| 摘要 |
<p>PURPOSE:To read data and to judge normality or abnormality even if writing to a EEPROM is inhibited during a power source turned on by forcibly impressing a signal at a prescribed level to an output enable terminal excepting the time of data writing, and inhibiting writing. CONSTITUTION:When a write inhibition terminal (b) is selected through a write inhibition selection switch 8 to attain write inhibition, the write inhibition terminal (b) is fixed to an earth potential, and a signal from the terminal (b) is inputted to the output enable terminal OE of the EEPROM (electrically erasable programmable read only memory) 2. Since the circuit is fixed to the earth potential when writing is inhibited with the power source turned on, the EEPROM 2 can read data, and it is fixed in the write inhibition state. Even if a contact point floats at the time of changing over the write inhibition selection switch 8, that state can be maintained because the output of an inverter 11 goes to the earth potential.</p> |
