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14.3.6 Port DH
Port DH is an 8-bit I/O port in which input or output can be specified in 1-bit units.
7
6
PDH
PDH7
PDH6
Bit Position
Bit Name
7 to 0
PDHn
(n = 7 to 0)
Besides functioning as a port, in control mode, this can operate as an address bus when memory is expanded
externally.
(1) Operation in control mode
Port
Port DH
PDH7 to
PDH0
(2) Setting in I/O mode and control mode
Port DH is set in I/O mode using the port DH mode register (PMDH). In control mode, it is set using the port
DH mode control register (PMCDH).
(a) Port DH mode register (PMDH)
This register can be read/written in 8-bit or 1-bit units.
7
6
PMDH
PMDH7
PMDH6
Bit Position
Bit Name
7 to 0
PMDHn
(n = 7 to 0)
CHAPTER 14 PORT FUNCTIONS
5
4
3
PDH5
PDH4
PDH3
I/O port
Alternate Pin Name
A23 to A16
Memory expansion address bus
5
4
3
PMDH5
PMDH4
PMDH3
Specifies input/output mode of PDHn pin.
0: Output mode (output buffer on)
1: Input mode (output buffer off)
User's Manual U14492EJ3V0UD
2
1
0
PDH2
PDH1
PDH0
Function
Remarks
2
1
0
PMDH2
PMDH1
PMDH0
Function
Address
Initial value
FFFFF006H
Undefined
Block Type
P
Address
Initial value
FFFFF026H
FFH
703
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