INT 67 - PC-NET, Alloy NTNX - LOCK SEMAPHORE AND WAIT
        AH = 00h
        DS:DX -> ASCIZ semaphore name (max 64 bytes)
Return: AL = status (see below)
SeeAlso: AH=01h,AH=02h"PC-NET",INT 7F/AH=00h

Values for 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

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