| 摘要 |
PURPOSE:To prevent the inadvertent destruction or leakage of the data be designating the readable and writable modes or unreadable and unwritable modes with operation of the switch key and then locking the key. CONSTITUTION:Gates 7 and 8 are provided to the read data signal read out of the disk plate and the write enable signal given from abroad, and these gates are controlled by contact signals 9 and 10 of switch 6 with key. As signals 9 and 10 feature the H level together when the contact of switch 6 is at A, gates 7 and 8 open to make possible both writing and reading. With contact at B, signal 10 and 9 feature L and H respectively, and thus the write enable signal's gate 8 closes to give reading and inhibit writing respectively. And with contact at C, signals 9 and 10 feature L, and thus both gates 7 and 8 close to inhibit both writing and reading. Accordingly, the contact is set at B excepting the time of the normal working, and as a result the recorded data is never disturbed to enable reading. Furthermore, if the contact is kept at C, no more data is read out to keep the secrecy. |
