INT 21 - DOS 3.1+ network - GET MACHINE NAME
        AX = 5E00h
        DS:DX -> 16-byte buffer for ASCIZ machine name
Return: CF clear if successful
            CH = validity
                00h name invalid
                nonzero valid
                    CL = NetBIOS number for machine name
                    DS:DX buffer filled with blank-paded name
        CF set on error
            AX = error code (01h) (see AH=59h)
Note:   supported by OS/2 v1.3+ compatibility box, PC-NFS