<PAGE>   1
                                                                     EXHIBIT 3.1


                       RESTATED ARTICLES OF INCORPORATION
                                       OF
                             WALL DATA INCORPORATED



        Pursuant to RCW 23B.10.070, the following constitute Restated Articles
of Incorporation of the undersigned, a Washington corporation. These Restated
Articles of Incorporation correctly set forth without change the corresponding
provisions of the Articles of Incorporation as heretofore amended and supersede
the original Articles of Incorporation and all amendments thereto.

                                 ARTICLE 1. NAME

        The name of this corporation is Wall Data Incorporated.

                               ARTICLE 2. DURATION

        The period of this corporation's duration shall be perpetual.

                         ARTICLE 3. PURPOSES AND POWERS

        This corporation is organized to engage in any business, trade or
activity which may lawfully be conducted by a corporation organized under the
Washington Business Corporation Act.

        This corporation shall have the authority to engage in any and all such
activities as are incidental or conducive to the attainment of the foregoing
purpose or purposes of this corporation and to exercise any and all powers
authorized or permitted under any laws that may be now or hereafter applicable
or available to this corporation.

                                ARTICLE 4. SHARES

        4.1  AUTHORIZED CAPITAL

        The total number of shares which this corporation is authorized to issue
is 50,000,000, consisting of 45,000,000 shares of Common Stock of no par value
and 5,000,000 shares of Preferred Stock of no par value. The Common Stock is
subject to the rights and preferences of the Preferred Stock as hereinafter set
forth.

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Restated Articles of Incorporation                                        Page 1

<PAGE>   2

        4.2    ISSUANCE OF PREFERRED STOCK IN SERIES

        The Preferred Stock may be issued from time to time in one or more
series in any manner permitted by law and the provisions of these Articles of
Incorporation, as determined from time to time by the Board of Directors and
stated in the resolution or resolutions providing for the issuance thereof,
prior to the issuance of any shares thereof. The Board of Directors shall have
the authority to fix and determine and to amend, subject to the provisions
hereof, the designation, preferences, limitations and relative rights of the
shares of any series that is wholly unissued or to be established. Unless
otherwise specifically provided in the resolution establishing any series, the
Board of Directors shall further have the authority, after the issuance of
shares of a series whose number it has designated, to amend the resolution
establishing such series to decrease the number of shares of that series, but
not below the number of shares of such series then outstanding.

        4.3    DIVIDENDS

        The holders of shares of the Preferred Stock shall be entitled to
receive dividends, out of the funds of the corporation legally available
therefor, at the rate and at the time or times, whether cumulative or
noncumulative, as may be provided by the Board of Directors in designating a
particular series of Preferred Stock. If such dividends on the Preferred Stock
shall be cumulative, then if dividends shall not have been paid, the deficiency
shall be fully paid or the dividends declared and set apart for payment at such
rate, but without interest on cumulative dividends, before any dividends on the
Common Stock shall be paid or declared and set apart for payment. The holders of
the Preferred Stock shall not be entitled to receive any dividends thereon other
than the dividends referred to in this section.

        4.4    REDEMPTION

        The Preferred Stock may be redeemable at such price, in such amount, and
at such time or times as may be provided by the Board of Directors in
designating a particular series of Preferred Stock. In any event, such Preferred
Stock may be repurchased by this corporation to the extent legally permissible.

        4.5    LIQUIDATION

        In the event of any liquidation, dissolution or winding up of the
affairs of this corporation, whether voluntary or involuntary, then, before any
distribution shall be made to the holders of the Common Stock, the holders of
the Preferred 


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Restated Articles of Incorporation                                        Page 2

<PAGE>   3

Stock at the time outstanding shall be entitled to be paid the preferential
amount or amounts per share as may be provided by the Board of Directors in
designating a particular series of Preferred Stock and dividends accrued thereon
to the date of such payment. The holders of the Preferred Stock shall not be
entitled to receive any distributive amounts upon the liquidation, dissolution
or winding up of the affairs of the corporation other than the distributive
amounts referred to in this section, unless otherwise provided by the Board of
Directors in designating a particular series of Preferred Stock.

        4.6    CONVERSION

        Shares of Preferred Stock may be convertible into Common Stock of the
corporation upon such terms and conditions, at such rate and subject to such
adjustments as may be provided by the Board of Directors in designating a
particular series of Preferred Stock.

        4.7    VOTING RIGHTS

        Holders of Preferred Stock shall have such voting rights as may be
provided by the Board of Directors in designating a particular series of
Preferred Stock.

                          ARTICLE 5. PREEMPTIVE RIGHTS

        No preemptive rights shall exist with respect to shares of stock or
securities convertible into shares of stock of this corporation.

                          ARTICLE 6. CUMULATIVE VOTING

        The right to cumulate votes in the election of Directors shall not exist
with respect to shares of stock of this corporation.

                                ARTICLE 7. BYLAWS

        The Board of Directors shall have the power to adopt, amend or repeal
the Bylaws of this corporation subject to approval by a majority of the
Continuing Directors (as defined in Article 14); provided, however, the Board of
Directors may not repeal or amend any bylaw that the shareholders have expressly
provided may not be amended or repealed by the Board of Directors. The
shareholders shall also have the power to adopt, amend or repeal the Bylaws of
this corporation by the affirmative vote of the holders of not less than
two-thirds of the outstanding shares and, to the extent, if any, provided by
resolution or resolutions of the Board of Directors providing for the issue of a
series of Common or Preferred Stock, not 


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Restated Articles of Incorporation                                        Page 3


<PAGE>   4

less than two-thirds of the outstanding shares entitled to vote thereon, voting
as a class.

                     ARTICLE 8. REGISTERED OFFICE AND AGENT

        The name of the current registered agent of this corporation and the
address of its current registered office are as follows:

                                  John R. Wall
                              17769 N.E. 78th Place
                            Redmond, Washington 98052

                              ARTICLE 9. DIRECTORS

        The number of Directors of this corporation shall be determined in the
manner provided by the Bylaws and may be increased or decreased from time to
time in the manner provided therein. The Board of Directors shall be divided
into three classes, with said classes to be as equal in number as may be
possible, with any Director or Directors in excess of the number divisible by
three being assigned to Class 3 and Class 2, as the case may be. At the first
election of Directors to such classified Board of Directors, each Class 1
Director shall be elected to serve until the next ensuing annual meeting of
shareholders, each Class 2 Director shall be elected to serve until the second
ensuing annual meeting of shareholders and each Class 3 Director shall be
elected to serve until the third ensuing annual meeting of shareholders. At each
annual meeting of shareholders following the meeting at which the Board of
Directors is initially classified, the number of Directors equal to the number
of Directors in the class whose term expires at the time of such meeting shall
be elected to serve until the third ensuing annual meeting of shareholders.
Notwithstanding any of the foregoing provisions of this Article 9, Directors
shall serve until their successors are elected and qualified or until their
earlier death, resignation or removal from office, or until there is a decrease
in the number of Directors.

