| 摘要 |
<p>PURPOSE:To obtain a one-chip microcomputer with improved reliability by writing a program word and a parity bit to a PROM, reading them at each prescribed operating condition so as to apply parity check. CONSTITUTION:An electrical PROM (EPROM) is used and a write control circuit WCON is provided, a voltage level applied from an external Vpp, a write/read operation mode is controlled and a write high voltage is fed to the EPROM. On the other hand, when an EPROM write high voltage is fed from an external terminal Vpp, a data input buffer of the EPROM is made to the operating state. According to the information applied from a data bus, a write signal of logical 0 by using a high voltage is processed, logical 0 is written to a selected memory cell. In this case, the EPROM addressing is applied by using address signal applied from the external terminal.</p> |
