NEC V854 UPD703006 User Manual page 360

(2) Setting input/output mode and control mode
The input/output mode of port 5 is set by port mode register 5 (PM5). The control mode (external expansion
mode) is set by mode specification pins MODEn and memory expansion mode register (MM: refer to 3.4.6
(1)) (n = 0 to 2).
Port 5 mode register (PM5)
This register can be read/written in 8- or 1-bit units.
7 6
PM5 PM57 PM56
Bit Position Bit Name
7 to 0 PM5n
(n = 7 to 0)
Operation mode of port 5
Bit of MM Register
MM2 MM1 MM0 P50
0 0 0
0 1 1
1 0 0
1 0 1
1 1 1
Others
360
CHAPTER 12 PORT FUNCTION
5 4 3
PM55 PM54 PM53 PM52
Port Mode
Sets P5n pin in input/output mode.
0: Output mode (output buffer ON)
1: Input mode (output buffer OFF)
Operation Mode
P51 P52 P53 P54
Port
Address/data bus
(AD8 to AD15)
RFU (reserved)
User's Manual U11969EJ3V0UM00
2 1 0
PM51 PM50
FFFFF02AH
Function
P55 P56 P57
Address After reset
FFH