        The Directors of this corporation may be removed only for cause by the
holders of not less than two-thirds of the shares entitled to elect the Director
or Directors whose removal is sought in the manner provided by the Bylaws.

                   ARTICLE 10. AMENDMENTS TO ARTICLES OF INCORPORATION

        This corporation reserves the right to amend or repeal, by the
affirmative vote of the holders of two-thirds of the outstanding shares and, to
the extent, if any, provided by resolution or resolutions of the Board of
Directors providing for the issue of a series of Common or Preferred stock,
two-


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Restated Articles of Incorporation                                        Page 4

<PAGE>   5

thirds of the outstanding shares entitled to vote thereon, voting as a class,
any of the provisions contained in these Articles of Incorporation; provided
that Article 1 ("Name"), Article 2 ("Duration"), Article 3 ("Purposes and
Powers"), Article 4 ("Shares"), Article 8 ("Registered Office and Agent") and
Article 11 ("Incorporator") may be amended in any manner now or hereafter
permitted by law. The rights of the shareholders of this corporation are granted
subject to this reservation; provided, however, that the holders of the
outstanding shares of a class shall be entitled to vote as a class upon a
proposed amendment if the amendment would increase or decrease the aggregate
number of authorized shares of such class, increase or decrease the par value of
the shares of such class, or alter or change the powers, preferences or special
rights of the shares of such class so as to affect them adversely. If any
proposed amendment would alter or change the powers, preferences or special
rights of one or more series of any class so as to affect them adversely, but
shall not affect the entire class, then only the shares of the series so
affected by the amendment shall be considered as a separate class for the
purposes of this Article 10. Irrespective of the provisions of this Article 10,
the number of authorized shares of any such class or classes of stock may be
increased by the affirmative vote of the holders of two-thirds of the stock of
this corporation entitled to vote thereon or decreased (but not below the number
of shares thereof then outstanding) by the affirmative vote of the holders of a
majority of the stock of this corporation entitled to vote thereon, if so
provided in any amendment which created such class or classes of stock or which
was adopted prior to the issuance of any shares of such class or classes of
stock, or in any amendment which was authorized by a resolution or resolutions
adopted by the affirmative vote of the holders of two-thirds of such class or
classes of stock.

                            ARTICLE 11. INCORPORATOR

        The name and address of the incorporator are as follows:

                              Charles J. Katz, Jr.
                          1201 Third Avenue, 40th Floor
                         Seattle, Washington 98101-3099

                  ARTICLE 12. LIMITATION OF DIRECTOR LIABILITY

        To the full extent that the Washington Business Corporation Act, as it
exists on the date hereof or may hereafter be amended, permits the limitation or
elimination of the liability of Directors, a Director of this corporation shall
not be liable to this corporation or its shareholders for monetary damages for
conduct as a Director. Any 


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Restated Articles of Incorporation                                        Page 5

<PAGE>   6

amendments to or repeal of this Article 12 shall not adversely affect any right
or protection of a Director of this corporation for or with respect to any acts
or omissions of such Directors occurring prior to such amendment or repeal.

                  ARTICLE 13. SPECIAL MEETINGS OF SHAREHOLDERS

        The Chairman of the Board of Directors, the President or the Board of
Directors may call special meetings of the shareholders for any purpose.
Further, a special meeting of the shareholders shall be held if the holders of
not less than twenty-five percent (25%) of all the votes entitled to be cast on
any issue proposed to be considered at such special meeting have dated, signed
and delivered to the Secretary one or more written demands for such meeting,
describing the purpose or purposes for which it is to be held; provided,
however, that upon qualification of the corporation as a "public company" under
Title 23B RCW the percentage of votes required to call a special meeting shall
be thirty percent (30%).

                     ARTICLE 14. SPECIAL VOTING REQUIREMENTS

        In addition to any affirmative vote required by law, these Articles of
Incorporation or otherwise, any "Business Combination" (as hereinafter defined)
involving this corporation shall be subject to approval in the manner set forth
in this Article 14.

        14.1  DEFINITIONS.

        For the purposes of this Article 14:

        (a) "Business Combination" means (i) a merger, share exchange or
consolidation of this corporation or any of its Subsidiaries with any other
corporation; (ii) the sale, lease, exchange, mortgage, pledge, transfer or other
disposition or encumbrance, whether in one transaction or a series of
transactions, by this corporation or any of its Subsidiaries of all or a
substantial part of the corporation's assets otherwise than in the usual and
regular course of business, or (iii) any agreement, contract or other
arrangement providing for any of the foregoing transactions.

        (b) "Continuing Director" means any member of the Board of Directors who
was a member of the Board of Directors on January 28, 1993 or who is elected to
the Board of Directors after January 28, 1993 upon the recommendation of a
majority of the Continuing Directors voting separately and as a subclass of
Directors on such recommendation.


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Restated Articles of Incorporation                                        Page 6

<PAGE>   7

        (c) "Subsidiary" means a domestic or foreign corporation that has a
majority of its outstanding voting shares owned, directly or indirectly, by this
corporation.

        14.2  VOTE REQUIRED FOR BUSINESS COMBINATIONS.

        14.2.1 Except as provided in subsection 14.2.2 of this Article 14, the
affirmative vote of not less than two-thirds of the outstanding shares and, to
the extent, if any, provided by resolution or resolutions of the Board of
Directors providing for the issue of a series of Common or Preferred Stock, not
less than two-thirds of the outstanding shares entitled to vote thereon, voting
as a class, shall be required for the adoption or authorization of a Business
Combination.

        14.2.2 Notwithstanding subsection 14.2.1 of this Article 14, if a
Business Combination shall have been approved by a majority of the Continuing
Directors, voting separately and as a subclass of Directors, and is otherwise
required by law to be approved by this corporation's shareholders, such Business
Combination shall require the affirmative vote of not less than fifty-one
percent (51%) of the outstanding shares entitled to vote thereon and, to the
extent, if any, provided by resolution or resolutions of the Board of Directors
providing for the issue of a series of Common or Preferred Stock, not less than
fifty-one percent (51%) of the outstanding shares of such series, voting as a
class; provided, however, if a Business Combination approved by a majority of
the Continuing Directors is not otherwise required by law to be approved by this
corporation's shareholders, then no vote of the shareholders of this corporation
shall be required.

