| 摘要 |
<p>PURPOSE:To prevent the third person from copying easily from data recorded in a memory cell constituting a ROM by providing a key word incorporating part where code information of a key word peculiar to a system is stored. CONSTITUTION:Code information of the key word peculiar to the system is stored in a key word incorporating part 3. The detection result of coincidence between the key word from the incorporating part 3 and code information of a latch circuit 2 in an exclusive OR circuit G1 is given to an exclusive OR circuit G2 provided in the output end of a memory cell part 1. Though the circuit G2 outputs data D0-Dn in accordance with this detection result of coincidence, correct output data are led out only for bits whose coincidence is detected. That is, if code information put onto an address line at a chip selection time hase bits which do not coincide with corresponding bits of the preliminarily set key word, this code information is not correct. As the result, the third person is prevented from copying from data recorded in a memory cell 1.</p> |
