MITSUBISHI MICROCOMPUTERS
M37274EFSP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
ROM CORRECTION FUNCTION
This can correct program data in ROM. Up to 2 addresses (2 blocks)
can be corrected, a program for correction is stored in the ROM cor-
rection memory in RAM. The ROM memory for correction is 32 bytes
✕ 2 blocks.
ROM correction address 1 (high-order) 024216
ROM correction address 1 (low-order) 024316
ROM correction address 2 (high-order) 024416
Block 1 : addresses 02C016 to 02DF16
Block 2 : addresses 02E016 to 02FF16
Set the address of the ROM data to be corrected into the ROM cor-
rection address register. When the value of the counter matches the
ROM data address in the ROM correction address, the main pro-
gram branches to the correction program stored in the ROM memory
for correction. To return from the correction program to the main pro-
gram, 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.
ROM correction address 2 (low-order)
024516
Fig. 103. ROM Correction Address Registers
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 main program to the correction program.
3 : Do not set the same ROM correction address to blocks
1 and 2.
ROM Correction Enable Register
b7 b6 b5 b4 b3 b2 b1 b0
ROM correction enable register (RCR) [Address 024616]
0
0
B
Name
Functions
After reset R W
0
Block 1 enable bit (RC0)
0: Disabled
1: Enabled
0
R W
1
Block 2 enable bit (RC1)
Fix these bits to “0.”
0: Disabled
1: Enabled
0
R W
2, 3
0
R W
Nothing is assigned. These bits are write disable bits. When
these bits are read out, the values are “0.”
4
to
7
0
R —
Fig. 104. ROM Correction Enable Register
101
RENESAS [ RENESAS TECHNOLOGY CORP ]