        These Restated Articles of Incorporation do not further amend the
Articles of Incorporation.

        These Restated Articles of Incorporation are executed by said
corporation by its duly authorized officer.

        DATED:  March 15, 1993

                                      WALL DATA INCORPORATED



                                      By  /s/ John R. Wall
                                          -------------------------------------
                                          John R. Wall
                                          Its Executive Vice President


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Restated Articles of Incorporation                                        Page 7

<PAGE>   8

                           ARTICLES OF SHARE EXCHANGE

                             WALL DATA INCORPORATED

                                       AND

                              CAPELLA SYSTEMS, INC.


        Pursuant to the provisions of RCW 23B.11.050, the following Articles of
Share Exchange are executed for the purpose of effecting the acquisition of all
of the outstanding shares of stock of Capella Systems, Inc., a Georgia
corporation, by Wall Data Incorporated, a Washington corporation.

        1. The Plan of Share Exchange approved by the Board of Directors of Wall
Data Incorporated is attached hereto as Exhibit A.

        2. Approval of the Plan of Exchange by the shareholders of Wall Data
Incorporated was not required.

        Dated:  September 09, 1993.


                                      WALL DATA INCORPORATED



                                      By  /s/ James Simpson
                                          --------------------------------------
                                          James Simpson
                                          President





                                                                          Page 1
<PAGE>   9
                                                                       EXHIBIT A

                         WALL DATA ARTICLES OF EXCHANGE


        THIS PLAN OF SHARE EXCHANGE ("Plan") is entered into as of August 17,
1993, by and between Wall Data Incorporated, a Washington corporation, and
Capella Systems, Inc., a Georgia corporation, sometimes collectively referred to
in this Plan as the "Constituent Corporations".


                                    RECITALS

        A. The name of the corporation whose shares will be acquired is Capella
Systems, Inc. ("Capella" or the "Company").

        B. The name of the acquiring corporation is Wall Data Incorporated (the
"Acquiring Corporation").

        C. The Acquiring Corporation, Capella and certain shareholders of
Capella have entered into an Agreement and Plan of Share Exchange dated August
17, 1993 (the "Agreement"), and Capella and the Acquiring Corporation have
deemed it advisable and in the best interests of Capella and the Acquiring
Corporation, respectively, and their respective shareholders, that all of the
outstanding shares of capital stock of Capella be exchanged for shares of common
stock of the Acquiring Corporation (the "Exchange"), and for the Acquiring
Corporation thereby to acquire all outstanding capital stock of Capella, as
authorized by the laws of the State of Washington ("Washington Law") and the
State of Georgia ("Georgia Law") and pursuant to the terms and conditions of the
Agreement. Terms not otherwise defined herein shall have the meanings given to
them in the Agreement.


                                    AGREEMENT

        In consideration of the foregoing recitals, the covenants and conditions
set forth herein, and other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties agree as follows:

1.      EXCHANGE; EFFECTIVENESS

        All outstanding shares of capital stock of Capella shall be acquired by
the Acquiring Corporation pursuant to the applicable provisions of Washington
Law, Georgia Law and in accordance with the terms and conditions of this Plan
and the Agreement. Upon (a) the execution by the Acquiring Corporation of
Articles of Share Exchange incorporating this Plan and the filing of such
Articles of Share Exchange with the Secretary of State of the State of
Washington and (b) the execution by 

                                                                          Page 1

<PAGE>   10

Capella of Articles of Share Exchange incorporating this Plan and the filing of
such Articles of Share Exchange with the Secretary of State of the State of
Georgia, the Exchange shall become effective (the "Effective Time").

2.      CONVERSION OF SHARES

        (a) Each share (a "Common Share") of common stock of the Company (the
"Company Common Stock") outstanding immediately prior to the Effective Time,
other than Dissenting Shares (as defined in Section 1.5 of the Agreement), shall
be automatically exchanged at the Effective Time, by virtue of the Exchange and
without any action on the part of the holder thereof or any party hereto, into
the right to receive at the Effective Time (i) a number of shares of Wall Data
Common Stock equal to (A) .0521 multiplied by the Aggregate Stock Amount (as
defined in Section 1.3(e) of the Agreement), divided by (B) 2,550,000, and (ii)
an amount in cash equal to (A) .0521 multiplied by the Aggregate Cash
Consideration (as defined in subsection (e) of this Section 1.3), divided by (B)
2,550,000, such shares and such cash together being referred to herein as the
"Common Consideration."

        (b) Each share (a "Series A Preferred Share") of Series A Preferred
Stock of the Company (the "Series A Preferred Stock") outstanding immediately
prior to the Effective Time, other than Dissenting Shares, shall be
automatically exchanged at the Effective Time, by virtue of the Exchange and
without any action on the part of the holder thereof or any party hereto, into
the right to receive at the Effective Time, in respect of each Series A
Preferred Share outstanding immediately prior to the Effective Time, (i) a
number of shares of Wall Data Common Stock equal to (A) .2242 multiplied by the
Aggregate Stock Amount, divided by (B) 990,000, and (ii) an amount in cash equal
to (A) .2242 multiplied by the Aggregate Cash Consideration, divided by (B)
990,000, such shares and such cash together being referred to herein as the
"Series A Consideration."

        (c) Each share (a "Series B Preferred Share") of Series B Preferred
Stock of the Company (the "Series B Preferred Stock" and, together with the
Series A Preferred Stock, the "Company Preferred Stock") outstanding immediately
prior to the Effective Time, other than Dissenting Shares, shall be
automatically exchanged at the Effective Time, by virtue of the Exchange and
without any action on the part of the holder thereof or any party hereto, into
the right to receive at the Effective Time, in respect of each Series B
Preferred Share outstanding immediately prior to the Effective Time, (i) a
number of shares of Wall Data Common Stock equal to (A) .7237 multiplied by the
Aggregate Stock Amount, divided by (B) 6,390,000, and (ii) an amount in cash
equal to (A) .7237 


                                                                          Page 2
<PAGE>   11

multiplied by the Aggregate Cash Consideration, divided by (B) 6,390,000, such
shares and such cash together being referred to herein as the "Series B
Consideration."

