Agreement.

      This Convertible Debenture due December 19, 2000 ("Debenture") is 
one of the Debentures (as defined in the Agreement) referred to in and 
issued pursuant to the Agreement, and is entitled to the benefits of, and 
subject to, the terms and provisions of the Agreement, including, without 
limitation, the terms and provisions relating to payment and conversion of 
the Debentures.  The outstanding principal amount of this Debenture shall 
be paid in full as provided in the Agreement and may only be prepaid in 
accordance with the provisions of the Agreement.

      Upon the occurrence of an Event of Default as defined in the 
Agreement, the Lenders (as such parties are defined in the Agreement) may 
declare the entire unpaid principal balance hereunder and any accrued and 
unpaid interest thereon immediately due and payable without notice, 
demand, presentment or protest (except as and to the extent required under 
the Agreement) and may exercise any of their rights under the Agreement.  
In the event that the Payee or any subsequent holder of this Debenture 
shall exercise or endeavor to exercise any of its remedies hereunder or 
under the Agreement, the Maker shall pay on demand all reasonable costs 
and expenses incurred in connection therewith including, without 
limitation, reasonable attorneys' fees, and the Payee may take judgment 
for all such amounts in addition to all other sums due hereunder.

      Except as otherwise specifically provided in the Agreement, the 
Maker, to the extent permitted by applicable law, waives presentment for 
payment, protest and demand, and notice of protest, demand and/or dishonor 
and nonpayment of this Debenture, notice of any Event of Default under the 
Agreement by Maker, and all other notices or demands otherwise required by 
law that the Maker may lawfully waive.  No unilateral consent or waiver by 
the Payee with respect to any action or failure to act which, without 
consent, would constitute a breach by Maker of any provision of this 
Debenture or the Agreement shall be valid and binding unless in writing 
and signed by a majority in interest of the Lenders as provided in 
accordance with Section 12.1 of the Agreement.

      Upon receipt of evidence satisfactory to the Maker of the loss, 
theft, destruction or mutilation of this Debenture and, in the case of any 
such loss, theft or destruction, upon delivery of indemnity satisfactory 
to the Maker, or in case of such mutilation, upon surrender and 
cancellation of this Debenture, the Maker will issue a new debenture, of 
like tenor, in lieu, and dated the date, of such lost, stolen, destroyed 
or mutilated Debenture.

      The rights and obligations of the Maker and all provisions hereof 
shall be governed by and construed in accordance with the laws of The 
Commonwealth of Massachusetts.

      All agreements between the Maker and the Payee are hereby expressly 
limited so that in no contingency or event whatsoever, whether by reason 
of acceleration of maturity of the indebtedness evidenced hereby or 
otherwise, shall the amount paid or agreed to be paid to the Payee for the 
use, forbearance or detention of the indebtedness evidenced hereby exceed 
the maximum permissible under applicable law.  As used herein, the term 
"applicable law" shall mean the law in effect as of the date hereof, 
provided, however, that in the event there is a change in the law which 
results in a higher permissible rate of interest than the highest 
permissible rate under applicable law in effect as of the date hereof, 
then this Debenture shall be governed by such new law as of its effective 
date.  If, from any circumstance whatsoever, fulfillment of any provision 
hereof or the Agreement at the time performance of such provision shall be 
due, shall involve transcending the limit of validity prescribed by law, 
then the obligation to be fulfilled shall automatically be reduced to the 
limit of such validity, and if from any circumstances the Payee should 
ever receive as interest an amount which would exceed the highest lawful 
rate, such amount which would be excessive interest shall be applied to 
the reduction of the principal balance evidenced hereby and not to the 
payment of interest, and if the principal amount of this Debenture has 
been paid in full, shall be refunded to the Maker.  This provision shall 
control every other provision of all agreements between the Maker and the 
Payee.

      IN WITNESS WHEREOF, the Maker has caused this Debenture to be 
executed by its duly authorized representative as of the day and year 
first above written.

WITNESS:   DATAMARINE INTERNATIONAL, INC.

           By:
           Name:
           Title:

WITNESS:   SEA INC. OF DELAWARE

           By: 
           Name:
           Title:

WITNESS:   NARROWBAND NETWORK SYSTEMS, INC.

           By:
           Name:
           Title:


EXHIBIT C

                    TERMS FOR CONVERTIBLE PREFERRED STOCK
                       AND REDEEMABLE PREFERRED STOCK

      A.   Convertible Preferred Stock.  This series of preferred stock 
par value $1.00 per share ("Preferred Stock") of Datamarine International, 
Inc. (the "Corporation") shall be comprised of 2,000 shares designated as 
"Redeemable Convertible Participating Preferred Stock" (hereinafter 
referred to as "Convertible Preferred Stock").  The relative rights, 
preferences, restrictions and other matters relating to the Convertible 
Preferred Stock are as follows:

      1.   Dividends.  The holders of the Convertible Preferred Stock 
shall be entitled to receive, out of funds legally available therefor, 
dividends at the same rate as dividends are paid with respect to this 
Corporation's common stock, par value $.01 per share (the "Common Stock") 
(treating each share of Convertible Preferred Stock as being equal to the 
number of shares of Common Stock into which each such share of Convertible 
Preferred Stock could be converted pursuant to the provisions of Section 
A.5 hereof with such number determined as of the record date for the 
determination of holders of Common Stock entitled to receive such 
dividend).

