CHAPTER 14 PORT FUNCTIONS
User’s Manual U14359EJ4V0UM
486
14.3.9 Port AH
Port AH (PAH) is a 16-bit I/O port that can be set in the input or output mode in 1-bit units.
When the higher 8 bits of port AH are used as port AHH (PAHH) and the lower 8 bits as port AHL (PAHL), port AH
becomes two 8-bit ports that can be set in the input or output mode in 1-bit units.
Bits 15 to 10 of port AH (bits 7 to 2 of port AHH) are undefined.
15
14
13
12
11
10
9
8
Address
After reset
PAH
–
–
–
–
–
–
PAH9
PAH8
FFFFF003H
Undefined
7
6
5
4
3
2
1
0
Address
PAH7
PAH6
PAH5
PAH4
PAH3
PAH2
PAH1
PAH0
FFFFF002H
Bit position
Bit name
Function
9 to 0
PAHn
(n = 9 to 0)
Port AH
I/O port
In addition to their functions as port pins, in the control mode, the port AH pins operate as an address bus for when
the memory is externally expanded.
(1) Operation in control mode
Port
Alternate Function Pin Name
Remark
Block Type
Port AH
PAL9 to
PAL0
A25 to A16
Address bus when memory
expanded
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