Rs-232C Connector Pinout - Tandy 26-3334 Service Manual

The pinout
for the
DIN connector
is
shown
in
Figure
5-14.
RS232C
OUT
Figure 5-14. RS-232C Connector
Pinout
The RS-232C interface
hardware
in
the
Color Computer
3
is
capable
of
communication with
any device
which
will operate with
the
minimum
three
signal interface.
It is
also possible
that
devices which use
a
larger set
of RS-232C signals may be used with
the
Color Computer
3.
This would
be
accomplished
by connecting unused
device inputs
to the correct high or
low level.
In software, the only RS-232C device
supported
by the BASIC ROM
is a
serial printer. For use with the
printer, the pin assignment
of the
connector differs
slightly from
the
above description:
1.
No
Connection
2.
Connected
to the BUSY output
(or
status line) of
the
printer
3
Ground
4.
Connected
to the Serial Data Input
of the printer
If your printer does not provide
a
status line, then pin
2
must
be
connected
to
a
positive voltage
of +3
to
+12 volts. Thi3 tells
the computer
that the
printer
is
ready
all of the
time.
In
order
to
operate, the software
must make several assumptions about
the printer. These assumptions
are:
1.
The printer operates at 600 baud.
2.
The printer width
is 132
coLumns.
3.
The printer generates
a
BUSY when
it
is
not ready.
4.
The printer will automatically
return
the
carriage
at the end of
the line.
It
will also do
a line
feed at this time.
5.
The data format
is
one start bit,
eight data bits, two stop
bits,
and no parity.
Some printers will require that these
assumptions
be
modified. This may
be
accomplished
by
changing RAM
variables
or
by
a
special driver
routine.
A list of all the printer variables
is
given
in Table
1.
Also, Table
2
lists some alternate values
for these
variables.
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