Question: What kind of group does Amstrad and BBC Micro have in common?

Context paragraphs:
Mini Office II: Mini Office II, published by Database Software in 1986, was an office suite available for several home computers, among which were the Amstrad CPC, the Atari 8-bit family, the BBC Micro, the Commodore 64, and others.  The software package could be purchased on cassette tape or floppy disk.  Mini Office II was originally written for the BBC Micro Computer (in 6502 assembler) and was also available in EPROM format.

The Micro User: The Micro User (titled BBC Micro User in the first three issues) was a British specialist magazine catering to users of the BBC Microcomputer series, Acorn Electron, Acorn Archimedes and, to a limited extent, the Cambridge Z88.  It had a comprehensive mix of reviews of games, application software, and the latest Acorn computers; type-in programs (duplicated on a "cover disk" which was available separately), a correspondence page offering help with computer problems, and approachable technical articles on programming and the BBC Micro's internals.

Gauntlet (Micro Power video game): Gauntlet is a clone of "Defender" written by Chris Terran published in the UK by Micro Power.  It was released on the Acorn Electron and BBC Micro in 1984 and on the Amstrad CPC in 1985.

Spy Snatcher: Spy Snatcher is a floppy disk-based text adventure released by Topologika Software in 1991 .  It was the last professional text adventure to be released on the BBC Micro and Acorn Electron.  It was also released for ZX Spectrum (+3 disk only), RISC OS, PC, Amstrad CPC, Amstrad PCW, Atari ST and Nimbus.

DK'Tronics: DK'Tronics Ltd (stylised as dk'tronics) was a British software and hardware company active during the 1980s.  It primarily made peripherals for the ZX Spectrum and Amstrad CPC but also released video games for the Spectrum, Commodore 64, Commodore Vic 20, BBC Micro, Memotech, MSX and Amstrad platforms.

BBC Micro: The BBC Microcomputer System, or BBC Micro, is a series of microcomputers and associated peripherals designed and built by the Acorn Computer company for the "BBC Computer Literacy Project", operated by the British Broadcasting Corporation.  Designed with an emphasis on education, it was notable for its ruggedness, expandability, and the quality of its operating system.  An accompanying 1982 television series ""The Computer Programme"" featuring Chris Serle learning to use the machine was also broadcast on BBC 2.

Ghouls (video game): Ghouls is an 8-bit computer game written by David Hoskins and published in the UK by Micro Power.  It was released on the Acorn Electron, BBC Micro, Commodore 64 and Amstrad CPC in 1984.

Amstrad: Amstrad is a British electronics company.  s of 2006 , Amstrad's main business is manufacturing Sky UK interactive boxes.

Doctor Who and the Mines of Terror: Doctor Who and the Mines of Terror is a game for the Amstrad CPC, BBC Micro and Commodore 64.  It was first released by Micro Power on the BBC Micro in 1985, and on the Amstrad CPC & C64 in 1986.

Match Day: Match Day is a football computer game, published by Ocean Software in 1984, originally on the ZX Spectrum and then later released on the Amstrad CPC, BBC Micro, & Commodore 64 systems.  It is the first game in the "Match Day" series, and the title and opening music are references to "Match of the Day".  It was the creation of programmer Jon Ritman.  The BBC Micro version was ported by Chris Roberts.

Supporting paragraphs: Amstrad BBC Micro
Answer: company