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Secure memory having multiple security levels

  • US 5,991,519 A
  • Filed: 10/03/1997
  • Issued: 11/23/1999
  • Est. Priority Date: 10/03/1997
  • Status: Expired due to Term
First Claim
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1. A secured memory comprising:

  • a first level security zone having an access code controlling access to said secured memory prior to an issuer fuse being blown;

    a security code attempts counter preventing access to said secured memory when a predetermined number of attempts at matching said access code have been made prior to resetting said security code attempts counter;

    a plurality of application zones, each of said plurality of application zones comprising;

    a storage memory zone;

    an application security zone having an application zone access code controlling access to said storage memory zone after an issuer fuse has been blown;

    an application zone security code attempts counter preventing access to said application zone when a predetermined number of attempts at matching said application zone access code have been made prior to resetting said application zone security code attempts counter;

    an erase key partition having an erase key code controlling erase access to said storage memory zone after an issuer fuse has been blown; and

    an erase key attempts counter preventing erase access to said application zone when a predetermined number of attempts at matching said erase key code have been made prior to resetting said erase key attempts counter.

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