Abstract: A Peripheral Component Interconnect (PCI) bridge between two buses prefetches read data into a cache. The number of cache lines to prefetch is predicted by a prefetch counter. One prefetch counter is kept for each type of memory-read command: basic memory-read (MR), memory-read-line (MRL) that reads a cache line, and memory-read-multiple (MRM) that reads multiple cache lines. For each type of read command, counters are kept of the number of completed commands, bus-disconnects (indicating under-fetch), and master-discard of data (indicating over-fetch). After a predetermined number of execution of each type of command, the command's prefetch counter is incremented if under-fetching occurred, or decremented if over-fetching occurred, as indicated by the disconnect and discard counters for that type of read command. The command's other counters are reset. Prefetching is optimized for each type of read command. MRM can prefetch more data than MRL or MR.

Abstract: A multi-port Peripheral Component Interconnect (PCI) bus bridge allows for cascading of PCI buses and reduction of bus loading and traffic. The multi-port PCI bridge has three or more ports that connect to PCI buses. At each destination port, a pair of data FIFOs is provided for each source port, for read and write data. Each destination port has three address FIFOs, one for posted-memory-write (PMW) addresses, another for delayed-transaction-request (DTR) addresses and data, and a third for delayed-transaction-completion (DTC) addresses. An address mux receives addresses from all source ports and combines them into the three address FIFOs. When addresses arrive concurrently, the address mux delays one address until the first address has been written into the address FIFO, and then writes the delayed address. Since separate data FIFOs are used for each source port, data is not delayed. Concurrent transactions from different source ports to the same destination port can occur.