      2.   Preference on Liquidation.  In the event of any liquidation, 
dissolution or winding up of the Corporation, the holders of the 
Convertible Preferred Stock shall be entitled to share in any distribution 
of any of the assets, capital, surplus or earnings of the Corporation 
ratably with the holders of the Common Stock of the Corporation (after the 
payment in full of the liquidation preference on the Redeemable Preferred 
Stock), based upon the amount which such Convertible Preferred Stock would 
have been entitled to receive in connection with such liquidation, 
dissolution or winding up if such share had been converted into Common 
Stock at the Conversion Price (as defined in Section A.5 below) in effect 
on such date, together with an amount equal to all declared but unpaid 
dividends on the Convertible Preferred Stock as provided in Section A.1 
above, if any.  

      3.   Redemption.

            (a)   At the election of the Corporation, subject to the 
holders' of Convertible Preferred Stock rights of conversion pursuant to 
the terms of Section 5 hereof, the Corporation may redeem all, but not 
less than all, of the shares of Convertible Preferred Stock then 
outstanding on or after December 31, 2000, so long as the Redeemable 
Preferred Stock shall have been redeemed in full on or prior to such date.  
If the Corporation elects to redeem the Convertible Preferred Stock, it 
shall give written notice of such election at least 60 days prior to the 
date of redemption, together with the date of redemption, and, if the 
Corporation's Common Stock is not then publicly held, the Corporation's 
estimate of the Fair Market Value of the Convertible Preferred Stock, to 
the holders of the Convertible Preferred Stock and all shares of 
Convertible Preferred Stock will be redeemed on the date specified for 
redemption in the Company's notice (the "Redemption Date") for a per share 
cash purchase price equal to the Fair Market Value (as determined in 
Section A.3(d) below) of the Convertible Preferred Stock plus any 
accumulated and unpaid dividends (the "Redemption Price").  On or after 
the Redemption Date, each holder of shares of Convertible Preferred Stock 
called for redemption shall surrender the certificate evidencing such 
shares to the Corporation at the place designated in such notice and shall 
thereupon be entitled to receive payment of the Redemption Price.

            (b)   Rights.  From and after the Redemption Date,  unless 
there shall have been a default in payment or tender by the Corporation of 
the Redemption Price, all rights of the holders with respect to such 
redeemed shares of Convertible Preferred Stock (except the right to 
receive the Redemption Price in accordance with the terms hereof upon 
surrender of their certificate) shall cease and such shares shall not 
thereafter be transferred on the books of this Corporation or be deemed to 
be outstanding for any purpose whatsoever. 

            (c)   Insufficient Funds.  If the funds of the Corporation 
legally available for redemption of shares of Convertible Preferred Stock 
on the Redemption Date are insufficient to redeem the total number of 
shares of Convertible Preferred Stock, the Corporation shall use those 
funds which are legally available to redeem the maximum possible number of 
such shares ratably among the holders of such shares to be redeemed.  At 
any time thereafter when additional funds of the Corporation are legally 
available for the redemption of shares of Convertible Preferred Stock, 
such funds will immediately be used to redeem the balance of the shares 
which the Corporation has become obligated to redeem on the Redemption 
Date but which it has not redeemed at the Redemption Price together with 
any accrued interest thereon as provided below.  If any shares of 
Convertible Preferred Stock are not redeemed because the Corporation 
failed to pay or tender to pay the aggregate Redemption Price on all 
outstanding shares of Convertible Preferred Stock, all shares which have 
not been redeemed shall remain outstanding and entitled to all the rights 
and preferences provided herein, and the Corporation shall pay interest on 
the unpaid portion of the Redemption Price for the unredeemed portion at a 
per annum rate equal to twenty percent (20%) or the maximum rate of 
interest permitted under applicable law, whichever is less.  

            (d)   Fair Market Value Determination.  If the Corporation's 
Common Stock is publicly traded at the Redemption Date, the Fair Market 
Value of each share of Convertible Preferred Stock shall equal the product 
of the number of shares of Common Stock into which each share of the 
Convertible Preferred Stock may then be converted multiplied by the 
average closing price for the Corporation's Common Stock for the thirty 
(30) trading days immediately preceding the Redemption Date.  If the 
Corporation's Common Stock is not publicly traded on the Redemption Date, 
the Fair Market Value shall be determined in accordance with the following 
provisions.  If the holders of a majority in interest of the Convertible 
Preferred Stock do not object in writing to the Corporation's estimate of 
the Fair Market Value of the Convertible Preferred Stock within fifteen 
(15) days after receipt of the Corporation's written notice of redemption, 
such estimate shall be the Fair Market Value for purposes of determining 
the Redemption Price of the Convertible Preferred Stock.  If the holders 
of a majority in interest of the Convertible Preferred Stock do timely 
object to the Corporation's estimate of Fair Market Value, the Corporation 
and such holders shall seek for a ten (10) day period thereafter to 
negotiate the Fair Market Value in good faith.  If the Corporation and the 
holders of a majority in interest of the Convertible Preferred Stock are 
unable to agree upon such Fair Market Value by the end of such period, 
each of the Corporation and the holders (acting by a majority in interest) 
shall, within ten (10) days thereafter, select an unaffiliated investment 
banking firm of nationally recognized standing in the telecommunications 
equipment industry to appraise the Fair Market Value of the Convertible 
Preferred Stock.  Each such firm will deliver its appraisal of the Fair 
Market Value within fifteen (15) days thereafter, and if the lower 
appraisal is at least 90% of the higher appraisal, the arithmetic mean of 
the two shall be the Fair Market Value.  If the two appraisals vary by 
more than 10%, the two firms shall promptly select a third investment 
banking firm of nationally recognized standing in the telecommunications 
equipment industry.  Such third firm shall, within ten (10) days 
thereafter, deliver its appraisal of the Fair Market Value of the 
Convertible Preferred Stock, the two appraisals which are closest together 
in value shall be averaged and such amount shall be the Fair Market Value 
for purposes of determining the Redemption Price.  The Fair Market Value 
of the Convertible Preferred Stock shall be determined: (i) without regard 
to the illiquid nature of such stock or for any discount attributable to 
the minority interest represented by such stock; (ii) with the Corporation 
valued as a going concern (including all net working capital); and (iii) 
on the basis of what a willing buyer would pay to a seller under no 
compunction to sell.  All costs of the appraisals hereunder shall be borne 
by the Corporation.

