<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-08-31</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0000094673</issuerCik>
        <issuerName>STORAGE TECHNOLOGY CORP</issuerName>
        <issuerTradingSymbol>STK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001225110</rptOwnerCik>
            <rptOwnerName>JOHNSON MERCEDES</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>ONE STORAGETEK DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LOUISVILLE</rptOwnerCity>
            <rptOwnerState>CO</rptOwnerState>
            <rptOwnerZipCode>80028</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-08-31</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2641</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>37</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Options (Right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>25.75</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-08-31</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>29000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>11.25</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2014-01-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>29000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Options (Right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>26.39</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-08-31</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>4000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.61</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F4"/>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2014-05-20</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>4000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Options (Right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>28.58</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-08-31</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>7500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>8.42</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F4"/>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-04-26</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>7500</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F4">One-third of the option shares vest on each of the first three anniversaries of the date of grant.</footnote>
        <footnote id="F2">Notwithstanding the original vesting schedule cited in other footnotes to this form, all unvested shares were accelerated at the effective time of the merger.  This option was canceled in the merger in exchange for a cash payment representing the difference between the exercise price of the option and the merger consideration of $37.00 per share on the effective date of the merger.</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="F3">5,000 shares vest six months after the date of grant; 4,667 shares vest on the first anniversary of the date of grant; 4,666 shares vest on the second and third anniversaries of the date of grant; 3,333 shares vest on the fourth anniversary of the date of grant; and 3,334 shares vest on the fifth and sixth anniversaries of the date of grant.</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
0001225110
JOHNSON MERCEDES
ONE STORAGETEK DRIVE
LOUISVILLE
CO
80028
1
0
0
0
Common Stock
2005-08-31
4
D
0
2641
37
D
0
D
Stock Options (Right to buy)
25.75
2005-08-31
4
D
0
29000
11.25
D
2014-01-01
Common Stock
29000
0
D
Stock Options (Right to buy)
26.39
2005-08-31
4
D
0
4000
10.61
D
2014-05-20
Common Stock
4000
0
D
Stock Options (Right to buy)
28.58
2005-08-31
4
D
0
7500
8.42
D
2015-04-26
Common Stock
7500
0
D
One-third of the option shares vest on each of the first three anniversaries of the date of grant.
Notwithstanding the original vesting schedule cited in other footnotes to this form, all unvested shares were accelerated at the effective time of the merger.  This option was canceled in the merger in exchange for a cash payment representing the difference between the exercise price of the option and the merger consideration of $37.00 per share on the effective date of the merger.
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.
5,000 shares vest six months after the date of grant; 4,667 shares vest on the first anniversary of the date of grant; 4,666 shares vest on the second and third anniversaries of the date of grant; 3,333 shares vest on the fourth anniversary of the date of grant; and 3,334 shares vest on the fifth and sixth anniversaries of the date of grant.
Donald H. Kronenberg, Attorney-in-Fact
2005-09-02