| 摘要 |
<p>PURPOSE:To enable the confirmation of safety for PROM usage, by the storage so that the career of write-in and erase of PROM can be read out with additional memories. CONSTITUTION:PROMs 5, 8, 13... of additional memory section are conductive when the power supply voltage Vcc is at high level and the output is at low level. Then, when Vcc delay is at high level, the output of the latch circuits 6, 10... is at high level, the switches 7, 11... are conductive and the gates of ROMs 5, 8... are grounded. Next, when the write-in voltage VDD is at high level, the data 1 is written in PROM 5 and it remains to be written in even if the voltage Vcc is at a low level. Similarly, data 1 is sequentially written in ROMs 8, 13..., and the career of the number of repetition of erase and write-in is held without holding power supply. The career can be read out via the lines 9, 12... when the Vcc delay is high level, allowing to confirm the safety based on the career of PROM.</p> |