      4.   Voting.  Except as otherwise provided herein or as required by 
law, the shares of the Convertible Preferred Stock shall be voted together 
with the Corporation's Common Stock as a single voting group at any annual 
or special meeting of the stockholders of the Corporation, or may act by 
written consent as a single voting group with the Corporation's Common 
Stock, and shall otherwise have the same voting rights of the Common 
Stock.  Each share of Convertible Preferred Stock shall entitle the holder 
thereof to such number of votes per share as shall equal the number of 
shares of Common Stock into which such share of Convertible Preferred 
Stock is then convertible.  

      5.   Conversion Rights.  The holders of Convertible Preferred Stock 
shall have conversion rights as follows:

            (a)   Conversion at Holder's Election.  Each share of 
Convertible Preferred Stock shall be converted promptly upon the written 
election to so convert by holders of a majority in interest of the 
Convertible Preferred Stock into shares of Common Stock, initially at a 
conversion price equal to $9.00 per share of Common Stock, which price 
shall be adjusted as hereinafter provided (and, as so adjusted, is 
hereinafter sometimes referred to as the "Conversion Price"), with each 
share of Convertible Preferred Stock being valued for such purpose at 
$737.85. 

            (b)   Conversion at the Company's Election.  At any time on or 
after December 19, 2000, the Company may, in its sole discretion, elect to 
convert each share of Convertible Preferred Stock into shares of Common 
Stock, at the Conversion Price, with each share of Convertible Preferred 
Stock being valued for such purpose at $737.85, by providing written 
notice of the Company's election to each holder of Convertible Preferred 
Stock specifying a date not earlier than sixty (60) days from the mailing 
date of such notice as the date for surrender of certificates of 
Convertible Preferred Stock in connection with such conversion (the 
"Initial Surrender Date") and provided that the Company shall redeem all 
outstanding shares of Redeemable Preferred Stock (defined below) at or 
prior to the Initial Surrender Date.

            (c)   Dividends.  If Convertible Preferred Stock is converted 
pursuant to Section A.5(a) or Section A.5(b) and at such time there are 
declared and unpaid dividends or other amounts due on such shares, such 
dividends shall be paid in full by the Corporation in connection with such 
conversion.

            (d)   Conversion Procedures.  Any holder of Convertible 
Preferred Stock whose shares are converted into shares of Common Stock 
shall promptly, in the case of conversion pursuant to Section A.5(a), or 
at or within five (5) days after the Initial Surrender Date, in the case 
of conversion pursuant to Section A.5(b), surrender the certificate or 
certificates representing the Convertible Preferred Stock being converted, 
duly assigned or endorsed for transfer to the Corporation (or accompanied 
by duly executed stock powers relating thereto), at the principal 
executive office of the Corporation or the offices of the transfer agent 
for the Convertible Preferred Stock or such office or offices in the 
continental United States of an agent for conversion as may from time to 
time be designated by notice to the holders of the Convertible Preferred 
Stock by the Corporation, accompanied, in the case of a voluntary 
conversion pursuant to Section A.5(a), by written notice of conversion.  
Such notice of conversion shall specify (i) the number of shares of 
Convertible Preferred Stock to be converted, (ii) the name or names in 
which such holder wishes the certificate or certificates for Common Stock 
to be issued, and (iii) the address to which such holder wishes delivery 
to be made of such new certificates to be issued upon such conversion.  
Upon surrender of a certificate representing Convertible Preferred Stock 
for conversion, the Corporation shall issue and send by hand delivery, by 
courier or by overnight courier to the holder thereof or to such holder's 
designee, at the address designated by such holder, a certificate or 
certificates for the number of shares of Common Stock to which such holder 
shall be entitled upon conversion.

            (e)   Effective Date of Conversion.  The issuance by the 
Corporation of shares of Common Stock upon a conversion of Convertible 
Preferred Stock into shares of Common Stock pursuant to Section A.5(a) or 
Section A.5(b) hereof shall be effective as of the date of the surrender 
of the certificate or certificates for the Convertible Preferred Stock to 
be converted, duly assigned or endorsed for transfer to the Corporation 
(or accompanied by duly executed stock powers relating thereto); provided, 
however, that in the event of conversion pursuant to Section A.5(b), any 
shares of Convertible Preferred Stock in respect of which certificates 
have not been surrendered in accordance with Section A.5(d) by the 
Corporation's close of business on the fifth day after the Initial 
Surrender Date (such day, the "Final Surrender Date") shall be 
automatically converted into shares of Common Stock in accordance with 
Section A.5(b), without any further action on the part of the holder of 
such shares, effective as of the Final Surrender Date.  On and after the 
effective date of conversion, the person or persons entitled to receive 
the Common Stock issuable upon such conversion shall be treated for all 
purposes as the record holder or holders of such shares of Common Stock.

