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Keyboard Control
BREAK
With a point-to-point communications link, pressing the
. . key transmits a 200 ms space on the asynchronous
data communications line or sets the secondary channel
low for 200 ms (depending upon whether the terminal is in
transmit or receive state). This serves as a "break" signal to
interrupt computer operation.
BELL
The keyboard includes an imbedded speaker for sounding
an audible tone in response to the ASCII Bell
«BELL»
control code and for alerting the terminal operator to cer-
tain conditions (errors, end-of-line, end-of-field).
Note that the bell speaker can be enabled and disabled
through the use of the
"BELL"
parameter in the terminal
configuration menu. When that parameter is set to
"OFF",
the bell will NOT sound when the cursor nears the end of
a line nor when the cursor advances from one field to the
next in a formatted display. The bell will, however, still
sound in response to an ASCII Bell control code (decimal 7;
'control-G).
From the keyboard you generate the Bell code by simul-
taneously pressing the. and
G
keys.
From a program executing in a host computer, you trigger
the bell tone by transmitting an ASCII Bell control code
(decimal 7).
3-12
WAIT
From a user key or from a program executing in a host ( '
computer, you can cause the terminal to pause for ap-
proximately 1 second using the following escape sequence:
<ESC>@
Multiple uses of this escape sequence in succession can be
used to obtain virtually any desired time delay.
Note that while an
<ESC>@
is in effect the cursor
disappears from the screen, the keyboard is locked, and the
passing of data from the data comm firmware to display
memory is inhibited.
For example, if you want to sound the bell tone twice in
succession with a two second delay between tones, you
could do so using the following control sequence:
<BELL> <ESC>@<ESC>@ <BELL>
MODEM DISCONNECT
You can direct the terminal to "hang up" the modem by
sending an
<ESC>f.
The terminal accomplishes the modem ( '
disconnect by lowering the TRlCD (Terminal Ready) line for
2 seconds.
(
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