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System and method for accessing memory connected to different bus and requesting subsystem

  • US 4,205,373 A
  • Filed: 05/22/1978
  • Issued: 05/27/1980
  • Est. Priority Date: 05/22/1978
  • Status: Expired due to Term
First Claim
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1. In a data processing system including first and second busses each having a plurality of addressable ports, a system comprising in combination:

  • (a) a memory subsystem connected to a first port of said second bus;

    (b) a subsystem connected to a second port of said first bus, said subsystem includingi. a plurality of input/output means for transmitting a request message to said first bus;

    ii. means for inserting first identification information into said request message, representing a one of said input/output means from which said request message is transmitted;

    (c) means coupled to said first and second busses, respectively, for routing said request message from said first bus to said second bus and routing any memory response message produced in response to said request message by said memory subsystem from said second bus to said first bus, said routing means includingi. means for receiving said request message from said first bus and determining if said request message requires a response from said memory subsystem;

    ii. means for temporarily storing said first identification information;

    iii. means responsive to said request message receiving means for modifying said request message to contain second identification information representing an addressable port on said second bus and the location of said stored first identification information in said means for temporarily storing;

    iv. means for transmitting said modified request message to said memory subsystem via said second bus.

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