            (f)   Fractional Shares.  The Corporation shall not be 
obligated to deliver to holders of Convertible Preferred Stock any 
fractional share of Common Stock issuable upon any conversion of such 
Convertible Preferred Stock, but in lieu thereof may make a cash payment 
in respect thereof in any manner permitted by law.

            (g)   Reservation of Common Stock.  The Corporation shall at 
all times reserve and keep available out of its authorized and unissued 
Common Stock, solely for issuance upon the conversion of Convertible 
Preferred Stock as herein provided, free from any preemptive rights or 
other obligations, such number of shares of Common Stock as shall from 
time to time be issuable upon the conversion of all the Convertible 
Preferred Stock then outstanding.  The Corporation shall prepare and shall 
use its best efforts to obtain and keep in force such governmental or 
regulatory permits or other authorizations as may be required by law, 
excluding permits or authorizations relating to registration under Federal 
or state securities laws,  in order to enable the Corporation lawfully to 
issue and deliver to each holder of record of Convertible Preferred Stock 
such number of shares of its Common Stock as shall from time to time be 
sufficient to effect the conversion of all Convertible Preferred Stock 
then outstanding and convertible into shares of Common Stock.

            (h)   Adjustments to Conversion Price.  The Conversion Price 
in effect from time to time shall be subject to adjustment from and after 
December 19, 1995 and through the effective date of the conversion of all 
of the then outstanding Convertible Preferred Stock and regardless of 
whether any shares of Convertible Preferred Stock are then issued and 
outstanding as follows:

                 (I)   Stock Dividends, Subdivisions and Combinations.  
Upon the issuance of additional shares of Common Stock as a dividend or 
other distribution on outstanding Common Stock, the subdivision of 
outstanding shares of Common Stock into a greater number of shares of 
Common Stock, or the combination of outstanding shares of Common Stock 
into a smaller number of shares of  Common Stock, the Conversion Price 
shall, simultaneously with the happening of such dividend, subdivision or 
split be adjusted by multiplying the then effective Conversion Price by a 
fraction, the numerator of which shall be the number of shares of Common 
Stock outstanding immediately prior to such event and the denominator of 
which shall be the number of shares of Common Stock outstanding 
immediately after such event.  An adjustment made pursuant to this Section 
A.5(g)(I) shall be given effect, upon payment of such a dividend or 
distribution, as of the record date for the determination of stockholders 
entitled to receive such dividend or distribution (on a retroactive basis) 
and in the case of a subdivision or combination shall become effective 
immediately as of the effective date thereof.

                 (II)   Sale of Common Stock.  In the event the 
Corporation shall at any time, or from time to time, issue, sell or 
exchange any shares of Common Stock (including shares held in the 
Corporation's treasury but excluding any shares of Common Stock issued (i) 
to employees or officers of the Corporation under the Corporation's 
Datamarine Employee Investment Plan (401(k) Plan) and/or the 1980 Employee 
Stock Purchase Plan, each as in effect as of November 1, 1995 or (ii) to 
officers, directors, employees, consultants, advisors or agents of the 
Corporation upon the exercise of Excluded Options (as defined in Section 
5(g)(III) below)), for a consideration per share less than the Conversion 
Price in effect immediately prior to the issuance, sale or exchange of 
such shares, then, and thereafter successively upon each such issuance, 
sale or exchange, the Conversion Price in effect immediately prior to the 
issuance, sale or exchange of such shares shall forthwith be reduced to an 
amount determined by multiplying such Conversion Price by a fraction:

      (A)   the numerator of which shall be (i) the number of shares of 
Common Stock of all classes outstanding immediately prior to the issuance 
of such additional shares of Common Stock (excluding treasury shares but 
including all shares of Common Stock issuable upon conversion, exercise or 
exchange of any outstanding Preferred Stock, options, warrants, rights or 
convertible or exchangeable securities (including the convertible 
debentures due December 19, 2000 issued by this Corporation (the 
"Convertible Debentures") pursuant to that certain Debenture Purchase 
Agreement dated as of December 19, 1995 among the Company and the parties 
named on the signature pages and Exhibit A thereto (the "Debenture 
Purchase Agreement.)), plus (ii) the number of shares of Common Stock 
which the net aggregate consideration received by the Corporation for the 
total number of such additional shares of Common Stock so issued would 
purchase at the Conversion Price (prior to adjustment), and

      (B)   the denominator of which shall be (i) the number of shares of 
Common Stock of all classes outstanding immediately prior to the issuance 
of such additional shares of Common Stock (excluding treasury shares but 
including all shares of Common Stock issuable upon conversion, exercise or 
exchange of any outstanding Preferred Stock, options, warrants, rights or 
convertible or exchangeable securities (including the Convertible 
Debentures)), plus (ii) the number of such additional shares of Common 
Stock so issued.

                 (III)   Sale of Options, Rights or Convertible 
Securities.  In the event the Corporation shall at any time or from time 
to time, issue options, warrants or rights to subscribe for shares of 
Common Stock (other than any options or warrants for shares of Common 
Stock granted to officers, directors, employees, consultants, advisors or 
agents of the Corporation pursuant to either (a) the Corporation's 1991 
Stock Option Plan at an exercise price equal to at least 80% of the then 
current fair market value of the Common Stock, or (b) the Corporation's 
1992 Stock Option Plan for Non-Employee Directors at exercise prices equal 
to the then current fair market value of the Common Stock (the "Excluded 
Options")), or issue any securities convertible into or exchangeable for 
shares of Common Stock, for a consideration per share (determined by 
dividing the Net Aggregate Consideration (as determined below) by the 
aggregate number of shares of Common Stock that would be issued if all 
such options, warrants, rights or convertible or exchangeable securities 
were exercised, converted or exchanged to the fullest extent permitted by 
their terms) less than the Conversion Price in effect immediately prior to 
the issuance of such options, warrants, rights or convertible or 
exchangeable securities, the Conversion Price in effect immediately prior 
to the issuance of such options, warrants, rights or convertible or 
exchangeable securities shall forthwith be reduced to an amount determined 
by multiplying such Conversion Price by a fraction:

