The BBC Microcomputer System, or BBC Micro, was a series of microcomputers and associated peripherals designed and built by Acorn Computers.

Acorn pitted their machine against Sinclair Research in the bid to produce a computer for the for the BBC Computer Literacy Project, operated by the British Broadcasting Corporation. Their computer won the competition ahead of the Sinclair ZX Spectrum.

Designed with an emphasis on education, it was notable for its ruggedness, expandability and the quality of its operating system.  It was a great success for Acorn, forming the cornerstone of computer education in schools for the 1980s, backed up with the BBC's The Computer Programme,  and also achieving a level of success as a home computer.

The BBC Micro covers six models -

BBC Micro Model A (with 16K memory),

BBC Micro Model B (with 32k memory)

BBC Micro Model B+64 (with 64k memory and floppy disk drive)

BBC Micro Model B+128 (with 128k memory)

the BBC Master 128 (with 128K memory)

the BBC Master compact (same as teh Master 128, but divided into two parts - so the main part could sit under a monitor).

The Model A and Model B machines included a number of extra I/O  interfaces: serial and parallel  printer ports; an 8-bit general purpose digital I/O port; a port offering four analogue inputs, a light pen input, and switch inputs; and an expansion connector (the "1 MHz bus") that enabled other hardware to be connected. Extra ROMs could be fitted (four on the PCB or sixteen with expansion hardware) and accessed via paged memory. An Econet network interface and a disk drive interface were available as options. 

Acorn also released a Tube interface which enabled a second processor to be connected.

The BBC still remains popular today.