Program controller of mask rom

Abstract

Abstract PURPOSE:To avoid program errors easily by detecting an address of an error program on a mask ROM and executing a correction program on a PROM. CONSTITUTION:When a program is executed through a CPU1 and a mask ROM2 and an address of an error program of the ROM2 can be detected, an address holding part 21 of a correcting program holding memory 10 is collated. The contents of a correcting program in its address data holding part 22 are outputted from a memory 10. An FF responds to the contents of a set index bit part 23 and a reset index bit part 24, and gates 12 and 13 are closed and opened. An output from the ROM2 is interrupted and a correcting program from the memory 10 is supplied to the CPU1. In the same manner, correcting programs are sequentially outputted and by a jump instruction of the final correcting program, an operation is returned to a normal program. With this constitution, program errors can be easily avoided without the entire rewriting of a mask ROM.

Inventors

• 👤 Koji Mita
• 👤 浩司 三田

Bibliographic Details