Method for implementing synchronous pipeline exception recovery

Abstract

Pipelined CPUs achieve high-performance by fine tuning the pipe stages to execute typical instruction sequences. Atypical instruction sequences result in pipeline exceptions. The disclosed method provides graceful exception handling and recovery in a micropipelined memory interface. The use of a memory reference restart command latch allows an implementation that requires no additional logic for conditional writing of states pending exception checking. The exception handling hardware is minimized because instructions which cause exceptions are never re-executed, and exception handling microcode executes in-line with the normal microcode flow.