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Copy reproduction machine with controller self check system

  • US 4,266,294 A
  • Filed: 04/09/1979
  • Issued: 05/05/1981
  • Est. Priority Date: 08/30/1977
  • Status: Expired due to Term
First Claim
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1. In an electrophotographic machine with a plurality of processing elements and with a controller having a CPU and a plurality of control modules, the controller having address and data lines for identifying a particular processing element of the electrophotographic machine and providing data flow with the particular processing element identified, the address and data lines interconnecting the CPU, the control modules, and the processing elements, the method of verifying the integrity of one of said address and data lines associated with one of said plurality of control modules comprising the steps of:

  • looping a test bit through one of the address and data lines, between the CPU and a first one of the plurality of control modules,reading the bit returned,comparing the returned bit with the test bit sent,looping a test bit through one of the address and data lines between the CPU, the first one of the plurality of control modules, and the second one of the plurality of control modules, reading the bit returned and comparing the bit returned with the test bit sent anddeclaring a fault when the returned bit differs from the test bit.

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