| 摘要 |
<p>PURPOSE:To prevent various signals from an external part from turning into data by fitting a read-only external terminal, setting it to execute reading in a certain state and setting it to execute regular functioning in other state. CONSTITUTION:An H level or an L level is statically fixed to the external terminal 11, and it is connected to an internal circuit. At the time of the H level, a mode is set to a regular one, namely, writing into and reading from a memory can be executed and a signal with which the system comes to a write mode is received. At the time of the L level, only reading is executed and the write mode is turned off. Thus, the memory can sufficiently protect an unstable signal and an unexpected signal, both of which come from the external part.</p> |
