Radio Shack Quick Printer II Technical Reference Manual

RS232C
DEVICES
The RS232C
Interface hardware in the Color Computer 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
RS232C
signals may be used
with the Color Computer. 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
8K
BASIC ROM is a
serial printer. For use
with the printer, the
pin assignment
of
P2
differs from that
listed in the
RS232C
Interface section.
Pin
1 is not used.
Pin
2 is connected
to
the busy output
(or status line) of the
printer.
Pin 3 is ground.
Pin 4 is the computer
output to the printer.
If
your printer does not
provide
a
status line, then pin 2 must
be
connected to
a positive voltage of
+3
volts or greater
(up to
the
maximum +12 volts).
This tells the computer
that the
printer is ready
all of the time.
In order
to operate, the software
must
make several assump-
tions about
the printer. These assumptions are:
1.
600 Baud
2.
The Printer
width is 132 columns.
3. The printer
generates
a
busy output when it is not ready.
4.
The printer
will automatically carriage
return
at the end
of
a line.
5.
The
data
format is one start bit
(logical zero),
seven
data
bits (LSB first), two stop bits
(logical one), and no
parity.
<
1
>
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 of the printer variables
is given in Table 6. Also,
Table
7 lists some alternate values for these
variables. The last
comma
field variable
*
2
'
should be set equal to
the width value
minus the comma
field width. The comma field
width will
normally stay at 16.
NOTES:
<
1
>
In Revision 1.1
ROM's
this format
has been
changed
from seven to eight data bits.
<
2
>
Comma field
is the number of spaces allowed
to print
a
variable value.
TABLE 6.
LINE
PRINTER
VARIABLES
INITIAL
VALUE
HEXIDECIMAL
DECIMAL
HEXI-
VARIABLE
ADDRESS
ADDRESS DECIMAL
DECIMAL
BAUD RATE
MSB
0095 149
00
BAUD RATE
LSB
0096 150 57
87
LINE DELAY
MSB
0097 151
00
LINE DELAY
LSB
0098 152
01 1
COMMA FIELD WIDTH
0099
153
10
16
LAST
COMMA FIELD
009A 154
70 112
LINE PRINTER WIDTH
009B
155
84 132
38

Radio Shack Quick Printer II Specifications

General

Brand	Radio Shack
Model	Quick Printer II
Category	Desktop
Language	English