CountDwn displays the
10 count-down numbers 9,...0 in steps of 1 second in the Header after
having quickly made a garbage collection, and then turns the calculator
It can be interrupted with any key. If this is CANCEL, the calculator turns off immediately, otherwise the Count down will simply be aborted. This is the ideal program for STARTOFF.
STARTOFF is a reserved variable on the HP49 which runs each time when the calculator turns off, either by itself after 5 minutes, or after the time coded in the reserved variable TOFF. A good time is 40 seconds. This means
to have # 50000h in TOFF. Store the variable Countdwn in STARTOFF. If then the calculator is ON but idle, STARTOFF runs CountDwn to announce a TurnOff.
Its run may be interrupted at any moment. This avoids spontaneous garbage collection in applications. STARTOFF will not run when being in edit mode (while programming, say) since then more time is needed, in general.
REMARK: CountDwn is the same as the command CntDn in the library Alarms.