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Protected address range in an electrically erasable programmable read only memory

  • US 6,009,495 A
  • Filed: 11/08/1995
  • Issued: 12/28/1999
  • Est. Priority Date: 12/29/1989
  • Status: Expired due to Term
First Claim
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1. An apparatus for protecting writes to a programmable address range of a memory device, said programmable address range comprising an addressable area smaller than the total addressable area of said memory device, said memory device being readable and writable, said apparatus comprising:

  • means for defining a protected address range of said memory device, said protected address range being of a predetermined selectable variable size and adapted to be physically configurable in hardware;

    means responsive to said defining means for decoding the address range defined by said defining means to generate an address decode signal in response to an address signal that corresponds to the protected address range;

    means responsive to said address decode signal for preventing writes to the protected address range in said memory device while enabling data in the protected address range in said memory device to be read; and

    means for programmably disabling said preventing means, said disabling means including means for allowing reads and writes to said protected address range in said memory device.

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