DEBUGGING SYSTEM

PURPOSE:To attain debug in which that the common resource of a system does not change is set as a premise by giving a sole bus use right to a processor where a debug exception occurs. CONSTITUTION:A circuit 42 storing a processor in the middle of obtaining a bus and a circuit 43 detecting the reading of a vector for debug exception are used. A bus mediation circuit 4 giving the sole bus use right to the processor where the debug exception occurs is constituted, and programs to be debugged existing on the system are all stopped. Namely, the execution of the program to be debugged is interrupted in the processor where the debug exception occurs, and the execution of a debug program is started instead. At that time, all the programs to be debugged are stopped. Thus, debug in a state where the common resource is freezed is attained.