      (A)   the numerator of which shall be (i) the number of shares of 
Common Stock of all classes outstanding immediately prior to the issuance 
of such options, rights or convertible or exchangeable securities 
(excluding treasury shares but including all shares of Common Stock 
issuable upon conversion, exercise or exchange of any outstanding 
Preferred Stock, options, warrants, rights or convertible securities 
(including the Convertible Debentures)), plus (ii) the number of shares of 
Common Stock which the total amount of consideration received by the 
Corporation for the issuance of such options, warrants, rights or 
convertible or exchangeable securities plus the minimum amount set forth 
in the terms of such security as payable to the Corporation upon the 
exercise, conversion or exchange thereof (the "Net Aggregate 
Consideration") would purchase at the Conversion Price prior to 
adjustment, and

      (B)   the denominator of which shall be (i) the number of shares of 
Common Stock of all classes outstanding immediately prior to the issuance 
of such options, warrants, rights or convertible or exchangeable 
securities (excluding treasury shares but including all shares of Common 
Stock issuable upon conversion, exercise or exchange of any outstanding 
Preferred Stock, options, warrants, rights or convertible or exchangeable 
securities (including the Convertible Debentures)), plus (ii) the 
aggregate number of shares of Common Stock that would be issued if all 
such options, warrants, rights or convertible or exchangeable securities 
were exercised, converted or exchanged.

                 (IV)   Expiration or Change in Price.  If the 
consideration per share provided for in any options, warrants or rights to 
subscribe for shares of Common Stock or any securities exchangeable for or 
convertible into shares of Common Stock changes at any time, the 
Conversion Price in effect at the time of such change shall be readjusted 
to the Conversion Price which would have been in effect at such time had 
such options, warrants rights or convertible or exchangeable securities 
provided for such changed consideration per share (determined as provided 
in Section A.5(g)(III) hereof), at the time initially granted, issued or 
sold; provided, that such adjustment of the Conversion Price will be made 
only as and to the extent that the Conversion Price effective upon such 
adjustment remains less than or equal to the Conversion Price that would 
be in effect if such options, warrants, rights or convertible or 
exchangeable securities had not been issued.  No adjustment of the 
Conversion Price shall be made under this Section A.5 upon the issuance of 
any shares of Common Stock which are issued pursuant to the exercise of 
any options, warrants or other subscription or purchase rights or pursuant 
to the exercise of any conversion or exchange rights in any convertible or 
exchangeable securities if an adjustment shall previously have been made 
upon the issuance of such options, warrants, rights or convertible or 
exchangeable securities.  Any adjustment of the Conversion Price shall be 
disregarded if, as, and when the rights to acquire shares of Common Stock 
upon exercise or conversion of the options, warrants, rights or 
convertible or exchangeable securities which gave rise to such adjustment 
expire or are canceled without having been exercised, so that the 
Conversion Price effective immediately upon such cancellation or 
expiration shall be equal to the Conversion Price in effect at the time of 
the issuance of the expired or cancelled warrants, options, rights or 
convertible securities, with such additional adjustments as would have 
been made to that Conversion Price had the expired or cancelled warrants, 
options, rights or convertible securities not been issued.

      (i)   Other Adjustments.  In the event the Corporation shall make or 
issue, or fix a record date for the determination of holders of Common 
Stock entitled to receive, a non-cash dividend or other distribution 
payable in securities of the Corporation other than shares of Common 
Stock, then and in each such event lawful and adequate provision shall be 
made so that the holders of Convertible Preferred Stock shall receive upon 
conversion thereof in addition to the number of shares of Common Stock 
receivable thereupon, the number of securities of the Corporation which 
they would have received had their Convertible Preferred Stock been 
converted into Common Stock on the date of such event and had they 
thereafter, during the period from the date of such event to and including 
the Conversion Date (as that term is hereafter defined), retained such 
securities receivable by them as aforesaid during such period.

      If the Common Stock issuable upon the conversion of the Convertible 
Preferred Stock shall be changed into the same or different number of 
shares of any class or classes of stock, whether by reorganization, 
reclassification or otherwise (other than a subdivision or combination of 
shares or stock dividend provided for above, or a reorganization, merger, 
consolidation or sale of assets provided for elsewhere in this Section 
A.5), then and in each such event the holder of each share of Convertible 
Preferred Stock shall have the right thereafter to convert such share into 
the kind and amount of shares of stock and other securities and property 
receivable upon such reorganization, reclassification or other change, by 
holders of the number of shares of Common Stock into which such shares of 
Convertible Preferred Stock might have been converted immediately prior to 
such reorganization, reclassification or change, all subject to further 
adjustment as provided herein.

