IBM PC Network

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The IBM PC Network was perhaps IBM's first LAN system.[1][2] It consisted of network cards, cables, and a small device driver known as NetBIOS (Network Basic Input/Output System). It used a data rate of 2 Mbit/s.

The original PC Network hardware was available in two varieties, baseband and broadband.

The baseband version connected computers in daisy-chain style using twisted-pair cables with RJ45 connectors. Interface cards had two RJ45 sockets for connecting to left and right neighbor nodes. The unused sockets at the ends of the network segment had to be fitted with terminators.

The more expensive and less widely used broadband version communicated over 75 Ω RG-11-type cable on separate transmit and receive frequency ranges, using a head-end device to translate between the two signals.

When the proprietary PC Network hardware was replaced by token ring in IBM's later offerings, backwards compatibility with the NetBIOS application programming interface (API) was retained through an optional loadable program module.


  1. ^ IBM. PC Network Announcement Letter. 1984-08-14 ([1]).
  2. ^ IBM. PC Network Program Announcement Letter. 1985-04-02 ([2]).