KEY(n)
======

Function
--------

**KEY(n)** activates and terminates trapping of soft keys.

Syntax
------

| KEY(n) ON
| KEY(n) OFF
| KEY(n) STOP

n is a numeric expression in the range 1 to 8 to reference the soft key.

Example
-------

::

   10 ON KEY (1) GOSUB 1000
   20 KEY (1) ON
   .
   .
   .
   900 END 'FINISH OF MAIN ROUTINE
   1000 REM SOFT KEY (1) TRAP ROUTINE
   1990 RETURN
   .
   .
   .

Remarks
-------

The KEY(n) statement is used for trapping either soft key entries or
cursor entries during program execution. It is intiialised with the
:doc:`on-key` statement.

KEY (n) ON, when executed, activates trapping of the keys. A
:doc:`gosub` is automatically executed when a key is pressed to
the line number specified in the ON KEY statement.

The display of the soft key function is not altered with this statement.

If the same key is pressed again while the subroutine is being
processed, then the interrupt is stored until the program returns from
the interrupt routine when the GOSUB will be executed again.

If a different key is pressed while one interrupt routine is being
processed, then another GOSUB is immediately executed. Different key
trapping routines may be nested, but each individual routine cannot be
re-entered.

KEY (n) OFF
   The trapping routine is deactivated, and the key press is ignored.
KEY (n) STOP
   Immediate execution of the trapping routine does not take place, but
   the key is remembered and left pending until a KEY (n) ON statement
   is encountered.