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Method and apparatus for operating a microprocessor in synchronism with a video signal

  • US 4,464,679 A
  • Filed: 07/06/1981
  • Issued: 08/07/1984
  • Est. Priority Date: 07/06/1981
  • Status: Expired due to Term
First Claim
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1. In a television receiver, including a source of video signals including synchronizing signal components, and a synchronizing signal separator circuit responsive to said video signals for producing separated horizontal line rate synchronizing signals, apparatus comprising:

  • a microprocessor having a clock input for receiving a clock signal, a data input coupled to receive said synchronizing signals, and an output at which a control signal is produced, said microprocessor being capable of executing a program of instructions, the execution of an instruction cycle taking a given number of clock signal cycles;

    means having an input coupled to receive said synchronizing signals and an output for producing a clock signal which is substantially aligned in phase with said synchronizing signals;

    means for coupling said output of said clock signal producing means to said clock input of said microprocessor, the frequency of said clock signal being chosen as an integer multiple of said horizontal line rate for enabling said microprocessor to execute an integer number of instruction cycles during a horizontal line interval to sample the state of said data input synchronously with said synchronizing signals; and

    a signal utilization circuit coupled to said output of said microprocessor.

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