| 摘要 |
<p>PURPOSE:To facilitate confirmation and verification of program contents and to prevent the contents from being copied by controlling a gate connected to an external output terminal by writing on the 2nd EPROM. CONSTITUTION:When writing on the 2nd EPROMM 2 is not performed, an output of a sense amplifier 10 goes to L, an output of a AND ate AN2 goes to H via an inverter IV2, the write content of an original EPROM cell M1 is outputted to an external terminal O2 via a NAND gate NA1 in the same way as an internal terminal O1 to facilitate the confirmation and verification of the content of the cell M1. In writing the cell 2 next, the output of the gate AN2 goes to L, the output of the terminal O2 goes always to H independently of the write content of the cell M1 via the gate NA1 and the contents of the cell M1 are prevented surely from being copied.</p> |
