UPD784938 Datasheet, PDF (604/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 24 LOCAL BUS INTERFACE FUNCTION
Figure 24-1. Memory Expansion Mode Register (MM) Format
7
6
5
4
3
2
1
0 Address After reset R/W
MM IFCH 0
AW
0 MM3 MM2 MM1 MM0 0FFC4H
20H
R/W
MM3 MM2 MM1 MM0
Mode
Port 4
Port 5
P60 to P63 P64/ P65/ ^ASTB
RD WR ^/CLK
OUT
0
0
0
0 Single-chip
Port
Port
mode
Port
Port Port ASTB
0
0
1
1 256-byte
AD0 to AD7 Port
expansion mode
Port
RD WR
0
1
0
0 1-Kbyte
AD0 to AD7 A8, A9 Port Port
expansion mode
RD WR
0
1
0
1 4-Kbyte
AD0 to AD7 A8 to A11 Port Port
expansion mode
RD WR
0
1
1
0 16-Kbyte
AD0 to AD7 A8 to A13 Port _Port
expansion mode
RD WR
0
1
1
1 64-Kbyte
AD0 to AD7 A8 to A15 Port
expansion mode
RD WR
1
0
0
0 256-Kbyte
AD0 to AD7 A8 to A15 A16, Port RD WR
expansion mode
A17
1
0
0
1 1-Mbyte
AD0 to AD7 A8 to A15 A16 to A19 RD WR
expansion mode
Other than the above
Setting prohibited
AW
Address Wait Specification
0 Disabled
1 Enabled
IFCH
Internal ROM Fetches
0 Fetch performed at same speed as
external memory
All wait control settings valid
1 High-speed fetches performed
Wait control specification invalid
604
Preliminary User’s Manual U13987EJ1V0UM00