UPD78320GJ-5BJ NEC, UPD78320GJ-5BJ Datasheet - Page 48

• Manufacturer Part Number: UPD78320GJ-5BJ
• Description: 16/8-BIT SINGLE-CHIP MICROCONTROLLER
• Manufacturer: NEC

48
6. EXTERNAL DEVICE EXPANSION FUNCTION
to FFFFH) except the internal ROM and RAM areas. Tables 6-1 through 6-3 shows the pin used for external device access
and the pin function setting procedure.
expanded memory size. The memory can be expanded in steps from 256 bytes to about 48K 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 PD78322 can expand external devices (data memory, program memory or peripheral device) for areas (4000H
For P50 to P57 pins, the number of bits which serve as address buses can be changed according to the externally
0
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
P56
Port
Port
Port
A14
Table 6-2. Port and Address Setting for Port 5 ( PD78322)
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 ( PD78322)
Table 6-3. Setting Pin Function ( PD78320)
P54
Port
Port
A12
A12
AD0 to AD7
AD0 to AD7
P40 to P47
AD to AD7
Port
P53
A11
A11
A11
P52
A10
A10
A10
Port
Set to A8 to
A15 in steps
P50 to P57
A8 to A15
A8 to A15
Port
P51
A9
A9
A9
Setting prohibited
Pin Function
General port
Pin Function
Port
P50
A8
A8
A8
P90
RD
RD
RD
External Address Space
256 bytes or less
4K bytes or less
16K bytes or less
About 48K bytes or less
P91
WR
WR
WR
purpose port
purpose port
TAS
TAS
TAS
P92
P92
General-
General-
TMD
TMD
TMD
P93
P93
PD78320, 78322
connection mode
connection mode
External device
connection mode
emulation mode
External device
connection mode
PD71P301
PD78322
PD71P301
Remarks
Remarks