| 摘要 |
PURPOSE:To easily confirm the normality of a program ROM code by comparing a value adding the parity bits of all the ROM codes with the total sum of ROM code parity bits registered on a register at the time of manufacture. CONSTITUTION:This device incorporates a program for checking the contents of a program ROM at a single chip microcomputer. The total sum number of all the parities of the program ROM is stored in a register a11 beforehand at the time of microcomputer manufacture. When an initial reset signal is turned to a low level for checking a program ROM 6, a program counter 1 is successively counted up by an internal clock PHI1. When the address value of the counter 1 is supplied to the program ROM 6 and the relevant ROM code is outputted, a parity bit is generated by a parity generator 18. This parity bit is added by an adder 9 and compared with the contents of the register a11. |
