HIGH-PERFORMANCE RISC MICROPROCESSOR ARCHITECTURE

摘要

The high-performance, RISC core based microprocessor architecture permits concurrent execution of instructions obtained from memory through an instruction prefetch unit having multiple prefetch paths allowing for the main program instruction stream, a target conditional branch instruction stream and a procedural instruction stream. The target conditional branch prefetch path allows both possible instruction streams for a conditional branch instruction to be prefetched. The procedural instruction prefetch path allows a supplementary instruction stream to be accessed without clearing the main or target prefetch buffers. Each instruction set includes a plurality of fixed length instructions. An instruction FIFO is provided for buffering instruction sets in a plurality of instruction set buffers including a first buffer and a second buffer. An instruction execution unit including a register file and a plurality of functional units is provided with an instruction control unit capable of examining the instruction sets within the first and second buffers and scheduling any of the instructions for execution by available functional units. Multiple data paths between the functional units and the register file allow multiple independent accesses to the register file by the functional units as necessary for the execution of the respective instructions.