      (j)   Mergers and Other Reorganizations.  If at any time or from 
time to time there shall be a capital reorganization of the Common Stock 
(other than a subdivision, combination, reclassification or exchange of 
shares provided for elsewhere in this Section A.5) or a merger or 
consolidation of the Corporation with or into another corporation or the 
sale of all or substantially all of the Corporation's properties and 
assets to any other person, then, as a part of and as a condition to the 
effectiveness of such reorganization, merger, consolidation or sale, 
lawful and adequate provision shall be made so that the holders of the 
Convertible Preferred Stock shall thereafter be entitled to receive upon 
conversion of the Convertible Preferred Stock the number of shares of 
stock or other securities or property of the Corporation or of the 
successor corporation resulting from such merger or consolidation or sale, 
to which such holders would have been entitled upon such capital 
reorganization, merger, consolidation or sale had such holders converted 
their shares of Convertible Preferred Stock into Common Stock immediately 
prior to such capital reorganization, merger, consolidation, or sale.  In 
any such case, appropriate provisions shall be made with respect to the 
rights of the holders of the Convertible Preferred Stock after the 
reorganization, merger, consolidation or sale to the end that the 
provisions of this Section A.5 (including without limitation provisions 
for adjustment of the Conversion Price and the number of shares 
purchasable upon conversion of the Convertible Preferred Stock) shall 
thereafter be applicable, as nearly as may be, with respect to any shares 
of stock, securities or assets to be deliverable thereafter upon the 
conversion of the Convertible Preferred Stock.

      (k)   Notices.  In each case of an adjustment or readjustment of the 
Conversion Price, the Corporation will furnish each holder of Convertible 
Preferred Stock or any Convertible Debentures with a certificate, prepared 
by the chief financial officer of the Corporation, showing such adjustment 
or readjustment, and stating in detail the facts upon which such 
adjustment or readjustment is based; provided, however, that the 
Corporation shall be entitled to deliver any such notices to the 
representative of the holders as set forth in Section 12.6 of the 
Debenture Purchase Agreement.

      6.    Restrictions and Limitations.  So long as the Convertible 
Preferred Stock remains outstanding, the Corporation shall not without the 
affirmative vote or written consent of the holders of a majority in 
interest of the then outstanding shares of the Convertible Preferred Stock 
(adjusted appropriately for stock splits, stock dividends and the like):

      (i)   Redeem, purchase or otherwise acquire for value (or pay into 
or set aside for a sinking fund for such purpose), any share or shares of 
stock other than redemption of the Redeemable Preferred Stock in 
accordance with the terms thereof or pursuant to Section A.2 or Section 
A.3 hereof; provided, however, that this restriction shall not apply to 
the repurchase or redemption of shares of Common Stock issued pursuant to 
stock repurchase or similar agreements under which the Company has the 
option to repurchase such shares upon the occurrence of certain events, 
including the termination of employment and involuntary transfers by 
operation of law, provided that (unless the purchase is approved by 
unanimous vote of the Board of Directors of the Corporation) the 
repurchase price paid by the Corporation does not exceed the purchase 
price paid to the Corporation for such shares;

      (ii)   Authorize or issue, or obligate itself to issue, any other 
equity security senior to the Convertible Preferred Stock as to 
liquidation preferences, redemptions, or dividend rights or with any 
special voting rights (other than the Redeemable Preferred Stock);

      (iii)   Increase or decrease (other than by conversion as permitted 
hereby) the total number of authorized shares of Convertible Preferred 
Stock or Redeemable Preferred Stock;

      (iv)   Pay any dividends on any of its capital stock or otherwise 
make any payments to any holders of its Common Stock, except as otherwise 
expressly permitted in the Debenture Purchase Agreement;

      (v)   Authorize any merger or consolidation of the Corporation or 
SEA, Inc. with or into any other corporation, partnership or entity (other 
than a wholly-owned subsidiary of the Corporation or in connection with an 
acquisition which is permitted under the terms of a certain Debenture 
Purchase Agreement dated December 19, 1995 by and among the holders of the 
Corporation's Convertible Debentures issued thereunder and the Corporation 
(the "Debenture Purchase Agreement"), authorize or permit the liquidation, 
dissolution or winding up of the Corporation, SEA, Inc. of Delaware or 
Narrowband Network Systems, Inc. or authorize or permit the sale of all or 
any substantial portion of the capital stock or assets of the Corporation, 
SEA, Inc. of Delaware or Narrowband Network Systems, Inc. (except as 
permitted pursuant to Sections 5.11 and 5.12 of the Debenture Purchase 
Agreement); or

      (vi)   Amend the Amended and Restated Articles of Incorporation or 
By-Laws of the Corporation in a manner which, or take any other action or 
enter into any other agreements which, could prohibit or conflict with the 
Corporation's obligations hereunder with respect to the holders of the 
Convertible Preferred Stock.

      7.   No Reissuance of Convertible Preferred Stock.  No share or 
shares of the Convertible Preferred Stock acquired by the Corporation by 
reason of redemption, purchase, conversion or otherwise shall be reissued, 
and all such shares shall be canceled, retired, and eliminated from the 
shares which the Corporation shall be authorized to issue.  The 
Corporation may from time to time take such appropriate corporate action 
as may be necessary to reduce the authorized number of shares of the 
Convertible Preferred Stock accordingly.

      8.   Notices of Record Date.  In the event (i) the Corporation 
establishes a record date to determine the holders of any class of 
securities who are entitled to receive any dividend or other distribution, 
or (ii) there occurs any capital reorganization of the Corporation, any 
reclassification or recapitalization of the capital stock of the 
Corporation, any merger or consolidation of the Corporation, and any 
transfer of all or substantially all of the assets of the Corporation to 
any other Corporation, or any other entity or person, or any voluntary or 
involuntary dissolution, liquidation or winding up of the Corporation, the 
Corporation shall mail to the representative of the holders of Convertible 
Preferred Stock as set forth in Section 12.6 of the Debenture Purchase 
Agreement at least twenty (20) days prior to the record date specified 
therein, a notice specifying (a) the date of such record date for the 
purpose of such dividend or distribution and a description of such 
dividend or distribution, (b) the date on which any such reorganization, 
reclassification, transfer, consolidation, merger, dissolution, 
liquidation or winding up is expected to become effective, and (c) the 
time, if any, that is to be fixed, as to when the holders of record of 
Common Stock (or other securities) shall be entitled to exchange their 
shares of Common Stock (or other securities) for securities or other 
property deliverable upon such reorganization, reclassification, transfer, 
consolidation, merger, dissolution, liquidation or winding up.

