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Lock converting bus-to-bus interface system

  • US 5,088,028 A
  • Filed: 06/17/1991
  • Issued: 02/11/1992
  • Est. Priority Date: 04/07/1989
  • Status: Expired due to Term
First Claim
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1. An apparatus for providing data communications between first and second computer systems, each computer system having a bus master coupled to a bus to arbitrate for control of the bus, to read and write access data storage locations mapped to separate addresses within an address space, and then to relinquish control of the bus, with a bus master writing or reading data to or from a particular data storage location by placing on the bus an address to which the particular data storage location is mapped and transmitting or receiving the data via the bus, the apparatus comprising:

  • first means coupled to the first computer system bus for mapping an address within the first computer system address space to an address within the second computer system address space as a function of first mapping data loaded into the first mapping means, for asserting a first request signal for access to an internal bus of the apparatus as a function of the address from the first computer system and the first mapping data, and for receiving a first lock signal from the first computer system, the first lock signal barring access to the first computer system bus by other devices of the first computer system;

    second means coupled to the second computer system bus for mapping an address within the second computer system address space to an address within the first computer system address space as a function of second mapping data loaded into the second mapping means, for asserting a second request signal for access to the internal bus of the apparatus as a function of the address from the second computer system and the second mapping data, and for receiving a second lock signal from the second computer system, the second lock signal barring access to the second computer system bus by other devices of the second computer system; and

    means coupled to the first and second mapping means for arbitrating for access to the internal bus in response to the first and second request signals, for controlling data flow between the first computer system and the second computer system via the internal bus of the apparatus when the internal bus is accessed by one of the computer systems according to the result of arbitrating between the first and second request signals, and for converting the first lock signal to the second lock signal, and vice versa, so that when the first computer system has access to the internal bus and asserts the first lock signal the bus of the second computer system is locked to bar access by devices of the second computer system, and vice versa.

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