Abstract: In a computer system that contains plural computer resource elements, such as multiple processor and memory units, with those elements communicating digital information over a common communications bus, high communications bus efficiency is achieved. An interface permits each of said processor and memory elements to individually and independently access either the data bus, without busying the address bus, or the address bus without busying the data bus, with bus access being limited to a fixed interval of time. Different ones of said processor and memory units may thus simultaneously transfer digital information over the respective address and data bus. The foregoing system includes a bus contention and priority protocol to eliminate the possibility of data collision and includes identification lines for identifying each processor element accessing the bus.

Abstract: Data messages are transmitted between host data processors and a communications processor. Data messages from a communications processor are transformed for the host processor to which the message is assigned. Data messages from a host processor are transformed for the communications processor. Protocol is established between (a) untransformed data messages from the communications processor and transformed data messages for the communications processor, and (b) untransformed data messages from each host processor and transformed data messages for each host processor. A device interface connects a plurality of host processors to a plurality of buses, each bus being connected to one communications processor. The device interface handles the protocol, transformation and control function in parallel so that messages between a given host processor and terminal connected to a communications processor are processed through a device interface.

Abstract: A data communications apparatus transfers data between two channels, the data formats of each being incompatible with the other. Index registers receive index addresses from each channel to access a pointer in a pointer RAM. The pointer addresses a data location in a data RAM to permit data to be stored or read from either channel at the data transfer rate and byte size for that channel. Registers are provided between each RAM and at least one of the channels to concatenate smaller byte words for transfer between the RAMs and the one channel. Counter apparatus drives the pointer RAM to access successive locations in the data RAM, as desired.