ROM REWRITE SYSTEM, ROM-LOADED CIRCUIT DEVICE USED IN THE SYSTEM AND CONNECTING DEVICE CONNECTED TO THE ROM- LOADED CIRCUIT DEVICE

摘要

PROBLEM TO BE SOLVED: To rewrite the program data of a flash ROM 12 loaded to a printed circuit board having a power generating part 14 without adversely affecting a ROM writer 3.;SOLUTION: A bus master 11 is made to be in a sleep state and the flash ROM 12 is disconnected, meanwhile, the ROM writer 3 is connected through a buffer 23, the buffer 23 is made to have high impedance while the ROM writer 3 does not operate, an address bus line and a data bus line of the buffer 23 are made conductive when the ROM writer 23 operates, and the buffer 23 is controlled by a read/write control signal to control reading and writing data from/to the ROM 12.;COPYRIGHT: (C)2002,JPO