External Device Expansion Control Register - NEC 78014Y Series User Manual

19.2 External Device Expansion Control Register

The external device expansion function is controlled by the memory expansion mode register (MM). MM sets the
wait count and external expansion area. MM also sets the input/output of port 4.
MM is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets this register to 10H.
Symbol 7
MM 0
MM2
0
0
0
1
1
1
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Other than above
PW1
0
0
1
1
Note The full-address mode allows external expansion to the entire 64 Kbytes address space except for the internal
ROM, RAM and SFR areas and the reserved areas.
Remark P60 to P63 pins enter the port mode regardless of the single-chip mode or memory expansion mode.
476
CHAPTER 19 EXTERNAL DEVICE EXPANSION FUNCTION
Figure 19-2. Memory Expansion Mode Register Format
6 5 4 3
0 PW1 PW0 0
MM1 MM0 Single-chip/Memory
Expansion Mode Selection P40 to P47
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 Without 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
P50 to P53
Port Input Port mode
mode Output
AD0 to AD7 Port mode
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