<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType>
    <periodOfReport>2003-07-01</periodOfReport>
    <notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0000826083</issuerCik>
        <issuerName>DELL COMPUTER CORP</issuerName>
        <issuerTradingSymbol>DELL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001077821</rptOwnerCik>
            <rptOwnerName>MARENGI JOSEPH A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>
   <nonDerivativeSecurity>
      <securityTitle>
          <value>Common Stock</value>
      </securityTitle>
      <transactionDate>
          <value>2003-07-01</value>
      </transactionDate>
      <transactionCoding>
          <transactionFormType>4</transactionFormType>
          <transactionCode>S</transactionCode>
          <equitySwapInvolved>0</equitySwapInvolved>
      </transactionCoding>
      <transactionTimeliness>
      <value />
      </transactionTimeliness>
      <transactionAmounts>
          <transactionShares>
              <value>12100</value>
          </transactionShares>
          <transactionValue>
              <value>31.6941</value>
          </transactionValue>
          <transactionAcquiredDisposedCode>
              <value>D</value>
          </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <postTransactionAmounts>
          <sharesOwnedFollowingTransaction>
              <value>79100</value>
              <footnoteId id="F1" />
          </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
          <directOrIndirectOwnership>
              <value>D</value>
          </directOrIndirectOwnership>
      </ownershipNature>
   </nonDerivativeSecurity>
<footnotes>
   <footnote id="F1">Represents 33,660 unrestricted stock and 45,440 restricted shares vesting on 7/1/04.  </footnote>
</footnotes>
    <ownerSignature>
       <signatureName>Joseph A.  Marengi</signatureName>
       <signatureDate>2003-07-02</signatureDate>
    </ownerSignature>
    <ownerSignature>
       <signatureName>Thomas H. Welch, Jr.,  Attorne</signatureName>
       <signatureDate>2003-07-02</signatureDate>
    </ownerSignature>
</ownershipDocument>

