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KnowledgeBase 00019: Keyboard Input Problems

Last updated: 17 Feb 2017
Applies to: All versions
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Every line of terminal input from a telnet connection appears to have an ASCII nul character in it

QM assumes that telnet connections start with binary mode disabled. If your terminal emulator works in binary mode but does not send the related telnet negotiation parameter, the nul characters that appear after every newline will be treated as data. The solution is either to turn off binary mode in the emulator or to upgrade to an emulator that supports binary mode negotiation.


The backspace key does not erase the character preceding the cursor

Some terminals (e.g. Wyse 50 and Wyse 60) send the same character for the backspace key and the cursor left key. QM is unable to distinguish these and may interpret the backspace as a cursor left or vice versa depending on how the input data is being processed. If possible, either use a different terminal type or modify the code sent by the emulator for cursor left (and the corresponding terminfo entry) to something different. If this is not possible, deleting the terminfo definition for the cursor left key (kcub1) will ensure that the key is always interpretted as a backspace.


My cursor keys do not function correctly over a telnet connection

QM uses the terminfo library to identify control sequences sent by terminals when special keys are pressed. The usual reason for incorrect recognition of cursor keys is that the wrong terminal type has been selected. The standard Microsoft telnet emulator provided with Windows used to use a vt100 emulation. Later versions are vt220 emulation.

Alternatively, some vt100 terminal emulators have an option to send variations of the cursor key codes.

In either case, the problem is almost certainly that your terminal emulator does not match the terminal type selected using the TERM command.


My function keys, home, end, etc do not work correctly over a telnet connection

The standard Microsoft telnet emulator provided with later versions of Windows does not recognise the function keys. You will need to find an alternative terminal emulator if you need to use the function keys.


Related Articles

00017: Terminal Support



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