<PAGE>
 
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                                                                     EXHIBIT 4.4

                           PLATINUM technology, inc.

                                    ISSUER,

                                      AND

             AMERICAN NATIONAL BANK AND TRUST COMPANY OF CHICAGO,

                                  AS TRUSTEE,

                                   INDENTURE

                         Dated as of November 18, 1996

                                 $100,000,000
                6 3/4% Convertible Subordinated Notes due 2001


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<PAGE>
 
                             TABLE OF CONTENTS
<TABLE> 
<CAPTION> 
                                                                            Page
<S>                                                                         <C>
1.   DEFINITIONS AND INCORPORATION BY REFERENCE............................   1
     1.1.  DEFINITIONS.....................................................   1
     1.2.  INCORPORATION BY REFERENCE OF TIA...............................   8
     1.3.  RULES OF CONSTRUCTION...........................................   8

2.   THE SECURITIES........................................................   9
     2.1.  FORM AND DATING.................................................   9
     2.2.  EXECUTION AND AUTHENTICATION....................................   9
     2.3.  REGISTRAR, PAYING AGENT AND DEPOSITARY..........................  11
     2.4.  PAYING AGENT TO HOLD ASSETS IN TRUST............................  12
     2.5.  SECURITY HOLDER LISTS...........................................  12
     2.6.  TRANSFER AND EXCHANGE...........................................  12
     2.7.  REPLACEMENT SECURITIES..........................................  15
     2.8.  OUTSTANDING SECURITIES..........................................  15
     2.9.  TREASURY SECURITIES.............................................  16
     2.10. TEMPORARY SECURITIES............................................  16
     2.11. CANCELLATION....................................................  16
     2.12. DEFAULTED INTEREST..............................................  17

3.   REDEMPTION............................................................  18
     3.1.  RIGHT OF REDEMPTION.............................................  18
     3.2.  NOTICES TO TRUSTEE..............................................  18
     3.3.  SELECTION OF SECURITIES TO BE REDEEMED..........................  18
     3.4.  NOTICE OF REDEMPTION............................................  19
     3.5.  EFFECT OF NOTICE OF REDEMPTION..................................  20
     3.6.  DEPOSIT OF REDEMPTION PRICE.....................................  20
     3.7.  SECURITIES REDEEMED IN PART.....................................  21

4.   COVENANTS.............................................................  21
     4.1.  PAYMENT OF SECURITIES...........................................  21
     4.2.  INTENTIONALLY OMITTED...........................................  21
     4.3.  CORPORATE EXISTENCE.............................................  21
     4.4.  PAYMENT OF TAXES AND OTHER CLAIMS...............................  21
     4.5.  MAINTENANCE OF PROPERTIES AND INSURANCE.........................  22
     4.6.  COMPLIANCE CERTIFICATE; NOTICE OF DEFAULT.......................  23
     4.7.  REPORTS.........................................................  23
     4.8.  LIMITATION ON STATUS AS INVESTMENT COMPANY......................  23
     4.9.  WAIVER OF STAY, EXTENSION OR USURY LAWS.........................  24

5.   SUCCESSOR CORPORATION.................................................  24
     5.1.  LIMITATION ON MERGER, SALE OR CONSOLIDATION.....................  24
     5.2.  SUCCESSOR CORPORATION SUBSTITUTED...............................  25

6.   EVENTS OF DEFAULT AND REMEDIES........................................  25
     6.1.  EVENTS OF DEFAULT...............................................  25
     6.2.  ACCELERATION OF MATURITY DATE; RESCISSION AND ANNULMENT.........  27
</TABLE> 
                                       i
<PAGE>
 
                               TABLE OF CONTENTS
                                  (continued)
<TABLE>
<CAPTION>
<S>        <C>                                                                          <C> 
     6.3.  COLLECTION OF INDEBTEDNESS AND SUITS FOR ENFORCEMENT BY TRUSTEE...............28
     6.4.  TRUSTEE MAY FILE PROOFS OF CLAIM..............................................29
     6.5.  TRUSTEE MAY ENFORCE CLAIMS WITHOUT POSSESSION OF SECURITIES...................29
     6.6.  PRIORITIES....................................................................30
     6.7.  LIMITATION ON SUITS...........................................................30
     6.8.  UNCONDITIONAL RIGHT OF HOLDERS TO RECEIVE PRINCIPAL, PREMIUM AND
           INTEREST......................................................................31
     6.9.  RIGHTS AND REMEDIES CUMULATIVE................................................31
     6.10. DELAY OR OMISSION NOT WAIVER..................................................31
     6.11. CONTROL BY HOLDERS............................................................32
     6.12. WAIVER OF PAST DEFAULT........................................................32
     6.13. UNDERTAKING FOR COSTS.........................................................32
     6.14. RESTORATION OF RIGHTS AND REMEDIES............................................33

7.   TRUSTEE.............................................................................33
     7.1.  RIGHTS OF TRUSTEE.............................................................34
     7.2.  INDIVIDUAL RIGHTS OF TRUSTEE..................................................35
     7.3.  TRUSTEE'S DISCLAIMER..........................................................35
     7.4.  DUTIES OF TRUSTEE.............................................................33
     7.5.  NOTICE OF DEFAULT.............................................................35
     7.6.  REPORTS BY TRUSTEE TO HOLDERS.................................................36
     7.7.  COMPENSATION AND INDEMNITY....................................................36
     7.8.  REPLACEMENT OF TRUSTEE........................................................37
     7.9.  SUCCESSOR TRUSTEE BY MERGER, ETC..............................................38
     7.10. ELIGIBILITY; DISQUALIFICATION.................................................38
     7.11. PREFERENTIAL COLLECTION OF CLAIMS AGAINST COMPANY.............................38

8.   SATISFACTION AND DISCHARGE..........................................................38
     8.1.  SATISFACTION AND DISCHARGE OF INDENTURE.......................................38
     8.2.  PAYMENT TO THE COMPANY........................................................39

9.   AMENDMENTS, SUPPLEMENTS AND WAIVERS.................................................39
     9.1.  SUPPLEMENTAL INDENTURES WITHOUT CONSENT OF HOLDERS............................39
     9.2.  AMENDMENTS, SUPPLEMENTAL INDENTURES AND WAIVERS WITH CONSENT OF HOLDERS.......40
     9.3.  COMPLIANCE WITH TIA...........................................................41
     9.4.  REVOCATION AND EFFECT OF CONSENTS.............................................41
     9.5.  NOTATION ON OR EXCHANGE OF SECURITIES.........................................42
     9.6.  TRUSTEE TO SIGN AMENDMENTS, ETC...............................................42

10.  RIGHT TO REQUIRE REPURCHASE UPON A CHANGE OF CONTROL................................42
     10.1. REPURCHASE OF SECURITIES AT OPTION OF THE HOLDER UPON A CHANGE OF CONTROL.....42

11.  SUBORDINATION.......................................................................45
     11.1. SECURITIES SUBORDINATED TO SENIOR INDEBTEDNESS................................45
     11.2. NO PAYMENT ON SECURITIES IN CERTAIN CIRCUMSTANCES.............................45
</TABLE> 
                                      ii
<PAGE>
 
                               TABLE OF CONTENTS
                                  (continued)
<TABLE>
<CAPTION>
<S>         <C>                                                                         <C> 
     11.3.  SECURITIES SUBORDINATED TO PRIOR PAYMENT OF ALL SENIOR INDEBTEDNESS
            ON DISSOLUTION, LIQUIDATION OR REORGANIZATION................................46
     11.4.  SECURITYHOLDERS TO BE SUBROGATED TO RIGHTS OF
            HOLDERS OF SENIOR INDEBTEDNESS...............................................47
     11.5.  OBLIGATIONS OF THE COMPANY UNCONDITIONAL.....................................48
     11.6.  TRUSTEE ENTITLED TO ASSUME PAYMENTS NOT PROHIBITED IN ABSENCE OF
            NOTICE.......................................................................48
     11.7.  APPLICATION BY TRUSTEE OF ASSETS DEPOSITED WITH IT...........................49
     11.8.  SUBORDINATION RIGHTS NOT IMPAIRED BY ACTS OR OMISSIONS OF THE
            COMPANY OR HOLDERS OF SENIOR INDEBTEDNESS....................................49
     11.9.  SECURITY HOLDERS AUTHORIZE TRUSTEE TO EFFECTUATE SUBORDINATION OF
            SECURITIES...................................................................49
     11.10. RIGHT OF TRUSTEE TO HOLD SENIOR INDEBTEDNESS.................................50
     11.11. ARTICLE 11 NOT TO PREVENT EVENTS OF DEFAULT..................................50
     11.12. NO FIDUCIARY DUTY OF TRUSTEE TO HOLDERS OF SENIOR INDEBTEDNESS...............50

12.  CONVERSION OF SECURITIES............................................................51
     12.1.  CONVERSION PRIVILEGE.........................................................51
     12.2.  EXERCISE OF CONVERSION PRIVILEGE.............................................51
     12.3.  FRACTIONAL INTERESTS.........................................................52
     12.4.  CONVERSION PRICE.............................................................53
     12.5.  ADJUSTMENT OF CONVERSION PRICE...............................................53
     12.6.  CONTINUATION OF CONVERSION PRIVILEGE IN CASE OF RECLASSIFICATION,
            CHANGE, MERGER, CONSOLIDATION OR SALE OF ASSETS..............................57
     12.7.  NOTICE OF CERTAIN EVENTS.....................................................58
     12.8.  TAXES ON CONVERSION..........................................................59
     12.9.  COMPANY TO PROVIDE STOCK.....................................................59
     12.10. DISCLAIMER OF RESPONSIBILITY FOR CERTAIN MATTERS.............................60
     12.11. RETURN OF FUND DEPOSITED FOR REDEMPTION OF CONVERTED SECURITIES..............60

13.  MISCELLANEOUS.......................................................................61
     13.1.  TIA CONTROLS.................................................................61
     13.2.  NOTICES......................................................................61
     13.3.  COMMUNICATIONS BY HOLDERS WITH OTHER HOLDERS.................................62
     13.4.  CERTIFICATE AND OPINION AS TO CONDITIONS PRECEDENT...........................62
     13.5.  STATEMENTS REQUIRED IN CERTIFICATE OR OPINION................................62
     13.6.  RULES BY TRUSTEE, PAYING AGENT, REGISTRAR....................................63
     13.7.  LEGAL HOLIDAYS...............................................................63
     13.8.  GOVERNING LAW................................................................63
     13.9.  NO ADVERSE INTERPRETATION OF OTHER AGREEMENTS................................64
     13.10. NO RECOURSE AGAINST OTHERS...................................................64
     13.11. SUCCESSORS...................................................................64
     13.12. DUPLICATE ORIGINALS..........................................................64
     13.13  SEVERABILITY.................................................................64
     13.14. TABLE OF CONTENTS, HEADINGS, ETC.............................................64
     13.15. QUALIFICATION OF INDENTURE...................................................65
</TABLE> 
                                      iii
<PAGE>
 
                             CROSS-REFERENCE TABLE
<TABLE>
<CAPTION>
TIA                                                                    INDENTURE
SECTION                                                                SECTION
<S>                                                                    <C>
310(a)(1)..........................................................        7.10
  (a)(2)...........................................................        7.10
  (a)(3)...........................................................        N.A.
  (a)(4)...........................................................        N.A.
  (a)(5)...........................................................        7.10
  (b)..............................................................        7.8;
  .................................................................       7.10;
  .................................................................        13.2
  (c)..............................................................        N.A.
311(a).............................................................        7.11
  (b)..............................................................        7.11
  (c)..............................................................        N.A.
312(a).............................................................         2.5
  (b)..............................................................        13.3
  (c)..............................................................        13.3
313(a).............................................................         7.6
  (b)(l)...........................................................        N.A.
  (b)(2)...........................................................         7.6
  (c)..............................................................        7.6;
  .................................................................        13.2
  (d)..............................................................         7.6
314(a).............................................................        4.7;
  .................................................................        13.2
  (b)..............................................................        N.A.
  (c)(l)...........................................................        2.2;
  .................................................................        7.2;
  .................................................................        13.4
  (c)(2)...........................................................        7.2;
  .................................................................        13.4
  (c)(3)...........................................................        N.A.
  (d)..............................................................        N.A.
  (e)..............................................................        13.5
  (f)..............................................................        N.A.
315(a).............................................................      7.1(b)
  (b)..............................................................        7.5;
  .................................................................        13.2
  (c)..............................................................      7.1(a)
  (d)..............................................................       6.11;
  ................................................................. 7.1(b)&(c);
  .................................................................      7.2(c)
</TABLE> 
                                      iv
<PAGE>

<TABLE>
<CAPTION>
<S>                                                                                   <C>
  (e)...........................................................................       6.13
316(a)(1ast sentence)...........................................................        2.9
  (a)(l)(A).....................................................................       6.11
  (a)(l)(B).....................................................................       6.12
  (a)(2)........................................................................       N.A.
  (b)...........................................................................      6.12;
  ..............................................................................        6.7
317(a)(1).......................................................................        6.3
  (a)(2)........................................................................        6.4
  (b)...........................................................................        2.4
318(a)..........................................................................       13.1
</TABLE>
N.A. Means Not Applicable.
Note: This Cross-Reference Table shall not, for any purpose, be deemed to be a
part of the Indenture.

                                       v
<PAGE>
 
     INDENTURE, dated as of November 18, 1996, between PLATINUM technology,
inc., a Delaware corporation (the "Company"), and American National Bank and
Trust Company of Chicago, a national banking association, as trustee (The
"Trustee").

     Each party hereto agrees as follows for the benefit of each other party and
for the equal and ratable benefit of the Holders of the Company's 63/4%
Convertible Subordinated Notes due 2001:

                                    ARTICLE
                                      1.
                  DEFINITIONS AND INCORPORATION BY REFERENCE

1.1. DEFINITIONS.

     "ACCELERATION NOTICE" shall have the meaning specified in Section 6.2.

     "AFFILIATE" means (i) any person directly or indirectly controlling or
controlled by or under direct or indirect common control with the Company, (ii)
any spouse, immediate family member, or other relative who has the same
principal residence of any person described in clause (i) above, and (iii) any
trust in which any person described in clause (i) or (ii) above has a beneficial
interest. For purposes of this definition, the term "control" means the power to
direct the management and policies of a person, directly or through one or more
intermediaries, whether through the ownership of voting securities, by contract
or otherwise.

     "AGENT" means any Registrar, Paying Agent or co-Registrar.

     "BANKRUPTCY LAW" means Title ll, U.S. Code, or any similar Federal, state
or foreign law for the relief of debtors.

     "BOARD OF DIRECTORS" means, with respect to any Person, the Board of
Directors of such Person or any committee of the Board of Directors of such
Person authorized, with respect to any particular matter, to exercise the power
of the Board of Directors of such Person.

     "BOARD RESOLUTION" means, with respect to any Person, a duly adopted
resolution of the Board of Directors of such Person.

     "BUSINESS DAY" means each Monday, Tuesday, Wednesday, Thursday and Friday
that is not a day on which banking institutions in New York, New York are
authorized or obligated by law or executive order to close.

     "CAPITALIZED LEASE OBLIGATIONS" means rental obligations under a lease that
are required to be capitalized for financial reporting purposes in accordance
with GAAP, and the amount of Indebtedness represented by such obligations shall
be the capitalized amount of such obligations, as determined in accordance with
GAAP.

                                       1
<PAGE>
 
     "CAPITAL STOCK" means, with respect to any corporation, any and all shares,
interest, rights to purchase (other than convertible or exchangeable
Indebtedness), warrants, options, participations or other equivalents of or
interests (however designated) in stock issued by that corporation.

     "CASH" means such coin or currency of the United States of America as at
the time of payment shall be legal tender for the payment of public and private
debts.

     "CHANGE OF CONTROL" occurs upon the occurrence of any of the following
events: (i) upon any merger or consolidation of the Company with or into any
Person or any sale, transfer or other conveyance, whether direct or indirect, of
all or substantially all of the assets of the Company, on a consolidated basis,
in one transaction or a series of related transactions, if, immediately after
giving effect to such transaction, any "person" or "group" other than the
Company is or becomes the "beneficial owner," directly or indirectly, of more
than 50% of the voting power in the aggregate normally entitled to vote in the
election of directors, managers, or trustees, as applicable, of the transferee
or surviving entity, (ii) when any "person" or "group" is or becomes the
"beneficial owner," directly or indirectly, of more than 50% of the voting power
in the aggregate normally entitled to vote in the election of directors of the
Company, (iii) when, during any period of 12 consecutive months after the Issue
Date, individuals who at the beginning of any such 12-month period constituted
the Board of Directors of the Company (together with any new directors whose
election by such Board or whose nomination for election by the stockholders of
the Company was approved by a vote of a majority of the directors then still in
office who were either directors at the beginning of such period or whose
election or nomination for election was previously so approved) cease for any
reason to constitute a majority of the Board of Directors of the Company then in
office, or (iv) the pro rata distribution by the Company to its shareholders of
substantially all of its assets.

     For purposes of this definition, (i) the terms "person" and "group" shall
have the meaning used for purposes of Rules 13d-3 and 13d-5 of the Exchange Act
as in effect on the Issue Date, whether or not applicable; and (ii) the term
"beneficial owner" shall have the meaning used in Rules 13d-3 and 13d-5 under
the Exchange Act as in effect on the Issue Date, whether or not applicable,
except that a "person" shall be deemed to have "beneficial ownership" of all
shares that any such person has the right to acquire, whether such right is
exercisable immediately or only after the passage of time or upon the occurrence
of certain events.

     "CODE" means the Internal Revenue Code of 1986, as amended.

     "COMMON STOCK" means the Company's common stock, par value $.001 per share,
or as such stock may be reconstituted from time to time.

     "COMPANY" means PLATINUM technology, inc. until a successor replaces it
pursuant to the Indenture, and thereafter means such successor.

     "CONVERSION PRICE" shall have the meaning specified in Section 12.4.

                                       2
<PAGE>
 
     "CONVERSION SHARES" shall have the meaning specified in Section 12.1.

     "CUSTODIAN" means any receiver, trustee, assignee, liquidator, sequestrator
or similar official under any Bankruptcy Law.

     "DATE OF CONVERSION" shall have the meaning specified in Section 12.2.

     "DEFAULT" means any event or condition that is, or after notice or passage
of time or both would be, an Event of Default.

     "DEFAULTED INTEREST" shall have the meaning specified in Section 2.12.

     "DEFINITIVE SECURITIES" means Securities that are in the form of Security
attached hereto as Exhibit A that do not include the information called for by
footnotes 1 and 2 thereof.

     "DEPOSITARY" means the sole holder of the Global Security, as specified in
Section 2.3 until a successor shall have been appointed and become such pursuant
to the applicable provision of this Indenture, and, thereafter, "Depositary"
shall mean or include such successor.

     "DISQUALIFIED CAPITAL STOCK" means (a) except as set forth in (b), with
respect to any Person, Capital Stock of such Person that, by its terms or by the
terms of any security into which it is convertible, exercisable or exchangeable,
is, or upon the happening of an event or the passage of time would be, required
to be redeemed or repurchased (including at the option of the holder thereof) by
such Person or any of its Subsidiaries, in whole or in part, on or prior to the
Stated Maturity of the Securities and (b) with respect to any Subsidiary of such
Person (including with respect to any Subsidiary of the Company), any Capital
Stock other than any common stock with no preference, privileges, or redemption
or repayment provisions.

     "DISTRIBUTION DATE" shall have the meaning specified in Section 12.5(k).

     "DTC" shall have the meaning specified in Section 2.3.

     "EVENT OF DEFAULT" shall have the meaning specified in Section 6.1.

     "EXCHANGE ACT" means the Securities Exchange Act of 1934, as amended, and
the rules and regulations promulgated by the SEC thereunder.

     "EXPIRATION TIME" shall have the meaning specified in Section 12.5(e).

     "GAAP" means United States generally accepted accounting principles set
forth in the opinions and pronouncements of the Accounting Principles Board of
the American Institute of Certified Public Accountants and statements and
pronouncements of the Financial Accounting Standards Board ("FASB") or in such
other statements by such other entity as approved by a significant segment of
the accounting profession which are in effect in the United States; PROVIDED,
HOWEVER, that for purposes of determining compliance with covenants in the

                                       3
<PAGE>
 
Indenture, "GAAP" means such generally accepted accounting principles which are
in effect as of the Issue Date.

     "GLOBAL SECURITY" means a Security held by the Depositary for the benefit
of beneficial owners, and which contains the paragraph referred to in footnote 1
and the schedule referred to in footnote 2 of the form of Security attached
hereto as Exhibit A.

     "HOLDER" or "SECURITY HOLDER" means the Person in whose name a Security is
registered on the Registrar's books.

     "INDEBTEDNESS" of any Person means, without duplication, (a) all
liabilities and obligations, contingent or otherwise, of any such Person, (i) in
respect of borrowed money (whether or not the recourse of the lender is to the
whole of the assets of such Person or only to a portion thereof), (ii) evidenced
by bonds, notes, debentures or similar instruments, (iii) representing the
balance deferred and unpaid of the purchase price of any property or services,
except such as would constitute trade payables to trade creditors in the
ordinary course of business that are not more than ninety (90) days past their
original due date, (iv) evidenced by bankers' acceptances or similar instruments
issued or accepted by banks, (v) for the payment of money relating to a
Capitalized Lease Obligation, or (vi) evidenced by a letter of credit or a
reimbursement obligation of such Person with respect to any letter of credit;
(b) all net obligations of such Person under Interest Swap and Hedging
Obligations; (c) all liabilities of others of the kind described in the
preceding clause (a) or (b) that such Person has guaranteed or that is otherwise
its legal liability and all obligations to purchase, redeem or acquire any
Capital Stock; and (d) any and all deferrals, renewals, extensions, refinancings
and refundings (whether direct or indirect) of any liability of the kind
described in any of the preceding clauses (a), (b) or (c), or this clause (d),
whether or not between or among the same parties.

     "INDENTURE" means this indenture, as amended or supplemented from time to
time in accordance with the terms hereof.

     "INTEREST PAYMENT DATE" means the stated due date of an installment of
interest on the Securities.

     "INTEREST SWAP AND HEDGING OBLIGATIONS" means any obligation of any Person
pursuant to any interest rate swap agreement, interest rate cap agreement,
interest rate collar agreement, interest rate exchange agreement, currency
exchange agreement or any other agreement or arrangement designed to protect
against fluctuations in interest rates or currency values, including, without
limitation, any arrangement whereby, directly or indirectly, such Person is
entitled to receive from time to time periodic payments calculated by applying
either a fixed or floating rate of interest on a stated notional amount in
exchange for periodic payment made by such Person calculated by applying a fixed
or floating rate of interest on the same notional amount.

     "ISSUE DATE" means the date of first issuance of the Securities under this
Indenture.

