Econet
From Wikipedia, the free encyclopedia
- This is about the network system. For the mobile phone company, see Econet Wireless.
Econet was Acorn's low-cost local area networking system, intended for use by schools and small businesses. Econet is rumoured to be an abbreviation of Economy Network, but Acorn were always careful to stress the Greek root, oikos, meaning "house". It was used in the early 1980s by Acorn to provide computer networking for the BBC Micro. Modules were later produced for the BBC Master and Master Compact models, which were even used in the Acorn Archimedes series. The Econet system was supported on all Acorn machines except the Acorn Electron, the A3010 and the eventually cancelled Phoebe 2100. There were PC interface cards produced for the ISA bus. The system was based around the Motorola MC6854 Advanced Data Link Controller IC. The system was supported by the BBC Micro OS, the BBC Master MOS, Acorn'sRISC OS and RISCiX. There was third-party support for Econet in MS DOS. The protocol is also supported by the Linux kernel, though it is doubtful if anyone has tried using the hardware drivers under Linux 2.6.
Econet is a 5-wire bus network. One pair of wires are used for the clock, one pair for data transmission and one wire is a common ground. Connections were established using a four-way handshake. The sender would broadcast. There could be up to 254 devices on a network, and up to 127 networks bridged together. Machines and appliances such as filestores and bridges were configured with station numbers using jumpers or CMOS RAM settings. and The clock signal was generated either by a stand-alone clock box, by a BBC Microcomputer with a modified Issue 4 mainboard or by a fileserver. Only one clock generator could be used on each network. While the network was originally specified to run at 210kHz, practical clock frequencies could range from about 40kHz to around 800kHz; the presence of older machines on the network or the capacitance of a long network cable would reduce the maximum data rate reliably available.