        (d) The Board of Directors of the Company shall take such actions and
adopt such resolutions as are necessary (i) to cause all outstanding options,
warrants or other rights, if any, to purchase capital stock of the Company to
lapse, terminate or be exercised immediately prior to or at the Effective Time
and (ii) to cause 450,000 shares of Company Common Stock held by William Hiller
as of the date of this Agreement to be redeemed, repurchased or cancelled
immediately prior to the Closing, such that no more than 2,550,000 shares of
Company Common Stock will then be outstanding.

        (e) (i) The "Aggregate Cash Consideration" shall mean an amount in cash
equal to the number determined in clause (B) of subparagraph (ii) below
multiplied by the average of the high and low trading prices per share of Wall
Data Common Stock on the NASDAQ National Market System for the five trading days
immediately prior to the Closing Date.

               (ii) The "Aggregate Stock Amount" shall mean a number equal to
(A) 150,000, less a number equal to (1) the aggregate amount of consideration
payable in connection with the transactions specified in clause (i) of Section
1.3(d) of the Agreement plus the amount owing from the Company to King &
Spalding, the Company's legal counsel, in respect of fees and expenses
associated with the transactions contemplated hereby, as specified on an invoice
to be delivered by King & Spalding at the Closing, divided by (2) the average of
the high and low trading prices per share of Wall Data Common Stock on the
NASDAQ National Market System for the five trading days immediately prior to the
Closing Date, less (B) one percent (1%) of the number determined pursuant to the
preceding clause (A).

        (f) Appropriate adjustments to the provisions of subsections (a), (b)
and (c) of Section 1.3 of the Agreement will be made in the event that any
Series A Preferred Shares or Series B Preferred Shares are converted into
Company Common Stock after the date of this Agreement but prior to the Effective
Time.

        (g) The Acquiring Corporation shall be deemed to be the holder of all
outstanding shares of Company Common Stock and Company Preferred Stock and shall
have the right to receive stock certificates representing such stock.



<PAGE>   12

                                                                          Page 3
3.      IMPLEMENTATION

        Each of the Constituent Corporations shall take, or cause to be taken,
all action or do, or cause to be done, all things necessary, proper or advisable
under Washington Law and Georgia Law to consummate and make effective the
Exchange.

4.      TERMINATION

        This Plan may be terminated for any reason at any time before the filing
of Articles of Share Exchange with the Secretary of State of the State of
Washington or the State of Georgia (whether before or after approval by the
shareholders of Capella) by resolution of the Board of Directors of both of the
Constituent Corporations.

5.      AMENDMENT

        This Plan may, to the extent permitted by law, be amended, supplemented
or interpreted at any time by action taken by the Board of Directors of both of
the Constituent Corporations; provided, however, that this Plan may not be
amended or supplemented after having been approved by the shareholders of
Capella except by a vote or consent of shareholders of Capella in accordance
with applicable law.

        IN WITNESS WHEREOF, the parties hereto have duly executed and delivered
this Wall Data Articles Of Exchange as of the date first set forth above.

                                      WALL DATA INCORPORATED


                                      By /s/James Simpson
                                         --------------------------------------
                                         James Simpson
                                         President



                                      CAPELLA SYSTEMS, INC.


                                      By /s/ James F. Ottinger
                                         ---------------------------------------
                                         James F. Ottinger, President


                                         /s/ James F. Ottinger
                                         ---------------------------------------
                                         James F. Ottinger


                                         /s/ William Hiller
                                         ---------------------------------------
                                         William Hiller



                                                                          Page 4


<PAGE>   13

                               ARTICLES OF MERGER

                             WALL DATA INCORPORATED

                                       AND

                              CAPELLA SYSTEMS, INC.


        Pursuant to the provisions of RCW 23B.11.040, the following Articles of
Merger are executed for the purpose of merging Capella Systems, Inc., a Georgia
corporation, into Wall Data Incorporated, a Washington corporation.

        1. The Plan of Merger approved by the Board of Directors of Wall Data
Incorporated is attached hereto as Exhibit A.

        2. Approval of the Plan of Merger by the shareholders of Wall Data
Incorporated was not required.

        3. These Articles of Merger shall be effective on December 31, 1993.

        Dated:  December 16, 1993.

                                      WALL DATA INCORPORATED



                                      By  /s/ Angelo F. Grestoni
                                          --------------------------------------
                                          Angelo F. Grestoni
                                          Vice President, Finance & 
                                          Administration


--------------------------------------------------------------------------------

<PAGE>   14
                                                                       Exhibit A


                                 PLAN OF MERGER
                                     BETWEEN
                              CAPELLA SYSTEMS, INC.
                             (A GEORGIA CORPORATION)
                                       AND
                             WALL DATA INCORPORATED
                           (A WASHINGTON CORPORATION)

                                   DATED AS OF
                                DECEMBER 31, 1993



<PAGE>   15


                                 PLAN OF MERGER

        This PLAN OF MERGER (the "Plan") dated as of December 31, 1993, provides
for the merger of Capella Systems, Inc., a Georgia corporation (the "Georgia
Company"), into Wall Data Incorporated, a Washington corporation (the
"Washington Company"). The Georgia Company and the Washington Company are
sometimes collectively referred to in this Plan as the "Constituent
Corporations."

                                    RECITALS

        A. The Georgia Company is a corporation organized and existing under the
laws of the State of Georgia, with its principal office in Atlanta, Georgia. The
authorized capital stock of the Georgia Company consists of 25,000,000 shares of
common stock having no stated par value, of which 2,550,000 shares have been
duly issued and are outstanding on the date hereof, 1,500,000 shares of Series A
preferred stock having no stated par value, of which 990,000 shares have been
duly issued and are outstanding on the date hereof, and 7,200,000 shares of
Series B preferred stock having no stated par value, of which 6,390,000 shares
have been duly issued and are outstanding on the date hereof. All of the capital
stock of the Georgia Company is held by the Washington Company.

        B. The Washington Company is a corporation organized and existing under
the laws of the State of Washington, with its principal office in Redmond,
Washington. The authorized capital stock of the Washington Company consists of
45,000,000 shares of common stock having no par value, of which 8,679,031 shares
were outstanding as of September 30, 1993, and 5,000,000 shares of preferred
stock having no par value, none of which shares are outstanding.

        C. The Georgia Company is a wholly-owned subsidiary of the Washington
Company.

        D. It is deemed advisable and in the best interests of each corporation
and the shareholders thereof that the Georgia Company be merged into the
Washington Company as authorized by the laws of the States of Georgia and
Washington and pursuant to the terms and conditions of this Plan.