                                       4
<PAGE>
 
     "JUNIOR SECURITY" of any Person means any Qualified Capital Stock and any
Indebtedness of such Person that is subordinated in right of payment to the
Securities and has no scheduled installment of principal due, by redemption,
sinking fund payment or otherwise, on or prior to the Stated Maturity of the
Securities.

     "LAST SALE PRICE" shall have the meaning specified in Section 12.3.

     "LEGAL HOLIDAY" shall have the meaning specified in Section 13.7.

     "LIEN" means any mortgage, lien, pledge, charge, security interest or other
encumbrance of any kind, whether or not filed, recorded or otherwise perfected
under applicable law (including any conditional sale or other title retention
agreement and any lease deemed to constitute a security interest and any option
or other agreement to give any security interest).

     "NON-ELECTING SHARE" shall have the meaning specified in Section 12.6.

     "NOTICE OF DEFAULT" shall have the meaning specified in Section 6.1(3).

     "OFFER" shall have the meaning specified in Section 12.5(e).

     "OFFICER" means, with respect to the Company, the Chief Executive Officer,
the President, any Vice President, the Chief Financial Officer, the Treasurer,
the Controller or the Secretary of the Company.

     "OFFICERS' CERTIFICATE" means, with respect to the Company, a certificate
signed by two Officers or by an Officer and an Assistant Secretary of the
Company and otherwise complying with the requirements of Sections 13.4 and 13.5.

     "OPINION OF COUNSEL" means a written opinion from legal counsel who is
reasonably acceptable to the Trustee and which complies with the requirements of
Sections 13.4 and 13.5.

     "PAYING AGENT" shall have the meaning specified in Section 2.3.

     "PAYMENT BLOCKAGE PERIOD" shall have the meaning specified in Section
11.2(b).

     "PAYMENT DEFAULT" shall have the meaning specified in Section 11.2(a).

     "PAYMENT NOTICE" shall have the meaning specified in Section 11.2(b).

     "PERSON" means any corporation, individual, limited liability company,
joint stock company, joint venture, partnership, unincorporated association,
governmental regulatory entity, country, state or political subdivision thereof,
trust, municipality or other entity.

                                       5
<PAGE>
 
     "PRINCIPAL" of any Indebtedness means the principal of such Indebtedness
plus, without duplication, any applicable premium, if any, on such Indebtedness.

     "PROPERTY" means any right or interest in or to property or assets of any
kind whatsoever, whether real, personal or mixed and whether tangible or
intangible.

     "PURCHASED SHARES" shall have the meaning specified in Section 12.5(e).

     "QUALIFIED CAPITAL STOCK" means any Capital Stock of the Company that is
not Disqualified Capital Stock.

     "RECORD DATE" means a Record Date specified in the Securities whether or
not such Record Date is a Business Day.

     "REDEMPTION DATE," when used with respect to any Security to be redeemed,
means the date fixed for such redemption pursuant to Article 3 of this Indenture
and Paragraph 5 in the form of Security attached hereto as Exhibit A.

     "REDEMPTION PRICE," when used with respect to any Security to be redeemed,
means the redemption price for such redemption pursuant to Paragraph 5 in the
form of Security attached hereto as Exhibit A, which shall include, without
duplication, in each case, accrued and unpaid interest, if any, to and including
the Redemption Date.

     "REGISTRAR" shall have the meaning specified in Section 2.3.

     "REPURCHASE DATE" shall have the meaning specified in Section 10.1(a).

     "REPURCHASE OFFER" shall have the meaning specified in Section 10.1(b).

     "REPURCHASE OFFER PERIOD" shall have the meaning specified in Section
10.1(b).

     "REPURCHASE PRICE" shall have the meaning specified in Section 10.1(a).

     "REPURCHASE PUT DATE" shall have the meaning specified in Section 10.1(b).

     "SEC" means the Securities and Exchange Commission.

     "SECURITIES" means, collectively, the unsecured 6 3/4% convertible
subordinated notes due 2001 issued by the Company under this Indenture, as
supplemented from time to time in accordance with the terms hereof, limited in
aggregate principal amount to $100,000,000 ($115,000,000 if the Underwriters'
over-allotment option is exercised in full).

     "SECURITIES ACT" means the Securities Act of 1933, as amended, and the
rules and regulations of the SEC promulgated thereunder.

                                        6
<PAGE>
 
     "SECURITIES CUSTODIAN" means the Trustee, as custodian with respect to the
Global Security, or any successor entity thereto.

     "SENIOR INDEBTEDNESS" means any Indebtedness of the Company, whether
outstanding on the date of the Indenture or thereafter created, incurred,
assumed, guaranteed or in effect guaranteed by the Company, unless the
instrument creating or evidencing such Indebtedness provides that such
Indebtedness is not senior or superior, in right of payment, to the Securities
or to other Indebtedness which is PARI PASSU with, or subordinated to, the
Securities; PROVIDED, that in no event shall Senior Indebtedness include (a)
Indebtedness of the Company owed or owing to any Subsidiary of the Company or
any officer, director or employee of the Company or any Subsidiary of the
Company, (b) Indebtedness to trade creditors, or (c) any liability for taxes
owed or owing by the Company.

     "SIGNIFICANT SUBSIDIARY" means any Subsidiary which is a "significant
subsidiary" of the Company within the meaning of Rule 1.02(w) of Regulation S-X
promulgated by the SEC as in effect on the date of this Indenture.

     "SPECIAL RECORD DATE" for payment of any Defaulted Interest means a date
fixed by the Trustee pursuant to Section 2.12.

     "STATED MATURITY," when used with respect to any Security, means November
15, 2001.

     "SUBSIDIARY" with respect to any Person, means (i) a corporation a majority
of whose Capital Stock with voting power normally entitled to vote in the
election of directors is at the time, directly or indirectly, owned by such
Person, by such Person and one or more Subsidiaries of such Person or by one or
more Subsidiaries of such Person, (ii) a partnership in which such Person or a
Subsidiary of such Person is, at the time, a general partner and owns alone or
together with one or more Subsidiaries of such Person a majority of the
partnership interests, or (iii) any other Person (other than a corporation or
partnership) in which such Person, one or more Subsidiaries of such Person, or
such Person and one or more Subsidiaries of such Person, directly or indirectly,
at the date of determination thereof has at least majority ownership interest.

     "TIA" means the Trust Indenture Act of 1939 (15 U.S. Code Sections 77aaa-
77bbbb) as in effect on the date of the execution of this Indenture.

     "TRADING DAY" means each Monday, Tuesday, Wednesday, Thursday and Friday,
other than any day on which securities are not traded on the Nasdaq National
Market.

     "TRUSTEE" means American National Bank and Trust Company of Chicago, as
trustee, until a successor replaces it in accordance with the provisions of this
Indenture and thereafter means such successor.

     "TRUST OFFICER" means any officer within the corporate trust division (or
any successor group) of the Trustee or any other officer of the Trustee
customarily performing

                                       7
<PAGE>
 
functions similar to those performed by the Persons who at that time shall be
such officers, and also means, with respect to a particular corporate trust
matter, any other officer of the Trustee to whom such trust matter is referred
because of his or her knowledge of and familiarity with the particular subject.

     "UNDERWRITERS" means Donaldson, Lufkin & Jenrette Securities Corporation,
Hambrecht & Quist LLC and Robertson, Stephens & Company LLC.

     "UNDERWRITING AGREEMENT" means that certain Underwriting Agreement, dated
November 18, 1996, by and between the Company and the Underwriters, as such
agreement may be amended, modified or supplemented from time to time in
accordance with the terms thereof.

     "U.S. GOVERNMENT OBLIGATIONS" means direct non-callable obligations of, or
non-callable obligations guaranteed by, the United States of America for the
payment of which obligation or guarantee the full faith and credit of the United
States of America is pledged.

1.2. INCORPORATION BY REFERENCE OF TIA.

     Whenever this Indenture refers to a provision of the TIA, such provision is
incorporated by reference in and made a part of this Indenture. The following
TIA terms used in this Indenture have the following meanings:

     "COMMISSION" means the SEC.

     "INDENTURE SECURITIES" means the Securities.

     "INDENTURE SECURITY HOLDER" means a Holder or a Security Holder.

     "INDENTURE TO BE QUALIFIED" means this Indenture

     "INDENTURE TRUSTEE" or "INSTITUTIONAL TRUSTEE" means the Trustee.

     "OBLIGOR" on the Securities means the Company and any other obligor on the
Securities.

     All other TIA terms used in this Indenture that are defined by the TIA,
defined by TIA reference to another statute or defined by SEC rule and not
otherwise defined herein have the meanings assigned to them thereby.

1.3. RULES OF CONSTRUCTION.

     Unless the context otherwise requires:

     (1)  a term has the meaning assigned to it;

                                       8
<PAGE>
 
     (2) an accounting term not otherwise defined has the meaning assigned to it
in accordance with GAAP;

     (3) "or" is not exclusive;
 
     (4) words in the singular include the plural, and words in the plural
include the singular;

     (5) provisions apply to successive events and transactions;

     (6) "herein," "hereof" and other words of similar import refer to this
Indenture as a whole and not to any particular Article, Section or other
subdivision; and

     (7) references to Sections or Articles means reference to such Sections or
Articles in this Indenture, unless stated otherwise.

                                     ARTICLE
                                        2.
                                  THE SECURITIES

2.1. FORM AND DATING.

     The Securities and the Trustee's certificate of authentication, in respect
thereof, shall be substantially in the form of Exhibit A hereto, which Exhibit
is part of this Indenture. The Securities may have notations, legends or
endorsements required by law, stock exchange rule or usage. The Company shall
approve the form of the Securities and any notation, legend or endorsement on
them. Any such notations, legends or endorsements not contained in the form of
Security attached as Exhibit A hereto shall be delivered in writing to the
Trustee. Each Security shall be dated the date of its authentication.

     The terms and provisions contained in the forms of Securities shall
constitute, and are hereby expressly made, a part of this Indenture and, to the
extent applicable, the Company and the Trustee, by their execution and delivery
of this Indenture, expressly agree to such terms and provisions and to be bound
thereby.

2.2. EXECUTION AND AUTHENTICATION.

     Two Officers shall sign, or one Officer shall sign and one Officer shall
attest to, the Security for the Company by manual or facsimile signature. The
Company's seal shall be impressed, affixed, imprinted or reproduced on the
Securities and may be in facsimile form.

     If an Officer whose signature is on a Security was an Officer at the time
of such execution but no longer holds that office at the time the Trustee
authenticates the Security, the Security shall be valid nevertheless and the
Company shall nevertheless be bound by the terms of the Securities and this
Indenture.

                                       9
<PAGE>
 
     A Security shall not be valid until an authorized signatory of the Trustee
manually signs the certificate of authentication on the Security but such
signature shall be conclusive evidence that the Security has been authenticated
pursuant to the terms of this Indenture. Notwithstanding anything herein to the
contrary, if any Security shall have been authenticated and delivered hereunder
but never issued or sold by the Company, and the Company shall deliver such
Security to the Trustee for cancellation, for all purposes of this Indenture
such Security shall be deemed never to have been authenticated and delivered
hereunder and shall never be entitled to the benefits of this Indenture.

     The Trustee shall authenticate the Securities for original issue in the
aggregate principal amount of up to $115,000,000 upon a written order of the
Company in the form of an Officers' Certificate. The Officers' Certificate shall
specify the amount of Securities to be authenticated and the date the Securities
are to be authenticated. The aggregate principal amount of Securities
outstanding at any time may not exceed $115,000,000, except as provided in
Section 2.7; PROVIDED, that Securities in excess of $100,000,000 shall not be
issued other than pursuant to the over-allotment option granted by the Company
to the Underwriters as provided in the Underwriting Agreement, or pursuant to
Section 2.7. Upon the written order of the Company in the form of an Officers'
Certificate, the Trustee shall authenticate Securities in substitution of
Securities originally issued to reflect any name change of the Company.

     The Trustee may appoint an authenticating agent acceptable to the Company
to authenticate Securities. Unless otherwise provided in the appointment, an
authenticating agent may authenticate Securities whenever the Trustee may do so.
Each reference in this Indenture to authentication by the Trustee includes
authentication by such agent. An authenticating agent has the same rights as an
Agent to deal with the Company, any Affiliate of the Company, or any of their
respective Subsidiaries.

     Securities shall be issuable only in registered form without coupons in
denominations of $1,000 and any integral multiple thereof.

2.3. REGISTRAR, PAYING AGENT AND DEPOSITARY.

     The Company shall maintain an office or agency in the Borough of Manhattan,
The City of New York, where Securities may be presented for registration of
transfer or exchange and for conversion ("Registrar") and an office or agency
where Securities may be presented for payment ("Paying Agent") and where notices
and demands to or upon the Company in respect of the Securities may be served.
The Company may act as Registrar or Paying Agent, except that, for the purposes
of Articles 3, 8 and 10 and as otherwise specified in the Indenture, neither the
Company nor any Affiliate of the Company shall act as Paying Agent. The
Registrar shall keep a register of the Securities and of their transfer,
exchange and conversion. The Company hereby initially appoints the corporate
trust office of First Chicago Trust Company of New York ("First Chicago of New
York") as Registrar and Paying Agent, and First Chicago of New York hereby
agrees to so act.

                                        10
<PAGE>
 
     The Company shall give prompt written notice to the Trustee of any change
in the location of the Registrar or Paying Agent. If at any time the Company
shall fail to maintain a Registrar or Paying Agent, or shall fail to furnish the
Trustee with the address thereof, such presentations, surrenders, notices and
demands may be made or served at the address of the Trustee set forth in Section
13.2.

     The Company may also from time to time designate one or more other offices
or agencies where the Securities may be presented or surrendered for any or all
such purposes described in this Section 2.3 and may from time to time rescind
such designations; PROVIDED, HOWEVER, that no such designation or rescission
shall in any manner relieve the Company of its obligation to maintain an office
or agency in the Borough of Manhattan, The City of New York, for such purposes.
The Company shall give prompt written notice to the Trustee of any such
designation or rescission and of any change in the location of any such other
office or agency. The term "Paying Agent" includes any additional Paying Agent
and the term "Registrar" includes any additional Registrar.

     The Company shall enter into an appropriate written agency agreement with
any Agent which is not an Affiliate, which agreement shall implement the
provisions of this Indenture that relate to such Agent. The Company shall
promptly notify the Trustee in writing of the name and address of any such
Agent. If the Company fails to maintain a Registrar or Paying Agent, the Trustee
shall act as such.

     The Company initially appoints the Depository Trust Company ("DTC") to act
as Depositary with respect to the Global Securities.

2.4. PAYING AGENT TO HOLD ASSETS IN TRUST.

     The Company shall require each Paying Agent other than the Trustee to agree
in writing that such Paying Agent shall hold in trust for the benefit of Holders
or the Trustee all assets held by the Paying Agent for the payment of principal
of, premium, if any, and interest on the Securities (whether such assets have
been distributed to it by the Company or any other obligor on the Securities),
and shall notify the Trustee in writing of any Default in making any such
payment. If either of the Company or a Subsidiary of the Company acts as Paying
Agent, it shall segregate such assets and hold them as a separate trust for the
benefit of the Holders or the Trustee. The Company at any time may require a
Paying Agent to distribute all assets held by it to the Trustee and account for
any assets distributed and the Trustee may at any time during the continuance of
any Payment Default, upon written request to a Paying Agent, require such Paying
Agent to distribute all assets held by it to the Trustee and to account for any
assets distributed. Upon distribution to the Trustee of all assets that shall
have been delivered by the Company to the Paying Agent, the Paying Agent (if
other than the Company or an Affiliate of the Company) shall have no further
liability for such assets.

                                      11
<PAGE>
 
2.5. SECURITY HOLDER LISTS.

     The Trustee shall preserve in as current a form as is reasonably
practicable the most recent list available to it of the names and addresses of
Holders. If the Trustee is not the Registrar, the Company shall furnish to the
Trustee on or before the third Business Day preceding each Interest Payment Date
and at such other times as the Trustee may request in writing a list in such
form and as of such date as the Trustee reasonably may require of the names and
addresses of Holders.

2.6. TRANSFER AND EXCHANGE.

     (a) TRANSFER AND EXCHANGE OF DEFINITIVE SECURITIES. When Definitive
Securities are presented to the Registrar or a co-Registrar with a request:

          (x) to register the transfer of such Definitive Securities; or

          (y) to exchange such Definitive Securities for an equal principal
     amount of Definitive Securities of other authorized denominations;

the Registrar or co-Registrar shall register the transfer or make the exchange
as requested if its reasonable requirements for such transaction are met;
PROVIDED, HOWEVER, that the Definitive Securities surrendered for transfer or
exchange shall be duly endorsed or accompanied by a written instrument of
transfer in a form reasonably satisfactory to the Company and the Registrar or
co-Registrar, duly executed by the Holder thereof or his attorney duly
authorized in writing.

     (b) RESTRICTIONS ON TRANSFER OF A DEFINITIVE SECURITY FOR A BENEFICIAL
INTEREST IN A GLOBAL SECURITY. A Definitive Security may not be exchanged for a
beneficial interest in a Global Security except upon satisfaction of the
requirements set forth below. Upon receipt by the Trustee of a Definitive
Security, duly endorsed or accompanied by appropriate instruments of transfer,
in form satisfactory to the Trustee, together with written instructions
directing the Trustee to make, or to direct the Securities Custodian to make, an
endorsement on the Global Security to reflect an increase in the aggregate
principal amount of the Securities represented by the Global Security, the
Trustee shall cancel such Definitive Security and cause, or direct the
Securities Custodian to cause, in accordance with the standing instructions and
procedures existing between the Depositary and the Securities Custodian, the
aggregate principal amount of Securities represented by the Global Security to
be increased accordingly. If no Global Securities are then outstanding, the
Company shall issue and the Trustee shall authenticate a new Global Security in
the appropriate principal amount.

     (c) TRANSFER AND EXCHANGE OF GLOBAL SECURITIES. The transfer and exchange
of Global Securities or beneficial interests therein shall be effected through
the Depositary, in accordance with this Indenture (including the restrictions on
transfer set forth herein) and the procedures of the Depositary therefor.

                                        12
<PAGE>
 
     (d) TRANSFER OF A BENEFICIAL INTEREST 1N A GLOBAL SECURITY FOR A DEFINITIVE
SECURITY.

          (i) Upon receipt by the Trustee of written instructions or such other
     form of instructions as is customary for the Depositary from the Depositary
     or its nominee on behalf of any Person having a beneficial interest in a
     Global Security (all of which may be submitted by facsimile), and if such
     beneficial interest is being transferred to the Person designated by the
     Depositary as being the beneficial owner, a certification from such Person
     to that effect (in substantially the form set forth on the reverse of the
     Security), the Trustee or the Securities Custodian, at the direction of the
     Trustee, will cause, in accordance with the standing instructions and
     procedures existing between the Depositary and the Securities Custodian,
     the aggregate principal amount of the Global Security to be reduced and,
     following such reduction, the Company will execute and, upon receipt of an
     authentication order in the form of an Officers' Certificate, the Trustee
     will authenticate and deliver to the transferee a Definitive Security.

          (ii) Definitive Securities issued in exchange for a beneficial
     interest in a Global Security pursuant to this Section 2.6(d) shall be
     registered in such names and in such authorized denominations as the
     Depositary, pursuant to instructions from its direct or indirect
     participants or otherwise, shall instruct the Trustee. The Trustee shall
     deliver such Definitive Securities to the Persons in whose names such
     Securities are so registered.

     (e) RESTRICTIONS ON TRANSFER AND EXCHANGE OF GLOBAL SECURITY.
Notwithstanding any other provisions of this Indenture (other than the
provisions set forth in subsection (f) of this Section 2.6), a Global Security
may not be transferred as a whole except by the Depositary to a nominee of the
Depositary, by a nominee of the Depositary to the Depositary or another nominee
of the Depositary or by the Depositary or any such nominee to a successor
Depositary or a nominee of such successor Depositary.

     (f) AUTHENTICATION OF DEFINITIVE SECURITIES IN ABSENCE OF DEPOSITARY. If at
any time:

          (i) The Depositary for the Securities notifies the Company and the
     Company notifies the Trustee in writing that the Depositary is no longer
     willing or able to continue as Depositary for the Global Security and a
     successor Depositary for the Global Security is not appointed by the
     Company within 90 days after delivery of such notice; or

          (ii) The Company, in its sole discretion, notifies the Trustee in
     writing that it elects to cause the issuance of Definitive Securities under
     this Indenture,

then the Company will execute, and the Trustee, upon receipt of an Officers'
Certificate requesting the authentication and delivery of Definitive Securities,
will authenticate and deliver Definitive Securities to each person that the
Depositary identified as the beneficial owner of the

                                      13
<PAGE>
 
Global Security, in an aggregate principal amount equal to the principal amount
of the Global Security, in exchange for such Global Security.

     (g) CANCELLATION AND/OR ADJUSTMENT OF GLOBAL SECURITY. At such time as all
beneficial interests in a Global Security have either been exchanged for
Definitive Securities, redeemed, repurchased or canceled, such Global Security
shall be returned to or retained and canceled by the Trustee. At any time prior
to such cancellation, if any beneficial interest in a Global Security is
exchanged for Definitive Securities, redeemed, repurchased or canceled, the
principal amount of Securities represented by such Global Security shall be
reduced and an endorsement shall be made on such Global Security, by the Trustee
or the Securities Custodian, at the direction of the Trustee, to reflect such
reduction.

     (h) OBLIGATIONS WITH RESPECT TO TRANSFERS AND EXCHANGES OF DEFINITIVE
SECURITIES.

          (i) To permit registrations of transfers and exchanges, the Company
     shall execute and the Trustee shall authenticate Definitive Securities and
     the Global Security at the Registrar's or co-Registrar's request.

          (ii) No service charge shall be made for any registration of transfer
     or exchange, but the Company may require payment of a sum sufficient to
     cover any transfer taxes, assessments or similar governmental charge
     payable in connection therewith (other than any such transfer taxes,
     assessments or similar governmental charge payable upon exchanges or
     transfers pursuant to Sections 2.2 (fourth paragraph), 2.10, 3.7, 9.5, or
     10.1 (final paragraph)).

          (iii) The Registrar or co-Registrar shall not be required to register
     the transfer of or exchange of (a) any Definitive Security selected for
     redemption in whole or in part pursuant to Article 3, except the unredeemed
     portion of any Definitive Security being redeemed in part, or (b) in the
     event that the Trustee has been notified of an offer to repurchase
     Securities pursuant to Article 10 hereof or of a redemption of Securities
     pursuant to Article 3 hereof, any Security for a period beginning 15 days
     before the mailing of a notice of an offer to repurchase or the mailing of
     a notice of redemption and ending at the close of business on the day of
     such mailing.

