IBM 3270 Operator's Manual page 21

2. To communicate between your display station and the
computer program, some of the keys on the keyboard will
cause signals to be sent directly to the computer. To
prevent interruption of these signals, the INPUT
INHIBITED indicator turns on when any of the following
keys are pressed: CLEAR, ENTER, TEST REO, and any
PA or PF key. The INPUT INHIBITED indicator will also
turn on when a selector pen is in use.
Note: The program mayor may not turn off INPUT
INHIBITED as a result of receiving one of these signals. If
it does turn it off, it may do it so quickly you won't realize
that it was on. There may be times, however, when the
program will be busy and not able to take immediate
action on your signal. During these times, INPUT
INHIBITED will be on longer.
3. One input operation must be completed before another
can begin. If your display station has a selector pen or a
card reader, remember that they, like your keyboard, are
input devices. If an operation started with one of your
input devices is not completed, and if you attempt to input
data with one of the other devices, that device will have no
effect and the INPUT INHIBITED indicator will turn on.
4. If your display station has the Numeric Lock optional
feature, INPUT INHIBITED will turn on if you key a
non-numeric character into a formatted numeric field.
To turn off INPUT INHIBITED and activate your input
devices, press the RESET key.
Operating the 3270
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