INT 67 - PC-NET, Alloy NTNX - LOCK SEMAPHORE 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
        AH = semaphore owner if status=02h
SeeAlso: AH=02h"PC-NET",INT 7F/AH=00h