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(3) Memory expansion mode register (MM)
The registers are used to set port 4 input/output.
MM is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets MM to 10H.
Symbol
7
MM
0
MM2
0
0
0
1
1
1
Other than above
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PW1
0
0
1
1
Note
Full-address mode is the mode that can execute external expansion to all the areas other than internal ROM,
RAM, SFR areas and the reserved areas in 64 K address space.
Remarks 1. P60 to P63 pins enter the port mode regardless of the single-chip mode or memory expansion mode.
2. Besides it is used to set port 4 input/output, MM has functions to set the number of waits and external
expansion area.
150
CHAPTER 6 PORT FUNCTIONS
Figure 6-18. Memory Expansion Mode Register Format
6
5
4
3
0
PW1
PW0
0
MM1
MM0
Single-chip/Memory
Expansion Mode Selection P40 to P47 P50 to P53
0
0
Single-chip mode
0
1
1
1
Memory
256 bytes
expansion
mode
0
0
mode
4 Kbytes
mode
0
1
16 Kbytes
mode
1
1
Full-address
mode
Setting prohibited
PW0
Wait Control
0
No wait
1
With wait (1-wait state insertion)
0
Setting prohibited
1
Wait control with an external wait pin
2
1
0
Address
MM2
MM1
MM0
FFF8H
P40 to P47, P50 to P57, P64 to P67 Pins Condition
Port Input
Port mode
mode Output
AD0 to
Port mode
AD7
A8 to A11
Note
When Reset
R/W
10H
R/W
P54, P55
P56, P57
P64 to P67
P64 = RD
P65 = WR
Port mode
P66 = WAIT
P67 = ASTB
A12, A13
Port mode
A14, A15
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