INT 6F - 10-NET - LOCK SEMAPHORE, RETURN IMMEDIATELY
        AH = 0Bh
        AL = drive number or 0
        ES:SI = Ethernet address or 0
        DS:BX -> 31-byte ASCIZ semaphore name
Return: AL = status
            00h successful
            01h semaphore currently locked
            02h server not responding
            03h invalid semaphore name
            04h semaphore list is full
            05h invalid drive ID
            06h invalid Ethernet address
            07h not logged in
            08h write to network failed
            09h semaphore already logged in this CPU
Note:   same as INT 60/AH=12h
SeeAlso: INT 60/AH=12h