Debugging device for microprocessor

TL;DR: In this paper, the authors present a debugging device that can measure an accurate coverage of a microprocessor having a prefetching function for instruction causing the pipeline processing, by having comparison of contents between a coverage memory and a flag memory.

Abstract: PURPOSE:To obtain a debugging device that can measure an accurate coverage of a microprocessor having a prefetching function for instruction causing the pipeline processing, by having comparison of contents between a coverage memory and a flag memory. CONSTITUTION:The execution of a target CPU 1 is started after 3-state buffers 9, 14 and 15 are turned off together with buffers 6, 12 and 14 turned on respectively. An instruction tracking circuit 3 detects an instruction with which an address flow becomes discontinuous and then activates the preset input LD of a presettable counter 2 and applies a clock CK pulse to preset again the address of the CPU 1. Thus data are written to a coverage memory 7 while the execution of a fetched instruction is detected. In case '1' is already written in a range of the coverage measuring addresses of the memory 7 and the contents of the memory 7 are changed to 0 from 1, it is considered that the relevant address has a hit. Thus it is possible to extract a hit factor and an unhit address by comparing the contents of a flag memory 16 stored previously with the contents of the memory 7.