System bus with serially connected PCI interface

摘要

A low pin count, moderate speed serial data bus that has a variable width for the transfer of data between devices of a computer system. The serial data bus can be selectively configured to be 1-bit, 4-bit, 8-bit or 16-bit wide. Data (including bus commands and addresses) carried by wider parallel buses are serialized into data blocks, which are then transferred by the serial data bus at a high speed. One feature of the present invention is that the pin count requirement for the present invention is low: only four control pins are required for controlling the data transfer mechanisms of the data bus. Another significant feature of the present invention is that the host and companion interfaces of the serial data bus can have non-matching widths. To allow for host and companion interfaces with non-matching widths, an initialization protocol is used to establish the effective width of the data bus at power-on reset.