<?xml version="1.0"?>
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    <periodOfReport>2005-08-31</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
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        <issuerName>STORAGE TECHNOLOGY CORP</issuerName>
        <issuerTradingSymbol>STK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
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            <rptOwnerName>KOCOL ROBERT S</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>ONE STORAGETEK DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LOUISVILLE</rptOwnerCity>
            <rptOwnerState>CO</rptOwnerState>
            <rptOwnerZipCode>80028</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
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            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Corporate VP and CFO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
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                </transactionShares>
                <transactionPricePerShare>
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                </transactionPricePerShare>
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                <value>2005-08-31</value>
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                </transactionShares>
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                </transactionPricePerShare>
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                <footnoteId id="F3"/>
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            </expirationDate>
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                <underlyingSecurityTitle>
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                </underlyingSecurityTitle>
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            <transactionDate>
                <value>2005-08-31</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
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            <transactionTimeliness>
                <value></value>
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                <transactionPricePerShare>
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            <expirationDate>
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            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
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                <value>Stock Options (Right to buy)</value>
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            <transactionDate>
                <value>2005-08-31</value>
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                <transactionPricePerShare>
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                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
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            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>54375</value>
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        <derivativeTransaction>
            <securityTitle>
                <value>Stock Options (Right to buy)</value>
            </securityTitle>
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                <value>31.79</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-08-31</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>42895</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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            <exerciseDate>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
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            <expirationDate>
                <value>2015-02-08</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
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                    <value>42895</value>
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        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Options (Right to buy)</value>
            </securityTitle>
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                <value>37.0625</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-08-31</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
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                <value></value>
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                    <value>0</value>
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                    <value>Common Stock</value>
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    <footnotes>
        <footnote id="F2">One-fourth of the option shares vest on each of the first four anniversaries of the date of grant.</footnote>
        <footnote id="F3">Notwithstanding the original option vesting schedule cited in other footnotes to this form, all unvested shares were accelerated at the effective time of the merger.  This option was assumed by Sun Microsystems in the merger and replaced with an option to purchase a number of Sun shares determined by multiplying 10.1788 (the &quot;Option Ratio&quot;) by the number of underlying Storage Technology option shares and rounding down to the nearest whole number.  The per share exercise price for the  replacement option has been adjusted to a price determined by dividing the per share exercise price of the Storage Technology option by 10.1788, the Option Ratio, and rounding up to the nearest whole cent.</footnote>
        <footnote id="F1">Disposed of pursuant to merger agreement between Storage Technology Corporation and Sun Microsystems in exchange for a cash consideration of $37.00 per share on the effective date of the merger.</footnote>
        <footnote id="F5">All options currently exercisable</footnote>
        <footnote id="F4">All shares in this award will vest four years from the date of grant, except that the vesting of one-fourth of the shares in the award may be accelerated on each of the first, second and third anniversaries of the date of grant if StorageTek meets predetermined performance criteria, set by the Human Resources and Compensation Committee of the Board of Directors.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Donald H. Kronenberg, Attorney-in-Fact</signatureName>
        <signatureDate>2005-09-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0202
4
2005-08-31
1
0000094673
STORAGE TECHNOLOGY CORP
STK
0001210155
KOCOL ROBERT S
ONE STORAGETEK DRIVE
LOUISVILLE
CO
80028
0
1
0
0
Corporate VP and CFO
Common Stock
2005-08-31
4
D
0
161055.12
37
D
0
D
Stock Options (Right to buy)
22.03
2005-08-31
4
D
0
34800
0
D
2013-02-10
Common Stock
34800
0
D
Stock Options (Right to buy)
23.9
2005-08-31
4
D
0
3625
0
D
2012-02-15
Common Stock
3625
0
D
Stock Options (Right to buy)
29
2005-08-31
4
D
0
54375
0
D
2014-02-02
Common Stock
54375
0
D
Stock Options (Right to buy)
31.79
2005-08-31
4
D
0
42895
0
D
2015-02-08
Common Stock
42895
0
D
Stock Options (Right to buy)
37.0625
2005-08-31
4
D
0
59548
0
D
2009-02-05
Common Stock
59548
0
D
One-fourth of the option shares vest on each of the first four anniversaries of the date of grant.
Notwithstanding the original option vesting schedule cited in other footnotes to this form, all unvested shares were accelerated at the effective time of the merger.  This option was assumed by Sun Microsystems in the merger and replaced with an option to purchase a number of Sun shares determined by multiplying 10.1788 (the "Option Ratio") by the number of underlying Storage Technology option shares and rounding down to the nearest whole number.  The per share exercise price for the  replacement option has been adjusted to a price determined by dividing the per share exercise price of the Storage Technology option by 10.1788, the Option Ratio, and rounding up to the nearest whole cent.
Disposed of pursuant to merger agreement between Storage Technology Corporation and Sun Microsystems in exchange for a cash consideration of $37.00 per share on the effective date of the merger.
All options currently exercisable
All shares in this award will vest four years from the date of grant, except that the vesting of one-fourth of the shares in the award may be accelerated on each of the first, second and third anniversaries of the date of grant if StorageTek meets predetermined performance criteria, set by the Human Resources and Compensation Committee of the Board of Directors.
Donald H. Kronenberg, Attorney-in-Fact
2005-09-02