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Apparatus for synchronizing the operation of a microprocessor with a television synchronization signal useful in generating an on-screen character display

  • US 4,631,585 A
  • Filed: 05/07/1984
  • Issued: 12/23/1986
  • Est. Priority Date: 05/07/1984
  • Status: Expired due to Fees
First Claim
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1. Apparatus comprising:

  • computing means operating in response to stored program instructions generated in timed relationship to instruction cycles occurring at a rate synchronously related to a clock signal;

    clock signal generating means for generating said clock signal and for controlling the phase and frequency of said clock signal in response to a control signal;

    a source of a reference frequency signal having a reference frequency;

    said computing means being programmed to generate a comparison signal each time a predetermined number of instruction cycles have occurred; and

    comparison means for comparing the phase and frequency of said comparison signal and said reference signal and generating said control signal in response thereto.

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