      B.   Redeemable Preferred Stock.  This series of Preferred Stock of 
the Corporation shall be comprised of 2,000 shares designated as 
"Redeemable Preferred Stock" (hereinafter referred to as "Redeemable 
Preferred Stock").  The relative rights, preferences, restrictions and 
other matters relating to the Redeemable Preferred Stock are as follows:

      1.   Dividends.  The holders of the Redeemable Preferred Stock shall 
be entitled to receive, and the Corporation shall be bound to pay on the 
earlier of the RPF Redemption Date or the Optional Redemption Date (unless 
sooner paid at the election of the Company), cumulative dividends in an 
amount per share determined by (i) accruing dividends for each calendar 
year or portion thereof that any shares of the Redeemable Preferred Stock 
are outstanding (A) through December 31, 1996 at the per annum rate of 
$100.00, (B) during calendar year 1997 at the per annum rate of $110.00, 
(C) during calendar year 1998 at the per annum rate of $120.000, (D) 
during calendar year 1999 at the per annum rate of $140.00, and (E) during 
calendar year 2000 and thereafter at the per annum rate of $150.00, and 
(ii) compounding such dividends on each calendar year end until paid (or 
through any date on which such dividends are to be paid) at the per annum 
dividend rate for such year.

      2.   Preference on Liquidation.

      (a)   In the event of any liquidation, dissolution or winding up of 
the Corporation, the holders of the Redeemable Preferred Stock shall be 
entitled to receive in cash and prior and in preference to any 
distribution of any assets, capital, surplus or earnings of the 
Corporation to the holders of any other capital stock of the Corporation 
(including the Convertible Preferred Stock and the Common Stock), the 
amount of $1,000.00 per share for each share of Redeemable Preferred Stock 
then held by them (adjusted for any stock split, combination, 
consolidation, or stock distributions or stock dividends with respect to 
such shares) together with all accrued but unpaid cumulative dividends on 
the Redeemable Preferred Stock (the "Liquidation Preference Amount").  If 
the assets and funds thus distributed among the holders of the Redeemable 
Preferred Stock shall be insufficient to permit the payment to such 
holders of the full Liquidation Preference Amount then the entire assets 
and funds of the Corporation legally available for distribution shall be 
distributed ratably among the holders of the Redeemable Preferred Stock.  

      (b)   The following shall be deemed to be a liquidation, dissolution 
or winding up within the meaning of this Section B.2 (with each such event 
being referred to herein as a "Corporate Disposition"): (i) a 
consolidation or merger of this Corporation with or into any other 
corporation or corporations (other than a wholly-owned subsidiary or in 
connection with an acquisition permitted under the Debenture Purchase 
Agreement); (ii) the sale, transfer or other disposition of all or 
substantially all of the assets of this Corporation; or (iii) the 
effectuation by the Corporation or its shareholders of a transaction or 
series of related transactions in which more than 50% of the voting power 
of the Corporation is disposed of (other than as permitted under the 
Debenture Purchase Agreement).

      3.   Redemption.

      (a)   Mandatory Redemption.  The Corporation shall redeem all of the 
shares of Redeemable Preferred Stock then outstanding on December 19, 
2000.  On or prior to June 30, 1999, the Corporation shall give written 
notice by mail, postage prepaid, to the holders of the then outstanding 
Redeemable Preferred Stock at the address of each such holder appearing on 
the books of the Corporation or given by such holder to the Corporation 
for the purpose of notice.  Such notice shall set forth the date specified 
for redemption (December 19, 2000) and the Redemption Price (which shall 
be the Liquidation Preference Amount).  The notice shall further call upon 
such holders to surrender to the Corporation on or before the applicable 
redemption date at the place designated in the notice such holder's 
certificate or certificates representing the shares to be redeemed on 
December 19, 2000 (the "RPF Redemption Date") or an indemnification and 
loss certificate.  On or before the applicable RPF Redemption Date, each 
holder of shares of Redeemable Preferred Stock called for redemption shall 
surrender the certificate evidencing such shares, or such indemnification 
and loss certificate, to the Corporation.  At such time, the Corporation 
shall pay to each of the holders of Redeemable Preferred Stock a per share 
cash price equal to the Redemption Price. 

      (b)   Optional Redemption.  The Corporation may, in its sole 
discretion, at any time after December 19, 1997, redeem all of the shares 
of Redeemable Preferred Stock then outstanding.  The Corporation shall 
give the holders of the then outstanding Redeemable Preferred Stock not 
less than sixty (60) days prior written notice by mail, postage prepaid, 
at the address of each such holder appearing on the books of the 
Corporation or given by such holder to the Corporation for the purpose of 
such notice.  Such notice shall set forth the date specified for 
redemption (the "Optional Redemption Date") and the Redemption Price 
(which shall be the Liquidation Preference Amount).  The notice shall 
further call upon such holders to surrender to the Corporation on or 
before the Optional Redemption Date at the place designated in the notice 
such holder's certificate or certificates representing the shares to be 
redeemed on the Optional Redemption Date or an indemnification and loss 
certificate.  On or before the applicable Optional Redemption Date, each 
holder of shares of Redeemable Preferred Stock called for redemption shall 
surrender the certificate evidencing such shares, or such indemnification 
and loss certificate, to the Corporation.  At such time, the Corporation 
shall pay to each of the holders of Redeemable Preferred Stock a per share 
cash price equal to the Redemption Price.  

