Reverse Convertible Securities

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

CERTIFICATE OF AUTHENTICATION

This is one of the Securities of the series designated therein referred to in the within-mentioned Indenture.

F-2

[REVERSE OF NOTE]

CREDIT SUISSE FIRST BOSTON (USA), INC.
Reverse Convertible Securities Linked to the Performance of Silicon Laboratories, Inc.

due March 31, 2006

This Note is one of a duly authorized issue of debentures, notes, bonds or other evidences of indebtedness of the Company (the “Securities”) of the series hereinafter specified, all issued or to be issued under and pursuant to a senior indenture, dated as of June 1, 2001 (the “Indenture”), between the Company and JPMorgan Chase Bank, as trustee (the “Trustee”), to which Indenture and all indentures supplemental thereto reference is hereby made for a description of the rights, limitations of rights, obligations, duties and immunities thereunder of the Trustee, the Company, and the Holders of the Securities.  The Securities may be issued in one or more series, which different series may be issued in various aggregate principal amounts, may mature at different times, may bear interest (if any) at different rates, may be subject to different redemption provisions (if any), may be subject to different sinking, purchase or analogous funds (if any) and may otherwise vary as provided in the Indenture.  This Note is one of a series designated as the Reverse Convertible Securities Linked to the Performance of Silicon Laboratories, Inc. due March 31, 2006 (the “Note”).

A coupon will be payable on this Note of 15.00% per annum on the principal amount from March 31, 2005.  The coupon will represent an interest component and an option premium.  The coupon payment will be payable quarterly in arrears on June 30, 2005, September 30, 2005, December 30, 2005 and March 31, 2006.

This Note is payable in the manner, with the effect and subject to the conditions provided in the Indenture. 

If a payment date is not a Business Day as defined in the Indenture at a place of payment, payment may be made at that place on the next succeeding day that is a Business Day, and no interest shall accrue for the intervening period.

The Indenture provides that, without prior notice to any Holders, the Company and the Trustee may amend the Indenture and the Securities of any series with the written consent of the Holders of a majority in principal amount of the outstanding Securities of all series affected by such amendment (all such series voting as one class), and the Holders of a majority in principal amount of the outstanding Securities of all series affected thereby (all such series voting as one class) may waive future compliance by the Company with any provision of the Indenture or the Securities of such series by written notice to the Trustee; provided that, without the consent of each Holder of the Securities of each series affected thereby, an amendment or waiver, including a waiver of past defaults, may not: (i) extend the stated maturity of the Principal of, or any sinking fund obligation or any installment of interest on, such Holder’s Security, or reduce the principal amount thereof or the rate of interest thereon (including any amount in respect of original issue discount), or any premium payable with respect thereto, or adversely affect the rights of such Holder under any mandatory redemption or repurchase provision or any right of redemption or repurchase at the option of such Holder, or reduce the amount of the Principal of an Original Issue Discount Security that would be due and payable

R-1

upon an acceleration of the maturity thereof or the amount thereof provable in bankruptcy, or change any place of payment where, or the currency in which, any Security of such series or any premium or the interest thereon is payable, or impair the right to institute suit for the enforcement of any such payment on or after the due date therefor; (ii) reduce the percentage in principal amount of outstanding Securities of the relevant series the consent of whose Holders is required for any such supplemental indenture, for any waiver of compliance with certain provisions of the Indenture or certain Defaults and their consequences provided for in the Indenture; (iii) waive a Default in the payment of Principal of or interest on any Security of such Holder; or (iv) modify any of the provisions of the Indenture governing supplemental indentures with the consent of Securityholders except to increase any such 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.

The Indenture provides that, subject to certain conditions, the Holders of at least a majority in principal amount (or, if any Securities are Original Issue Discount Securities, such portion of the Principal as is then accelerable) of the outstanding Securities of all series affected (voting as a single class), by notice to the Trustee, may waive an existing Default or Event of Default with respect to the Securities of such series and its consequences, except a Default in the payment of Principal of or interest on any Security or in respect of a covenant or provision of the Indenture which 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 with respect to the Securities of such series arising therefrom shall be deemed to have been cured, for every purpose of the Indenture; but no such waiver shall extend to any subsequent or other Default or Event of Default or impair any right consequent thereto.

The Indenture provides that a series of Securities may include one or more tranches (each a “tranche”) of Securities, including Securities issued in a Periodic Offering.  The Securities of different tranches may have one or more different terms, including authentication dates and public offering prices, but all the Securities within each such tranche shall have identical terms, including authentication date and public offering price.  Notwithstanding any other provision of the Indenture, subject to certain exceptions, with respect to sections of the Indenture concerning the execution, authentication and terms of the Securities, redemption of the Securities, Events of Default of the Securities, defeasance of the Securities and amendment of the Indenture, if any series of Securities includes more than one tranche, all provisions of such sections applicable to any series of Securities shall be deemed equally applicable to each tranche of any series of Securities in the same manner as though originally designated a series unless otherwise provided with respect to such series or tranche pursuant to a board resolution or a supplemental indenture establishing such series or tranche.

No reference herein to the Indenture and no provision of this Note or of the Indenture shall alter or impair the obligation of the Company, which is absolute and unconditional, to pay the Redemption Amount of this Note in the manner, at the place, at the time and in the coin or currency herein prescribed.