                                        14
<PAGE>
 
2.7. REPLACEMENT SECURITIES.

     If a mutilated Security is surrendered to the Trustee or if the Holder of a
Security claims and submits an affidavit or other evidence, satisfactory to the
Trustee, to the Trustee to the effect that the Security has been lost, destroyed
or wrongfully taken, the Company shall issue and the Trustee shall authenticate
a replacement Security if the Trustee's requirements are met. If required by the
Trustee or the Company, such Holder must provide an indemnity bond or other
indemnity, sufficient in the judgment of both the Company and the Trustee, to
protect the Company, the Trustee or any Agent from any loss which any of them
may suffer if a Security is replaced. The Company may charge such Holder for its
reasonable, out-of-pocket expenses in replacing a Security. In case any such
mutilated, destroyed, lost or stolen Security has become or is about to become
due, the Company, in its discretion, may instead of issuing a new Security, pay
such Security.

     Every replacement Security is an additional obligation of the Company.

     The provisions of this Section 2.7 are exclusive and, to the extent lawful,
preclude other rights and remedies with respect to replacement or payment of
mutilated, destroyed, lost or stolen Securities.

2.8. OUTSTANDING SECURITIES.

     Securities outstanding at any time are all of the Securities that have been
authenticated by the Trustee (including any Security represented by a Global
Security) except those canceled by it, those delivered to it for cancellation,
those reductions in the interest in a Global Security effected by the Trustee
hereunder and those described in this Section 2.8 as not outstanding. A Security
does not cease to be outstanding because the Company or an Affiliate of the
Company holds the Security, except as provided in Section 2.9.

     If a Security is replaced pursuant to Section 2.7 (other than a mutilated
Security surrendered for replacement), it ceases to be outstanding unless the
Trustee receives proof satisfactory to it that the replaced Security is held by
a BONA FIDE purchaser. A mutilated Security ceases to be outstanding upon
surrender of such Security and replacement thereof pursuant to Section 2.7.

     If on a Redemption Date the Paying Agent (other than the Company or an
Affiliate of the Company) holds Cash or U.S. Government Obligations sufficient
to pay all of the principal and interest due on the Securities payable on that
date in accordance with Section 3.6 hereof and payment of the Securities called
for redemption is not otherwise prohibited pursuant to Article 11 hereof or
otherwise, then on and after that date such Securities cease to be outstanding
and interest on them ceases to accrue.

                                        15
                                        
<PAGE>
 
2.9. TREASURY SECURITIES.

     In determining whether the Holders of the required principal amount of
Securities have concurred in any direction, amendment, supplement, waiver or
consent, Securities owned by the Company or an Affiliate of the Company shall be
disregarded, except that, for the purposes of determining whether the Trustee
shall be protected in relying on any such direction, amendment, supplement,
waiver or consent, only Securities that the Trustee knows are so owned shall be
disregarded.

2.10. TEMPORARY SECURITIES.

     Until the Securities are ready for delivery in their definitive form, the
Company may prepare and the Trustee shall authenticate temporary Securities.
Temporary Securities shall be substantially in the form of definitive Securities
but may have variations that the Company reasonably and in good faith considers
appropriate for temporary Securities. Without unreasonable delay, the Company
shall prepare and the Trustee shall authenticate Securities in their definitive
form in exchange for temporary Securities. Until so exchanged, the temporary
Securities shall in all respects be entitled to the same benefits under this
Indenture as Securities in their definitive form authenticated and delivered
hereunder.

2.1 1. CANCELLATION.

     The Company at any time may deliver Securities to the Trustee for
cancellation. The Registrar and the Paying Agent shall forward to the Trustee
any Securities surrendered to them for transfer, exchange, conversion, payment
or cancellation. The Trustee, or at the direction of the Trustee, the Registrar
or the Paying Agent (other than the Company or an Affiliate of the Company), and
no one else, shall cancel and dispose of all Securities surrendered for
transfer, exchange, conversion, payment or cancellation, and shall deliver a
cancellation certificate to the Company. Subject to Section 2.7, the Company may
not issue new Securities to replace Securities that have been paid or delivered
to the Trustee for cancellation. No Securities shall be authenticated in lieu of
or in exchange for any Securities canceled as provided in this Section 2.11,
except as expressly permitted in the form of Securities and as permitted by this
Indenture.

2.12. DEFAULTED INTEREST.

     Interest on any Security which is payable, and is punctually paid or duly
provided for, on any Interest Payment Date shall be paid to the person in whose
name the Security (or one or more predecessor Securities) is registered at the
close of business on the Record Date for such interest.

     Any interest on any Security which is payable, but is not punctually paid
or duly provided for, on any Interest Payment Date plus, to the extent lawful,
any interest payable on the defaulted interest (herein called "Defaulted
Interest") shall forthwith cease to be payable to the registered holder on the
relevant Record Date, and such Defaulted Interest may be paid by the Company at
its election in each case, as provided in clause (1) or (2) below:

                                      16
<PAGE>
 
          (1)  The Company may elect to make payment of any Defaulted Interest
     to the persons in whose names the Securities (or their respective
     predecessor Securities) are registered at the close of business on a
     Special Record Date for the payment of such Defaulted Interest, which shall
     be fixed in the following manner. The Company shall notify the Trustee in
     writing of the amount of Defaulted Interest proposed to be paid on each
     Security and the date of the proposed payment, and at the same time the
     Company shall deposit with the Trustee an amount of Cash equal to the
     aggregate amount proposed to be paid in respect of such Defaulted Interest
     or shall make arrangements satisfactory to the Trustee for such deposit
     prior to the date of the proposed payment, such Cash when deposited to be
     held in trust for the benefit of the persons entitled to such Defaulted
     Interest as provided in this clause (1). Thereupon the Trustee shall fix a
     Special Record Date for the payment of such Defaulted Interest which shall
     be not more than 15 days and not less than 10 days prior to the date of the
     proposed payment and not less than 10 days after the receipt by the Trustee
     of the notice of the proposed payment. The Trustee shall promptly notify
     the Company of such Special Record Date and, in the name and at the expense
     of the Company, shall cause notice of the proposed payment of such
     Defaulted Interest and the Special Record Date therefor to be mailed, 
     first-class postage prepaid, to each Holder at his address shown upon the
     registry books of the Registrar not less than 10 days prior to such Special
     Record Date. Notice of the proposed payment of such Defaulted Interest and
     the Special Record Date therefor having been mailed as aforesaid, such
     Defaulted Interest shall be paid to the persons in whose names the
     Securities (or their respective predecessor Securities) are registered on
     such Special Record Date and shall no longer be payable pursuant to the
     following clause (2).

          (2)  The Company may make payment of any Defaulted Interest in any
     other lawful manner not inconsistent with the requirements of any
     securities exchange or market on which the Securities may be listed, and
     upon such notice as may be required by such exchange or market, if, after
     notice given by the Company to the Trustee of the proposed payment pursuant
     to this clause, such be deemed practicable by the Trustee.

     Subject to the foregoing provisions of this Section 2.12, each Security
delivered under this Indenture upon transfer of or in exchange for or in lieu of
any other Security shall carry the rights to interest accrued and unpaid, and to
accrue, which were carried by such other Security.

                                    ARTICLE
                                      3.
                                  REDEMPTION

3.1. RIGHT OF REDEMPTION.

     Redemption of Securities, as permitted by any provision of this Indenture,
shall be made in accordance with Paragraph 5 of the form of Securities attached
hereto as Exhibit A and this Article 3. The Company will not have the right to
redeem any Securities prior to November 15, 1999. At any time on or after
November 15, 1999, upon not less than 30 nor more than 60 days notice to each
Holder of Securities, the Company will have the right to redeem all or any part
of

                                      17
<PAGE>
 
the Securities at the Redemption Prices specified in Paragraph 5 therein under
the caption "Redemption," in each case including accrued and unpaid interest to
the Redemption Date.

3.2. NOTICES TO TRUSTEE.

     If the Company elects to redeem Securities pursuant to Paragraph 5 of the
form of Securities attached hereto as Exhibit A, it shall notify the Trustee in
writing of the Redemption Date and the principal amount of Securities to be
redeemed and whether it wants the Trustee to give notice of redemption to the
Holders.

     If the Company elects to reduce the principal amount of Securities to be
redeemed pursuant to Paragraph 5 of the form of Securities attached hereto as
Exhibit A by crediting against any such redemption Securities in its possession
which it has not previously delivered to the Trustee for cancellation, it shall
so notify the Trustee of the amount of the reduction and deliver such Securities
with such notice.

     The Company shall give each notice provided for in this Section 3.2 to the
Trustee at least 45 days before the Redemption Date (unless a shorter notice
shall be satisfactory to the Trustee). Any such notice may be canceled at any
time prior to notice of such redemption being mailed to any Holder and shall
thereby be void and of no effect.

3.3. SELECTION OF SECURITIES TO BE REDEEMED.

     If less than all of the Securities are to be redeemed pursuant to Paragraph
5 of the form of Securities attached hereto as Exhibit A, the Trustee shall
promptly redeem the Securities to be redeemed on a pro rata basis, in such
manner as the Trustee shall determine to be fair and appropriate and in such
manner as complies with any applicable Depositary, legal and stock exchange
requirements.

     The Trustee shall make the selection from the Securities outstanding and
not previously called for redemption and shall promptly notify the Company in
writing of the Securities selected for redemption and, in the case of any
Security selected for partial redemption, the principal amount thereof to be
redeemed. Securities in denominations of $1,000 may be redeemed only in whole.
The Trustee may select for redemption portions (equal to $1,000 or any integral
multiple thereof) of the principal of Securities that have denominations larger
than $1,000. Provisions of this Indenture that apply to Securities called for
redemption also apply to portions of Securities called for redemption. If any
Security selected for partial redemption is thereafter converted in part before
termination of the conversion right as provided by Section 12.1 hereof, the
portion of the Security so converted shall be deemed to have been a part of the
portion selected for redemption such that only the excess, if any, of the amount
selected for partial redemption over the amount so converted, shall be redeemed.

                                      18
<PAGE>
 
3.4. NOTICE OF REDEMPTION.

     At least 30 days but not more than 60 days before a Redemption Date, the
Company shall mail a notice of redemption by first-class mail, postage prepaid,
to the Trustee and each Holder whose Securities are to be redeemed. At the
Company's request, the Trustee shall give the notice of redemption in the
Company's name and at the Company's expense. Each notice for redemption shall
identify the Securities to be redeemed and shall state:

     (1) the Redemption Date, and that the Securities called for redemption may
not be converted after the fifth Business Day prior to the Redemption Date;

     (2) the Redemption Price, including the amount of accrued and unpaid
interest, if any, to be paid upon such redemption;

     (3) the name, address and telephone number of the Paying Agent;

     (4) that Securities called for redemption must be surrendered to the Paying
Agent at the address specified in such notice to collect the Redemption Price;

     (5) that, unless (a) the Company defaults in its obligation to deposit Cash
with the Paying Agent in accordance with Section 3.6 hereof or (b) such
redemption is prohibited pursuant to Article 11 hereof or otherwise, interest on
the Securities called for redemption ceases to accrue on and after the
Redemption Date and the only remaining right of the Holders of such Securities
is to receive payment of the Redemption Price, including accrued and unpaid
interest, if any, to the Redemption Date, upon surrender to the Paying Agent of
the Securities called for redemption and to be redeemed;

     (6) if any Security is being redeemed in part, the portion of the principal
amount, equal to $1,000 or any integral multiple thereof, of such Security to be
redeemed and that, after the Redemption Date, and upon surrender of such
Security, a new Security or Securities in aggregate principal amount equal to
the unredeemed portion thereof will be issued;

     (7) if less than all the Securities are to be redeemed, the identification
of the particular Securities (or portion thereof) to be redeemed, as well as the
aggregate principal amount of such Securities to be redeemed and the aggregate
principal amount of Securities to be outstanding after such partial redemption;

     (8) the CUSIP number of the Securities to be redeemed; and

     (9) that the notice is being sent pursuant to this Section 3.4 and pursuant
to the redemption provisions of Paragraph 5 of the form of Securities attached
hereto as Exhibit A.

3.5. EFFECT OF NOTICE OF REDEMPTION.

                                        19
<PAGE>
 
     Once notice of redemption is mailed in accordance with Section 3.4,
Securities called for redemption become due and payable on the Redemption Date
and at the Redemption Price, including accrued and unpaid interest, if any, to
the Redemption Date. Upon surrender to the Trustee or Paying Agent, such
Securities called for redemption shall be paid at the Redemption Price,
including accrued and unpaid interest, if any, to the Redemption Date; PROVIDED
that if the Redemption Date is after a regular Record Date and on or prior to
the corresponding Interest Payment Date, the accrued interest, if any, shall be
payable to the Holder of the redeemed Securities registered on the relevant
Record Date; and PROVIDED, FURTHER, that if a Redemption Date is a Legal
Holiday, payment shall be made on the next succeeding Business Day and no
interest shall accrue for the period from such Redemption Date to such
succeeding Business Day.

3.6. DEPOSIT OF REDEMPTION PRICE.

     On or prior to the Redemption Date, the Company shall deposit with the
Paying Agent (other than the Company or an Affiliate of the Company) Cash
sufficient to pay the Redemption Price of, including accrued and unpaid interest
on, all Securities to be redeemed on such Redemption Date (other than Securities
or portions thereof called for redemption on that date that have been delivered
by the Company to the Trustee for cancellation). The Paying Agent shall promptly
return to the Company any Cash so deposited which is not required for that
purpose upon the written request of the Company.

     If the Company complies with the preceding paragraph and the other
provisions of this Article 3 and payment of the Securities called for redemption
is not prohibited under Article 11 or otherwise, interest on the Securities to
be redeemed will cease to accrue on the applicable Redemption Date, whether or
not such Securities are presented for payment. Notwithstanding anything herein
to the contrary, if any Security surrendered for redemption in the manner
provided in the Securities shall not be so paid upon surrender for redemption
because of the failure of the Company to comply with the preceding paragraph,
interest shall continue to accrue and be paid from the Redemption Date until
such payment is made on the unpaid principal, and, to the extent lawful, on any
interest not paid on such unpaid principal, in each case at the rate and in the
manner provided in Section 4.1 hereof and the Security.

3.7. SECURITIES REDEEMED IN PART.

     Upon surrender of a Security that is to be redeemed in part, the Company
shall execute and the Trustee shall authenticate and deliver to the Holder,
without service charge to the Holder, a new Security or Securities equal in
principal amount to the unredeemed portion of the Security surrendered.

                                      20
                                        
<PAGE>
 
                                    ARTICLE
                                      4.
                                   COVENANTS

4.1. PAYMENT OF SECURITIES.

     The Company shall pay the principal of and interest on the Securities on
the dates and in the manner provided in the Securities and this Indenture. An
installment of principal of or interest on the Securities shall be considered
paid on the date it is due if the Trustee or Paying Agent (other than the
Company or an Affiliate of the Company) holds for the benefit of the Holders, on
or before 10:00 a.m. New York City time on that date, Cash deposited and
designated for and sufficient to pay the installment.

     The Company shall pay interest on overdue principal and on overdue
installments of interest at the rate specified in the Securities compounded
semi-annually, to the extent lawful.

4.2. INTENTIONALLY OMITTED.

4.3. CORPORATE EXISTENCE.

     Subject to Article 5, the Company shall do or cause to be done all things
necessary to preserve and keep in full force and effect its corporate existence
and the corporate or other existence of each of its Subsidiaries in accordance
with the respective organizational documents of each of them and the rights
(charter and statutory) and corporate franchises of the Company and each of its
Subsidiaries; PROVIDED, HOWEVER, that the Company shall not be required to
preserve, with respect to itself, any right or franchise, and with respect to
any of its Subsidiaries, any such existence, right or franchise, if (a) the
Company shall determine that the preservation thereof is no longer desirable in
the conduct of the business of such entity and (b) the loss thereof is not
disadvantageous in any material respect to the Holders.

4.4. PAYMENT OF TAXES AND OTHER CLAIMS.

     Except with respect to immaterial items, the Company shall, and shall cause
each of its Subsidiaries to, pay or discharge or cause to be paid or discharged,
before the same shall become delinquent, (i) all taxes, assessments and
governmental charges (including withholding taxes and any penalties, interest
and additions to taxes) levied or imposed upon the Company or any of its
Subsidiaries or any of their respective properties and assets and (ii) all
lawful claims, whether for labor, materials, supplies, services or anything
else, which have become due and payable and which by law have or may become a
Lien upon the property and assets of the Company or any of its Subsidiaries;
PROVIDED, HOWEVER, that neither the Company nor any Subsidiary shall be required
to pay or discharge or cause to be paid or discharged any such tax, assessment,
charge or claim whose amount, applicability or validity is being contested in
good faith by appropriate proceedings and for which disputed amounts adequate
reserves have been established in accordance with GAAP.

                                      21
<PAGE>
 
4.5. MAINTENANCE OF PROPERTIES AND INSURANCE.

     The Company shall cause all material properties used or useful to the
conduct of its business and the business of each of its Subsidiaries to be
maintained and kept in good condition, repair and working order (reasonable wear
and tear excepted) and supplied with all necessary equipment and shall cause to
be made all necessary repairs, renewals, replacements, betterments and
improvements thereof, all as in their reasonable judgment may be necessary, so
that the business carried on in connection therewith may be properly conducted
at all times; PROVIDED, HOWEVER, that nothing in this Section 4.5 shall prevent
the Company or any Subsidiary from discontinuing any operation or maintenance of
any of such properties, or disposing of any of them, if such discontinuance or
disposal is (a), in the judgment of the Company, desirable in the conduct of the
business of such entity and (b) not disadvantageous in any material respect to
the Holders.

     The Company shall provide, or cause to be provided, for itself and each of
its Subsidiaries, insurance (including appropriate self-insurance) against loss
or damage of the kinds that, in the reasonable, good faith opinion of the
Company is adequate and appropriate for the conduct of the business of the
Company and such Subsidiaries in a prudent manner, with (except for self-
insurance) reputable insurers or with the government of the United States of
America or an agency or instrumentality thereof, in such amounts, with such
deductibles, and by such methods as shall be customary, in the reasonable, good
faith opinion of the Company and adequate and appropriate for the conduct of the
business of the Company and such Subsidiaries in a prudent manner for entities
similarly situated in the industry, unless failure to provide such insurance
(together with all other such failures) would not have a material adverse effect
on the financial condition or results of operations of the Company or such
Subsidiary.

4.6. COMPLIANCE CERTIFICATE; NOTICE OF DEFAULT.

     (a)  The Company shall deliver to the Trustee within 120 days after the end
of its fiscal year an Officers' Certificate complying with Section 314(a)(4) of
the TIA and stating that a review of its activities and the activities of its
Subsidiaries during the preceding fiscal year has been made under the
supervision of the signing Officers with a view to determining whether the
Company has kept, observed, performed and fulfilled its obligations under this
Indenture and further stating, as to each such Officer signing such certificate,
whether or not the signer knows of any failure by the Company or any Subsidiary
of the Company to comply with any conditions or covenants in this Indenture and,
if such signor does know of such a failure to comply, the certificate shall
describe such failure with particularity. The Officers' Certificate shall also
notify the Trustee should the relevant fiscal year end on any date other than
the current fiscal year end date.

     (b)  The Company shall, so long as any of the Securities are outstanding,
deliver to the Trustee, promptly upon becoming aware of any Default, Event of
Default or fact which would prohibit the making of any payment to or by the
Trustee in respect of the Securities, an Officers' Certificate specifying such
Default, Event of Default or fact and what action the Company is taking or
proposes to take with respect thereto. The Trustee shall not be deemed to have

                                      22
<PAGE>
 
knowledge of any Default, any Event of Default or any such fact unless one of
its Trust Officers receives notice thereof from the Company or any of the
Holders.

4.7. REPORTS.

     Whether or not the Company is subject to the reporting requirements of
Section 13 or 15(d) of the Exchange Act, the Company shall deliver to the
Trustee and to each Holder, within 30 days after it is or would have been
required to file such with the SEC, annual and quarterly consolidated financial
statements substantially equivalent to financial statements that would have been
included in reports filed with the SEC if the Company was subject to the
requirements of Section 13 or 15(d) of the Exchange Act, including, with respect
to annual information only, a report thereon by the Company's certified
independent public accountants as such would be required in such reports to the
SEC and, in each case, together with a management's discussion and analysis of
financial condition and results of operations which would be so required.

4.8. LIMITATION ON STATUS AS INVESTMENT COMPANY.

     Neither the Company nor any of its Subsidiaries shall become an "investment
company" (as that term is defined in the Investment Company Act of 1940, as
amended).

4.9. WAIVER OF STAY, EXTENSION OR USURY LAWS.

     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 or extension law or any usury law or
other law which would prohibit or forgive the Company from paying all or any
portion of the principal of, or premium or interest on, the Securities as
contemplated herein, wherever enacted, now or at any time hereafter in force, or
which may affect the covenants or the performance of this Indenture; and (to the
extent that it may lawfully do so) the Company hereby expressly waives all
benefit or advantage of any such law and covenants that it will not hinder,
delay or impede the execution of any power herein granted to the Trustee, but
will suffer and permit the execution of every such power as though no such law
had been enacted.

                                    ARTICLE
                                      5.
                             SUCCESSOR CORPORATION

5.1. LIMITATION ON MERGER, SALE OR CONSOLIDATION.

     (a)  The Company shall not, directly or indirectly, consolidate with or
merge with or into another Person or sell, lease, convey or transfer all or
substantially all of its assets (computed on a consolidated basis), whether in a
single transaction or a series of related transactions, to another Person or
group of affiliated Persons, unless (i) either (a) in the case of a merger or
consolidation, the Company is the surviving entity or (b) the resulting,
surviving or transferee entity is a corporation organized under the laws of the
United States, any state thereof or the

                                      23
<PAGE>
 
District of Columbia and expressly assumes by supplemental indenture all of the
obligations of the Company in connection with the Securities and the Indenture;
(ii) no Default or Event of Default shall exist or shall occur immediately
before or after giving effect on a pro forma basis to such transaction; and
(iii) the Company has delivered to the Trustee an Officers' Certificate and an
Opinion of Counsel, each stating that such consolidation, merger or transfer
and, if a supplemental indenture is required, such supplemental indenture comply
with the Indenture and that all conditions precedent relating to such
transactions have been satisfied.

     (b)  For purposes of clause (a) of this Section 5.1, the sale, lease,
conveyance, assignment, transfer or other disposition of all or substantially
all of the properties and assets of one or more Subsidiaries of the Company,
which properties and assets, if held by the Company instead of such
Subsidiaries, would constitute all or substantially all of the properties and
assets of the Company on a consolidated basis, shall be deemed to be the
transfer of all or substantially all of the properties and assets of the
Company.

5.2. SUCCESSOR CORPORATION SUBSTITUTED.

     Upon any consolidation or merger or any sale, lease, conveyance or transfer
of all or substantially all of the assets of the Company in accordance with the
foregoing, the successor corporation formed by such consolidation or into which
the Company is merged or to which such sale, lease, conveyance or transfer is
made (the "Successor Corporation"), shall succeed to, and be substituted for,
and may exercise every right and power of, the Company under the Indenture with
the same effect as if such successor corporation had been named therein as the
Company, and when a successor corporation duly assumes all of the obligations of
the Company pursuant hereto and pursuant to the Securities, the predecessor
shall be released from such obligations (except with respect to any obligations
that arise from or as a result of such transaction), provided, however, that if
the Successor Corporation is a Subsidiary, the consolidated net worth of which
is less than that of the Company immediately prior to such merger,
consolidation, sale, lease, conveyance or transfer, the Company shall not be
released from such obligations but shall remain jointly and severally liable
therefor with the Successor Corporation.

