| 摘要 |
PURPOSE:To make it possible to drive a CPU, a ROM and a RAM by a simple constitution at the time of executing a test by using the counter value of a timer for the address of the RAM, writing data in the RAM, the address of the ROM, and an instruction to the CPU at the time of a test mode. CONSTITUTION:When a test signal TEST to be applied from the external to a test terminal 20 is set to '1' to set up the test mode, a transfer gate in a gate 15 is turned to a conductive state and the counter value '0000H' of the timer 14 is outputted to an internal bus 16. Since the counter output of the timer 14 is used as the address and data of the RAM 12, the address of the ROM 13 and the instruction code of a single chip microcomputer, data writing in the RAM 12, the operation of a transistor in the ROM 13 and the operation of the CPU 11 can be executed. Consequently, effective and simple dynamic BT screening can be attained. |
