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Device for detecting whether an attached external memory stores valid data, if not, whether the external memory is capable of storing data

  • US 5,257,388 A
  • Filed: 04/26/1990
  • Issued: 10/26/1993
  • Est. Priority Date: 04/27/1989
  • Status: Expired due to Term
First Claim
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1. A data processing device adapted to attachably and detachably couple with an external memory unit to which data are written and from which data are read, said external memory unit storing data even when not coupled to said data processing device, said data processing device comprising:

  • discriminating means for determining whether said external memory unit is coupled to said data processing device;

    judging means for judging if a predetermined kind of data are stored in said external memory unit when said discriminating means determines that said external memory unit is coupled to said data processing device;

    another judging means for judging if said predetermined kind of data stored in said external memory unit are usable when said judging means judges that said predetermined kind of data are stored in said external memory unit, said another judging means including means for performing a sum check on said predetermined data and comparing said sum check result with a sum result stored in said external memory unit;

    error indicating means for indicating that said predetermined kind of data are not usable when said another judging means judges that said predetermined kind of data are not usable; and

    ,third judging means for judging whether said external memory unit is capable of storing data when said judging means judges that said predetermined kind of data are not stored in said external memory unit, said third judging means including means for writing test data to said external memory unit, means for reading said test data from said external memory unit and means for comparing said test data read from said external memory unit with said known test data whereby to check the integrity of said external memory unit.

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