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System for dynamic association of a variable number of device addresses with input/output devices to allow increased concurrent requests for access to the input/output devices

  • US 5,530,897 A
  • Filed: 10/01/1993
  • Issued: 06/25/1996
  • Est. Priority Date: 10/01/1993
  • Status: Expired due to Fees
First Claim
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1. A data processing system for allocating unit control blocks and associated subchannels on a dynamic basis among input/output devices thereby allowing increased presentation of concurrent requests for access to multiple exposure input/output devices, the data processing system comprising:

  • a plurality of peripheral input/output devices;

    a computer system having a plurality of unit control blocks for use in controlling input/output operations between main storage of the computer and the peripheral input/output devices;

    a controller providing an interface for connection of the computer system and the plurality of peripheral input/output devices;

    association tables accessible to the controller for listing device address and indicating whether each device address is valid or invalid, is an actual device or an alias device address, and to which actual device the alias device is bound;

    means for dividing unit control blocks between first and second groups where the first group comprises base unit control blocks having a one to one correspondence with and dedicated to the peripheral input/output devices and the second group comprises alias unit control blocks available for association with selected peripheral input/output devices on demand;

    the alias unit control blocks each having a unique alias;

    means for linking in a free pool, alias unit control blocks which are not associated with a peripheral input/output device; and

    means responsive to access of an alias unit control block for an input/output operation to a target peripheral input/output device for removing the alias unit control block from the free pool and dynamically linking the alias unit control block to an exposure chain depending from the base unit control block dedicated to target peripheral input/output device.

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