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CHAPTER 3 CPU
3.9.3
Memory Access Mode
There are two modes in the memory access mode: bus mode and external access
mode.
• Bus mode: Sets access area (internal)
I Bus Modes
Figure 3.9-4 shows the memory map in the mode.
000000
0000C0
000100
Address #1
003900
004000
010000
FE0000
FF0000
FFFE00
FFFFFF
* In MB90F897/S, if read the FE0000
can be read the data of FF0000
Reference:
For details on access areas, see 3.1 "Memory Space".
G
Single-chip mode (internal-ROM internal-access)
• Only internal ROM and internal RAM are used and no external access occurs.
• Ports 1 to 3 can be used as general-purpose I/O ports.
156
Figure 3.9-4 Memory map in the mode
When ROM mirror is enabled
H
Peripheral
H
H
RAM area
Register
H
Extended I/O area
H
ROM area
(imge of
FF Bank)
H
H
*
ROM area
H
ROM area
H
H
Internal access memory
Access prohibited
Hardwired reset vectors
FEFFFF
area,
H
H
FFFFFF
.
H
H
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