Radio Shack TRS-80 Model II Reference Manual page 211

Technical Information
Contents of B
(Decimal) Option (details are given later)
o
Get printer status only (see Exit Conditions)
1 Select serial printer driver (you must initialize channel B first)
2 Select parallel printer driver
3 Reset current line count; register C contains new count
4 Reset current character count on current line; register C contains the
new count
5 Begin transparent mode
6 End transparent mode
7 Begin dummy mode
8 End dummy mode
9 Begin auto line-feed after carriage return
10 End auto line-feed after carriage return
Exit Conditions
NZ
=
Error Occurred.
Z
= SVC
completed without error.
B
=
Page Length
C
=
Maximum number of lines to be printed on each page
D
=
Maximum number of characters to be printed on each line
E
=
ASCII
"P" or "S" (Indicates which printer option, Parallel or
Serial Printer, is selected.)
H
=
Number of characters printed on current line since last carriage return
L
=
Number of lines printed since last top of form
Explanation of Options
Serial/Parallel Printer Option
While the serial printer option is selected, allowing printer output to Channel B,
two input characters are recognized from Channel B. These will affect all serial
printer output operations:
ASCII
Name
DC3, "CTRL-S"
DC 1, "CTRL-Q"
Hex
Code
13
11
Result
Pause printing
Resume printing
Line count/Character Count
TRSDOS
maintains a single line counter and a single character counter. These are
updated for either serial or parallel printing.
TRSDOS
does not maintain separate
counters for serial and parallel printing.
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