      (c)   Termination of Rights.  From and after any applicable RPF 
Redemption Date or Optional Redemption Date, unless there shall have been 
a default in payment or tender by the Corporation of the Redemption Price, 
all rights of the holders with respect to such redeemed shares of 
Redeemable Preferred Stock (except the right to receive the Redemption 
Price upon surrender of their certificate) shall cease and such shares 
shall not thereafter be transferred on the books of this Corporation or be 
deemed to be outstanding for any purpose whatsoever.

      (d)   Insufficient Funds.  If the funds of the Corporation legally 
available for redemption of shares of Redeemable Preferred Stock on the 
applicable RPF Redemption Date or Optional Redemption Date are 
insufficient to redeem the total number of shares of Redeemable Preferred 
Stock on such redemption date, the Corporation shall use those funds which 
are legally available to redeem the maximum possible number of such shares 
ratably among the holders of such shares to be redeemed.  At any time 
thereafter when additional funds of the Corporation are legally available 
for the redemption of shares of Redeemable Preferred Stock, such funds 
will immediately be used to redeem the balance of the shares which the 
Corporation has become obligated to redeem on the applicable RPF 
Redemption Date or Optional Redemption Date, but which it has not 
redeemed, at the Redemption Price together with any accrued interest 
thereon as provided below.  If any shares of Redeemable Preferred Stock 
are not redeemed for the foregoing reason or because the Corporation 
otherwise failed to pay or tender to pay the aggregate Redemption Price on 
all outstanding shares of Redeemable Preferred Stock, all shares which 
have not been redeemed shall remain outstanding and entitled to all the 
rights and preferences provided herein, and the Corporation shall pay 
interest on the unpaid portion of the Redemption Price for the unredeemed 
portion at an aggregate per annum rate equal to twenty percent (20%) or 
the maximum rate permitted by applicable law, whichever is less.

      4.   Voting.   Except as required by law, the shares of the 
Redeemable Preferred Stock shall not have any voting rights or powers.

      5.   No Reissuance of Redeemable Preferred Stock.  No share or 
shares of the Redeemable Preferred Stock acquired by the Corporation by 
reason of redemption, purchase, conversion or otherwise shall be reissued, 
and all such shares shall be canceled, retired, and eliminated from the 
shares which the Corporation shall be authorized to issue.  The 
Corporation may from time to time take such appropriate corporate action 
as may be necessary to reduce the authorized number of shares of the 
Redeemable Preferred Stock accordingly.


                              IRREVOCABLE PROXY


      Each of the undersigned agrees to, and hereby grants to Alta 
Subordinated Debt Partners III, L.P. ("ASDP III"), an irrevocable proxy to 
vote, or to execute and deliver written consents or otherwise act with 
respect to, all shares of common stock, par value $.01 per share (the 
"Stock"), of Datamarine International, Inc. (the "Company") now owned or 
hereafter acquired by the undersigned as fully, to the same extent and 
with the same effect as the undersigned might or could do under any 
applicable laws or regulations governing the rights and powers of 
stockholders of a Massachusetts corporation, in connection with the 
election of one director (an "ASDP Designee") of the Company, designated 
for such directorship by ASDP III as provided in Section 5.10 of that 
certain Debenture Purchase Agreement (the "Agreement"), dated as of 
December __, 1995, among the Company, SEA Inc. of Delaware, Narrowband 
Network Systems, Inc., and ASDP III.

      With respect to each of the foregoing proxies, each of the 
undersigned further agrees to vote his shares of Stock for the removal of 
any ASDP Designee upon the request of ASDP III and for the election of a 
substitute ASDP Designee nominated by ASDP III.  Each of the undersigned 
further agrees to vote his shares of Stock in such manner as shall be 
necessary or appropriate so as to ensure that any vacancy occurring for 
any reason in a position on the board of directors of the Company held by 
an ASDP Designee shall be filled only by an individual who is nominated 
directly or indirectly by ASDP III.

      The undersigned hereby affirms that these proxies are given as a 
condition of the Agreement, and as such are coupled with an interest and 
are irrevocable.  It is understood by the undersigned and ASDP III that 
each proxy may be exercised during only the period beginning the date 
hereof and ending on the earliest date that ASDP III (or its permitted 
successors, assigns or transferees under Section 12.2 of the Agreement) do 
not hold any Debentures and/or Preferred Shares obtained under the 
Agreement, unless sooner terminated by mutual agreement of ASDP III (or 
its permitted successors, assigns or transferees under Section 12.2 of the 
Agreement) and each of the undersigned.  Notwithstanding the foregoing, 
this irrevocable proxy will terminate immediately upon such time as none 
of Debentures, Redeemable Preferred Stock or Convertible Preferred Stock 
remains outstanding.

      Any defined terms used herein and not otherwise defined shall have 
the meaning ascribed to them in the Agreement.

      This irrevocable proxy may be executed simultaneously in any number 
of counterparts, each of which when so executed and delivered shall be 
taken to be an original; but such counterparts shall together constitute 
but one and the same document.

                                 
                     David C. Thompson
                                    
                     Peter D. Brown
                                    
                     David M. Brown