Table 9-1 Input/Output Port Summary
Expanded Modes Single-Chip Mode
Port Description Pins Mode 1 Mode 2 Mode 3 Mode 4 (Mode 7)
Port 1 8-Bit input/output P1
7 / TMO These input/output pins double as and
P1
6 / IRQ1 inputs and as IRQ0 and IRQ1 input and
P1
5 / IRQ0 output pin (TMO) for the 8-bit timer.
P1
4 / WAIT These pins function as WAIT, BREQ, Input/output
P1
3 / BREQ and BACK when necessary control- port
P1
2 / BACK register bits are set to “1.”
P1
1 / E These pins function as input pins or as
P1
0 / ø clock (E, ø) output pins, depending on
the data direction register setting.
Port 2 5-Bit input/output P2
4 / WR Bus control signal outputs Input/output
port P2
3 / RD (WR, RD, DS, R/W, AS) port
P2
2 / DS
P2
1 / R/W
P2
0 / AS
Port 3 8-Bit input/output P3
7 - P30 / Data bus (D7 – D0) Input/output
port D
7 – D0 port
Port 4 8-Bit input/output P4
7 – P40 / Low address bits (A7 – A0) Input/output
port A
7 – A0 port
Can drive a LED
Port 5 8-Bit input/output P5
7 – P50 / High High High High Input/output
port A
15 – A8 address address address address port
Built-in input bus bus if bus bus if
pull-up (MOS) (A
15 – DDR is (A15 – DDR is
A
8) set to “1” A8) set to “1”
Port 6 4-Bit input/output P6
3 –P60 / Input/output port Page Page Input/output
port A
19 – A16 address address port
Built-in input bus bus if DDR
pull-up (MOS) (A
19 – is set to “1,”
A
16) input port if
DDR is set
to “0”
140
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