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Adapter for raster output scanning printer

  • US 4,279,002 A
  • Filed: 04/24/1978
  • Issued: 07/14/1981
  • Est. Priority Date: 04/24/1978
  • Status: Expired due to Term
First Claim
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1. An adapter for interfacing a digital electronic image processor with a raster output scanning printer, said adapter having dedicated input and output connections for printer control and operation, said adapter comprising:

  • means for receiving at a first dedicated input connection digital command data from said electronic image processor and for initiating control functions in response thereto;

    means for receiving at a second dedicated input connection digital clock signals of a predetermined uniform frequency transmitted thereto by said electronic image processor and for distributing said clock signals throughout said adapter;

    means for receiving in bit parallel format at a set of third dedicated input connections packets of video print information from said electronic image processor and for retiming said video information for transmission to said printer;

    means for monitoring the transmission of video print information to said printer and for generating data request signals at a first dedicated output connection to said electronic image processor in order to thereby request additional packets of video print information from said electronic image processor;

    means for monitoring the status of said adapter and said printer and for serializing status information and generating said status information at a second dedicated output connection for transmittal to said electronic image processor; and

    said means for receiving command data and for initiating control functions in response thereto comprises sampling means responsive to command bits which occur at a frequency which is an integer quotient of the frequency of said digital clock pulses, said sampling means including means for detecting command bit polarity with the occurrence of consecutive ones of said digital clock pulses during command pulses, means for comparing the command bit polarities detected, and means for generating an error signal when said means for comparing registers an unequal comparison in order to abort the performance of control functions in response to command data including any data bit in which sampling and comparison as aforesaid produces an unequal comparison.

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