                                    ARTICLE
                                      6.
                        EVENTS OF DEFAULT AND REMEDIES

6.1. EVENTS OF DEFAULT.

     "Event of Default," wherever used herein, means any one of the following
events (whatever the reason for such Event of Default and whether it shall be
caused voluntarily or involuntarily or effected, without limitation, by
operation of law or pursuant to any judgment, decree or order of any court or
any order, rule or regulation of any administrative or governmental body):

                                      24
<PAGE>
 
     (1)  failure to pay any installment of interest on the Securities as and
when the same becomes due and payable, or to perform any conversion of the
Securities required under this Indenture, and the continuance of such default
for a period of 30 days, whether or not such payment is prohibited by 
Article 11;

     (2)  failure to pay all or any part of the principal of, or premium, if any
on the Securities when and as the same become due and payable at maturity,
redemption, by acceleration or otherwise, including, without limitation, default
in the payment of the Repurchase Price on the Repurchase Date in accordance with
Article 10, whether or not such payment is prohibited by Article 11;

     (3)  failure by the Company to observe or perform any covenant, agreement
or warranty contained in the Securities or this Indenture (other than a default
in the performance of any covenant, agreement or warranty which is specifically
dealt with elsewhere in this Section 6.1), and continuance of such failure for a
period of 60 days after there has been given, by registered or certified mail,
to the Company by the Trustee, or to the Company and the Trustee by Holders of
at least 25% in aggregate principal amount of the then outstanding Securities,
a written notice specifying such default or breach, requesting it to be remedied
and stating that such notice is a "Notice of Default" hereunder;

     (4)  a default under Indebtedness of the Company or any of its Subsidiaries
with an aggregate principal amount in excess of $5,000,000 (a) resulting from
the failure to pay principal at maturity or (b) as a result of which the
maturity of such Indebtedness has been accelerated prior to its stated maturity;

     (5)  a decree, judgment, or order by a court of competent jurisdiction
shall have been entered adjudging the Company or any of its Significant
Subsidiaries as bankrupt or insolvent, or approving as properly filed a petition
seeking reorganization of the Company or any of its Significant Subsidiaries
under any bankruptcy or similar law, and such decree or order shall have
continued undischarged and unstayed for a period of 75 days; or a decree or
order of a court of competent jurisdiction over the appointment of a receiver,
liquidator, trustee, or assignee in bankruptcy or insolvency of the Company, any
of its Significant Subsidiaries, or of the property of any such Person, or for
the winding up or liquidation of the affairs of any such Person, shall have been
entered, and such decree, judgment, or order shall have remained in force
undischarged and unstayed for a period of 75 days;

     (6)  the Company or any of its Significant Subsidiaries shall institute
proceedings to be adjudicated a voluntary bankrupt, or shall consent to the
filing of a bankruptcy proceeding against it, or shall file a petition or answer
or consent seeking reorganization under any bankruptcy or similar law or similar
statute, or shall consent to the filing of any such petition, or shall consent
to the appointment of a Custodian, receiver, liquidator, trustee, or assignee in
bankruptcy or insolvency of it or any of its assets or property, or shall make a
general assignment for the benefit of its creditors, or

                                      25
                                        
<PAGE>
 
     shall admit in writing its inability to pay its debts generally as they
     become due, or shall, within the meaning of any Bankruptcy Law, become
     insolvent, fail generally to pay its debts as they become due, or take any
     corporate action in furtherance of or to facilitate, conditionally or
     otherwise, any of the foregoing; or

          (7)  final unsatisfied judgments not covered by insurance aggregating
     in excess of $5,000,000 at any one time shall have been rendered against
     the Company or any of its Subsidiaries and have not been stayed, bonded or
     discharged for a period (during which execution shall not be effectively
     stayed) of 30 days (or, in the case of any such final judgment which
     provides for payment over time, which shall so remain unstayed, unbonded or
     undischarged 30 days beyond any applicable payment date provided therein).

     Notwithstanding the 60-day period and notice requirement contained in
Section 6.1(3) above, with respect to a default under Article 10 the 60-day
period referred to in Section 6.1(3) shall be deemed to have begun as of the
date the Change of Control notice is required to be sent in the event that the
Company has not complied with the provisions of Section 10.1 and the Trustee or
Holders of at least 25% in principal amount of the outstanding Securities
thereafter give the Notice of Default referred to in Section 6.1(3) to the
Company and, if applicable, the Trustee; PROVIDED, HOWEVER, that if the breach
or default is a result of a default in the payment when due of the Repurchase
Price on the Repurchase Date, such Event of Default shall be deemed, for
purposes of this Section 6.1, to arise no later than on the Repurchase Date.

     If a Default occurs and is continuing, the Trustee shall, within 90 days
after the occurrence of such default, give to the Holders notice of such
default.

6.2. ACCELERATION OF MATURITY DATE; RESCISSION AND ANNULMENT.

     If an Event of Default (other than an Event of Default specified in Section
6.1(5) or (6) relating to the Company or any of its significant Subsidiaries)
occurs and is continuing, then, and in every such case, unless the principal of
all of the Securities shall have already become due and payable, either the
Trustee or the Holders of not less than 25% in aggregate principal amount of
then outstanding Securities, by a notice in writing to the Company (and to the
Trustee if given by Holders) (an "Acceleration Notice"), may declare all of the
principal of the Securities (or the Repurchase Price if the Event of Default
includes failure to pay the Repurchase Price, determined as set forth below),
including in each case accrued interest thereon, to be due and payable
immediately. If an Event of Default specified in Section 6.1(5) or (6) relating
to the Company or any Significant Subsidiary occurs, all principal and accrued
interest thereon will be immediately due and payable on all outstanding
Securities without any declaration or other act on the part of Trustee or the
Holders.

     At any time after such a declaration of acceleration has been made and
before a judgment or decree for payment of the money due has been obtained by
the Trustee as hereinafter provided in this Article 6, the Holders of no less
than a majority in aggregate principal amount of then

                                      26
<PAGE>
 
outstanding Securities, by written notice to the Company and the Trustee, may
rescind, on behalf of all Holders, any such declaration of acceleration if:

          (1)  the Company has paid or deposited with the Trustee Cash
               sufficient to pay

               (i)   all overdue interest on all Securities,

               (ii)  the principal of (and premium, if any, applicable to) any
          Securities which would then be due otherwise than by such declaration
          of acceleration, and interest thereon at the rate borne by the
          Securities,

               (iii) to the extent that payment of such interest is lawful,
          interest upon overdue interest at the rate borne by the Securities,

               (iv)  all sums paid or advanced by the Trustee hereunder and the
          compensation, expenses, disbursements and advances of the Trustee, its
          agents and counsel, and

          (2)  all Events of Default, other than the non-payment of the
     principal of, premium, if any, and interest on Securities that have become
     due solely by such declaration of acceleration, have been cured or waived
     as provided in Section 6.12, including, if applicable, any Event of Default
     relating to the covenants contained in Section 10.1.

     Notwithstanding the previous sentence of this Section 6.2, no waiver shall
be effective against any Holder for any Event of Default or event which with
notice or lapse of time or both would be an Event of Default with respect to any
covenant or provision which cannot be modified or amended without the consent of
the Holder of each outstanding Security affected thereby, unless all such
affected Holders agree, in writing, to waive any subsequent Default or Event or
Default or impair any right consequent thereon.

6.3. COLLECTION OF INDEBTEDNESS AND SUITS FOR ENFORCEMENT BY TRUSTEE

     The Company covenants that if an Event of Default in payment of principal,
premium or interest specified in clause (1) or (2) of Section 6.1 occurs and is
continuing, the Company shall, upon demand of the Trustee, pay to it, for the
benefit of the Holders of such Securities, the whole amount then due and payable
on such Securities for principal, premium (if any), interest and, to the extent
that payment of such interest shall be legally enforceable, interest on any
overdue principal (and premium, if any) and on any overdue interest, at the rate
borne by the Securities, and, in addition thereto, such further amount as shall
be sufficient to cover the costs and expenses of collection, including
compensation to, and expenses, disbursements and advances of the Trustee, its
agents and counsel.

                                      27
<PAGE>
 
     If the Company fails to pay such amounts forthwith upon such demand, the
Trustee, in its own name and as Trustee of an express trust in favor of the
Holders, may institute a judicial proceeding to judgment or final decree and may
enforce the same against the Company or any other obligor upon the Securities
and collect the moneys adjudged or decreed to be payable in the manner provided
by law out of the property of the Company or any other obligor upon the
Securities, wherever situated.

     If an Event of Default occurs and is continuing, the Trustee may in its
discretion proceed to protect and enforce its rights and the rights of the
Holders by such appropriate judicial proceedings as the Trustee shall deem most
effective to protect and enforce any such rights, whether for the specific
enforcement of any covenant or agreement in this Indenture or in aid of the
exercise of any power granted herein, or to enforce any other proper remedy.

6.4. TRUSTEE MAY FILE PROOFS OF CLAIM.

     In case of the pendency of any receivership, insolvency, liquidation,
bankruptcy, reorganization, arrangement, adjustment, composition or other
judicial proceeding relative to the Company or any other obligor upon the
Securities or the property of the Company or of such obligor or their creditors,
the Trustee (irrespective of whether the principal of the Securities shall then
be due and payable as therein expressed or by declaration or otherwise and
irrespective of whether the Trustee shall have made any demand on the Company
for the payment of overdue principal or interest) shall be entitled and
empowered, by intervention in such proceeding or otherwise to take any and all
actions under the TIA, including:

          (1)  to file and prove a claim for the whole amount of principal (and
     premium, if any) and interest owing and unpaid in respect of the Securities
     and to file such other papers or documents as may be necessary or advisable
     in order to have the claims of the Trustee (including any claim for the
     reasonable compensation, expenses, disbursements and advances of the
     Trustee, its agent and counsel) and of the Holders allowed in such judicial
     proceeding, and

          (2)  to collect and receive any moneys or other property payable or
     deliverable on any such claims and to distribute the same; and any
     custodian, receiver, assignee, trustee, liquidator, sequestrator or other
     similar official in any such judicial proceeding is hereby authorized by
     each Holder to make such payments to the Trustee and, in the event that the
     Trustee shall consent to the making of such payments directly to the
     Holders, to pay to the Trustee any amount due it for the reasonable
     compensation, expenses, disbursements and advances of the Trustee, its
     agents and counsel, and any other amounts due the Trustee under Section
     7.7.

     Nothing herein contain shall be deemed to authorize the Trustee to
authorize or consent to or accept or adopt on behalf of any Holder any plan of
reorganization, arrangement, adjustment, or composition affecting the Securities
or the rights of any Holder thereof or to authorize the Trustee to vote in
respect of the claim of any Holder in any such proceeding.

                                      28
<PAGE>
 
6.5. TRUSTEE MAY ENFORCE CLAIMS WITHOUT POSSESSION OF SECURITIES.

     All rights of action and claims under this Indenture or the Securities may
be prosecuted and enforced by the Trustee without the possession of any of the
Securities or the production thereof in any proceeding relating thereto, and any
such proceeding instituted by the Trustee shall be brought it its own name as
trustee of an express trust in favor of the Holders, and any recovery of
judgment shall, after provision for the payment of reasonable compensation to,
and reasonable expenses, disbursement and advances of the Trustee, its agents
and counsel, be for the ratable benefit of the Holders of the Securities in
respect of which such judgment has been recovered.

6.6. PRIORITIES.

     Any money collected by the Trustee pursuant to this Article 6 shall be
applied in the following order, at the date or dates fixed by the Trustee and,
in case of the distribution of such money on account of principal, premium (if
any) or interest, upon presentation of the Securities and the notation thereon
of the payment if only partially paid and upon surrender thereof if fully paid:

     FIRST: To the Trustee in payment of all amounts due pursuant to Section 
7.7;

     SECOND: To the holders of the Senior Indebtedness of the Company to the
extent provided in Article 11;

     THIRD: To the Holders in payment of the amounts then due and unpaid for
principal of, premium (if any), and interest on, the Securities in respect or
for the benefit of which such money has been collected, ratably, without
preference or priority of any kind, according to the amounts due and payable on
such Securities for principal, premium (if any) and interest, respectively; and

     FOURTH: To whomsoever may be lawfully entitled thereto, the remainder, if
any.

6.7. LIMITATION ON SUITS.

     No Holder of any Security shall have any right to order or direct the
Trustee to institute any proceeding, judicial or otherwise, with respect to this
Indenture, or for the appointment of a receiver or trustee, or for any other
remedy hereunder, unless

          (A)  such Holder has previously given written notice to the Trustee of
     a continuing Event of Default;

          (B)  the Holders of not less than 25% in principal amount of then
     outstanding Securities shall have made written request to the Trustee to
     institute proceedings in respect of such Event of Default in its own name
     as Trustee hereunder;

                                        29
<PAGE>
 
          (C)  such Holder or Holders have offered to the Trustee reasonable
     security or indemnity against the costs, expenses and liabilities to be
     incurred or reasonably probable to be incurred in compliance with such
     request;

          (D)  the Trustee for 60 days after its receipt of such notice, request
     and offer of indemnity has failed to institute any such proceeding; and

          (E)  no direction inconsistent with such written request has been
     given to the Trustee during such 60-day period by the Holders of a majority
     in principal amount of then outstanding Securities;

     it being understood and intended that no one or more Holders may have any
right in any manner whatever by virtue of, or by availing of, any provision of
this Indenture to affect, disturb or prejudice the rights of any other Holders,
or to obtain or to seek to obtain priority or preference over any other Holders
or to enforce any right under this Indenture, except in the manner herein
provided and for the equal and ratable benefit of all the Holders.

6.8. UNCONDITIONAL RIGHT OF HOLDERS TO RECEIVE PRINCIPAL, PREMIUM AND INTEREST

     Notwithstanding any other provision of this Indenture, the Holder of any
Security shall have the right, which is absolute and unconditional, to receive
payment of the principal of, and premium (if any) and interest on, such Security
when due (including, in the case of redemption, the Redemption Price on the
applicable Redemption Date, and in the case of the Repurchase Price, on the
applicable Repurchase Date) and to institute suit for the enforcement of any
such payment after such respective dates, and such rights shall not be impaired
without the consent of such Holder.

6.9. RIGHTS AND REMEDIES CUMULATIVE.

     Except as otherwise provided with respect to the replacement or payment of
mutilated, destroyed, lost or stolen Securities in Section 2.7, no right or
remedy herein conferred upon or reserved to the Trustee or to the Holders is
intended to be exclusive of any other right or remedy, and every right and
remedy shall, to the extent permitted by law, be cumulative and in addition to
every other right and remedy given hereunder or now or hereafter existing at law
or in equity or otherwise. The assertion or employment of any right or remedy
hereunder, or otherwise, shall not prevent the concurrent assertion or
employment of any other appropriate right or remedy.

6.10. DELAY OR OMISSION NOT WAIVER.

     No delay or omission by the Trustee or by any Holder of any Security to
exercise any right or remedy arising upon any Event of Default shall impair the
exercise of any such right or remedy or constitute a waiver of any such Event of
Default. Every right and remedy given by this Article 6, or by law to the
Trustee or to the Holders may be exercised from time to time, and as often as
may be deemed expedient, by the Trustee or by the Holders, as the case may be.

                                        30
<PAGE>
 
6.11. CONTROL BY HOLDERS.

     The Holder or Holders of no less than a majority in aggregate principal
amount of then outstanding Securities shall have the right to direct the time,
method and place of conducting any proceeding for any remedy available to the
Trustee or exercising any trust or power conferred upon the Trustee, PROVIDED,
that

          (1)  such direction shall not be in conflict with any rule of law or
     with this Indenture,

          (2)  the Trustee shall not determine that the action so directed would
     be unjustly prejudicial to the Holders not taking part in such direction,
     and

          (3)  the Trustee may take any other action deemed proper by the
     Trustee which is not inconsistent with such direction.

6.12. WAIVER OF PAST DEFAULT.

     Subject to Section 6.8, the Holder or Holders of not less than a majority
in aggregate principal amount of then outstanding Securities may, on behalf of
all Holders, prior to the declaration of acceleration of the maturity of the
Securities, waive any past Default hereunder and its consequences, except a
Default

          (A)  in the payment of the principal of, or premium, if any, or
interest on, any Security not yet cured as specified in clauses (1) and (2) of
Section 6.1, or

          (B)  in respect of a covenant or provision hereof, which, under
Article 9, cannot be modified or amended without the consent of the Holder of
each outstanding Security affected.

     Upon any such waiver, such Default shall cease to exist, and any Event of
Default arising from such a Default shall be deemed to have been cured for every
purpose of this Indenture; but no such waiver shall extend to any subsequent or
other Default or impair the exercise of any right arresting therefrom.

6.13. UNDERTAKING FOR COSTS.

      All parties to this Indenture agree, and each Holder of any Security by
his acceptance thereof shall be deemed to have agreed, that any court may in its
discretion require, in any suit for the enforcement of any right or remedy under
this Indenture, or in any suit against the Trustee for any action taken,
suffered or omitted to be taken by it as Trustee, the filing by any party
litigant in such suit of an undertaking to pay the costs of such suit, and that
such court may in its discretion assess reasonable costs, including reasonable
attorneys' fees, against any party litigant in such suit, having due regard to
the merits and good faith of the claims or defenses made by

                                      31
<PAGE>
 
such party litigant; but the provisions of this Section 6.13 shall not apply to
any suit instituted by the Company, to any suit instituted by the Trustee, to
any suit instituted by any Holder, or group of Holders, holding in the aggregate
more than 10% in aggregate principal amount of then outstanding Securities, or
to any suit instituted by any Holder for enforcement of the payment of principal
of, premium (if any), or interest on, any Security on or after the respective
Stated Maturity of such Security (including, in the case of redemption, on or
after the Redemption Date).

6.14. RESTORATION OF RIGHTS AND REMEDIES.

     If the Trustee or any Holder has instituted any proceeding to enforce any
right or remedy under this Indenture and such proceeding has been discontinued
or abandoned for any reason, or has been determined adversely to the Trustee or
to such Holder, then and in every case, subject to any determination in such
proceeding, the Company, the Trustee and the Holders shall be restored severally
and respectively to their former positions hereunder and thereafter all rights
and remedies of the Trustee and the Holders shall continue as though no such
proceeding had been instituted.

                                    ARTICLE
                                      7.
                                    TRUSTEE

     The Trustee hereby accepts the trust imposed upon it by this Indenture and
covenants and agrees to perform the same, as herein expressed.

7.1. DUTIES OF TRUSTEE.

     (a)  If a Default or an Event of Default has occurred and is continuing,
the Trustee shall exercise such of the rights and powers vested in it by this
Indenture and use the same degree of care and skill in their exercise as a
prudent Person would exercise or use under the circumstances in the conduct of
his own affairs.

     (b)  Except during the continuance of a Default or an Event of Default:

          (1)  The Trustee need perform only those duties as are specifically
     set forth in this Indenture and no others, and no covenants or obligations
     shall be implied in or read into this Indenture which are adverse to the
     Trustee.

          (2)  In the absence of bad faith on its part, the Trustee may
     conclusively rely, as to the truth of the statements and the correctness of
     the opinions expressed therein, upon certificates or opinions furnished to
     the Trustee and conforming to the requirements of this Indenture. However,
     the Trustee shall examine the certificates and opinions to determine
     whether or not they conform to the requirements of this Indenture.

                                      32
<PAGE>
 
     (c)  The Trustee may not be relieved from liability for its own negligent
action, its own negligent failure to act, or its own willful misconduct, except
that:

          (1)  This paragraph does not limit the effect of paragraph (b) of this
     Section 7.1.

          (2)  The Trustee shall not be liable for any error of judgment made in
     good faith by a Trust Officer, unless it is proved that the Trustee was
     negligent in ascertaining the pertinent facts.

          (3)  The Trustee shall not be liable with respect to any action it
     takes or omits to take in good faith in accordance with a direction
     received by it pursuant to Section 6.11.

     (d)  No provision of this Indenture shall require the Trustee to expend or
risk its own funds or otherwise incur any financial liability in the performance
of any of its duties hereunder or to take or omit to take any action under this
Indenture or at the request, order or direction of the Holders or in the
exercise of any of its rights or powers if it shall have reasonable grounds for
believing that repayment of such funds or adequate indemnity against such risk
or liability is not reasonably assured to it.

     (e)  Every provision of this Indenture that in any way relates to the
Trustee is subject to paragraphs (a), (b), (c), (d) and (f) of this Section 7.1.

     (f)  The Trustee shall not be liable for interest on any assets received by
it except as the Trustee may agree in writing with the Company. Assets held in
trust need not be segregated from other assets except to the extent required by
law.

7.2. RIGHTS OF TRUSTEE.

     Subject to Section 7.1:

     (a)  The Trustee may rely on any document believed by it to be genuine and
to have been signed or presented by the proper Person. The Trustee need not
investigate any fact or matter stated in the document.

     (b)  Before the Trustee acts or refrains from acting, it may consult with
counsel and may require an Officers' Certificate on or Opinion of Counsel, which
shall conform to Sections 13.4 and 13.5. The Trustee shall not be liable for any
action it takes or omits to take in good faith in reliance on such certificate
or advice of counsel.

     (c)  The Trustee may act through its attorneys and agents and shall not be
responsible for the misconduct or negligence of any agent appointed with due
care.

                                      33
<PAGE>
 
     (d)  The Trustee shall not be liable for any action it takes or omits to
take in good faith which it believes to be authorized or within its rights or
powers conferred upon it by this Indenture.

     (e)  The Trustee shall not be bound to make any investigation into the
facts or matters stated in any resolution, certificate, statement, instrument,
opinion, notice, request, direction, consent, order, bond, debenture or other
paper or document, but the Trustee, in its discretion, may make such further
inquiry or investigation into such facts or matters as it may see fit.

     (f)  The Trustee shall be under no obligation to exercise any of the rights
or powers vested in it by this Indenture at the request, order or direction of
any of the Holders, pursuant to the provisions of this Indenture, unless such
Holders shall have offered to the Trustee reasonable security or indemnity
against the costs, expenses and liabilities which may be incurred therein or
thereby.

     (g)  Unless otherwise specifically provided for in this Indenture, any
demand, request, direction or notice from the Company shall be sufficient if
signed by an Officer of the Company.

     (h)  The Trustee shall have no duty to inquire as to the performance of the
Company's covenants in Article 4 hereof. In addition, the Trustee shall not be
deemed to have knowledge of any Default or Event of Default except (i) any Event
of Default occurring pursuant to Sections 6.1(1), 6.1(2) or 5.1, or (ii) any
Default or Event of Default of which the Trustee shall have received written
notification or obtained actual knowledge.

