Appeal No. 97-2470 Page 2
Application No. 08/201,817
BACKGROUND
The invention at issue in this appeal relates to bridges
for interconnecting buses. A fast, Peripheral Component
Interconnect (PCI) bus and a slow, secondary bus connect the
components of a computer. Accesses to one of the buses by a
component, i.e., a “bus master,” on the other bus is
accomplished through a bridge connecting the buses.
The bridge accelerates the transfer of data in the
computer by two means. First, after a PCI bus master is
denied access to the secondary bus when it is busy, the bridge
masks any retry by the bus master until the bus is again
available. Because retries are masked, the PCI bus is not
occupied needlessly by a retrying bus master. Second, after
the secondary bus is again available, the bridge guarantees a
PCI bus master access to the bus in favor of a secondary bus
master. This reduces “thrashing” on the PCI bus that results
when a PCI bus master is force to continually retry access to
the secondary bus.
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