• _shells
  • integrate communication technologies of LAN software and LAN hardware
  • examples
    • IPX, NetBIOS
• _{operating systems}
  • _{host operation systems}
    • _MVS
  • network operating systems
    • Novell Netware
    • Windows NT
    • Unix
  • workstation operating systems
    • DOS
    • Windows 95
    • Windows NT
    • Unix