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Keyboard controlled vital digital communication system

  • US 4,368,534 A
  • Filed: 06/09/1980
  • Issued: 01/11/1983
  • Est. Priority Date: 01/29/1979
  • Status: Expired due to Term
First Claim
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1. A vital digital control system with keyboard inputs for activating at least one output device in response to a manual keyboard selection of a sequence of a predetermined number of operation instructions, comprising:

  • keyboard encoder means for generating the operation instructions in the form of multi-digit keyboard words;

    vital decoding means coupled to said keyboard encoding means for identifying said keyboard words and for producing message words, diverse output words and diverse display words based on said keyboard words, and display echo words based on said display words;

    display means coupled to said decoding means for displaying a representation of said display words;

    said vital decoding means including means for sequentially producing diverse multi-bit checkwords based on predetermined words generated by said system indicative of system performance, said predetermined words including said message words, said display words, and said display echo words in response to receipt of said keyboard words, and means for checking that successive of said checkwords are diverse, said checking means including,means for comparing each generated checkword to a predetermined constant multi-bit pattern, and for producing a validation signal if sequential ones of said checkwords are complementary and corresponding to said constant multi-bit pattern, said vital decoding means activating the output device in accordance with the keyboard instructions only if said validation signal is produced.

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