                                      PLAN

        The Washington Company hereby adopts the following plan of merger:


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                                                                          Page 1
<PAGE>   16



1.      MERGER

        The Georgia Company be merged into the Washington Company (hereinafter
sometimes called the "Surviving Corporation") pursuant to Section 23B.11.040 of
the Revised Code of Washington, Section 14-2-1104 of the Georgia Business
Corporation Code and in accordance with the terms and conditions of this Plan.
Upon completion of the following events:

        (a) the approval of the plan of merger as stated herein by the Board of
Directors of the Washington Company, and

        (b) the execution in duplicate by the Surviving Corporation of Articles
of Merger incorporating this Plan, the filing of such Articles of Merger with
the Secretaries of State of the States of Georgia and Washington, the issuance
of appropriate certificates by such Secretaries of State, and the occurrence of
the "Effective Date" as defined below,

the merger shall be deemed effective and the "date of the merger" as that phrase
is used herein shall be the "Effective Date" set forth below.

2.      EFFECTIVE DATE

        As of December 31, 1993 (the "Effective Date"), the identity, existence,
purposes, powers, objects, franchises, privileges, rights and immunities of the
Washington Company continue in effect unimpaired by the merger; the corporate
franchises, existence and rights of the Georgia Company be merged into the
Washington Company and the Washington Company, as the Surviving Corporation, be
fully vested therewith; and the separate existence and corporate organization of
the Georgia Company, except as they may continue by statute, cease as of the
Effective Date.

3.      ARTICLES OF INCORPORATION

        The Articles of Incorporation of the Washington Company in effect on the
date of the merger be and remain the Articles of Incorporation of the Surviving
Corporation until the same shall be altered, amended or repealed as therein
provided.

4.      BYLAWS

        The Bylaws of the Washington Company in effect on the date of the merger
be and remain the Bylaws of the Surviving Corporation until the same shall be
altered, amended or repealed as therein provided.


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                                                                          Page 2
<PAGE>   17


5.      DIRECTORS AND OFFICERS

        The directors and officers of the Washington Company continue in office
as the directors and officers of the Surviving Corporation and hold office in
accordance with and subject to the Articles of Incorporation and Bylaws of the
Surviving Corporation.

6.      CANCELLATION OF SHARES OF GEORGIA COMPANY

        On the Effective Date of the merger, by virtue of the merger and without
any action on the part of the holder of any shares of stock of the Georgia
Company, all issued and outstanding shares of capital stock of the Georgia
Company that are owned directly or indirectly by the Washington Company shall be
canceled and no consideration shall be delivered in exchange therefor.

7.      RIGHTS, DUTIES, POWERS, LIABILITIES, ETC.

        On the Effective Date of the merger, the separate existence of the
Georgia Company cease, and the Georgia Company shall be merged in accordance
with the provisions of this Plan into the Surviving Corporation which shall
possess all the properties and assets, and all the rights, privileges, powers,
immunities and franchises, of whatever nature and description, and shall be
subject to all restrictions, disabilities, duties and liabilities, of each of
the Constituent Corporations; and all such things shall be taken and deemed to
be transferred to and vested in the Surviving Corporation without further act or
deed; and the title to any real estate, or any interest therein, vested by deed
or otherwise in either of the Constituent Corporations, shall not revert or be
in any way impaired by reason of such merger, but shall pass to and be owned by
the Surviving Corporation without further act or deed. Any claim existing or
action or proceeding, whether civil, criminal or administrative, pending by or
against either Constituent Corporation, may be prosecuted to judgment or decree
as if such merger had not taken place, and the Surviving Corporation may be
substituted in any such action or proceeding.

8.      IMPLEMENTATION

        (a) At any time or from time to time as and when requested by the
Surviving Corporation, or by its successors or assigns, each Constituent
Corporation will so far as it is legally able, execute and deliver, or cause to
be executed and delivered in its name by its last acting officers, or by the
corresponding officers of the Surviving Corporation, each of whom is hereby
irrevocably appointed as attorney-in-fact for such purposes, all such
conveyances, assignments, transfers, 

--------------------------------------------------------------------------------
                                                                          Page 3
<PAGE>   18


deeds or other instruments, and will take or cause to be taken such further or
other actions as the Surviving Corporation, its successors or assigns, may deem
necessary or desirable in order to evidence the transfer, vesting and devolution
of any property, right, privilege, power, immunity or franchise to vest or
perfect in or confirm to the Surviving Corporation, its successors or assigns,
title to and possession of all the property, rights, privileges, powers,
immunities, franchises and interests referred to in this Plan and otherwise to
carry out the intent and purposes hereof.

        (b) Each of the Constituent Corporations shall take, or cause to be
taken, all action or do, or cause to be done, all things necessary, proper or
advisable under the laws of the States of Georgia and Washington to consummate
and make effective the merger.

9.      TERMINATION

        This Plan may be terminated for any reason at any time before the filing
of Articles of Merger by the Secretaries of State of the States of Georgia and
Washington by resolution of the Board of Directors of the Washington Company.

10.     AMENDMENT

        This Plan may, to the extent permitted by law, be amended, supplemented
or interpreted at any time by action taken by the Board of Directors of the
Washington Company.

        Dated as of December 31, 1993.

                                      WALL DATA INCORPORATED


                                      By /s/ Angelo F. Grestoni
                                         --------------------------------------
                                         Angelo F. Grestoni
                                         Vice President, Finance &
                                           Administration

--------------------------------------------------------------------------------
                                                                          Page 4
<PAGE>   19

                              ARTICLES OF AMENDMENT
                                       OF
                             WALL DATA INCORPORATED



        Pursuant to RCW 23B.06.020, the following Articles of Amendment are
executed by the undersigned, a Washington corporation:

        1. The name of the corporation is Wall Data Incorporated.

        2. Effective upon filing these Articles of Amendment with the Secretary
of State of the State of Washington, Article 4 of the Restated Articles of
Incorporation of the corporation is amended to add a new Subsection 4.8 as set
forth on Exhibit A attached hereto.

        3. The amendment was duly adopted by the Board of Directors of the
corporation on July 18, 1995 and shareholder approval was not required.

        These Articles of Amendment are executed by said corporation by its duly
authorized officer.

        DATED:  July 18, 1995.



