06h AL$ZERO collapse an allocator cell
Input X register - Tag of the cell to be zeroed.
Output - none -

Decreases the size of a cell to zero but does not de-allocate the cell.

If the value of X is not in the correct range ($2000-$203E) result will be unpredictable.

Example For example, to zero the permanent (device) cell whose tag is $2000:
        LDX     #2000h          ; set X to the device tag
        OS      AL$ZERO
Errors - none -