CHAPTER 2 PIN FUNCTIONS
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User’s Manual U14359EJ4V0UM
(13) PAH0 to PAH9 (Port AH) ··· 3-state I/O
PAH0 to PAH9 function as an 8- or 10-bit I/O port that can be set to input or output in 1-bit units.
Besides functioning as a port, in control mode (external expansion mode), these pins operate as an address
bus (A16 to A25) for when the memory is expanded externally.
The operation mode can be set to port or control mode in 1-bit units, specified by the port AH mode control
register (PMCAH).
(a) Port mode
PAH0 to PAH9 can be set to input or output in 1-bit units using the port AH mode register (PMAH).
(b) Control mode
PAH0 to PAH9 can be set to function alternately as A16 to A25 using the PMCAH register.
(i)
A16 to A25 (Address) ··· 3-state output
These are the address output pins of the higher 10 bits of the address bus’s 26-bit address when
the external memory is accessed.
The output changes in synchronization with the fall of the CLKOUT signal in the T1 state. In the idle
state (TI), the address of the bus cycle immediately before is retained.
(14) PAL0 to PAL15 (Port AL) ··· 3-state I/O
PAL0 to PAL15 function as an 8- or 16-bit I/O port that can be set to input or output in 1-bit units.
Besides functioning as a port, in control mode (external expansion mode), these pins operate as an address
bus (A0 to A15) for when the memory is expanded externally.
The operation mode can be set to port or control mode in 1-bit units, specified by the port AL mode control
register (PMCAL).
(a) Port mode
PAL0 to PAL15 can be set to input or output in 1-bit units using the port AL mode register (PMAL).
(b) Control mode
PAL0 to PAL15 can be set to function alternately as A0 to A15 using the PMCAL register.
(i)
A0 to A15 (Address) ··· 3-state output
These are the address output pins of the lower 16 bits of the address bus’s 26-bit address when the
external memory is accessed.
The output changes in synchronization with the fall of the CLKOUT signal in the T1 state. In the idle
state (TI), the address of the bus cycle immediately before is retained.