KEY(n)                   Enable/Disable Key Trapping

 KEY(n) {ON | OFF | STOP}

    Enables or disables the trapping of a specified key via ON KEY(n).

           n    A numeric expression in the range 1 to 31, specifying the
                key to trap, as follows:

                1-10,30,31    Function keys F1 through F10, F11, F12
                11            Cursor Up
                12            Cursor Left
                13            Cursor Right
                14            Cursor Down
                15-25         Keys defined via KEY n, CHR$(KBflag) +
                                                      CHR$(scancode)

          ON    KEY(n) ON activates trapping. If an ON KEY(n) GOSUB
                statement has been executed, Turbo Basic checks before
                executing each statement to see if the specified key has
                been pressed. If it has, Turbo Basic performs the
                indicated GOSUB.

         OFF    KEY(n) OFF deactivates trapping.

        STOP    KEY(n) STOP also deactivates trapping, but Turbo Basic
                continues checking to see if the specified key has been
                pressed. If it has been pressed, a subsequent KEY(n) ON
                results in an immediate trap (provided an ON KEY(n)
                statement with a nonzero line number has been executed).

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      Notes:    With event trapping in effect, Turbo Basic checks for the
                specified event after each program statement. The $EVENT
                metastatement can be used to turn event trapping on and
                off at specified points within a program.