UPD78323 NEC, UPD78323 Datasheet - Page 47

• Manufacturer Part Number: UPD78323
• Description: 16/8-BIT SINGLE-CHIP MICROCONTROLLER
• Manufacturer: NEC

6. EXTERNAL DEVICE EXPANSION FUNCTION
FAFFH) except the internal ROM and RAM areas. Table 6-1 and 6-2 show the pin used for external device access and the
pin function setting procedure.
bytes to about 32K bytes. The pins which are not used as the address bus can be used as the general-purpose input/output
port.
EA Pin
EA Pin
ASTB
The PD78324 can expand external devices (data memory, program memory peripheral device) for areas (8000H to
P50 to P57 pins according to the externally expanded memory size. The memory can be expanded in steps from 256
1
1
MM0 to MM2
Memory Expansion
Memory Expansion
Port mode
Expansion
Mode Register
Mode Register
mode
MM7
––
0
1
P57
Port
Port
Port
A15
MM7
0
1
0
1
Port
Port
Port
P56
A14
Table 6-2. Port and Address Setting for Port 5 ( PD78324)
Fetch Cycle
Fetch Cycle
Except 00H
Except 00H
Register
Register
Control
Control
00H
00H
00H
P55
Port
Port
A13
A13
Table 6-1. Pin Function Setting ( PD78324)
Table 6-3. Pin Function Setting ( PD78323)
Port
Port
P54
A12
A12
AD0 to AD7
AD0 to AD7
AD0 to AD7
P40 to P47
P53
Port
A11
A11
A11
P52
A10
A10
A10
Port
Set to A8 to
A15 in steps
P50 to P57
A8 to A15
A8 to A15
P51
Port
A9
A9
A9
Setting prohibited
Pin Function
General port
Pin Function
P50
Port
A8
A8
A8
P90
RD
RD
RD
External Address Space
256 bytes or less
4K bytes or less
16K bytes or less
About 32K bytes or less
P91
WR
WR
WR
General port
General port
TAS
TAS
P92
P92
TAS
TMD
TMD
TMD
P93
P93
PD78323, 78324
connection mode
connection mode
External device
connection mode
emulation mode
External device
connection mode
PD71P301
PD78324
PD71P301
Remarks
Remarks
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