| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce time required for writing protection setting by dividing a writing region into specific blocks, and by simultaneously setting writing protection information to a plurality of arbitrarily specified blocks of a device for preventing storage information from being rewritten in blocks. SOLUTION: A writing protection circuit 1 for constituting a semiconductor storage is constituted of a writing protection control circuit 22, an input buffer circuit 23, a decode circuit 24, and a writing protection circuit 21. Writing protection setting is executed in blocks based on external control signals OE and WE and address signals A6 and Ai. The writing protection control circuit 22 has a function that executes control for setting writing protection information. When the writing protection control circuit 22 detects the change in the control signal OE from 0 V to 12 V, crest differentiation is made in a delay circuit, an inverter, and an NOR gate, hence the reset signal of 1 pulse is generated, and a latch circuit is reset.</p> |