                                            WALL DATA INCORPORATED



                                            By: /s/ Alexandra A. Brookshire
                                                --------------------------------
                                                Alexandra A. Brookshire



<PAGE>   20




                                                                       Exhibit A


        4.8    DESIGNATION OF RIGHTS AND PREFERENCES OF SERIES A JUNIOR
               PARTICIPATING PREFERRED STOCK

        The following series of Preferred Stock is hereby designated, which
series shall have the rights, preferences, privileges and limitations as set
forth below:

        4.8.1. Designation of Series A Junior Participating Preferred Stock and
Amount. The shares of such series shall be designated as "Series A Junior
Participating Preferred Stock" (the "Series A Preferred Stock") and the number
of shares constituting the Series A Preferred Stock shall be 450,000. Such
number of shares may be increased or decreased by resolution of the Board of
Directors; provided, however, that no decrease shall reduce the number of shares
of Series A Preferred Stock to a number less than the number of shares then
outstanding plus the number of shares reserved for issuance upon the exercise of
outstanding options, rights or warrants or upon the conversion of any
outstanding securities issued by the corporation convertible into Series A
Preferred Stock.

        4.8.2. Dividends and Distributions.

               (A) Subject to the rights of the holders of any shares of any
series of Preferred Stock (or any similar stock) ranking prior and superior to
the Series A Preferred Stock with respect to dividends, the holders of shares of
Series A Preferred Stock, in preference to the holders of Common Stock, no par
value per share (the "Common Stock"), of the corporation, and of any other
junior stock, shall be entitled to receive, when, as and if declared by the
Board of Directors out of funds legally available for the purpose, quarterly
dividends payable in cash on the first day of March, June, September and
December in each year (each such date being referred to herein as a "Quarterly
Dividend Payment Date"), commencing on the first Quarterly Dividend Payment Date
after the first issuance of a share or fraction of a share of Series A Preferred
Stock, in an amount per share (rounded to the nearest cent) equal to the greater
of (i) $1 and (ii) subject to the provision for adjustment hereinafter set
forth, 100 times the aggregate per share amount of all cash dividends, and 100
times the aggregate per share amount (payable in kind) of all non-cash dividends
or other distributions, other than a dividend payable in shares of Common Stock
or a subdivision of the outstanding shares of Common Stock (by reclassification
or otherwise), declared on the Common Stock since the immediately preceding
Quarterly Dividend Payment Date or, with respect to the first Quarterly Dividend
Payment Date, since the first issuance of any share or fraction of a share of
Series A Preferred Stock. 

                                                                               1
<PAGE>   21


In the event the corporation shall at any time declare or pay any dividend on
the Common Stock payable in shares of Common Stock, or effect a subdivision or
combination or consolidation of the outstanding shares of Common Stock (by
reclassification or otherwise than by payment of a dividend in shares of Common
Stock) into a greater or lesser number of shares of Common Stock, then in each
such case the amount to which holders of shares of Series A Preferred Stock were
entitled immediately prior to such event under clause (ii) of the preceding
sentence shall be adjusted by multiplying such amount by a fraction, the
numerator of which is the number of shares of Common Stock outstanding
immediately after such event and the denominator of which is the number of
shares of Common Stock that were outstanding immediately prior to such event.

               (B) The corporation shall declare a dividend or distribution on
the Series A Preferred Stock as provided in paragraph (A) of this Section 4.8.2
immediately after it declares a dividend or distribution on the Common Stock
(other than a dividend payable in shares of Common Stock); provided, however,
that, in the event no dividend or distribution shall have been declared on the
Common Stock during the period between any Quarterly Dividend Payment Date and
the next subsequent Quarterly Dividend Payment Date, a dividend of $1 per share
on the Series A Preferred Stock shall nevertheless be payable on such subsequent
Quarterly Dividend Payment Date.

               (C) Dividends shall begin to accrue and be cumulative on
outstanding shares of Series A Preferred Stock from the Quarterly Dividend
Payment Date next preceding the date of issue of such shares, unless the date of
issue of such shares is prior to the record date for the first Quarterly
Dividend Payment Date, in which case dividends on such shares shall begin to
accrue from the date of issue of such shares, or unless the date of issue is a
Quarterly Dividend Payment Date or is a date after the record date for the
determination of holders of shares of Series A Preferred Stock entitled to
receive a quarterly dividend and before such Quarterly Dividend Payment Date, in
either of which events such dividends shall begin to accrue and be cumulative
from such Quarterly Dividend Payment Date. Accrued but unpaid dividends shall
not bear interest. Dividends paid on the shares of Series A Preferred Stock in
an amount less than the total amount of such dividends at the time accrued and
payable on such shares shall be allocated pro rata on a share-by-share basis
among all such shares at the time outstanding. The Board of Directors may fix a
record date for the determination of holders of shares of Series A Preferred
Stock entitled to receive payment of a dividend or distribution declared
thereon, which record date shall be not more than 60 days prior to the date
fixed for the payment thereof.


                                                                               2

<PAGE>   22

        4.8.3. Voting Rights. The holders of shares of Series A Preferred Stock
shall have the following voting rights:

               (A) Subject to the provision for adjustment hereinafter set
forth, each share of Series A Preferred Stock shall entitle the holder thereof
to 100 votes on all matters submitted to a vote of the shareholders of the
corporation. In the event the corporation shall at any time declare or pay any
dividend on the Common Stock payable in shares of Common Stock, or effect a
subdivision or combination or consolidation of the outstanding shares of Common
Stock (by reclassification or otherwise than by payment of a dividend in shares
of Common Stock) into a greater or lesser number of shares of Common Stock, then
in each such case the number of votes per share to which holders of shares of
Series A Preferred Stock were entitled immediately prior to such event shall be
adjusted by multiplying such number by a fraction, the numerator of which is the
number of shares of Common Stock outstanding immediately after such event and
the denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.

               (B) Except as otherwise provided herein, in any other Articles of
Amendment creating a series of Preferred Stock or any similar stock, or by law,
the holders of shares of Series A Preferred Stock and the holders of shares of
Common Stock and any other capital stock of the corporation having general
voting rights shall vote together as one class on all matters submitted to a
vote of shareholders of the corporation.

               (C) Except as set forth herein, or as otherwise provided by law,
holders of Series A Preferred Stock shall have no special voting rights and
their consent shall not be required (except to the extent they are entitled to
vote with holders of Common Stock as set forth herein) for taking any corporate
action.

