INT 7F - Alloy NTNX, MW386 - SEMAPHORE LOCK AND WAIT
        AH = 00h
        DS:DX -> ASCIZ semaphore name (max 64 bytes)
Return: AL = status
            00h successful
            01h invalid function
            02h semaphore already locked
            03h unable to lock semaphore
            04h semaphore space exhausted
            05h host/target PC did not respond (NTNX)
        AH = semaphore owner if status=02h
SeeAlso: AH=02h,AH=41h,INT 67/AH=00h