| 摘要 |
PURPOSE:To facilitate an easy change of the contents of an ROM and to improve the operability of a microcomputer by checking the fixed data within the ROM by means of a parity bit within an RAM. CONSTITUTION:When a reading command (a) is transmitted to an ROM5 from a CPU1, a gate 3 is opened and at the same time a reading command (c) is supplied to the ROM5 via a gate 11. The fixed data within the ROM5 is led into the CPU1 as well as to a parity check circuit 8. While the parity bit written to an RAM10 is read out by the command (a) and fed to the circuit 8. The circuit 8 checks the fixed data of the ROM5 for each data by the parity bit given from the RAM10. |
