Specifications
Interlace
Connectors
3.2.1
Typical
Three-Wire
lntertace
The
simplest
1/0
port
intertace
requires
only
three
ot
the
serial
1/0
connector
be
wired.
These
three
wires
are:
Pin
2-TxD,
Pin
3-
RxD
ana
Pin
7-Signal
Ground.
This
three-wire
contiguration
will
satisty
many
serial
devices
and
most
terminals.
3.2.2
Four-Wire
1ntertace
Some
serial
devices
require
a
"handshake"
signal
tor
normal
protocol.
In
these
cases
the
tour-wire
intertace
contiguration
will
normally
work.
This
contiguration
is
the
safiLe
as
the
three-wire
contiguration
(pins
2,3
and
7
connected
with
the
additional
tourth
wire
being
pin
20
-
DTR).
3.2.3
Serial
Printer
lntertace
Most
serial
printers
require
a
"Busy"
signal
to
maintain
data
tlow.
With
such
printers,
the
tour-wire
contiguration
will
normally
work
where
pin
20 - DTR,
is
used
as
the
"Busy"
signal.
3.3
Parallel
I/O
Port
Connectors
The
two
parallel
I/O
port
connectors
(J6
and
J7)
have
the
pin
assignments
and
are
Centronic
printer
compatible.
The
assignments
tor
these
two
connectors
are
shown
in
Table
3-2.
same
pin
One
ot
the
parallel
I/O
port
25-pin
connectors
is
driven
by
the
SUPER
QUAD
PlO
channel
A,
the
other
is
driven
by
the
PlO
channel
B.
Table
3-2
does
not
distinguish
between
A
or
B
since
both
are
the
same.
3-2