Panasonic F77G User Manual page 83

The ROM correction setup procedure is as follows.
(1) Set the head address of the program to be corrected to the ROM correction address setting
register (RCnAPH/M/L).
(2) Set the correct program at RAM area.
(3) Set the head address of the correct program to RC vector table (RCnV(L), RCnV(H)).
(4) Set the RCnEN flag of ROM correction control register (RCCTR) to enable the ROM correction.
When the instruction of the corrected program head address is the half-byte instruction, the
ROM correction checks the execution instruction of the half-byte. Therefore, set the address
by a byte to the ROM correction address setting register.
When the instruction of the corrected program last address is the half-byte instruction, the
recover address should be set by half byte.
Chapter 2 CPU Basics
II - 31
ROM Correction