MICROCOMPUTER

摘要

PROBLEM TO BE SOLVED: To facilitate an external communication and to obtain a debugging instruction from an off-chip position by connecting an external computer to a debugging port and debugging an on-chip CPU. SOLUTION: A parallel communication path 15 is formed between CPUs 12 and 13 which have registers 119 on an integrated circuit chip 11 and a local 1st memory 120. The chip 11 is connected to an external debugging computer device 123 which has a 2nd memory 125 by a debugging port 30 through the bus 15. the external computer 123 sends a control signal through the port 30 to stop the execution of an instruction obtained from the 1st memory 120 by the CPU 12 and allow the CPU 12 to execute a debugging routine from a 2nd memory 125. Then the operation of the CPU 12 after the routine is restarted with the instruction in an address determined by the external computer device 123. Consequently, the CPU 12 becomes able to operate with codes in the 1st memory 120.