CUSTOM IC

PURPOSE:To execute the IC test by a CPU and to monitor easily the input and the output of an IC even after the IC is assembled in the system by providing the interface mode setting part, plural interfaces and buses. CONSTITUTION:The mode in interfaces i/F 3, 4 and 5 has a usual mode and a test mode, and is changed over by sending a mode change-over signal from a CPU7 through a bus G to an i/F mode setting part 6. In the test mode, the CPU7 outputs the signal for testing, and the signal is inputted through a data bus F, an i/F5, a bus H, i/F and a bus B to a processing part 2. The processing part 2 responds to the test signal, and transmits the response signal through a bus D, i/F4, a bus E, i/F5 for the test output and a fus F to the CPU7. Thus, even after the IC is assembled into the system, an IC test can be executed by the CPU7, and the input and output of the IC can be easily monitored by the CPU7.