The Securities are issuable initially only in registered form without coupons in denominations of $10,000 or any integral multiple thereof at the office or agency of the

R-2

Company in the Borough of Manhattan, The City of New York, and in the manner and subject to the limitations provided in the Indenture.

The Securities will not be redeemable at the option of the Company prior to maturity.

The Company will not be required to pay any Additional Amounts on the Securities.

Maturity Date

The Maturity Date of the Securities is March 31, 2006 (the “Maturity Date”); however, if a Market Disruption Event exists on any valuation date, as determined by the Calculation Agent, the Maturity Date will be the later of March 31, 2006 and the third Business Day following the date on which the final share price is calculated. 

Redemption Amount

The Company will redeem the Securities at maturity for a Redemption Amount that will be based upon the performance of the common stock of Silicon Laboratories, Inc. (the “reference shares”) during the term of the Securities (the “Redemption Amount”).   The Redemption Amount is calculated as follows:

(1)    If the price of the reference shares on the Nasdaq National Market (the “relevant exchange”) is not less than or equal to the knock-in level, which is 80% of the Initial Share Price, at all times from but not including March 28, 2005, which is the initial setting date, to and including March 24, 2006 (the “valuation date”), the Redemption Amount will equal a cash payment equal to 100% of the principal amount of the Securities at maturity.

(2)    If (i) the price of the reference shares on the relevant exchange is less than or equal to the knock-in level at any time from but not including the initial setting date to and including the valuation date and (ii) the closing price of the reference shares on that exchange on the valuation date (the “final share price”), is greater than or equal to the Initial Share Price, the Redemption Amount will equal a cash payment equal to 100% of the principal amount of the Securities at maturity.

(3)    Otherwise, Holders will receive the physical delivery amount.  The physical delivery amount will be the number of reference shares per $1,000 principal amount of the Securities equal to $1,000 divided by the Initial Share Price. 

The “Initial Share Price” is equal to $30.00.  

A “Business Day” is a day, other than a Saturday, Sunday or a day on which banking institutions in New York, New York are generally authorized or obligated by law or executive order to close and that is also a trading day. 

R-3

A “Market Disruption Event” is, the occurrence or existence of any suspension of or limitation imposed on trading (by reason of movements in price exceeding limits permitted by any relevant exchange or market or otherwise) of, or the unavailability, through a recognized system of public dissemination of transaction information, of accurate price, volume or related information in respect of (a) the reference shares or (b) any options or futures contracts, or any options on such futures contracts, relating to the reference shares if, in each case, in the determination of the Calculation Agent, in its sole discretion, any such suspension, limitation or unavailability is material. 

A “trading day” means any day, as determined by the Calculation Agent, on which trading is generally conducted for reference shares (or, but for the occurrence of a Market Disruption Event, would have been generally conducted) on the relevant exchange and on the Chicago Mercantile Exchange and the Chicago Board Options Exchange (collectively, the “related exchanges”), other than a day on which the relevant exchange or the related exchanges are scheduled to close prior to their regular weekday closing time. 

Market Disruption Events

If no final share price is available on the valuation date because of a Market Disruption Event, as determined by the Calculation Agent in its sole discretion, the Calculation Agent may postpone the calculation of the final share price until the earlier of the date such Market Disruption Event has ceased or three trading days after the valuation date, as the case may be.  On such third trading day, in the event there still exists a Market Disruption Event, the Calculation Agent will determine the final share price using its good faith estimate of the value for the reference shares as of the closing time on the relevant exchange on such date.  If a Market Disruption Event exists on the valuation date, the Maturity Date of the Securities will be the later of March 31, 2006 and the third Business Day following the day on which the final share price is calculated.  No interest will accrue or other payment be payable because of any postponement of the Maturity Date.

For purposes of determining whether a Market Disruption Event has occurred:  (1) a limitation on the hours or number of days of trading will not constitute a Market Disruption Event if it results from an announced change in the regular business hours of the relevant exchange; (2) a decision permanently to discontinue trading in the relevant options or futures contract will not constitute a Market Disruption Event; (3) limitations pursuant to New York Stock Exchange Rule 80A—Index Arbitrage Trading Restrictions (or any applicable rule or regulation enacted or promulgated by the New York Stock Exchange, any other self-regulatory organization or the Securities and Exchange Commission (the “SEC”) of similar scope as determined by the Calculation Agent) on trading during significant market fluctuations will constitute a Market Disruption Event; (4) a suspension of trading in an options contract on the reference shares by the primary securities market trading in such options, if available, by reason of (x) a price change exceeding limits set by such securities exchange or market, (y) an imbalance of orders relating to such contracts or (z) a disparity in bid and ask quotes relating to such contracts will constitute a suspension or material limitation of trading in options contracts related to the reference shares notwithstanding that such suspension or material limitation is less than two hours; (5) a suspension, absence or material limitation of trading on the primary securities market on which options contracts related to the reference shares are traded will not

R-4

include any time when such securities market is itself closed for trading under ordinary circumstances; and (6) a “suspension or material limitation” on an exchange or in a market will include a suspension or material limitation of trading by one class of investors provided that such suspension continues for more than two hours of trading or during the last one-half hour period preceding the close of trading on the relevant exchange or market (but will not include limitations imposed on certain types of trading under New York Stock Exchange Rule 80A or any applicable rule or regulation enacted or promulgated by the New York Stock Exchange, NASDAQ, any other self-regulatory organization or the SEC of a similar scope or as