| 摘要 |
PURPOSE:To easily add a parity bit, and to detect a fault of an ROM even during the execution of a processing program, by using a writable and readable volatile storage element in combination. CONSTITUTION:Through an advancing register (li) of a processor 1, an ROM2 and a writable and readable volatile storage element 3 used in combination with it are accessed, and the readout bit data of the ROM2 and its addition value are stored in registers (lg) and (lh). Then, a parity bit is written in the element 3 through the register (lg), a parity generator 6, etc. Since it is not written in the ROM, parity bit addition is faciliated and secured. Further, a parity checker 4 detects a fault of the ROM on the basis of the parity bit in the element 3 even during the execution of a processing program. |
