Inventors:
Allen W. Roberts - Union City CA
Harold L. McFarland - Santa Clara CA
Harlan Lau - Campbell CA
International Classification:
H04J 312
Abstract:
In a high speed data bus system, each functional unit has an associated port which operates to accept all related information that makes up a communication, or if this cannot be done, to accept none of the information. More particularly, an information transfer, depending on its nature, may comprise one BIQ or more than one BIQ (a "BIQ" is a bus information quantum which is placed on the bus for one bus cycle). To implement the indivisibility of multiple-BIQ transfers, the control logic for each port includes screening circuitry responsive to the state of the port's input buffers, and further responsive to flags from the functional unit for selectively accepting or rejecting BIQ's, and further includes screening constraint circuitry to ensure that the port accepts all or none of the BIQ's that make up the transfer. Depending on the flag, the rejection may be total, or may apply only to a designated class of transfers (for example, operations).