UPD784224 Datasheet, PDF (55/92 Pages) NEC – 16/8-BIT SINGLE-CHIP MICROCONTROLLERS

µPD784224, 784225, 784224Y, 784225Y
12. ROM CORRECTION
ROM correction is a function to replace part of the program in the internal ROM with a program in the internal
RAM.
By using the ROM correction function, instruction bugs found in the internal ROM can be avoided or the flow of
the program can be changed.
ROM correction can be used at up to four places in the internal ROM (program).
Figure 12-1. Block Diagram of ROM Correction
Program counter (PC)
Comparator
Coincidence
Correction branch processing
request signal
(CALLT instruction)
Correction address pointer n
Correction address registers
(CORAH, CORAL)
CORENn CORCHm
Internal bus
ROM correction control register (CORC)
Remark n = 0 to 3, m = 0 or 1
Data Sheet U12376EJ1V0DS00
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