Usage Example Of Rom Correction Function (M37221M8/Ma-Xxxsp); Connection Example; Correction Example; Fig. 5.3.1 Connection Example - Renesas 7200 Series User Manual

5.3 Usage example of ROM correction function (M37221M8/MA-XXXSP)

5.3 Usage example of ROM correction function (M37221M8/MA-XXXSP)
Application example using the ROM correction function is described below. In this example, it is assumed
that the program must be changed by specifications modification after completion of ROM mask. Also,
E 2 PROM is connected to this system.

5.3.1 Connection example

Fig. 5.3.1 Connection example

5.3.2 Correction example

The following is an example when 2 addresses (2 blocks) of ROM are corrected.
(1) Correction example 1
Program before correction
Address Machine
instructions
E120 A900
E122 3A
E123 8D1101
E126 60
Note: In , E126H is specified as the return destination address of JMP.
In this example, since the instruction at the return destination address is
even if RTS is used instead of JMP, the operation is the same as that of JMP.
As a result, the number of bytes is reduced.

Fig. 5.3.2 Correction example (1)

2
I C-BUS
<E 2 PROM>
Description style
LDA #00H
INC A
STA
0111H
RTS
7220 Group User's Manual
<Microcomputer>
Correction program
Address Machine
(block 1) instructions
02C0 A980
02C2 1A
02C3 8D1201
02C6 1A
02C7 8D1301
02CA 4C26E1
RTS,
APPLICATION
Description style
#80H
LDA
DEC A
0112H
STA
A
DEC
0113H
DEC
JMP E126H (See note)
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