COMPUTER BUS ARBITRATION FOR N PROCESSORS REQUIRING ONLY N UNIDIRECT- IONAL SIGNAL LEADS

A system and method for using N unidirectional lines to implement signals for arbitration, variable length transactions, automatic responses, and efficient burst transaction modes for a bus in a cache-coherent multi-processor computer system having N processors. Processors use arbitration lines to implement busy signals for variable length transactions. A processor needing to respond to a transaction is granted automatic access to a bus if it is the last processor asserting a busy signal. A processor in a burst transaction mode is granted automatic continuous access without arbitration if no other processors request access. The use of only N lines minimizes pin-out for an integrated processor. The use of unidirectional (one driver, N-1 receivers) lines further optimizes cost and speed.