Microprocessor bus structure

摘要

The present invention discloses a microprocessor bus structure that enables a processor chip to be designed with optional unidirectional or bi-directional I/O buses. The processor is designed with separate input and output bus internal to the chip. A gating network is coupled to these processor uni-directional busses that allows the chip to have an alternate externally wired bus structure. For the lowest cost and lowest performance only one set of bidirectional bus lines are wired external to the chip. These lines have a parallel driver and receiver with appropriate gating to allow the bus to be either in the send or receive mode. The signals from the processor uni-directional input and output buses are wired via appropriate gating to create a single bi-directional bus. For high performance operation where higher cost for higher bandwidth is justified, the bidirectional bus is gated to be a device output only bus and the alternate device input bus is gated to the processor input bus creating a true uni-directional bus structure. The bus enable line is wired to the appropriated stated depending on the wired microprocessor bus structure.