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Method and apparatus for providing enhanced data verification in a computer system

  • US 5,379,342 A
  • Filed: 01/07/1993
  • Issued: 01/03/1995
  • Est. Priority Date: 01/07/1993
  • Status: Expired due to Fees
First Claim
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1. A personal computer system compatible with application programs and operating system software, the personal computer system comprising:

  • a microprocessor;

    non-volatile memory electrically coupled to said microprocessor, said non-volatile memory storing a first portion of system microcode that is retrieved and executed by said microprocessor when said computer system is initially powered on,volatile memory electrically coupled to said microprocessor;

    a direct access storage device electrically coupled to said microprocessor, said direct access storage device storing a second portion of operating system microcode that is retrieved and executed by said microprocessor after said microprocessor has executed said first portion of microcode,said second portion of operating system microcode including a boot program which, during power on initialization of said system, receives control of said system from said first portion of system microcode, andmeans contained at least in part in said first portion of system microcode for enabling said microprocessor to verify that said boot program has not undergone unauthorized modification since said computer system was previously powered off, said last-mentioned means operating before control of said system is transferred from said first portion to said boot program.

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