7.3. INDIVIDUAL RIGHTS OF TRUSTEE.

     The Trustee in its individual or any other capacity may become the owner or
pledgee of Securities and may otherwise deal with the Company, any of its
Subsidiaries, or their respective affiliates with the same rights it would have
it if were not Trustee. Any Agent may do the same with like rights. However, the
Trustee must comply with Section 7.10 and 7.11.

7.4. TRUSTEE'S DISCLAIMER.

     The Trustee makes no representation as to the validity or adequacy of this
Indenture or the Securities and it shall not be accountable for the Company's
use of the proceeds from the Securities, and it shall not be responsible for any
statement in the Securities, other than the Trustee's certificate of
authentication, or the use or application of any funds received by a Paying
Agent other than the Trustee.

7.5. NOTICE OF DEFAULT.

     If a Default or an Event of Default occurs and is continuing and if it is
known to the Trustee, the Trustee shall mail to each Security Holder notice of
the uncured Default or Event of Default within 90 days after such Default or
Event of Default occurs. Except in the case of a Default or an Event of Default
in payment of principal (or premium, if any), or interest on, any

                                      34
<PAGE>
 
Security (including the payment of the Repurchase Price on the Repurchase Date
and the payment of the Redemption Price on the Redemption Date), the Trustee may
withhold the notice if and so long as a Trust Officer in good faith determines
that withholding the notice is in the interest of the Security Holders.

7.6. REPORTS BY TRUSTEE TO HOLDERS.

     Within 60 days after each November 15 beginning with the November 15
following the date of this Indenture, the Trustee shall, if required by law,
mail to each Security Holder a brief report dated as of such November 15 that
complies with the TIA Section 313(a). The Trustee also shall comply with TIA
Sections 313(b) and 313(c).

     The Company shall promptly notify the Trustee in writing if the Securities
become listed on any stock exchange, market or automatic quotation system.

     A copy of each report at the time of its mailing to Security Holders shall
be mailed to the Company and filed with the SEC and each stock exchange or
market, if any, on which the Securities are listed.

7.7. COMPENSATION AND INDEMNITY.

     The Company agrees to pay to the Trustee from time to time reasonable
compensation for its services. The Trustee's compensation shall not be limited
by any law on compensation of a trustee of an express trust. The Company shall
reimburse the Trustee upon request for all reasonable disbursements, expenses
and advances incurred or made by it. Such expenses shall include the reasonable
compensation, disbursements and expenses of the Trustee's agents, accountants,
experts and counsel.

     The Company agrees to indemnify the Trustee (in its capacity as Trustee)
and each of its officers, directors, attorneys-in-fact and agents for, and hold
it harmless against, any claim, demand, expense (including but not limited to
reasonable compensation, disbursements and expenses of the Trustee's agents and
counsel), loss or liability incurred by it without negligence, bad faith or
willful misconduct on its part, arising out of or in connection with the
administration of this trust and its rights or duties hereunder including the
reasonable costs and expenses of defending itself against any claim or liability
in connection with the exercise or performance of any of its powers or duties
hereunder. The Trustee shall notify the Company promptly of any claim asserted
against the Trustee for which it may seek indemnity. The Company shall defend
the claim and the Trustee shall provide reasonable cooperation at the Company's
expense in the defense. The Trustee may have separate counsel and the Company
shall pay the reasonable fees and expenses of such counsel; PROVIDED, that the
Company will not be required to pay such fees and expenses if it assumes the
Trustee's defense and there is no conflict of interest between the Company and
the Trustee in connection with such defense. The Company need not pay for any
settlement made without its written consent. The Company need not reimburse any
expense or indemnify against any loss or liability to the extent incurred by the
Trustee through its negligence, bad faith or willful misconduct.

                                      35
                                        
<PAGE>
 
        To secure the Company's payment obligations in this Section 7.7, the
Trustee shall have a lien prior to the Securities on all assets held or
collected by the Trustee, in its capacity as Trustee, except assets held in
trust to pay principal of, and premium, if any, or interest on particular
Securities.

        When the Trustee incurs expenses or renders services after an Event of
Default specified in Section 6.1(5) or (6) occurs, the expenses and the
compensation for the services are intended to constitute expenses of
administration under any Bankruptcy Law.

        The Company's obligations under this Section 7.7 and any lien arising
hereunder shall survive the resignation or removal of the Trustee, the discharge
of the Company's obligations pursuant to Article 8 of this Indenture and any
rejection or termination of this Indenture under any Bankruptcy Law.

7.8.    REPLACEMENT OF TRUSTEE.

        The Trustee may resign by so notifying the Company in writing. The
Holder or Holders of a majority in principal amount of then outstanding
Securities may remove the Trustee by so notifying the Company and the Trustee in
writing and may appoint a successor trustee with the Company's consent. The
Company may remove the Trustee if

               (a)  the Trustee fails to comply with Section 7.10;

               (b)  the Trustee is adjudged bankrupt or insolvent;

               (c)  a receiver, Custodian or other public officer takes charge
          of the Trustee or its property; or

               (d)  the Trustee becomes incapable of acting.

        If the Trustee resigns or is removed or if a vacancy exists in the
office of Trustee for any reason, the Company shall promptly appoint a successor
Trustee. Within one year after the successor Trustee takes office, the Holder or
Holders of a majority in principal amount of then outstanding Securities may
appoint a successor Trustee to replace the successor Trustee appointed by the
Company.

        A successor Trustee shall deliver a written acceptance of its
appointment to the retiring Trustee and to the Company. Immediately after that
and provided that all sums owing to the retiring Trustee provided for in Section
7.7 have been paid, the retiring Trustee shall transfer all property held by it
as trustee to the successor Trustee, subject to the lien provided in Section
7.7, the resignation or removal of the retiring Trustee shall become effective,
and the successor Trustee shall have all the rights, powers and duties of the
Trustee under this Indenture. A successor Trustee shall mail notice of its
succession to each Holder.

                                      36
<PAGE>
 
        If a successor Trustee does not take office within 60 days after the
retiring Trustee resigns or is removed, the retiring Trustee, the Company or the
Holder or Holders of at least 10% in principal amount of then outstanding
Securities may petition any court of competent jurisdiction for the appointment
of a successor Trustee.

        If the Trustee fails to comply with Section 7.10, any Security Holder
may petition any court of competent jurisdiction for the removal of the Trustee
and the appointment of a successor Trustee.

        Notwithstanding replacement of the Trustee pursuant to this Section 7.8,
the Company's obligations under Section 7.7 shall continue for the benefit of
the retiring Trustee.

7.9.    SUCCESSOR TRUSTEE BY MERGER, ETC.

        If the Trustee consolidates with, merges or converts into, or transfers
all or substantially all of its corporate trust business to, another
corporation, the resulting, surviving or transferee corporation without any
further act shall, if such resulting surviving or transferee corporation is
otherwise eligible hereunder, be the successor Trustee.

7.10.   ELIGIBILITY; DISQUALIFICATION

        The Trustee shall at all times satisfy the requirements of TIA Section
310(a)(1), (2) and (5). The Trustee shall have a combined capital and surplus of
at least $100,000,000 as set forth in its most recent published annual report of
condition. The Trustee shall comply with TIA Section 310(b).

7.11.   PREFERENTIAL COLLECTION OF CLAIMS AGAINST COMPANY

        The Trustee shall comply with TIA Section 311(a), excluding any creditor
relationship listed in TIA Section 311(b). A Trustee who has resigned or been
removed shall be subject to TIA Section 311(a) to the extent indicated.

                                    ARTICLE
                                      8.
                          SATISFACTION AND DISCHARGE

8.1.    SATISFACTION AND DISCHARGE OF INDENTURE.

        The Company may terminate its obligations under this Indenture (subject
to the provisions of this Article 8) when it shall have delivered to the Trustee
for cancellation all Securities theretofore authenticated (other than any
Securities which shall have been destroyed, lost or stolen and which shall have
been replaced or paid as provided in Article 2 hereof) and the following
conditions shall be satisfied:

               (1)  The Company has paid all sums payable under the Indenture;
          and

                                      37
<PAGE>
 
          (2)  The Company shall have delivered to the Trustee an Officers'
        Certificate and an Opinion of Counsel, each stating that all conditions
        precedent have been complied with as contemplated by this Section 8.1.

8.2.    PAYMENT TO THE COMPANY.

        Any money deposited with the Trustee or any Paying Agent, or then held
by the Company, for the payment of the principal of, premium, if any, or
interest on any Security and remaining unclaimed for two years after such
principal, premium, if any, or interest has become due and payable shall be paid
to the Company on its request; and the Holder of such Security shall thereafter
look only to the Company for payment thereof, and all liability of the Trustee
or such Paying Agent with respect to such trust money shall thereupon cease.

                                    ARTICLE
                                      9.
                      AMENDMENTS, SUPPLEMENTS AND WAIVERS

9.1.    SUPPLEMENTAL INDENTURES WITHOUT CONSENT OF HOLDERS.

        Without the consent of any Holder, the Company, when authorized by Board
Resolutions, and the Trustee, at any time and from time to time, may enter into
one or more indentures supplemental hereto, in form satisfactory to the Trustee,
for any of the following purposes:

          (1)  to cure any ambiguity, defect, or inconsistency, or to make any
        other provisions with respect to matters or questions arising under this
        Indenture which shall not be inconsistent with the provisions of this
        Indenture, PROVIDED, that such action pursuant to this clause (1) does
        not adversely affect the interests of any Holder in any respect;

          (2)  to create additional covenants of the Company for the benefit of
        the Holders, or to surrender any right or power herein conferred upon
        the Company or to make any other change that does not adversely affect
        the rights of any Holder, PROVIDED, that the Company has delivered to
        the Trustee an Opinion of Counsel stating that such change pursuant to
        this clause (2) does not adversely affect the rights of any Holder;

          (3)  to provide for collateral for, or guarantors of, the Securities;

          (4)  to evidence the succession of another Person to the Company and
        the assumption by any such successor of the obligations of the Company
        herein and in the Securities in accordance with Article 5: or

          (5)  to comply with the TIA.

                                      38
<PAGE>
 
9.2.    AMENDMENTS, SUPPLEMENTAL INDENTURES AND WAIVERS WITH CONSENT OF HOLDERS.

        Subject to Section 6.8 and the last sentence of this paragraph, with the
consent of the Holders of not less than a majority in aggregate principal amount
of then outstanding Securities, by written act of said Holders delivered to the
Company and the Trustee, the Company, when authorized by Board Resolutions, and
the Trustee may amend or supplement this Indenture or the Securities or enter
into an indenture or indentures supplemental hereto for the purpose of adding
any provisions to or changing in any manner or eliminating any of the provisions
of this Indenture or the Securities or of modifying in any manner the rights of
the Holders under this Indenture or the Securities. Subject to Section 6.8 and
the last sentence of this paragraph, the Holder or Holders of not less than a
majority in aggregate principal amount of then outstanding Securities may, in
writing, waive compliance by the Company with any provision of this Indenture or
the Securities. Notwithstanding any of the above, however, no such amendment,
supplemental indenture or waiver shall, without the consent of the Holder of
each outstanding Security affected thereby:

          (1)  change the Stated Maturity of any Security or reduce the
        principal amount thereof or the rate (or extend the time for payment) of
        interest thereon or any premium payable upon the redemption thereof, or
        change the place of payment where, or the coin or currency in which, any
        Security or any premium or the interest thereon is payable, or impair
        the right to institute suit for the enforcement of any such payment or
        the conversion of any Security on or after the due date thereof
        (including, in the case of redemption, on or after the Redemption Date),
        or reduce the Repurchase Price, or alter the Repurchase Offer or
        redemption provisions in a manner adverse to the Holders;

          (2)  reduce the percentage in principal amount of the outstanding
        Securities, the consent of whose Holders is required for any such
        amendment, supplemental indenture or waiver provided for in the
        Indenture;

          (3)  adversely affect the right of such Holder to convert Securities;
        or

          (4)  modify any of the waiver provisions, except to increase any
        required percentage or to provide that certain other provisions of the
        Indenture cannot be modified or waived without the consent of the Holder
        of each outstanding Security affected thereby.

        It shall not be necessary for the consent of the Holders under this
Section 9.2 to approve the particular form of any proposed amendment, supplement
or waiver, but it shall be sufficient if such consent approves the substance
thereof.

        After an amendment, supplement or waiver under this Section 9.2 becomes
effective, the Company shall mail to the Holders affected thereby a notice
briefly describing the amendment, supplement or waiver. Any failure of the
Company to mail such notice, or any defect therein,

                                      39
<PAGE>
 
shall not, however, in any way impair or affect the validity of any such
supplemental indenture or waiver.

     After an amendment, supplement or waiver under this Section 9.2 becomes
effective, it shall bind each Holder.

     In connection with any amendment, supplement or waiver under this Article
9, the Company may, but shall not be obligated to, offer to any Holder who
consents to such amendment, supplement or waiver, or (at the option of the
Company) to all Holders, consideration for consent to such amendment, supplement
or waiver.

9.3. COMPLIANCE WITH TIA.

     Every amendment, waiver or supplement of this Indenture or the Securities
shall comply with the TIA as then in effect.

9.4. REVOCATION AND EFFECT OF CONSENTS.

     Until an amendment, waiver or supplement becomes effective, a consent to it
by a Holder is a continuing consent by the Holder and every subsequent Holder of
a Security or portion of a Security that evidences the same debt as the
consenting Holder's Security, even if notation of the consent is not made on any
Security. However, any such Holder or subsequent Holder may revoke the consent
as to his Security or portion of his Security by written notice to the Company
or the Person designated by the Company as the Person to whom consents should be
sent if such revocation is received by the Company or such Person before the
date on which the Trustee receives an Officers' Certificate certifying that the
Holders of the requisite principal amount of Securities have consented (and not
theretofore revoked such consent) to the amendment, supplement or waiver.

     The Company may, but shall not be obligated to, fix a record date for the
purpose of determining the Holders entitled to consent to any amendment,
supplement or waiver, which record date shall be the date so fixed by the
Company notwithstanding the provisions of the TIA. If a record date is fixed,
then notwithstanding the last sentence of the immediately preceding paragraph,
those Persons who were Holders at such record date, and only those Persons (or
their duly designated proxies), shall be entitled to revoke any consent
previously given, whether or not such Persons continue to be Holders after such
record date. No such consent shall be valid or effective for more than 90 days
after such record date.

     After an amendment, supplement or waiver becomes effective pursuant to this
Section 9.4, it shall bind every Security Holder, unless it makes a change
described in any of clauses (1) through (4) of Section 9.2, in which case, the
amendment, supplement or waiver shall bind only each Holder of a Security who
has consented to it and every subsequent Holder of a Security or portion of a
Security that evidences the same debt as the consenting Holder's Security.

                                      40
<PAGE>
 
9.5. NOTATION ON OR EXCHANGE OF SECURITIES.

     If an amendment, supplement or waiver changes the terms of a Security, the
Trustee may require the Holder of the Security to deliver it to the Trustee or
require the Holder to put an appropriate notation on the Security. The Trustee
may place an appropriate notation on the Security about the changed terms and
return it to the Holder. Alternatively, if the Company or the Trustee so
determines, the Company in exchange for the Security shall issue and the Trustee
shall authenticate a new Security that reflects the changed terms. Any failure
to make the appropriate notation or to issue a new Security shall not affect the
validity of such amendment, supplement or waiver.

9.6. TRUSTEE TO SIGN AMENDMENTS, ETC.

     The Trustee shall execute any amendment, supplement or waiver authorized
pursuant to this Article 9; PROVIDED, that the Trustee may, but shall not be
obligated to, execute any such amendment, supplement or waiver which affects the
Trustee's own rights, duties or immunities under this Indenture. The Trustee
shall be entitled to receive, and shall be fully protected in relying upon, an
Opinion of Counsel stating that the execution of any amendment, supplement or
waiver authorized pursuant to this Article 9 is authorized or permitted by this
Indenture.

                                    ARTICLE
                                      10.
             RIGHT TO REQUIRE REPURCHASE UPON A CHANGE OF CONTROL

10.1. REPURCHASE OF SECURITIES AT OPTION OF THE HOLDER UPON A CHANGE OF CONTROL.

     (a) In the event that a Change of Control occurs, each Holder shall have
the right, at such Holder's option, subject to the terms and conditions of this
Indenture, to require the Company to repurchase all or any part of such Holder's
Securities (PROVIDED, that the principal amount of such Securities must be
$1,000 or an integral multiple thereof) on the date (the "Repurchase Date") that
is no later than 45 Business Days after the occurrence of such Change of
Control, at a cash price (the "Repurchase Price") equal to 100% of the principal
amount thereof, together with accrued and unpaid interest to the Repurchase
Date.

     (b) In the event that, pursuant to this Section 10.1, the Company shall be
required to commence an irrevocable and unconditional offer to purchase
Securities (a "Repurchase Offer"), the Company shall follow the procedures set
forth in this Section 10.1 as follows:

     (1) the Repurchase Offer shall commence within 30 Business Days following a
Change of Control;

     (2) the Repurchase Offer shall remain open for 15 Business Days following
its commencement, except to the extent that a longer period is required by
applicable law,

                                      41
<PAGE>
 
     but in any case not more than 45 Business Days following the Change of
     Control (the "Repurchase Offer Period");

          (3)  upon the expiration of a Repurchase Offer, the Company shall
     purchase all Securities tendered in response to the Repurchase Offer;

          (4)  if the Repurchase Date is on or after an interest payment record
     date and on or before the related Interest Payment Date, any accrued
     interest will be paid to the Person in whose name a Security is registered
     at the close of business on such record date, and no additional interest
     will be payable to Security Holders who tender Securities pursuant to the
     Repurchase Offer;

          (5)  the Company shall provide the Trustee with notice of the
     Repurchase Offer, at least 5 Business Days before the commencement of any
     Repurchase Offer; and

          (6)  on or before the commencement of any Repurchase Offer, the
     Company or the Trustee (upon the request and at the expense of the Company)
     shall send, by first-class mail, a notice to each of the Security Holders,
     which (to the extent consistent with this Indenture) shall govern the terms
     of the Repurchase Offer and shall state:

               (i)   that the Repurchase Offer is being made pursuant to such
          notice and this Section 10.1 and that all Securities, or portions
          thereof, tendered will be accepted for payment;

               (ii)  the Repurchase Price (including the amount of accrued and
          unpaid interest, if any), the Repurchase Date and the Repurchase Put
          Date (as defined below);

               (iii) that any Security, or portion thereof, not tendered or
          accepted for payment will continue to accrue interest, if any;

               (iv)  that, unless the Company defaults in depositing Cash with
          the Paying Agent in accordance with the last paragraph of this clause
          (b) or such payment is prevented pursuant to Article 11, any Security,
          or portion thereof, accepted for payment pursuant to the Repurchase
          Offer shall cease to accrue interest after the Repurchase Date;

               (v)   that Holders electing to have a Security, or portion
          thereof, purchased pursuant to a Repurchase Offer will be required to
          surrender the Security, with the form entitled "Option of Holder to
          Elect Purchase" on the reverse of the Security completed, to the
          Paying Agent (which may not for purposes of this Section 10.1,
          notwithstanding anything in this Indenture to the contrary, be the
          Company or any Affiliate of the Company) at the address specified in
          the notice prior to the close of business on the earlier of (a) the
          third Business Day prior to the Repurchase Date and (b) the third
          Business Day

                                      42
<PAGE>
 
          following the expiration of the Repurchase Offer (such earlier date
          being the "Repurchase Put Date");

               (vi)   that Holders will be entitled to withdraw their election,
          in whole or in part, if the Paying Agent (which may not for purposes
          of this Section 10.1, notwithstanding anything in this Indenture to
          the contrary, be the Company or any Affiliate of the Company)
          receives, up to the close of business on the Repurchase Put Date, a
          telegram, telex, facsimile transmission or letter setting forth the
          name of the Holder, the principal amount of the Securities the Holder
          is withdrawing and a statement that such Holder is withdrawing his
          election to have such principal amount of Securities purchased; and

               (vii)  a brief description of the events resulting in such Change
          of Control.

     Any such Repurchase Offer shall comply with all applicable provisions of
Federal and state laws, including those regulating tender offers, if applicable,
and any provisions of this Indenture which conflict with such laws shall be
deemed to be superseded by the provisions of such laws.

     On or before the Repurchase Date, the Company shall (i) accept for payment
Securities or portions thereof properly tendered pursuant to the Repurchase
Offer on or before the Repurchase Put Date, (ii) deposit with the Paying Agent
Cash sufficient to pay the Repurchase Price (together with accrued and unpaid
interest, if any) of all Securities or portions thereof so tendered and (iii)
deliver to the Trustee Securities so accepted together with an Officers'
Certificate listing the Securities or portions thereof being purchased by the
Company. The Paying Agent shall promptly mail to Holders of Securities so
accepted payment in an amount equal to the Repurchase Price (together with
accrued and unpaid interest, if any), and the Trustee shall promptly
authenticate and mail or deliver to such Holders a new Security or Securities
equal in principal amount to any unpurchased portion of the Securities
surrendered. Any Securities not so accepted shall be promptly mailed or
delivered by the Company to the Holder thereof. The Company will publicly
announce the results of the Repurchase Offer on or as soon as practicable after
the Repurchase Date.

                                    ARTICLE
                                      11.
                                 SUBORDINATION

11.1.   SECURITIES SUBORDINATED TO SENIOR INDEBTEDNESS.

        The Company and each Holder, by its acceptance of Securities, agree that
(a) the payment of the principal of, premium, if any, and interest on the
Securities and (b) any other payment in respect of the Securities, including on
account of the acquisition or redemption of the Securities by the Company
(including, without limitation, pursuant to Article 10) is subordinated, to the
extent and in the manner provided in this Article 11, to the prior payment in
full of all Senior

                                      43
<PAGE>
 
Indebtedness of the Company, whether outstanding at the date of this Indenture
or thereafter created, incurred, assumed or guaranteed, and that these
subordination provisions are for the benefit of the holders of Senior
Indebtedness.

        This Article 11 shall constitute a continuing offer to all Persons who,
in reliance upon such provisions, become holders of, or continue to hold, Senior
Indebtedness, and such provisions are made for the benefit of the holders of
Senior Indebtedness, and such holders are made obligees hereunder and any one or
more of them may enforce such provisions.

11.2.   NO PAYMENT ON SECURITIES IN CERTAIN CIRCUMSTANCES.

        (a)  No payment may be made by the Company on account of the principal
of, premium, if any, or interest on, the Securities, or to acquire any of the
Securities (including repurchases of Securities at the option of the Holder) for
cash or property (other than Junior Securities), or on account of the redemption
provisions of the Securities, (i) upon the maturity of any Senior Indebtedness
of the Company by lapse of time, acceleration (unless waived) or otherwise,
unless and until all principal of, premium, if any, and interest on such Senior
Indebtedness are first paid in full (or such payment is duly provided for), or
(ii) in the event of default in the payment of any principal of, premium, if
any, or interest on any Senior Indebtedness of the Company when it becomes due
and payable, whether at maturity or at a date fixed for prepayment or by
acceleration or otherwise (a "Payment Default"), unless and until such Payment
Default has been cured or waived or otherwise has ceased to exist.

