Two computer access circuit using address translation into common register file

Abstract

An access circuit for data swapping between two computers and a computer system including the access circuit. Each computer including an address bus for supplying addresses and a data bus for transferring data. The access circuit includes a register file and two address decoder circuits. The register file has a plurality of storage locations for storing data. The register file has dual data ports capable of simultaneous data transfer via the first data port with a first data storage location and via the second data port with a second, different storage location. Each address decoder is connected to the address bus of a corresponding computer and the register file. The address decoders translate an address received on the address bus to a storage location of the register file. Two handshakes circuits are connected to respective address decoders and digital computers. The first and second address decoders are connected to each other. When the storage location of the first address decoder equals the storage location of the second address decoder, one of the handshake circuits signals the corresponding digital computer a memory waitstate or memory fault. At least one of the decoders is be programmable to position in the address space of the corresponding computer. At least one the address decoders includes an autoincrement circuit advances the accessed storage location within the register file to a next storage location upon each data transfer.