NetBIOS

NetBIOS /ˈnɛtbʌɪ.ɒs/ is an acronym for Network Basic Input/Output System. It provides services related to the session layer of the OSI model allowing applications on separate computers to communicate over a local area network. As strictly an API, NetBIOS is not a . Older operating systems ran NetBIOS over IEEE 802.2 and IPX/SPX using the (NBF) and NetBIOS over IPX/SPX (NBX) protocols, respectively. In modern networks, NetBIOS normally runs over TCP/IP via the NetBIOS over TCP/IP (NBT) protocol. This results in each computer in the network having both an IP address and a NetBIOS name corresponding to a (possibly different) host name.

NetBIOS was developed in 1983 by Sytek Inc. as an API for software communication over IBM PC Network LAN technology. On PC-Network, as an API alone, NetBIOS relied on proprietary Sytek networking protocols for communication over the wire. Because PC Network only supported up to 80 devices in its most accommodating mode (baseband), NetBIOS was itself designed with limited nodes in mind.

In 1985, IBM went forward with the token ring network scheme and a NetBIOS emulator was produced to allow NetBIOS-aware applications from the PC-Network era to work over this new design. This emulator, named NetBIOS Extended User Interface (NetBEUI), expanded the base NetBIOS API with, among other things, the ability to deal with the greater node capacity of token ring. A new networking protocol, , was simultaneously produced to allow NetBEUI (NetBIOS) to provide its services over token ring – specifically, at the IEEE 802.2 Logical Link Control layer.

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