        (b)  Upon (i) the happening of an event of default (other than a Payment
Default) that permits the holders of Senior Indebtedness or their representative
immediately to accelerate its maturity and (ii) written notice of such event of
default given to the Company and the Trustee by the holders of an aggregate of
at least $5,000,000 principal amount outstanding of such Senior Indebtedness or
their representative (a "Payment Notice"), then, unless and until such event of
default has been cured or waived or otherwise has ceased to exist, no payment
(by set-off or otherwise) may be made by or on behalf of the Company on account
of the principal of, premium, if any, or interest on, the Securities, or to
acquire or repurchase any of the Securities for cash or property, or on account
of the redemption provisions of the Securities, in any such case other than
payments made with Junior Securities of the Company. Notwithstanding the
foregoing, unless (i) the Senior Indebtedness in respect of which such event of
default exists has been declared due and payable in its entirety within 179 days
after the Payment Notice is delivered as set forth above (the "Payment Blockage
Period"), and (ii) such declaration has not been rescinded or waived, at the end
of the Payment Blockage Period, the Company shall be required to pay all sums
not paid to the Holders of the Securities during the Payment Blockage Period due
to the foregoing prohibitions and to resume all other payments as and when due
on the Securities. Any number of Payment Notices may be given; PROVIDED,
HOWEVER, that (i) not more than one Payment Notice shall be given within a
period of any 360 consecutive days, and (ii) no default that existed upon the
date of such Payment Notice or the commencement of such Payment Blockage Period
(whether or not such event of default is on the same issue of Senior
Indebtedness) shall be made the basis for the commencement of any other Payment
Blockage Period.

                                      44
<PAGE>
 
        (c)  In furtherance of the provisions of Section 11.1, in the event
that, notwithstanding the foregoing provisions of this Section 11.2, any payment
or distribution of assets of the Company (other than Junior Securities) shall be
received by the Trustee or the Holders at a time when such payment or
distribution is prohibited by the provisions of this Section 11.2, then such
payment or distribution (subject to the provisions of Section 11.7) shall be
received and held in trust by the Trustee or such Holder or Paying Agent for the
benefit of the holders of Senior Indebtedness of the Company, and shall be paid
or delivered by the Trustee or such Holders or such Paying Agent, as the case
may be, to the holders of Senior Indebtedness of the Company remaining unpaid or
unprovided for, or their representative or representatives, or to the trustee or
trustees under any indenture pursuant to which any instruments evidencing any of
such Senior Indebtedness of the Company may have been issued, ratably according
to the aggregate amounts remaining unpaid on account of the Senior Indebtedness
of the Company held or represented by each, for application to the payment of
all Senior Indebtedness of the Company in full after giving effect to any
concurrent payment and distribution to the holders of such Senior Indebtedness.

11.3.   SECURITIES SUBORDINATED TO PRIOR PAYMENT OF ALL SENIOR INDEBTEDNESS ON
        DISSOLUTION, LIQUIDATION OR REORGANIZATION.

        Upon any distribution of assets of the Company upon any dissolution,
winding up, total or partial liquidation or reorganization of the Company,
whether voluntary or involuntary, in bankruptcy, insolvency, receivership or a
similar proceeding or upon assignment for the benefit of creditors or any
marshaling of assets or liabilities:

        (a)  the holders of all Senior Indebtedness of the Company shall first
be entitled to receive payments in full (or have such payment duly provided for)
before the Holders are entitled to receive any payment on account of the
principal of, premium, if any, and interest on, the Securities (other than
payment in Junior Securities);

        (b)  any payment or distribution of assets of the Company of any kind or
character, whether in cash, property or securities (other than payment in Junior
Securities) to which the Holders or the Trustee on behalf of the Holders would
be entitled (by setoff or otherwise), except for the provisions of this Article
11, shall be paid by the liquidating trustee or agent or other Person making
such a payment or distribution directly to the holders of Senior Indebtedness of
the Company or their representatives ratably according to the respective amounts
of such Senior Indebtedness held or represented by each, to the extent necessary
to make payment in full of all such Senior Indebtedness remaining unpaid, after
giving effect to any concurrent payment or distribution to the holders of such
Senior Indebtedness; and

        (c)  in the event that, notwithstanding the foregoing, any payment or
distribution of assets of the Company of any kind or character, whether in cash,
property or securities (other than Junior Securities), shall be received by the
Trustee or the Holders or any Paying Agent (or, if the Company or any Affiliate
of the Company is acting as its own Paying Agent, money for any such payment or
distribution shall be segregated or held in trust) on account of the principal
of or

                                      45
<PAGE>
 
interest on the Securities before all Senior Indebtedness of the Company is paid
in full, such payment or distribution (subject to the provisions of Section
11.7) shall be received and held in trust by the Trustee or such Holder or
Paying Agent for the benefit of the holders of such Senior Indebtedness, or
their respective representatives, ratably according to the respective amounts of
such Senior Indebtedness held or represented by each, to the extent necessary to
make payment as provided herein of all such Senior Indebtedness remaining unpaid
after giving effect to all concurrent payments and distributions and all
provisions therefor to or for the holders of such Senior Indebtedness, but only
to the extent that as to any holder of such Senior Indebtedness, as promptly as
practical following notice from the Trustee to the holders of such Senior
Indebtedness that such prohibited payment has been received by the Trustee,
Holder(s) or Paying Agent (or has been segregated as provided above), such
holder (or a representative therefor) notifies the Trustee of the amounts then
due and owing on such Senior Indebtedness, if any, held by such holder and only
the amounts specified in such notices to the Trustee shall be paid to the
holders of such Senior Indebtedness.

11.4.   SECURITYHOLDERS TO BE SUBROGATED TO RIGHTS OF HOLDERS OF SENIOR
        INDEBTEDNESS.

        Subject to the payment in full of all Senior Indebtedness of the Company
as provided herein, the Holders of Securities shall be subrogated to the rights
of the holders of such Senior Indebtedness to receive payments or distributions
of assets of the Company applicable to the Senior Indebtedness until all amounts
owing on the Securities shall be paid in full, and for the purpose of such
subrogation no such payments or distributions to the holders of such Senior
Indebtedness by the Company, or by or on behalf of the Holders by virtue of this
Article 11, which otherwise would have been made to the Holders shall, as
between the Company and the Holders, be deemed to be payment by the Company or
on account of such Senior Indebtedness, it being understood that the provisions
of this Article 11 are and are intended solely for the purpose of defining the
relative rights of the Holders, on the one hand, and the holders of such Senior
Indebtedness, on the other hand.

        If any payment or distribution to which the Holders would otherwise have
been entitled but for the provisions of this Article 11 shall have been applied,
pursuant to the provisions of this Article 11, to the payment of payable under
Senior Indebtedness of the Company, then the Holders be entitled to receive from
the holders of such Senior Indebtedness any payments or distributions received
by such holders of Senior Indebtedness in excess of the amount sufficient to pay
all amounts payable under or in respect of such Senior Indebtedness in full.

11.5.   OBLIGATIONS OF THE COMPANY UNCONDITIONAL.

        Nothing contained in this Article 11 or elsewhere in this Indenture or
in the Securities is intended to or shall impair as between the Company and the
Holders, the obligation of each such Person, which is absolute and
unconditional, to pay to the Holders the principal of, premium, if any, and
interest on, the Securities as and when the same shall become due and payable in
accordance with their terms, or is intended to or shall affect the relative
rights of the Holders and creditors of the Company other than the holders of the
Senior Indebtedness, nor shall anything

                                      46
<PAGE>
 
herein or therein prevent the Trustee or any Holder from exercising all remedies
otherwise permitted by applicable law upon default under this Indenture, subject
to the rights, if any, under this Article 11, of the holders of Senior
Indebtedness in respect of cash, property or securities of the Company received
upon the exercise of any such remedy. Notwithstanding anything to the contrary
in this Article 11 or elsewhere in this Indenture or in the Securities, upon any
distribution of assets of the Company referred to in this Article 11, the
Trustee, subject to the provisions of Sections 7.1 and 7.2, and the Holders
shall be entitled to rely upon any order or decree made by any court of
competent jurisdiction in which such dissolution, winding up, liquidation or
reorganization proceedings are pending, or a certificate of the liquidating
trustee or agent or other Person making any distribution to the Trustee or to
the Holders for the purpose of ascertaining the Persons entitled to participate
in such distribution, the holders of the Senior Indebtedness and other
Indebtedness of the Company, the amount thereof or payable thereon, the amount
or amounts paid or distributed thereon and all other facts pertinent thereto or
to this Article 11 so long as such court has been apprised of the provisions of,
or the order, decree or certificate makes reference to, the provisions of this
Article 11. Nothing in this Section 11.5 shall apply to the claims of, or
payments to, the Trustee under or pursuant to Section 7.7.

11.6. TRUSTEE ENTITLED TO ASSUME PAYMENTS NOT PROHIBITED IN ABSENCE OF NOTICE.

      The Trustee shall not at any time be charged with knowledge of the
existence of any facts which would prohibit the making of any payment to or by
the Trustee unless and until a Trust Officer of the Trustee or any Paying Agent
shall have received, no later than one Business Day prior to such payment,
written notice thereof from the Company or from one or more holders of Senior
Indebtedness or from any representative therefor and, prior to the receipt of
any such written notice, the Trustee, subject to the provisions of Sections 7.1
and 7.2, shall be entitled in all respects conclusively to assume that no such
fact exists.

11.7. APPLICATION BY TRUSTEE OF ASSETS DEPOSITED WITH IT.

      Amounts deposited in trust with the Trustee pursuant to and in accordance
with Section 8.2 shall be for the sole benefit of Security Holders and, to the
extent allocated for the payment of Securities, shall not be subject to the
subordination provisions of this Article 11. Otherwise, any deposit of assets
with the Trustee or the Agent (whether or not in trust) for the payment of
principal of or interest on any Securities shall be subject to the provisions of
Sections 11.1, 11.2, 11.3 and 11.4; PROVIDED THAT, if prior to one Business Day
preceding the date on which by the terms of this Indenture any such assets may
become distributable for any purpose (including, without limitation, the payment
of either principal of or interest on any Security) the Trustee or such Paying
Agent shall not have received with respect to such assets the written notice
provided for in Section 11.6, then the Trustee or such Paying Agent shall have
full power and authority to receive such assets and to apply the same to the
purpose for which they were received, and shall not be affected by any notice to
the contrary which may be received by it on or after such date.

                                        47
<PAGE>
 
11.8.  SUBORDINATION RIGHTS NOT IMPAIRED BY ACTS OR OMISSIONS OF THE COMPANY OR
       HOLDERS OF SENIOR INDEBTEDNESS.

       No right of any present or future holders of any Senior Indebtedness to
enforce subordination provisions contained in this Article 11 shall at any time
in any way be prejudiced or impaired by any act or failure to act on the part of
the Company or by any act or failure to act, in good faith, by any such holder,
or by any noncompliance by the Company with the terms of this Indenture,
regardless of any knowledge thereof which any such holder may have or be
otherwise charged with. The holders of Senior Indebtedness may extend, renew,
modify or amend the terms of the Senior Indebtedness or any security therefor
and release, sell or exchange such security and otherwise deal freely with the
Company, all without affecting the liabilities and obligations of the parties to
the Indenture or the Holders.

11.9.  SECURITY HOLDERS AUTHORIZE TRUSTEE TO EFFECTUATE SUBORDINATION OF
       SECURITIES.

       Each Holder of the Securities by his acceptance thereof authorizes and
expressly directs the Trustee on his behalf to take such action as may be
necessary or appropriate to effectuate the subordination provisions contained in
this Article 11 and to protect the rights of the Holders pursuant to this
Indenture, and appoints the Trustee his attorney-in-fact for such purpose,
including, in the event of any dissolution, winding up, liquidation or
reorganization of the Company (whether in bankruptcy, insolvency or receivership
proceedings or upon an assignment for the benefit of creditors of the Company),
the immediate filing of a claim for the unpaid balance of his Securities in the
form required in said proceedings and cause said claim to be approved. If the
Trustee does not file a proper claim or proof of debt in the form required in
such proceeding prior to 30 days before the expiration of the time to file such
claim or claims, then the holders of the Senior Indebtedness or their
representative are or is hereby authorized to have the right to file and are or
is hereby authorized to file an appropriate claim for and on behalf of the
Holders of said Securities. Nothing herein contained shall be deemed to
authorize the Trustee or the holders of Senior Indebtedness or their
representative to authorize or consent to or accept or adopt on behalf of any
Security Holder any plan of reorganization, arrangement, adjustment or
composition affecting the Securities or the rights of any Holder thereof, or to
authorize the Trustee or the holders of Senior Indebtedness or their
representative to vote in respect of the claim of any Security Holder in any
such proceeding.

11.10. RIGHT OF TRUSTEE TO HOLD SENIOR INDEBTEDNESS.

       The Trustee shall be entitled to all of the rights set forth in this
Article 11 in respect of any Senior Indebtedness, to the same extent as any
other holder of Senior Indebtedness, and nothing in this Indenture shall be
construed to deprive the Trustee of any of its rights as such holder.

11.11. ARTICLE 11 NOT TO PREVENT EVENTS OF DEFAULT.

                                        48
<PAGE>
 
       The failure to make a payment on account of principal of, premium, if
any, or interest on, the Securities by reason of any provision of this Article
11 shall not be construed as preventing the occurrence of a Default or an Event
of Default under Section 6.1 or in any way prevent the Holders from exercising
any right hereunder other than the right to receive payment on the Securities.

11.12. NO FIDUCIARY DUTY OF TRUSTEE TO HOLDERS OF SENIOR INDEBTEDNESS.

       The Trustee shall not be deemed to owe any fiduciary duty to the holders
of Senior Indebtedness, and shall not be liable to any such holders (other than
for its willful misconduct or negligence) if it shall in good faith mistakenly
pay over or distribute to the Holders of Securities or the Company or any other
Person, cash, property or securities to which any holders of Senior Indebtedness
shall be entitled by virtue of this Article 11 or otherwise. Nothing in this
Section 11.12 shall affect the obligation of any other such Person to hold such
payment for the benefit of, and to pay such payment over to, the holders of
Senior Indebtedness or their representatives.

                                    ARTICLE
                                      12.
                           CONVERSION OF SECURITIES

12.1.  CONVERSION PRIVILEGE.

       Subject to and upon compliance with the provisions of this Article 12, at
the option of the Holder thereof, any Security may at any time be converted, in
whole, or in part in multiples of $1,000 principal amount, into fully paid and
non-assessable shares of Common Stock issuable upon conversion of the Securities
(the "Conversion Shares"), at the conversion price in effect at the Date of
Conversion, until and including, but not after the close of business on the
Stated Maturity, or unless such Security or some portion thereof shall have been
called for redemption or delivered for repurchase prior to such date and no
Default is made in making due provision for the payment of the redemption price
in accordance with the terms of this Indenture, in which case, with respect to
such Security or portion thereof as has been so called for redemption or
delivered for repurchase, such Security or portion thereof may be so converted
until and including, but not after the close of business on the Business Day
prior to the Redemption Date or Repurchase Date, as applicable for such
Security, unless the Company subsequently fails to pay the applicable Redemption
Price or Repurchase Price, as the case may be.

12.2.  EXERCISE OF CONVERSION PRIVILEGE.

       In order to exercise the conversion privilege, the Holder of any Security
to be converted shall surrender such Security to the Company at any time during
usual business hours at the office of the Registrar, accompanied by a fully
executed written notice, in substantially the form set forth on the reverse of
the Security, that the Holder elects to convert such Security or a stated
portion thereof constituting a multiple of a $1,000 principal amount, and, if
such Security is surrendered for conversion during the period between the close
of business of any Record Date

                                        49
<PAGE>
 
and the opening of business on the next following Interest Payment Date and has
not been called for redemption on a Redemption Date which occurs within such
period, accompanied also by payment of an amount equal to the interest payable
on such Interest Payment Date on the principal amount of the Security being
surrendered for conversion, notwithstanding such conversion. The Holder of any
Security at the close of business on a Record Date will be entitled to receive
the interest payable on such Security on the corresponding Interest Payment Date
notwithstanding the conversion thereof after such Record Date. Holders will
receive the interest payment due on November 15, 1999 whether or not they
surrender Securities for conversion as a result of the Company's exercise of its
right to redeem Securities on or after November 15, 1999. Such notice of
conversion shall also state the name or names (with address) in which the
certificate or certificates for shares of Common issued. Securities surrendered
for conversion shall (if reasonably required by the Company or the Trustee) be
duly endorsed by, or be accompanied by a written instrument or instruments of
transfer in form satisfactory to the Company, duly executed by the Holder or his
attorney duly authorized in writing. As promptly as practicable after the
receipt of such notice and the surrender of such Security as aforesaid, the
Company shall, subject to the provisions of Section 12.8 hereof, issue and
deliver to such Holder, or on his written order, a certificate or certificates
for the number of full shares of Common Stock issuable on such conversion of
Securities in accordance with the provisions of this Article 12 and Cash, as
provided in Section 12.3 hereof, in respect of any fraction of a share of Common
Stock otherwise issuable upon such conversion. Such conversion shall be deemed
to have been effected immediately prior to the close of business on the date
(herein called the "Date of Conversion") on which such Security shall have been
surrendered as aforesaid, the person or persons in whose name or names any
certificate or certificates for shares of Common Stock shall be issuable upon
such conversion shall be deemed to have become on the Date of Conversion the
holder or holders of record of the shares represented thereby; PROVIDED,
HOWEVER, that any such surrender on any date when the stock transfer books of
the Company shall be closed shall cause the person or persons in whose name or
names the certificate or certificates for such shares are to be issued to be
deemed to have become the recordholder or holders thereof for all purposes at
the opening of business on the next succeeding day on which such stock transfer
books are open but such conversion shall nevertheless be at the conversion price
in effect at the close of business on the date when such Security shall have
been so surrendered with the conversion notice. In the case of conversion of a
portion, but less than all, of a Security, the Company shall as promptly as
practicable execute, and the Trustee shall authenticate and deliver to the
Holder thereof, at the expense of the Company, a Security or Securities in the
aggregate principal amount of the unconverted portion of the Security
surrendered. Except as otherwise expressly provided in this Indenture, no
payment or adjustment shall be made for interest accrued on any Security (or
portion thereof) converted or for dividends or distributions on any Common Stock
issued upon conversion of any Security.

12.3.  FRACTIONAL INTERESTS.

       No fractions of shares or scrip representing fractions of shares shall be
issued upon conversion of Securities. If more than one Security shall be
surrendered for conversion at one time by the same Holder, the number of full
shares which shall be issuable upon conversion thereof shall be basis of the
aggregate principal amount of the Securities so surrendered. If any

                                       50
<PAGE>
 
fraction of a share of Common Stock would, except for the foregoing provisions
of this Section 12.3, be issuable on the conversion of any Security or
Securities, the Company shall make payment in lieu thereof in an amount of Cash
equal to the value of such fraction computed on the basis of the last sale price
of the Common Stock as reported on the Nasdaq National Market (or if not listed
for trading thereon, then on the principal national securities exchange on which
the Common Stock is listed or admitted to trading) at the close of business on
the Date of Conversion or if no such sale takes place on such day, the last sale
price for such day shall be the average of the closing bid and asked prices
regular way on the Nasdaq National Market (or if not listed for trading thereon,
on the principal national securities exchange or market on which the Common
Stock last sale price being hereinafter referred to as the "Last Sale Price").
If on such Trading Day the Common Stock is not quoted by any such organization,
the fair value of such Common Stock on such day, as reasonably determined in
good faith by the Board of Directors of the Company, shall be used.

12.4. CONVERSION PRICE.

      The conversion price per share of Common Stock issuable upon conversion of
the Securities (the "Conversion Price") shall initially be $13.95 (or $13.95 in
principal amount of Securities for each such share of Common Stock).

12.5. ADJUSTMENT OF CONVERSION PRICE.

      The Conversion Price shall be subject to adjustment from time to time as
follows:

      (a) In case the Company shall (i) make or pay a dividend (or other
distribution) in shares of Common Stock on any class of Capital Stock of the
Company, (ii) subdivide its outstanding shares of Common Stock into a greater
number of shares or (iii) combine or reclassify its outstanding shares of Common
Stock into a smaller number of shares, the Conversion Price in effect
immediately prior to such action shall be adjusted so that the Holder of any
Security thereafter surrendered for conversion shall be entitled to receive the
number of shares of Common Stock that he would have owned immediately following
such action had such Security been converted immediately prior thereto. An
adjustment made pursuant to this subsection (a) shall become effective
immediately, except as provided in subsection (h) below, after the record date
in the case of a dividend or distribution and shall become effective immediately
after the effective date in the case of a subdivision or combination.

      (b) In case the Company shall issue rights, options or warrants to all
holders of Common Stock entitling them to subscribe for or purchase shares of
Common Stock at a price per share less than the then current market price per
share of the Common Stock (as determined pursuant to subsection (f) below) on
the record date mentioned below, the Conversion Price shall be adjusted to a
price, computed to the nearest cent, so that the same shall equal the price
determined by multiplying:

          (i)  the Conversion Price in effect immediately prior to the date of
     issuance of such rights or warrants by a fraction, of which

                                      51
<PAGE>
 
          (ii)  the numerator shall be (A) the number of shares of Common Stock
     outstanding on the date of issuance of such rights, options or warrants,
     immediately prior to such issuance, plus (B) the number of shares which the
     aggregate offering price of the total number of shares so offered for
     subscription or purchase would purchase at such current market price
     (determined by multiplying such total number of shares by the exercise
     price of such rights, options or warrants and dividing the product so
     obtained by such current market price), and of which

          (iii) the denominator shall be (A) the number of shares of Common
     Stock outstanding on the date of issuance of such rights, options or
     warrants, immediately prior to such issuance, plus (B) the number of
     additional shares of Common Stock which are so offered for subscription or
     purchase.

     Such adjustment shall become effective immediately, except as provided in
subsection (h) below, after the record date for the determination of holders
entitled to receive such rights, options or warrants; PROVIDED, HOWEVER, that if
any such rights, options or warrants issued by the Company as described in this
subsection (b) are only exercisable upon the occurrence of certain triggering
events relating to control and provided for in shareholder rights plans, then
the Conversion Price will not be adjusted as provided in this subsection (b)
until such triggering events occur.

