Asynchronous Terminals and Printer Processes Programming Manual

TERMINAL I/O
Conversational Mode Characteristics
Backspace
Four SYSGEN modifiers determine the action that takes place when
the terminal operator presses the BACKSPACE key
| • BSHARD Hard-copy terminal that backspaces. The host
| sends a line feed when it receives the first
| backspace. The line feed allows the previous line
| to be seen above the printhead as each additional
| backspace is entered.
|
| • NOBS Hard-copy terminal that does not backspace. The
| terminal prints a slash ("/") for every backspace
| it receives.
|
| • BSCRT Video terminal. The host echoes every backspace
| it receives. If the terminal cannot erase a
| character from the screen when backspacing, the
| deleted characters remain on the screen.
|
| • BSERASE Video terminal. The host echoes every backspace
| it receives with the <BS> <space> <BS> sequence.
| This sequence erases each character from the screen
| when backspacing. However, if the terminal is
| connected by means of a modem and the backspace key
| is pressed rapidly, unexpected characters may
| display on the screen. If so, use the BSCRT SYSGEN
| modifier instead.
For ATP6100 subdevices, you can change the value defined at
SYSGEN by including the BACKSPACE attribute in a CMI ALTER SU
command.
Line Spacing
Line spacing mode is controlled by SETMODE and CMI. The CMI
subdevice attribute SPACING has three values:
• NONE--the system does not add <CR><LF>
• PRE--<CR><LF> is sent before the output line
• POST--<CR><LF> is sent after the output line
Postspacing is the default. A SETMODE 6 procedure call turns
spacing on and off. SETMODE 27 determines whether prespacing
or postspacing is active. To write a blank line, select either
prespacing or postspacing, and write 0 characters.
2-8 November 1987