16.3.2 Console Operation
Special keys and signals are used by the console program:
•
Ctrl/U
Ignores the current command line. The console prompt appears on the next
line. This key sequence affects only the current line. The console program
echoes this as ‘‘^U.’’ Pressing
Ctrl/U
while a command is executing does not
abort the command.
• <
x
The Backspace/Delete key deletes single characters within a command
line. On video terminals, the deleted character(s) disappear; hard copy
terminals type a pair of backslash delimiters as the characters are deleted.
For unknown attached console terminals, the console program assumes they
are hard copy terminals.
•
Return
Terminates the command line, so that the console program can execute the
command.
•
Ctrl/S
and
Ctrl/Q
Are equivalent to the corresponding line pacing control characters XOFF and
XON. Characters received between the XOFF/XON pair may be ignored. The
Hold Screen
key on the built-in console device is not used for line pacing.
Supported on both the built-in and attached terminals, these keystrokes are
unavailable during system exerciser.
•
Ctrl/C
Aborts the current command, if the console program has not passed control
to another program, such as an operating system or loadable diagnostic. The
console program echoes this as ‘‘^C.’’
These keystrokes are unavailable during system exerciser.
•
Ctrl/O
Causes the console to discard transmissions to the console terminal, until the
next
Ctrl/O
is entered.
Ctrl/O
is echoed as ‘‘^O’’ when it disables output, but is
not echoed when it reenables output. Output is reenabled if the console prints
an error message, or prompts for a command from the terminal. Output is
also enabled by entering program I/O mode, and by pressing
Ctrl/C
.
• The console program prompt is three ‘‘greater than’’ symbols followed by a
space on a new line.
>>>
The character sequence used is 0D
16
,0A
16
,0D
16
,3E
16
,3E
16
,3E
16
,20
16
(which is <CR>, <LF>, <CR>, ’>>>’, <SP>); this character string can be used
by host software executing a binary load operation to the special attached
terminal port to determine when it may respond.
The following rules pertain to terminal input when the system is operating in
console mode:
• Commands are limited to 80 characters. Characters entered after the 80th
character replace the last character in the buffer. Characters so lost may be
Console 16–5
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