     (c)  In case the Company or any subsidiary of the Company shall distribute
to all holders of Common Stock, any of its assets, evidences of indebtedness,
cash or other assets or shares of Capital Stock other than Common Stock
(including securities, but other than (x) dividends or distributions exclusively
in cash or (y) any dividend or distribution for which an adjustment is required
to be made in accordance with subsection (a) or (b) above) then in each such
case the Conversion Price shall be adjusted so that the same shall equal the
price determined by multiplying the Conversion Price in effect immediately prior
to the date of such distribution by a fraction of which the numerator shall be
the then current market price per share of the Common Stock (determined as
provided in subsection (f) below) on the record date mentioned below less the
then fair market value (as reasonably determined in good faith by the Board of
Directors of the Company) of the portion of the assets so distributed applicable
to one share of Common Stock, and of which the denominator shall be such current
market price per share of the Common Stock. Such adjustment shall become
effective immediately, except as provided in subsection (h) below, after the
record date for the determination of stockholders entitled to receive such
distribution.

     (d)  In case the Company or any subsidiary of the Company shall make any
distribution consisting exclusively of cash (excluding any cash portion of
distributions for which an adjustment is required to be made in accordance with
(c) above, or cash distributed upon a merger or consolidation to which Section
12.6 applies) to all holders of Common Stock in an aggregate amount that,
combined together with (i) all other such all-cash distributions made within the
then preceding 12 months in respect of which no adjustment has been made and
(ii) any cash and the fair market value of other consideration paid or payable
in respect of any tender

                                        52
<PAGE>
 
offer by the Company or any of its Subsidiaries for Common Stock concluded
within the preceding 12 months in respect of which no adjustment has been made,
exceeds 10% of the Company's market capitalization (defined as being the product
of the then current market price of the Common Stock (determined as provided in
subsection (f) below) times the number of shares of Common Stock then 
outstanding) on the record date of such distribution, in each such case the
Conversion Price shall be adjusted so that the same shall equal the price
determined by multiplying the Conversion Price in effect immediately prior to
the date of such distribution by a fraction of which the numerator shall be the
then current market price per share of the Common Stock on such record date less
the amount of the cash so distributed applicable to one share of Common Stock,
and of which the denominator shall be such current market price per share of the
Common Stock. Such adjustment shall become effective immediately, except as
provided in subsection (h) below, after the record date for the determination of
stockholders entitled to receive such distribution.

        (e)  In case there shall be completed a tender or exchange offer made by
the Company or any Subsidiary of the Company for all or any portion of the
Common Stock (any such tender or exchange offer being referred to as an "Offer")
that involves an aggregate consideration having a fair market value as of the
expiration of such Offer (the "Expiration Time") that, together with (i) any
cash and the fair market value of any other consideration payable in respect of
any other Offer, as of the expiration of such other Offer, expiring within the
12 months preceding the expiration of such Offer and in respect for which no
Conversion Price adjustment pursuant to this subsection (e) has been made and
(ii) the aggregate amount of any all-cash distributions referred to in
subsection (d) of this Section 12.5 to all holders of Common Stock within the 12
months preceding the expiration of such Offer for which no Conversion Price
adjustment, pursuant to such subsection (d), has been made, exceeds 10% of the
product of the then current market price per share (determined as provided in
subsection (f) below) of the Common Stock on the Expiration Time times the
number of shares of Common Stock outstanding (including any tendered shares) on
the Expiration Time, the Conversion Price shall be reduced by multiplying such
Conversion Price in effect immediately prior to the Expiration Time by a
fraction of which the numerator shall be (i) the product of the then current
market price per share (determined as provided in subsection (f) below) on the
Expiration Time times the number of shares of Common Stock outstanding
(including any tendered shares) on the Expiration Time minus (ii) the fair
market value of the aggregate consideration payable to stockholders based on the
acceptance (up to any maximum specified in the terms of the Offer) of all shares
validly tendered and not withdrawn as of the Expiration Time (the shares deemed
so accepted being referred to as the "Purchased Shares") and the denominator
shall be the product of (i) such current market price per share on the
Expiration Time times (ii) such number of outstanding shares on the Expiration
Time less the number of Purchased Shares, such reduction to become effective
immediately prior to the opening of business on the day following the Expiration
Time.

        For purposes of this subsection (e), the fair market value of any
consideration with respect to an Offer shall be reasonably determined in good
faith by the Board of Directors of the Company and described in a Board
Resolution.

                                      53
<PAGE>
 
        (f)  For the purpose of any computation under subsections (b), (c), (d)
and (e) above, the current market price per share of Common Stock on any date
shall be deemed to be the average of the Last Sale Prices of a share of Common
Stock for the five consecutive Trading Days selected by the Company commencing
not more than 20 Trading Days before, and ending not later than, the earlier of
the date in question and the date before the "ex date," with respect to the
issuance, distribution or Offer requiring such computation. If on any such
Trading Day the Common Stock is not quoted by any organization referred to in
the definition of Last Sale Price in Section 12.3 hereof, the fair value of the
Common Stock on such day, as reasonably determined in good faith by the Board of
Directors of the Company, shall be used. For purposes of this paragraph, the
term "ex date," when used with respect to any issuance, distribution or payments
with respect to an Offer, means the first date on which the Common Stock trades
regular way on the Nasdaq National Market (or if not listed or admitted to
trading thereof, then on the principal market or exchange on which the Common
Stock is listed or admitted to trading) without the right to receive such
issuance, distribution or Offer.

        (g)  In addition to the foregoing adjustments in subsections (a), (b),
(c), (d) and (e) above, the Company will be permitted to make such reductions in
the Conversion Price as it considers to be advisable. In the event the Company
elects to make such a reduction in the conversion price, the Company will comply
with the requirements of Rule 14e-1 of the Exchange Act and any other Federal
and state laws and regulations thereunder if and to the extent that such laws
and regulations are applicable in connection with the reduction of the price of
the Notes; PROVIDED that any provisions of this Indenture which conflict with
such laws shall be deemed superseded by the provisions of such laws.

        (h)  In any case in which this Section 12.5 shall require that an
adjustment (including by reason of the last sentence of subsection (a) or (c)
above) be made immediately following a record date, the Company may elect to
defer the effectiveness of such adjustment (but in no event until a date later
than the effective time of the event giving rise to such adjustment), in which
case the Company shall, with respect to any Security converted after such record
date and on and before such adjustment shall have become effective (i) defer
paying any Cash payment pursuant to Section 12.3 hereof or issuing to the Holder
of such Security the number of shares of Common Stock and other Capital Stock of
the Company (or other assets or securities) issuable upon such conversion in
excess of the number of shares of Common Stock and other Capital Stock of the
Company issuable thereupon only on the basis of the Conversion Price prior to
adjustment, and (ii) not later than five Business Days after such adjustment
shall become effective, pay to such Holder the appropriate Cash payment pursuant
to Section 12.3 hereof and issue to such Holder the additional shares of Common
Stock and other Capital Stock of the Company issuable on such Conversion.

        (i)  No adjustment in the Conversion price shall be required unless such
adjustment would require an increase or decrease of at least 1.0% of the
Conversion Price; PROVIDED, that any adjustments which by reason of this
subsection (i) are not required to be made shall be carried forward and taken
into account in any subsequent adjustment. All calculations under this Article
12 shall be made to the nearest cent or to the nearest one-hundredth of a share,
as the case may be.

                                      54
<PAGE>
 
        (j)  Whenever the Conversion Price is adjusted as herein provided, the
Company shall promptly (i) file with the Trustee and the Registrar an Officers'
Certificate setting forth the Conversion Price after such adjustment and setting
forth a brief statement of the facts requiring such adjustment, which
certificate shall be conclusive evidence of the correctness of such adjustment,
and (ii) mail or cause to be mailed a notice of such adjustment to each Security
Holder at his address as the same appears on the registry books of the
Registrar.

        (k)  In the event that the Company distributes rights or warrants (other
than those referred to in subsection (b) above) pro rata to holders of Common
Stock, so long as any such rights or warrants have not expired or been redeemed
by the Company, the Company shall make proper provision so that the Holder of
any Security surrendered for conversion will be entitled to receive upon such
conversion, in addition to the Conversion Shares, a number of rights and
warrants to be determined as follows: (i) if such conversion occurs on or prior
to the date for the distribution to the holders of rights or warrants of
separate certificates evidencing such rights or warrants (the "Distribution
Date"), the same number of rights or warrants to which a holder of a number of
shares of Common Stock equal to the number of Conversion Shares is entitled at
the time of such conversion in accordance with the terms and provisions of and
applicable to the rights or warrants, and (ii) if such conversion occurs after
such Distribution Date, the same number of rights or warrants to which a holder
of the number of shares of Common Stock into which the principal amount of such
Security so converted was convertible immediately prior to such Distribution
Date would have been entitled on such Distribution Date in accordance with the
terms and provisions of and applicable to the rights or warrants.

12.6.   CONTINUATION OF CONVERSION PRIVILEGE IN CASE OF RECLASSIFICATION,
        CHANGE, MERGER, CONSOLIDATION OR SALE OF ASSETS.

        If any of the following shall occur, namely: (a) any reclassification or
change of outstanding shares of Common Stock issuable upon conversion of the
Securities (other than a change in par value, or from par value to no par value,
or from no par value, to par value, or as a result of a subdivision or
combination), (b) any consolidation or merger of the Company with or into any
other Person, or the merger of any other Person with or into the Company (other
than a merger which does not result in any reclassification, change, conversion,
exchange or cancellation of outstanding shares of Common Stock) or (c) any sale,
transfer or conveyance of all or substantially all of the assets of the Company
(computed on a consolidated basis), then the Company, or such successor or
purchasing entity, as the case may be, shall, as a condition precedent to such
reclassification, change, consolidation, merger, sale or conveyance, execute and
deliver to the Trustee a supplemental indenture providing that the Holder of
each Security then outstanding shall have the right to convert such Security
only into the kind and amount of shares of stock and other securities and
property (including cash) receivable upon such reclassification, change,
consolidation, merger, sale, transfer or conveyance by a holder of the number of
shares of Common Stock issuable upon conversion of such Security immediately
prior to such reclassification, change, consolidation, merger, sale, transfer or
conveyance assuming such holder of Common Stock of the Company failed to
exercise his rights of an election, if any,

                                      55
                                        
<PAGE>
 
as to the kind or amount of cash and other property receivable upon such
reclassification, change, consolidation, merger, sale, transfer or conveyance
(PROVIDED that if the kind or amount of securities, cash and other property
receivable upon such reclassification, change, consolidation, merger, sale,
transfer or conveyance is not the same for each share of Common Stock of the
Company held immediately prior to such reclassification, change, consolidation,
merger, sale, transfer or conveyance in respect of which such rights of election
shall not have been exercised ("Non-Electing Shares"), then for the purpose of
this Section 12.6, the kind and amount of securities, cash and other property
receivable upon such reclassification, change, consolidation, merger, sale,
transfer or conveyance by each Non-Electing Share shall be deemed to be the kind
and amount so receivable per share by a plurality of the Non-Electing Shares).
Such supplemental indenture shall provide for adjustments which shall be as
nearly equivalent as may be practicable to the adjustments provided for in this
Article 12. If, in the case of any such consolidation, merger, sale or
conveyance, the stock or other securities and property (including cash)
receivable thereupon by a holder of shares of Common Stock includes shares of
stock or other securities and property (including cash) of a corporation other
than the successor or purchasing corporation, as the case may be, in such
consolidation, merger, sale or conveyance, then such supplemental indenture
shall also be executed by such other corporation and shall contain such
additional provisions to protect the interests of the Holders of the Securities
as the Board of Directors of the Company shall reasonably consider necessary by
reason of the foregoing. The provisions of this Section 12.6 shall similarly
apply to successive consolidations, mergers, sales or conveyances.

        Notice of the execution of each such supplemental indenture shall be
mailed to each Holder of Securities at his address as the same appears on the
registry books of the Company.

        Neither the Trustee nor the Registrar shall be under any responsibility
to determine the correctness of any provisions contained in any such
supplemental indenture relating either to the kind or amount of shares of stock
or securities or property (including cash) receivable by Holders of Securities
upon the conversion of their Securities after any such reclassification, change,
consolidation, merger, sale or conveyance or to any adjustment to be made with
respect thereto, but, subject to the provisions of Article 7.1 and 7.2 hereof,
may accept as conclusive evidence of the correctness of any such provisions, and
shall be protected in relying upon, the Officers' Certificate (which the Company
shall be obligated to file with the Trustee prior to the execution of any such
supplemental indenture) with respect thereto.

12.7.   NOTICE OF CERTAIN EVENTS.

        In case:

        (a)  the Company shall declare a dividend (or any other distribution)
payable to the holders of Common Stock (other than cash dividends);

        (b)  the Company shall authorize the granting to all holders of Common
Stock of rights, warrants or options to subscribe for or purchase any shares of
stock of any class or of any other rights;

                                      56
<PAGE>
 
     (c)  the Company shall authorize any reclassification or change of the
Common Stock (including a subdivision or combination of its outstanding shares
of Common Stock), or any consolidation or merger to which the Company is a party
and for which approval of any stockholders of the Company is required, or the
sale or conveyance of all or substantially all the property or business of the
Company;

     (d)  there shall be proposed any voluntary or involuntary dissolution,
liquidation or winding-up of the Company; or

     (e)  the Company or any of its Subsidiaries shall complete an Offer;

then, the Company shall cause to be filed at the office of the Registrar, and
shall cause to be mailed to each Holder of Securities, at its address as it
shall appear on the registry books of the Registrar, at least 20 days before the
date hereinafter specified (or the earlier of the dates hereinafter specified,
in the event that more than one date is specified), a notice stating the date on
which (1) a record is expected to be taken for the purpose of such dividend,
distribution, rights, warrants or options or Offer, or if a record is not to be
taken, the date as of which the holders of Common Stock of record to be entitled
to such dividend, distribution, rights, warrants or options or to participate in
such Offer are to be determined, or (2) such reclassification, change,
consolidation, merger, sale, conveyance, dissolution, liquidation or winding-up
is expected to become effective and the date, if any is to be fixed, as of which
it is expected that holders of Common Stock of record shall be entitled to
exchange their shares of Common Stock for securities or other property
deliverable upon such reclassification, change, consolidation, merger, sale,
conveyance, dissolution, liquidation or winding-up. Neither the failure to give
notice nor any defect therein shall affect the legality or validity of the
events described in clauses (a) through (e) of this Section 12.7.

12.8. TAXES ON CONVERSION.

     The Company will pay any and all documentary, stamp or similar taxes
payable to the United States of America or any political subdivision or taxing
authority thereof or therein in respect of the issue or delivery of shares of
Common Stock on conversion of Securities pursuant thereto; PROVIDED, HOWEVER,
that the Company shall not be required to pay any tax which may be payable in
respect of any transfer involved in the issue or delivery of shares of Common
Stock in a name other than that of the Holder of the Securities to be converted
and no such issue or delivery shall be made unless and until the person
requesting such issue or delivery has paid to the Company the amount of any such
tax or has established, to the satisfaction of the Company, that such tax has
been paid. The Company extends no protection with respect to any other taxes
imposed in connection with conversion of Securities.

12.9. COMPANY TO PROVIDE STOCK.

     The Company shall reserve, free from preemptive rights, out of its
authorized but unissued shares, sufficient shares to provide for the conversion
of the Securities from time to

                                      57
<PAGE>

time as such Securities are presented for conversion, PROVIDED, that nothing
contained herein shall be construed to preclude the Company from satisfying its
obligations in respect of the conversion of Securities by delivery of
repurchased shares of Common Stock which are held in the treasury of the
Company.

     If any shares of Common Stock to be reserved for the purpose of conversion
of Securities hereunder require registration with or approval of any
governmental authority under any Federal or state law before such shares may be
validly issued or delivered upon conversion, then the Company covenants that it
will in good faith and as expeditiously as possible use its best efforts to
secure such registration or approval, as the case may be, PROVIDED, HOWEVER,
that nothing in this Section 12.9 shall be deemed to limit in any way the
obligations of the Company provided in this Article 12.

     Before taking any action which would cause an adjustment reducing the
Conversion Price below the then par value, if any, of the Common Stock, the
Company will take all corporate action which may, in the Opinion of Counsel, be
necessary in order that the Company may validly and legally issue fully paid and
non-assessable shares of Common Stock at such adjusted Conversion Price.

     The Company covenants that all shares of Common Stock which may be issued
upon conversion of Securities will upon issue be fully paid and non-assessable
by the Company and free of preemptive rights.

12.10. DISCLAIMER OF RESPONSIBILITY FOR CERTAIN MATTERS.

     Neither the Trustee nor any agent of the Trustee shall at any time be under
any duty or responsibility to any Holder of Securities to determine whether any
facts exist which may require any adjustment of the Conversion Price, or with
respect to the Officers' Certificate referred to in Section 12.5(j) hereof, or
with respect to the nature or extent of any such adjustment when made, or with
respect to the method employed, or herein or in any supplemental indenture
provided to be employed, in making the same. Neither the Trustee nor the
Registrar shall be accountable with respect to the validity or value (or the
kind or amount) of any shares of Common Stock, or of any securities or property
(including cash), which may at any time be issued or delivered upon the
conversion of any Security; and neither the Trustee nor any agent of the Trustee
makes any representation with respect thereto. Neither the Trustee nor any agent
of the Trustee shall be responsible for any failure of the Company to issue,
register the transfer of or deliver any shares of Common Stock or stock
certifcates or other securities or property (including cash) upon the surrender
of any Security for the purpose of conversion or, subject to Article 7 hereof,
to comply with any of the covenants of the Company contained in this Article 12.

12.11. RETURN OF FUNDS DEPOSITED FOR REDEMPTION OF CONVERTED SECURITIES.

     Any funds which at any time shall have been deposited by the Company or on
its behalf with the Trustee or any other Paying Agent for the purpose of paying
the principal of and interest

                                      58
<PAGE>
 
on any of the Securities and which shall not be required for such purposes
because of the conversion of such Securities, as provided in this Article 12,
shall after such conversion be repaid to the Company by the Trustee or such
other Paying Agent. All Securities delivered for conversion to the Trustee will
be canceled by or at the direction of the Trustee.

                                     ARTICLE
                                       13.
                                  MISCELLANEOUS

13.1. TIA CONTROLS.

     If any provision of this Indenture limits, qualifies or conflicts with the
duties imposed by operation of the TIA, the imposed duties, upon qualification
of this Indenture under the TIA, shall control.

13.2. NOTICES.

     Any notices or other communications to the Company or the Trustee required
or permitted hereunder shall be in writing, and shall be sufficiently given if
made by hand delivery, by overnight courier, by telecopier or registered or
certified mail, postage prepaid, return receipt requested, addressed as follows:

     if to the Company:

     PLATINUM technology, inc. 
     South Meyers Road 
     Oakbrook Terrace, Illinois 60181
     Attention: Chief Financial Officer 
     Telecopy: (630) 691-0710 
     with a copy to General Counsel at (630) 691-0454

     if to the Trustee:

     American National Bank and Trust Company of Chicago
     North LaSalle Street, 13th Floor
     Chicago, IL 60690
     Attention: Corporate Trust Division
     Telecopy: (312) 661-6491

     Any party by notice to each other party may designate additional or
different addresses as shall be furnished in writing by such party. Any notice
or communication to any party shall be deemed to have been given or made as of
the date so delivered, if personally delivered; the next Business Day, if by
overnight courier; when receipt is acknowledged, if telecopied; and five
Business Days after mailing if sent by registered or certified mail, postage
prepaid return receipt

                                      59
<PAGE>

requested (except that a notice of change of address shall not be deemed to have
been given until actually received by the addressee).

     Any notice or communication mailed to a Security Holder shall be mailed to
him by first class mail or other equivalent means at his address as it appears
on the registry books of the Registrar and shall be sufficiently given to him if
so mailed within the time prescribed.

     Failure to mail a notice or communication to a Security Holder or any
defect in it shall not affect its sufficiency with respect to other Security
Holders. If a notice or communication is mailed in the manner provided above, it
is duly given, whether or not the addressee receives it.

13.3. COMMUNICATIONS BY HOLDERS WTIH OTHER HOLDERS.

     Security Holders may communicate pursuant to TIA Section 312(b) with other
Security Holders with respect to their rights under this Indenture or the
Securities. The Company, the Trustee, the Registrar and any other Person shall
have the protection of TIA Section 312(c).

13.4. CERTIFICATE AND OPINION AS TO CONDITIONS PRECEDENT.

     Upon any request or application by the Company to the Trustee to take any
action under this Indenture, the Company shall furnish to the Trustee:

          (1) an Officers' Certificate (in form and substance reasonably
     satisfactory to the Trustee) stating that, in the opinion of the signers,
     all conditions precedent, if any, provided for in this Indenture relating
     to the proposed action have been complied with; and

          (2) an Opinion of Counsel (in form and substance reasonably
     satisfactory to the Trustee) stating that, in the opinion of such counsel,
     all such conditions precedent have been complied with.

13.5. STATEMENTS REQUIRED IN CERTIFICATE OR OPINION.

     Each Certificate or opinion with respect to compliance with a condition or
covenant provided for in this Indenture shall include:

          (1)  a statement that the Person making such certificate or opinion
     has read such covenant or condition;

          (2)  a brief statement as to the nature and scope of the examination
     or investigation upon which the statements or opinions contained in such
     certificate or opinion are based;

                                      60
<PAGE>
 
     (3)  A statement that, in opinion of such Person, he has made such
examination or investigation as is necessary to enable him to express an
informed opinion as to whether or not such covenant or condition has been
complied with; and

     (4)  a statement as to whether or not, in the opinion of each such Person,
such condition or covenant has been complied with; PROVIDED, HOWEVER, that with
respect to matters of fact an Opinion of Counsel may rely on an Officers'
Certificate or certificates of public officials.

13.6. RULES BY TRUSTEE, PAYING AGENT, REGISTRAR.

     The Trustee may make reasonable rules for action by or at a meeting of
Security Holders. The Paying Agent or Registrar may make reasonable rules for
its own functions.

13.7.  LEGAL HOLIDAYS.

     A "Legal Holiday" is a Saturday, a Sunday or a day on which banking
institutions in New York, New York are authorized or obligated by law or
executive order to close. If a payment date is a Legal Holiday at such place,
payment may be made at such place on the next succeeding day that is not a Legal
Holiday, and no interest shall accrue for the intervening period.

