Apparatus which prepares a master map portraying location of devices relative to bus interface circuits and copying the pertinent portion of the master map to each bus interface circuits

摘要

An I/O control system for a general-purpose computer having multiple bus branches separated by routing circuitry prepares a digital map of I/O device locations on the bus branches, and copies versions of the maps to registers in the routing circuitry on startup and reset. The routing maps provide immediate routing information for I/O requests issued by one or more CPUs in a system, allowing the routing circuitry between bus branches to immediately route requests to the proper device with a minimum of wait states. In one aspect I/O devices are polled for location at startup and reset, and in another aspect, a universal map protocol is a part of the BIOS or storage accessible by the BIOS, making a system self-configuring and providing the necessary information for the mapping for the routing circuitry.