Rom Correction Function; Fig. 2.12.1 Rom Correction Address Registers; Fig. 2.12.2 Rom Correction Enable Register - Renesas 7200 Series User Manual

2.12 ROM correction function

Only the M37221M8-XXXSP and the M37221MA-XXXSP have this function.
This can correct ROM program data in ROM. Up to 2 addresses (2 blocks) can be corrected, a program for
correction is stored in the ROM correction memory in RAM. The ROM memory for correction is 32 bytes
2 blocks.
Block 1 : addresses 02C0
Block 2 : addresses 02E0
Set an address of the ROM data to be corrected into the ROM correction address register. When the value
of the counter matches the ROM data address in the ROM correction address, the main program branches
to the correction program stored in the ROM correction memory. To return from the correction program to
the main program, the op code and operand of the JMP instruction (total of 3 bytes) are necessary at the
end of the correction program. When the blocks 1 and 2 are used in series, the above instruction is not
needed at the end of the block 1.
The ROM correction function is controlled by the ROM correction enable register.
Notes 1 : Specify the first address (op code address) of each instruction as the ROM correction address.
2 : Use the JMP instruction (total of 3 bytes) to return from
the correction program to the main program.
3 : Do not set the same address to ROM correction addresses 1 and 2 (addresses to 0217
021A ).
16
ROM correction address 1 (high-order)
ROM correction address 1 (low-order)
ROM correction address 2 (high-order)
ROM correction address 2 (low-order)

Fig. 2.12.1 ROM correction address registers

ROM Correction Enable Register
b7 b6 b5 b4 b3 b2 b1 b0

Fig. 2.12.2 ROM correction enable register

to 02DF
16 16
to 02FF
16 16
0217
16
0218
16
0219
16
021A
16
ROM correction enable register (RCR) [Address 0212
0 0
B Name
0 Block 1 enable bit (RCR0)
1 Block 2 enable bit (RCR1)
2, 3 Fix these bits to "0."
4 Nothing is assigned. These bits are write disable bits. When
these bits are read out, the values are "0."
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7220 Group User's Manual
FUNCTIONAL DESCRIPTION
2.12 ROM correction function
Functions
0: Disabled
1: Enabled
0: Disabled
1: Enabled
16
]
16
After reset R W
0
R W
0
R W
0
R —
0
R —
2-89
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