| 摘要 |
PURPOSE:To set the action of a microprocessor into a PROM writing state by releasing the prescribed terminal of the microprocessor, making the terminal into an intermediate potential and detecting it by a detecting circuit. CONSTITUTION:When the resistors have the same value, the potential of a line 14-1 becomes Vcc/2. On the other hand, the potential of a RESET terminal becomes Vcc/2, the output of a comparator 14-3 becomes active. By the output of the comparator 14-3, fanout of a circuit formed by a NAND 12 and a delay 13 is inverted and buffers 6-1 and 6-2 become active. That is to say, when the RESET terminal is Vcc/2, this microprocessor is set to execute a writing action into a PROM. When the RESET terminal is in a released state, the potential of the RESET is set in the intermediate potential by resistors 25-1 and 25-2 and therefore, the writing action state into the PROM is set. |
