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CHAPTER 26 ROM CORRECTION
User’s Manual U12697EJ3V0UM
26.4 Usage of ROM Correction
<1> The correct address and post-correction instruction (correction program) are stored in the microcontroller
external inactive memory (EEPROM™).
<2> A substitute instruction is read from the inactive memory with the use of a serial interface when the initialization
program is running after being reset, and this is stored in the peripheral RAM and external memory. The
correction channel is then selected, the address for the command that requires correction is read and set in
ROM correction address registers H, L (CORAH, CORAL), and the correction enable flag (COREN0 to 3) is
set at 1. A maximum of four locations can be set.
<3> Execute the CALLT instruction during execution of the corrected address.
CALLT execution
Program execution (internal ROM)
Correct address executed?
No
Yes
<4> CALLT routine branch
When matched with address pointer 0: CALLT table (0078H)
When matched with address pointer 1: CALLT table (007AH)
When matched with address pointer 2: CALLT table (007CH)
When matched with address pointer 3: CALLT table (007EH)
<5> Execute substitute instruction
<6> Add +3 to the stack pointer (SP)
<7> Restore to any addresses with the branch instruction (BR)
