Port 1 (Pi0 - P17) - Toshiba TLCS-90 Series Data Book

TOSHIBA
TMP90C840
In addition to the general-purpose I/O port function, it functions as
a data bus (DO - 07). Access of an external memory makes it
automatically function as a data bus.
H
:::l
rT
ro
11
Reset
Write POCR
:::l
Port 0
~
(POO - P07)
o
PJ
~
Write PO
g'
Ul
Read
PO
Fig. 3.5 (1) Port
a
3.5.2 Port I (PIO - PI7)
Port 1 is an 8-bit general-purpose I/O port (PL: memory address FFCIH)
whose I/O function is specified by the control register (PIC: bit 1 of
memory address FFC2H) for each byte. All bits of the output latch and
the control register are initialized to "0" by resetting, whereby Port
I is put in the input mode.
In addition to the general-purpose I/O port function, it functions as
an address bus (AO - A7). The address bus function can be selected by
setting the external extension control register (EXT: bit 2 of memory
address FFC2H) to "1" regardless of the status of the above control
register (p IC) . The EXT register is reset to "0" whereby Port land
Port 2 turn to the general-purpose I/O mode.
The EXT register of the TMP90C841 is always set to "1" so that Port 1
functions as an address bus (AO - A7).
MPU90-56