INT 21 - Novell NetWare 4.0, Alloy NTNX - LOG/LOCK PERSONAL FILE (FCB)
        AH = CAh
        DS:DX -> FCB (see AH=0Fh)
        if function C6h lock mode 01h:
            AL = log and lock flag
                00h log file only
                01h lock as well as log file
            BP = lock timeout in timer ticks (1/18 sec)
Return: AL = error code
            00h successful
            96h no dynamic memory for file
            FEh timeout
            FFh failed