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Communication line status scan technique for a communications processing system

  • US 4,336,588 A
  • Filed: 01/19/1977
  • Issued: 06/22/1982
  • Est. Priority Date: 01/19/1977
  • Status: Expired due to Term
First Claim
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1. In a data processing system including a communications processor coupled by means of a plurality of line adapters to transmit or receive data between a plurality of communications lines, each having a present status, and a main memory upon issuance of interrupt signals, an indication of the prior status of said lines being stored in said processor, said main memory coupled in the system to store said data, said system further including a central processing unit coupled to communicate control information to said processor, a process implemented by said communications processor after said system responds to said interrupt signals as issued by said central processing unit or one of said line adapters comprising the steps of:

  • A. determining the present status of one of said lines selected by said processor;

    B. comparing said present status with said stored prior status of said selected line;

    C. scanning for other data sources which may require service if said step of comparing produces an equal comparison; and

    D. executing, in response to a not equal comparison produced during said step of comparing, a command previously stored in said processor, said command enabling the servicing of said one of said lines, whereby line service operations are entered into in response to said interrupt signals only after the status of a line has changed.

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