13.8.  GOVERNING LAW.

     THIS INDENTURE AND THE SECURITES SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK, AS APPLED TO CONTRACTS MADE
AND PERFORMED WITHIN THE STATE OF NEW YORK. THE COMPANY HEREBY IRREVOCABLY
SUBMITS TO THE JURISDICTION OF ANY NEW YORK STATE COURT SITTING IN THE BOROUGH
OF MANHATTAN IN THE CITY OF NEW YORK OR ANY FEDERAL COURT SITTING IN THE BOROUGH
OF MANHATTAN IN THE CITY OF NEW YORK IN RESPECT OF ANY SUIT, ACTION OR
PROCEEDING ARISING OUT OF OR RELATING TO THIS INDENTURE AND THE SECURITES, AND
IRREVOCABLY ACCEPTS FOR ITSELF AND IN RESPECT OF ITS PROPERTY, GENERALLY AND
UNCONDITIONALLY, JURISDICTION OF THE AFORESAID COURTS. THE COMPANY IRREVOCABLY
WAIVES, TO THE FULLEST EXTENT IT MAY ELECTIVELY DO SO UNDER APPLICABLE LAW, ANY
OBJECTION WHICH IT MAY NOW OR HEREAFTER HAVE TO THE LAYING OF THE VENUE OF ANY
SUCH SUIT, ACTION OR PROCEEDING BROUGHT IN ANY SUCH COURT AND ANY CLAIM THAT ANY
SUCH SUIT, ACTION OR PROCEEDING BROUGHT IN ANY SUCH COURT HAS BEEN BROUGHT IN AN
INCONVENENT FORUM. NOTHING HEREIN SHALL AFFECT THE RIGHT OF THE TRUSTEE OR ANY
SECURITY HOLDER TO SERVE PROCESS IN ANY OTHER MANNER PERMITTED BY LAW OR TO
COMMENCE LEGAL PROCEEDINGS OR OTHERWISE PROCEED AGAINST THE COMPANY IN ANY OTHER
JURISDICTION.

                                      61
<PAGE>
 
13.9. NO ADVERSE INTERPRETATION OF OTHER AGREEMENTS.

     This Indenture may not be used to interpret another indenture, loan or debt
agreement of the Company or any of its Subsidiaries. Any such indenture, loan or
debt agreement may not be used to interpret this Indenture.

13.10. NO RECOURSE AGAINST OTHERS.

     No direct or indirect partner, employee, stockholder, director or officer,
as such, past, present or future of the Company or any successor corporation,
shall have any personal liability in respect of the obligations of the Company
under the Securities or this Indenture by reason of his, her or its status as
such partner, stockholder, employee, director or officer. Each Securityholder by
a Security waives and releases all such liability. Such waiver and release are
part of the consideration for the issuance of the Securities.

13.11. SUCCESSORS.

     All agreements of the Company in this Indenture and the Securities shall
bind its successors. All agreements of the Trustee in this Indenture shall bind
its successors.

13.12. DUPLICATE ORIGINALS.

     All parties may sign any number of copies or counterparts of this
Indenture. Each signed copy or counterpart shall be an original, but all of them
together shall represent the same agreement.

13.13. SEVERABILITY.

     In case any one or more of the provisions in this Indenture or in the
Securities shall be held invalid, illegal or unenforceable, in any respect for
any reason, the validity, legality and enforceability of any such provision in
every other respect and of the remaining provisions shall not in any way be
affected or impaired thereby, it being intended that all of the provisions
hereof shall be enforceable to the full extent permitted by law.

13.14. TABLE OF CONTENTS, HEADINGS, ETC.

     The Table of Contents, Cross-Reference Table and headings of the Articles
and the Sections of this Indenture have been inserted for convenience of
reference only, are not to be considered a part hereof and shall in no way
modify or restrict any of the terms or provisions hereof.

                                      62
<PAGE>
 
13.15. QUALIFICATION OF INDENTURE.

     The Company shall qualify this Indenture under the TIA and shall pay all
costs and expenses (including attorneys' fees for the Company and the Trustee)
incurred in connection therewith, including, but not limited to, costs and
expenses of qualification of the Indenture and the Securities and printing this
Indenture and the Securities. The Trustee shall be entitled to receive from the
Company any such Officers' Certificates, Opinions of Counsel or other
documentation as it may reasonably request in connection with any such
qualification of this Indenture under the TIA.










              (Remainder of this page left blank intentionally.)

                                      63
<PAGE>
 
SIGNATURES

IN WITNESS WHEREOF, the parties hereto have caused this Indenture to be duly
executed as of the date first written above.

                                     PLATINUM technology, inc., 
                                     a Delaware Corporation

                                     By: /s/ Michael P. Cullinane
                                         ----------------------------
                                     Name: MICHAEL P. CULLINANE
                                           --------------------------   
                                     Title: EXECUTIVE VICE PRESIDENT
                                            -------------------------   
Attest: Michael C. Wyatt                    CHIEF FINANCIAL OFFICER
       ---------------------------          ------------------------- 
       Secretary


                                     American National Bank and Trust Company of
                                     Chicago, a national banking association
                        
                                     as Trustee

                                     By: 
                                         ----------------------------
                                     Name: 
                                           --------------------------   
                                     Title: 
                                            -------------------------   

     The undersigned hereby acknowledges its appointment as Registrar and Paying
Agent as set forth in Section 2.3.

                                     First Chicago Trust Company of New York

                                     By: 
                                         ----------------------------
                                     Name: 
                                           --------------------------   
                                     Title: 
                                            -------------------------   
<PAGE>
 
SIGNATURES

IN WITNESS WHEREOF, the parties hereto have caused this Indenture to be duly
executed as of the date first written above.

                                     PLATINUM technology, inc., 
                                     a Delaware Corporation

                                     By: /s/ Andrew J. Filipowski
                                         ----------------------------
                                     Name: Andrew J. Filipowski
                                           --------------------------   
                                     Title: President, CEO & Chairman
                                            -------------------------   

Attest:
       -------------------------  
       Secretary

                                     American National Bank and Trust Company of
                                     Chicago, a national banking association

                                     as Trustee

                                     By: /s/ Anjali Gottreich 
                                         ----------------------------
                                     Name: Anjali Gottreich 
                                           --------------------------   
                                     Title: Trust Officer
                                            -------------------------      
Attest: 
       -------------------------  
       Second Vice President 

     The undersigned hereby acknowledges its appointment as Registrar and Paying
Agent as set forth in Section 2.3.

                                     First Chicago Trust Company of New York
                        
                                     By: /s/ Mary Kelly
                                         ----------------------------
                                     Name: Mary Kelly
                                           --------------------------   
                                     Title: Vice President
                                            -------------------------   
<PAGE>
 
                                   EXHIBIT A
                              [FORM OF SECURITY]

                           PLATINUM technology, inc.

                 6 3/4% CONVERTIBLE SUBORDINATED NOTE DUE 2001

                                                            CUSIP No. 72764T AA9
                                                                  $_____________

No.

     PLATINUM technology, inc., a Delaware corporation (hereinafter called the
"Company," which term includes any successors under the Indenture hereinafter
referred to), for value received, hereby promises to pay to _____________, or
registered assigns, the principal sum of _____ Dollars, on November 15, 2001.

     Interest Payment Dates: May 15 and November 15; commencing May 15, 1997.

     Record Dates: May 1 and November 1.

     Reference is made to the further provisions of this Security on the reverse
side, which will, for all purposes have the same effect as if set forth at this
place.

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

Dated:_______ __, 1996

                                     PLATINUM technology, inc., 
                                     a Delaware Corporation

                                     By: 
                                         ----------------------------
                                     Name: 
                                           --------------------------   
                                     Title: 
                                            -------------------------   

Attest:
       -----------------------
       Secretary
                                      A-l
<PAGE>
 
                FORM OF TRUSTEE'S CERTIFICATE OF AUTHENTICATION

     This is one of the Securities described in the within-mentioned Indenture

                                        AMERICAN NATIONAL BANK AND TRUST 
                                         COMPANY OF CHICAGO as Trustee

                                        By:
                                           ------------------------------       
                                             Authorized Signatory

Dated:____________


                                      A-2
<PAGE>
 
                           PLATINUM technology, inc.
                 6 3/4% CONVERTIBLE SUBORDINATED NOTE DUE 2001

     This Security is a Global Security within the meaning of the Indenture
hereinafter referred to and is registered in the name of a Depositary or a
nominee thereof. Unless and until it is exchanged in whole or in part for
Securities in definitive form, this Security may not be transferred except as a
whole by the Depositary to a nominee of the Depositary or by a nominee of the
Depositary to the Depositary or another nominee of the Depositary or by the
Depositary or any such nominee to a successor Depositary or a nominee of such
successor Depositary. Unless this certificate is presented by an authorized
representative of The Depository Trust Company, a New York corporation ("DTC"),
to the Company or its agent for registration of transfer, exchange or payment,
and any certificate issued is registered in the name of Cede & Co. or in such
other name as is requested by an authorized representative of DTC (and any
payment is made to Cede & Co. or to such other entity as is requested by an
authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR
VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered
owner hereof, Cede & Co., has an interest herein./1/

1.  INTEREST.

          PLATINUM technology, inc., a Delaware corporation (hereinafter called
the "Company," which term includes any successors under the Indenture
hereinafter referred to), promises to pay interest on the principal amount of
this Security at the rate of 6 3/4% per annum. To the extent it is lawful, the
Company promises to pay interest on any interest payment due but unpaid on such
principal amount at a rate of 6 3/4% per annum compounded semi-annually.

          The Company will pay interest semi-annually on May 15 and November 15
of each year (each, an "Interest Payment Date"), commencing May 15, 1997.
Interest on the Securities will accrue from the most recent date to which
interest has been paid or, if no interest has been paid on the Securities, from
November 22, 1996. Interest will be computed on the basis of a 360-day year
consisting of twelve 30-day months.

2.  METHOD OF PAYMENT.

          The Company shall pay interest on the Securities (except defaulted
interest) to the Persons who are the registered Holders at the close of business
on the Record Date immediately preceding the Interest Payment Date. Holders must
surrender Securities to a Paying Agent to collect principal payments. Any such
interest not so punctually paid, and defaulted interest relating thereto, may be
paid to the Persons who are registered Holders at the close of business on a
Special Record Date for the payment of such defaulted interest, as more fully
provided in the Indenture referred to below. Except as provided below, the
Company shall pay principal and interest in such coin or currency of the Untied
States of America as at the time of payment shall be legal tender for payment of
public and private debts ("U.S. Legal Tender"). The Securities will be payable
as to principal, premium and interest at the office or agency of the Company.
------------------
/1/ This paragraph should only be added if the Security is issued in global form

                                A-3
<PAGE>
 
maintained for such purpose within or without the City and State of New York, or
at the option of the Company, payment of principal, premium and interest may be
made by check mailed to the Holders at their addresses set forth in the registry
of Holders, and provided that payment by wire transfer of immediately available
funds will be required with respect to principal of, premium and interest on
Global Securities and all other Securities the Holders of which shall have
provided wire transfer instructions to the Company or the Paying Agent.

3.  PAYING AGENT AND REGISTRAR.

          Initially, First Chicago Trust Company of New York will act as Paying
Agent and Registrar. The Company may change any Paying Agent or Co-Paying Agent,
Registrar or Co-Registrar without notice to the Holders. The Company or any of
its Subsidiaries may, subject to certain exceptions, act as Paying Agent or 
Co-Paying Agent, Registrar or Co-Registrar.

4.  INDENTURE.

          The Company issued the Securities under an Indenture, dated as of
November 18, 1996 (the "Indenture"), between the Company and American National
Bank and Trust Company of Chicago, a national banking association (the
"Trustee"). Capitalized terms herein are used as defined in the Indenture unless
otherwise defined herein. The terms of the Securities include those stated in
the Indenture and those made part of the Indenture by reference to the Trust
Indenture Act, as in effect on the date of the Indenture. The Securities are
subject to all such terms, and Holders of Securities are referred to the
Indenture and said Act for a statement of them. The Securities are general
unsecured obligations of the Company limited in aggregate principal amount to
$10O,000,000 ($115,000,000 if the Underwriters exercise their overallotment
option in full).

5.  REDEMPTION.

          The Securities will not be subject to redemption prior to 1999. On or
after November 15, 1999 the Securities will be redeemable at the option of the
Company, in whole or in part, at the following Redemption Prices (expressed as a
percentage of principal amount) set forth below with respect to the indicated
Redemption Date, in each case, plus any accrued but unpaid interest to the
Redemption Date. The Securities may not be so redeemed prior to November 15,
1999.

          IF REDEEMED DURING
          THE 12-MONTH PERIOD
          BEGINNING                     REDEMPTION PRICE

               November 15, 1999             102.70 %
               November 15, 2000             101.35 %

          Any such redemption will comply with Article 3 of the Indenture.

                                        A-4
<PAGE>
 
          The Securities will not be subject to any sinking fund.

6.   NOTICE OF REDEMPTION.

          Notice of Redemption will be sent by first class mail, at least 30
days and not more than 60 days prior to the Redemption Date to the Holder of
each Security to be redeemed at such Holder's last address as then shown upon
the registry books of the Registrar. Securities may be redeemed in part in
multiples of $1,000 only.

          Except as set forth in the Indenture, from and after any Redemption
Date, if monies for the redemption of the Securities called for redemption shall
have been deposited with the Paying Agent on such Redemption Date and payment of
the Securities called for redemption is not prohibited under Article 11 of the
Indenture, the Securities called for redemption will cease to bear interest and
the only right of the Holders of such Securities will be to receive payment of
the Redemption Price, plus any accrued and unpaid interest to the Redemption
Date.

7. DENOMINATIONS; TRANSFER; EXCHANGE.

          The Securities are in registered form, without coupons, in
denominations of $1,000 and integral multiplies of $1,000. A Holder may register
the transfer of, or exchange Securities in accordance with, the Indenture. The
Registrar may require a Holder, among other things, to furnish appropriate
endorsements and transfer documents and to pay any taxes and fees required by
law or permitted by the Indenture. The Registrar need not register the transfer
of or exchange any Securities selected for redemption.

8. PERSONS DEEMED OWNERS.

          The registered Holder of a Security may be treated as the owner of it
for all purposes.

9.   UNCLAIMED MONEY.

          If money for the payment of principal or interest remains unclaimed
for two years, the Trustee and the Paying Agent(s) will pay the money back to
the Company at its written request. After that, all liability of the Trustee and
such Paying Agent(s) with respect to such money shall cease.

10.  AMENDMENT; SUPPLEMENT; WAIVER.

          Subject to certain exceptions, the Indenture or the Securities may be
amended or supplemented, and any existing Default or Event of Default or
compliance with any provision may be waived, with the written consent of the
Holders of a majority in aggregate principal amount of the Securities then
outstanding. Without notice to or consent of any Holder, the parties thereto may
amend or supplement the Indenture or the Securities to, among other things, cure
any

                                      A-5
<PAGE>
 
ambiguity, defect or inconsistency, or make any other change that does not
adversely affect the rights of any Holder of a Security.

11.  CONVERSION RIGHTS.

          Subject to the provisions of the Indenture, the Holders have the right
to convert the principal amount of the Securities into fully paid and
nonassessable shares of Common Stock of the Company at the initial conversion
price per share of Common Stock of $13.95 (or $13.95 in principal amount of
Securities for each such share of Common Stock), or at the adjusted conversion
price then in effect, if adjustment has been made as provided in the Indenture,
upon surrender of the Securities to the Company at the office of the Registrar,
together with a fully executed notice in substantially the form attached hereto
and, if required by the Indenture, an amount equal to accrued interest payable
on such Security.

12.  RANKING.

          Payment of principal, premium, if any, and interest on the Securities
is subordinated, in the manner and to the e~xtent set forth in the Indenture, to
the prior payment in full of all Senior Indebtedness.

13.  REPURCHASE AT OPTION OF HOLDER UPON A CHANGE OF CONTROL.

          If there is a Change of Control, the Company shall be required to
offer to purchase on the Repurchase Date all outstanding Securities at a
purchase price equal to 100% of the principal amount thereof, plus accrued and
unpaid interest, if any, to the Repurchase Date. Holders of Securities will
receive a Repurchase Offer from the Company prior to any related Repurchase Date
and may elect to have such Securities purchased by completing the form entitled
"Option of Holder to Elect Purchase" appearing below.

14.  SUCCESSORS.

          Except as provided in the Indenture, when a successor assumes all the
obligations of its predecessor under the Securities and the Indenture, the
predecessor will be released from those obligations.

15.  DEFAULTS AND REMEDIES.

          If an Event of Default occurs and is continuing (other than an Event
of Default relating to certain events of bankruptcy, insolvency or
reorganization), then in every such case, unless the principal of all of the
securities shall have already become due and payable, either the Trustee or the
Holders of 25% in aggregate principal amount of Securities then outstanding may
declare all the Securities to be due and payable immediately in the manner and
with the effect provided in the Indenture. Holders of Securities may not enforce
the Indenture or the Securities except as provided in the Indenture. The Trustee
may require indemnity satisfactory to it before it enforces the Indenture or the
Securities. Subject to certain limitations, Holders of a majority in

                                      A-6
<PAGE>
 
aggregate principal amount of the Securities then outstanding may direct the
Trustee in its exercise of any trust or power. The Trustee may withhold from
Holders of Securities notice of any continuing Default or Event of Default
(except a Default in payment of principal or interest), if it determines that
withholding notice is in their interest.

16.  TRUSTEE DEALINGS WITH COMPANY.

          The Trustee under the Indenture, in its individual or any other
capacity, may make loans to, accept deposits from, and perform services for the
Company or its Affiliates, and may otherwise deal with the Company or its
Affiliates as if it were not the Trustee.

17.  NO RECOURSE AGAINST OTHERS.

          No stockholder, director, officer or employee, as such, past, present
or future, of the Company or any successor corporation shall have any personal
liability in respect of the obligations of the Company under the Securities or
the Indenture by reason of his, her or its status as such stockholder, director,
officer or employee. Each Holder of a Security by accepting a Security waives
and releases all such liability. The waiver and release are part of the
consideration for the issuance of the Securities.

18.  AUTHENTICATION.

          The Security shall not be valid until the Trustee or authenticating
agent signs the certificate of authentication on the other side of this
Security.

19.  ABBREVIATIONS AND DEFINED TERMS.

          Customary abbreviations may be used in the name of a Holder of a
Security or an assignee, such as: TEN COM (= tenants in common), TEN ENT 
(= tenants by the entireties), JT TEN (= joint tenants with right of 
survivorship and not as tenants in common), CUST (= Custodian), and U/G/M/A 
(= Uniform Gifts to Minors Act).

20.  CUSIP NUMBERS.

Pursuant to a recommendation promulgated by the Committee on Uniform Security
Identification Procedures, the Company will cause CUSIP numbers to be printed on
the Securities as a convenience to the Holders of the Securities. No
representation is made as to the accuracy of such numbers as printed on the
Securities and reliance may be placed only on the other identification numbers
printed hereon.

                                       A-7
<PAGE>
 
                              FORM OF ASSIGNMENT


I or we assign this Security to


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


(Print or type name, address and zip code of assignee)

Please insert Social Security or other identifying number of assignee __________

and irrevocably appoint __________ agent to transfer this Security on the books
of the Company. The agent may substitute another to act for him.


Date:__________                   Signature: ___________________________________
                                             (Sign exactly as name appears on
                                             the other side of this Security)


                                      A-8
<PAGE>
 
                      OPTION OF HOLDER TO ELECT PURCHASE

     If you want to elect to have this Security purchased by the Company
pursuant to Article 10 of the Indenture, check the box: [ ]

     If you want to elect to have only part of this Security purchased by the
Company pursuant to Article 10 of the Indenture, state the amount you want to be
purchased: $_________



Date:___________                   Signature:___________________________________
                                             (Sign exactly as name appears on
                                             the other side of this Security)

                                      A-9
<PAGE>
 
               SCHEDULE OF EXCHANGES OF DEFINITIVE SECURITIES/2/

     The following exchanges of a part of this Global Security for Definitive
Securities have been made:
<TABLE> 
<CAPTION> 
                                                 Principal
             Amount of                           Amount of this
             decrease in       Amount of         Global Security   Signature of
             Principal Amount  Increase in       following such    authorized of Trustee
 Date of     of this Global    Principal Amount  decrease (or      or Securities
 Exchange    Security          of this Global    increase)         Custodian
                               Security
<S>          <C>               <C>               <C>               <C>
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------
========================================================================================
</TABLE> 



-----------------------------
/2/ This schedule should only be added if the Security is issued in global form.

                                       A-10
<PAGE>
 
         CERTIFICATE TO BE DELIVERED UPON EXCHANGE OR REGISTRATION OF
                            TRANSFER OF SECURITIES

RE:  6 3/4% CONVERTIBLE SUBORDINATED NOTES DUE 2001 OF PLATINUM technology, inc.

     This Certificate relates to $______, principal amount of Securities held in
*______ book-entry or ______ definitive form by ______________________ (the
"Transferor").

The Transferor:*

[ ]  (a)  has requested the Trustee by written order to deliver in exchange for
its beneficial interest in the Global Security held by the Depositary a Security
or Securities in definitive, registered form of authorized denominations and an
aggregate principal amount equal to its beneficial interest in such Global
Security (or the portion thereof indicated above); or

[ ]  (b)  has requested the Trustee by written order to exchange or register the
transfer of a Security or Securities.


                                     _____________________________________
                                     [insert name of transferor]


                                     By:__________________________________


Date:___________________________

*Check applicable box or blank.

Affiliation with the Company [check if applicable]

[ ]  (a)  The undersigned represents and warrants that it is, or at some time
          during which it held this Security was, an Affiliate of the Company

     (b)  If 2(a) above is checked AND if the undersigned was not an Affiliate
          of the Company at all times during which it held this Security,
          indicate the periods during which the undersigned was an affiliate of
          the Company:

     (c)  If 2(a) above is checked AND if the Transferee will not pay the full
          purchase price for the transfer of this Security on or prior to the
          date of transfer indicate when such purchase price will be paid:


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

                                     A-11
<PAGE>
 
If any of the above representations required to be made by the Transferor is not
made, the Registrar shall not be obligated to register this Security in the name
of any person other than the Holder hereof.

DATED:______________________        _____________________________________
                                    NOTICE:  The signature of the Holder to this
                                    assignment must correspond with the name as
                                    written upon the face of this particular
                                    Security without alteration or enlargement
                                    or any change whatsoever.


                                     A-12
<PAGE>
 
                                   EXHIBIT B

                           FORM OF CONVERSION NOTICE

To:  PLATINUM technology, inc.

     The undersigned owner of this Security hereby: (i) irrevocably exercises 
the option to convert this Security, or the portion hereof below designated, for
shares of Common Stock of PLATINUM technology, inc. in accordance with the terms
of this Indenture referred to in this Security and (ii) directs that such shares
of Common Stock deliverable upon the conversion, together with any check in 
payment for fractional shares and any Security(ies) representing any unconverted
principal amount hereof, be issued and delivered to the registered holder hereof
unless a different name has been indicated below. If shares are to be issued in 
the name of a person other than the undersigned, the undersigned will pay all 
transfer taxes payable with respect thereto. Any amount required to be paid by 
the undersigned on account of interest accompanies this Security.

Dated:_______________________

                              __________________________________________
                                             (Signature)               

Provide information below for registration of shares of Common Stock if to be 
issued, and of Securities if to be issued other than in the name of the 
registered holder.


____________________________________
     (Name)

____________________________________
     (Street Address)

____________________________________
     (City, State and Zip Code)
     (Please print name and address)

____________________________________
(Social Security or other Taxpayer 
Identifying Number)


                                   Principal Amount to be converted:  (in an
                                   integral multiple of $1000, if less than all)

                                   $___________________________


                                     A-13