NEC 78014Y Series, User Manual

Page: 150 / 547

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CHAPTER 6 PORT FUNCTIONS
150
(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.
Figure 6-18. Memory Expansion Mode Register Format
Symbol 7 6 5 4 3 2 1 0 Address When Reset R/W
MM 0 0 PW1 PW0 0 MM2 MM1 MM0 FFF8H 10H R/W
MM2 MM1 MM0 Single-chip/Memory P40 to P47, P50 to P57, P64 to P67 Pins Condition
Expansion Mode Selection P40 to P47 P50 to P53 P54, P55 P56, P57 P64 to P67
0 0 0 Single-chip mode Port Input Port mode
0 0 1 mode Output
0 1 1 Memory 256 bytes AD0 to Port mode P64 = RD
expansion mode AD7 P65 = WR
1 0 0 mode 4 Kbytes A8 to A11 Port mode P66 = WAIT
mode P67 = ASTB
1 0 1 16 Kbytes A12, A13 Port mode
mode
1 1 1 Full-address A14, A15
mode
Note
Other than above Setting prohibited
PW1 PW0 Wait Control
0 0 No wait
0 1 With wait (1-wait state insertion)
1 0 Setting prohibited
1 1 Wait control with an external wait pin
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.