        4.8.4. Certain Restrictions.

               (A) Whenever quarterly dividends or other dividends or
distributions payable on the Series A Preferred Stock as provided in Section
4.8.2 are in arrears, thereafter and until all accrued and unpaid dividends and
distributions, whether or not declared, on shares of Series A Preferred Stock
outstanding shall have been paid in full, the corporation shall not:

                       (i) declare or pay dividends, or make any other
        distributions, on any shares of stock ranking junior (either as to
        dividends or upon liquidation, dissolution or winding up) to the Series
        A Preferred Stock;


                                                                               3
<PAGE>   23

                      (ii) declare or pay dividends, or make any other
        distributions, on any shares of stock ranking on a parity (either as to
        dividends or upon liquidation, dissolution or winding up) with the
        Series A Preferred Stock, except dividends paid ratably on the Series A
        Preferred Stock and all such parity stock on which dividends are payable
        or in arrears in proportion to the total amounts to which the holders of
        all such shares are then entitled;

                     (iii) redeem or purchase or otherwise acquire for
        consideration shares of any stock ranking junior (either as to dividends
        or upon liquidation, dissolution or winding up) to the Series A
        Preferred Stock, provided that the corporation may at any time redeem,
        purchase or otherwise acquire shares of any such junior stock in
        exchange for shares of any stock of the corporation ranking junior
        (either as to dividends or upon dissolution, liquidation or winding up)
        to the Series A Preferred Stock; or

                      (iv) redeem or purchase or otherwise acquire for
        consideration any shares of Series A Preferred Stock, or any shares of
        stock ranking on a parity with the Series A Preferred Stock, except in
        accordance with a purchase offer made in writing or by publication (as
        determined by the Board of Directors) to all holders of such shares upon
        such terms as the Board of Directors, after consideration of the
        respective annual dividend rates and other relative rights and
        preferences of the respective series and classes, shall determine in
        good faith will result in fair and equitable treatment among the
        respective series or classes.

               (B) The corporation shall not permit any subsidiary of the
corporation to purchase or otherwise acquire for consideration any shares of
stock of the corporation unless the corporation could, under paragraph (A) of
this Section 4.8.4, purchase or otherwise acquire such shares at such time and
in such manner.

        4.8.5. Reacquired Shares. Any shares of Series A Preferred Stock
purchased or otherwise acquired by the corporation in any manner whatsoever
shall be retired and cancelled promptly after the acquisition thereof. All such
shares shall upon their cancellation become authorized but unissued shares of
Preferred Stock and may be reissued as part of a new series of Preferred Stock
subject to the conditions and restrictions on issuance set forth herein, in the
Articles of Incorporation, or in any other Articles of Amendment creating a
series of Preferred Stock or any similar stock or as otherwise required by law.

        4.8.6. Liquidation, Dissolution or Winding Up. Upon any liquidation,
dissolution or winding up of the corporation, no distribution shall be made (a)
to the 

                                                                               4
<PAGE>   24

holders of shares of stock ranking junior (either as to dividends or upon
liquidation, dissolution or winding up) to the Series A Preferred Stock unless,
prior thereto, the holders of shares of Series A Preferred Stock shall have
received $100 per share, plus an amount equal to accrued and unpaid dividends
and distributions thereon, whether or not declared, to the date of such payment,
provided that the holders of shares of Series A Preferred Stock shall be
entitled to receive an aggregate amount per share, subject to the provision for
adjustment hereinafter set forth, equal to 100 times the aggregate amount to be
distributed per share to holders of shares of Common Stock, or (b) to the
holders of shares of stock ranking on a parity (either as to dividends or upon
liquidation, dissolution or winding up) with the Series A Preferred Stock,
except distributions made ratably on the Series A Preferred Stock and all such
parity stock in proportion to the total amounts to which the holders of all such
shares are entitled upon such liquidation, dissolution or winding up. In the
event the corporation shall at any time declare or pay any dividend on the
Common Stock payable in shares of Common Stock, or effect a subdivision or
combination or consolidation of the outstanding shares of Common Stock (by
reclassification or otherwise than by payment of a dividend in shares of Common
Stock) into a greater or lesser number of shares of Common Stock, then in each
such case the aggregate amount to which holders of shares of Series A Preferred
Stock were entitled immediately prior to such event under the proviso in clause
(a) of the preceding sentence shall be adjusted by multiplying such amount by a
fraction the numerator of which is the number of shares of Common Stock
outstanding immediately after such event and the denominator of which is the
number of shares of Common Stock that were outstanding immediately prior to such
event.

        4.8.7. Consolidation, Merger, etc. In case the corporation shall enter
into any consolidation, merger, combination or other transaction in which the
shares of Common Stock are exchanged for or changed into other stock or
securities, cash and/or any other property, then in any such case each share of
Series A Preferred Stock shall at the same time be similarly exchanged or
changed into an amount per share, subject to the provision for adjustment
hereinafter set forth, equal to 100 times the aggregate amount of stock,
securities, cash and/or any other property (payable in kind), as the case may
be, into which or for which each share of Common Stock is changed or exchanged.
In the event the corporation shall at any time declare or pay any dividend on
the Common Stock payable in shares of Common Stock, or effect a subdivision or
combination or consolidation of the outstanding shares of Common Stock (by
reclassification or otherwise than by payment of a dividend in shares of Common
Stock) into a greater or lesser number of shares of Common Stock, then in each
such case the amount set forth in the preceding sentence with respect to the
exchange or change of shares of Series A Preferred Stock shall be adjusted by
multiplying such amount by a fraction, the numerator of which is the number of

                                                                               5
<PAGE>   25

shares of Common Stock outstanding immediately after such event and the
denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.

        4.8.8. No Redemption. The shares of Series A Preferred Stock shall not
be redeemable.

        4.8.9. Rank. The Series A Preferred Stock shall rank, with respect to
the payment of dividends and the distribution of assets, junior to all series of
any other class of the corporation's Preferred Stock.

        4.8.10. Amendment. The Articles of Incorporation of the corporation
shall not be amended in any manner that would materially alter or change the
powers, preferences or special rights of the Series A Preferred Stock so as to
affect them adversely without the affirmative vote of the holders of at least
two-thirds of the outstanding shares of Series A Preferred Stock, voting
together as a single class.


                                                                               6

<PAGE>   26

                               ARTICLES OF MERGER

                          CONCENTRIC DATA SYSTEMS, INC

                                       AND

                             WALL DATA INCORPORATED

        Pursuant to the provisions of RCW 23B.11.050, the following Articles of
Merger are executed for the purpose of merging Concentric Data Systems, Inc., a
Massachusetts corporation (the "Disappearing Corporation"), into Wall Data
Incorporated, a Washington Corporation (the "Surviving Corporation").

        1. The Agreement and Plan of Merger approved by the Board of Directors
of the Surviving Corporation is attached hereto as EXHIBIT A.

