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MB90495G Series
59
13. ROM Correction Function
In the case that the address of the instruction after the one that a program is currently processing matches the
address configured in the detection address configuration register, the program forces the next instruction to be
processed into an INT9 instruction, and branches to the interrupt process program. Since processing can be
conducted using INT9 interrupts, programs can be repaired using batch processing.
Overview of the ROM Correction Function
The address of the instruction after the one that a program is currently processing is always stored in an
address latch via the internal data bus. ROM correction constantly compares the address stored in the address
latch with the one configured in the detection address configuration register. If the two compared addresses
match, the CPU forcibly changes this instruction into an INT9 instruction, and executes an interrupt processing
program.
There are two detection address configuration registers : PADR0 and PADR1. Each register provides an
interrupt enable bit. This allows you to individually configure each register to enable/prohibit the generation of
interrupts when the address stored in the address latch matches the one configured in the detection address
configuration register.
ROM Correction Block Diagram
Address latch
Stores value of address output to internal data bus.
Address detection control register (PACSR)
Set this register to enable/prohibit interrupt output when an address match is detected.
Detection address configuration register (PADR0, PADR1)
Configure an address with which to compare the address latch value.
AD1E
AD0E
PADR1 (24 bit)
PADR0 (24 bit)
PACSR
Re-
served
Address detection control register (PACSR)
I
Address latch
Detection address configuration register 0
Detection address configuration register 1
Re-
served
Re-
served
Re-
served
Re-
served
Re-
served
C
INT9 instruction
(INT9 interrupt generation)
Reserved : Make sure this is always set to “01”