The 3B series computers are a line of minicomputers produced from the late 1970s by AT&T Computer Systems' Western Electric subsidiary for use with the company's UNIX operating system. The line primarily consists of the models 3B20, 3B5, 3B15, 3B2, and 3B4000.

<company> A UK computer manufacturer, part of the {Acorn Computer Group} plc. Acorn was founded on 1978-12-05, on a kitchen table in a back room. Their first creation was an electronic slot machine. After the Acorn System 1, 2 and 3, Acorn launched the first commercial microcomputer - the ATOM in March 1980. In April 1981, Acorn won a contract from the BBC to provide the PROTON. In January 1982 Acorn launched the BBC Microcomputer System. At one time, 70% of microcomputers bought for UK schools were BBC Micros. The Acorn Computer Group went public on the Unlisted Securities Market in September 1983. In April 1984 Acorn won the Queen's Award for Technology for the BBC Micro and in September 1985 Olivetti took a controlling interest in Acorn. The Master 128 Series computers were launched in January 1986 and the BBC Domesday System in November 1986. In 1983 Acorn began to design the Acorn RISC Machine (ARM), the first low-cost, high volume RISC processor chip (later renamed the Advanced RISC Machine). In June 1987 they launched the Archimedes range - the first 32-bit RISC based microcomputers - which sold for under UKP 1000. In February 1989 the R140 was launched. This was the first Unix workstation under UKP 4000. In May 1989 the A3000 (the new BBC Microcomputer) was launched. In 1990 Acorn formed Advanced RISC Machines Ltd. (ARM) in partnership with Apple Computer, Inc. and VLSI to develop the ARM processor. Acorn has continued to develop RISC based products. With 1992 revenues of 48.2 million pounds, Acorn Computers was the premier supplier of Information Technology products to UK education and had been the leading provider of 32-bit RISC based personal computers since 1987. Acorn finally folded in the late 1990s. Their operating system, RISC OS was further developed by a consortium of suppliers. Usenet newsgroups: news:comp.sys.acorn, news:comp.sys.acorn.announce, news:comp.sys.acorn.tech, news:comp.binaries.acorn, news:comp.sources.acorn, news:comp.sys.acorn.advocacy, news:comp.sys.acorn.games. Acorn's FTP server (ftp://ftp.acorn.co.uk/). {HENSA software archive (http://micros.hensa.ac.uk/micros/arch.html)}. {Computers Ltd.phudv/">Richard Birkby's Acorn page (http://csv.warwick.ac.uk/Acorn Computers Ltd.phudv/)}. RiscMan's Acorn page (http://geko.com.au/riscman/). Computers Ltd.rhh01/Main.html">Acorn On The Net (http://stir.ac.uk/Acorn Computers Ltd.rhh01/Main.html). {"The Jungle" by Simon Truss (http://csc.liv.ac.uk/users/u1smt/u1smt.html)}. [Recent history?] (2000-09-26)

Computers can be classified, or typed, in many ways. Some common classifications of computers are given below.