        2. The Plan of Merger was duly approved by the Board of Directors of the
Surviving Corporation and, pursuant to RCW 23B.11.040, shareholder approval was
not required.

        Dated: December 29, 1997

                                            WALL DATA INCORPORATED



                                            By: /s/ Alexandra A. Brookshire
                                                --------------------------------
                                                Alexandra A. Brookshire
                                                Vice President, General Counsel 
                                                and Secretary


                                       1

<PAGE>   27

                                                                       Exhibit A

                                 PLAN OF MERGER

                                     BETWEEN

                             WALL DATA INCORPORATED

                                       AND

                          CONCENTRIC DATA SYSTEMS, INC.

        This Agreement and Plan of Merger (this "Agreement") is entered into
this ___ day of December, 1997, by and between Wall Data Incorporated, a
Washington corporation ("Wall Data"), and Concentric Data Systems, Inc., a
Massachusetts corporation ("Concentric"). Wall Data and Concentric are sometimes
referred to jointly as the "Constituent Corporations".

                                    RECITALS

        A. Each of the Constituent Corporations is a corporation organized and
existing under the laws of its respective state as indicated in the first
paragraph of this Agreement.

        B. Wall Data owns 100% of the outstanding stock of Concentric.

        C. The directors of Wall Data have deemed it advisable for the benefit
of the Wall Data and its shareholders that Concentric be merged into Wall Data
pursuant to the provisions of the Washington Business Corporation Act, Section
23B.11.040, and the Massachusetts Business Corporation Law, Chapter 156B,
Section 82 (the "Merger").

                                    AGREEMENT

        NOW, THEREFORE, in accordance with the laws of the states of Washington
and Massachusetts, the Constituent Corporations agree that, (i) Concentric shall
be merged into Wall Data, (ii) Wall Data shall continue to be governed by the
laws of the state of Washington, and (iii) the terms of the Merger, and the mode
of carrying them into effect, shall be as follows:

1.      MERGER

        1.1 Articles of Merger shall be filed with the Secretary of State of the
state of Massachusetts and Articles of Merger and this Agreement with the
Secretary of State of the state of Washington.

        1.2 The Merger shall become effective at 5:00 p.m. (Pacific Time) on
December 31, 1997 (the "Effective Time of Merger").


<PAGE>   28

        1.3 At the Effective Time of Merger, Concentric shall be merged into
Wall Data (the "Surviving Corporation") and the separate corporate existence of
Concentric shall thereupon cease.

2.      ARTICLES OF WALL DATA

        The Articles of Incorporation of Wall Data as in effect prior to the
Effective Time of the Merger shall constitute the "Articles" of the Surviving
Corporation within the meaning of Section 23B.01.400(1) of the Washington
Business Corporation Act.

3.      BYLAWS

        The Bylaws of Wall Data in effect at the Effective Time of Merger shall
be and remain the Bylaws of the Surviving Corporation until the same shall be
altered, amended or repealed as therein provided.

4.      DIRECTORS AND OFFICERS

        The directors of Wall Data shall continue in office as the directors of
the Surviving Corporation, and the officers of Wall Data shall continue in
office as the officers of the Surviving Corporation, and such directors and
officers shall hold office in accordance with and subject to the Articles of
Incorporation and Bylaws of the Surviving Corporation.

5.      CANCELLATION OF SHARES

        At the Effective Time of Merger, each outstanding share of the common
stock of Concentric shall automatically be canceled.

6.      EFFECT OF THE MERGER

        6.1 RIGHTS, PRIVILEGES, ETC. The effect of the Merger shall be as
provided by the applicable provisions of the laws of Washington and
Massachusetts. Without limiting the generality of the foregoing, and subject
thereto, at the Effective Time of the Merger: the separate existence of
Concentric shall cease; the Surviving Corporation shall possess all assets and
property of every description, and every interest therein, wherever located, and
the rights, privileges, immunities, powers, franchises and authority, of a
public as well as a private nature, of each of the Constituent Corporations; all
obligations belonging to or due either of the Constituent Corporations shall be
vested in, and become the obligations of, the Surviving Corporation without
further act or deed; title to any real estate or any interest therein shall not
revert or in any way be impaired by reason of the Merger, but shall pass and be
owned by the Surviving Corporation without further act or deed; all rights of
creditors and all liens upon any property of either of the Constituent
Corporations shall be preserved unimpaired; and the Surviving Corporation shall
be liable for all the obligations of the Constituent Corporations and any claim
existing, or action or proceeding pending, by or against either of the

                                      -2-
<PAGE>   29

Constituent Corporations may be prosecuted to judgment with right of appeal, as
if the Merger had not taken place.

        6.2 FURTHER ASSURANCES. If at any time after the Effective Time of the
Merger the Surviving Corporation shall consider it to be advisable that any
further conveyances, agreements, documents, instruments and assurances of law or
any other things are necessary or desirable to vest, perfect, confirm or record
in the Surviving Corporation the title to any property, rights, privileges,
powers and franchises of the Constituent Corporations or otherwise to carry out
the provisions of this Agreement, the proper directors and officers of the
Constituent Corporations last in office shall execute and deliver, upon the
Surviving Corporation's request, any and all proper conveyances, agreements,
documents, instruments and assurances of law, and do all things necessary or
proper to vest, perfect or confirm title to such property, rights, privileges,
powers and title to such property, rights, privileges, powers and franchises in
the Surviving Corporation, and otherwise to carry out the provisions of this
Agreement.

7.      TERMINATION

        This Agreement may be terminated and the Merger abandoned by direction
of an officer of Wall Data at any time prior to the Effective Time of the
Merger.

8.      NO THIRD-PARTY BENEFICIARIES

        Except as otherwise specifically provided herein, nothing expressed or
implied in this Agreement is intended, or shall be construed, to confer upon or
give any person, firm or corporation, other than the Constituent Corporations
and their respective shareholders, any rights or remedies under or by reason of
this Agreement.


                                      -3-
<PAGE>   30




        IN WITNESS WHEREOF, the parties hereto have caused this Plan and
Agreement of Merger to be executed as of the date first above written.

                                            WALL DATA INCORPORATED,
                                            a Washington corporation



                                            By: /s/ Alexandra A. Brookshire
                                                --------------------------------
                                                Alexandra A. Brookshire
                                                Vice President, General Counsel 
                                                and Secretary





                                            CONCENTRIC DATA SYSTEMS, INC.,
                                            a Massachusetts corporation


                                            By: /s/ Alexandra A. Brookshire
                                                --------------------------------
                                                Alexandra A. Brookshire
                                                Clerk

                                      -4-