Canon Cat Reference Manual page 114

Screen
4:
Serial
Port Connection
If your
main
printer
is
connected
to the
Cat's
parallel port,
the
Cat's
serial
port
can be used
for
an
alternate
printer,
an
extemal
modem,
or
a
direct
cable
to
a
computer.
If your
main
printer
is
connected to
the
Cat's serial port,
the
Cat's
parallel port
can be used
for
an
alternate
printer.
4a.
Serial Port Connected
to Alternate
Printer
The
initial
value
for
the
Serial
Port Connection
is
Alter-
nate
Printer:
If your
alternate
printeris
amodel
otherthan
the
VP3l03II,
you
can
now select the appropriate
printer model.
There is
no difference between setting up the altemate
printer
and
setting
up the
main
printer.
For more
information, find
the
relevant
screen
referring to your
printer
type
in
the
Main
Printer
section, pages 99-107.