| 摘要 |
PURPOSE:To diagnose a CPU and its peripheral equipments in accordance with a display state of a display device, by making the CPU execute a program related to the display device periodically, in a state that an ROM storing said program has been substituted for an ROM storing a system program. CONSTITUTION:An operation check program is written in advance in an ROM except an ROM for storing a system program, and it is substituted for the ROM for storing a system program. In the operation check program, steps 10-13 are repeated at 1-second period, display is executed for 0.5sec in the 1-second period, and the time of 0.5sec in the steps 11, 13 is obtained by using a register provided in the inside of a CPU as a counter, therefore, in case when a flickering display by a display device is as prescribed by executing the operation check program as soon as the electric power supply is turned on, it is possible to decide that the CPU, the ROM and the display device are in the normal operation state. In the event of other display, one of said apparatus proves to be faulty. |
