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14.3.8 Port AL
Port AL (PAL) is a 16-bit I/O port that can be set to the input or output mode in 1-bit units.
When the higher 8 bits of port AL are used as port ALH (PALH) and the lower 8 bits as port ALL (PALL), port AL
becomes two 8-bit ports that can be set in the input or output mode in 1-bit units.
15
14
PAL
PAL15
PAL14
7
6
PAL7
PAL6
Bit position
Bit name
15 to 0
PALn
(n = 15 to 0)
In addition to their functions as port pins, in the control mode, the port AL pins operate as an address bus for when
the memory is externally expanded.
(1) Operation in control mode
Port
Port AL
PAL15 to
A15 to A0
PAL0
(2) I/O mode/control mode setting
The port AL I/O mode setting is performed by the port AL mode register (PMAL), and control mode setting is
performed by the port AL mode control register (PMCAL).
(a) Port AL mode register (PMAL)
The port AL mode register (PMAL) can be read/written in 16-bit units.
If the higher 8 bits of PMAL are used as port AL mode register H (PMALH), and the lower 8 bits as port
AL mode register L (PMALL), these two 8-bit port mode registers can be read/written in 8-bit or 1-bit
units.
15
14
PMAL
PMAL15 PMAL14 PMAL13 PMAL12 PMAL11 PMAL10
7
6
PMAL7
PMAL6
Bit position
Bit name
15 to 0
PMALn
(n = 15 to 0)
484
CHAPTER 14 PORT FUNCTIONS
13
12
11
PAL13
PAL12
PAL11
5
4
3
PAL5
PAL4
PAL3
Port AL
I/O port
Alternate Function
13
12
11
5
4
3
PMAL5
PMAL4
PMAL3
Port Mode
Specifies input/output mode for PALn pin.
0: Output mode (output buffer on)
1: Input mode (output buffer off)
User's Manual U14359EJ4V0UM
10
9
8
PAL10
PAL9
PAL8
2
1
0
PAL2
PAL1
PAL0
Function
Remark
Address bus when memory
expanded
10
9
8
PMAL9
PMAL8
2
1
0
PMAL2
PMAL1
PMAL0
Function
Address
After reset
FFFFF001H Undefined
Address
FFFFF000H
Block Type
J
Address
After reset
FFFFF021H
FFFFH
Address
FFFFF020H
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