Return shell version (INT 21h, EAh - Novell NetWare 4.6)

        Entry:
          AH = EAh
          AL = subfunction
                 00h return code in
                     Return: AL = hardware type
                            00h IBM PC
                            01h Victor 9000
                 01h get workstation environment string
                     ES:DI -> 40-byte buffer
                     Return: Buffer filled with three null-terminated
                             entries:
                                Major operating system
                                Version
                                Hardware type
        Return:
          AH = 0 if DOS