[5] The QL was conceived in 1981 under the code name ZX83, as a portable computer for business users, with a built-in ultra-thin flat-screen CRT display similar to the later TV80 pocket TV, printer and modem.

As development progressed it eventually became clear that the portability features were over-ambitious and the specification was reduced to a conventional desktop configuration.

[10] While the CPU clock speed is comparable to that of the Macintosh, and the later Atari ST and Amiga, the 8-bit databus and cycle stealing of the ZX8301 gate array limit the QL's performance.

[citation needed] Although the computer was hyped as being advanced for its time, and relatively cheap, it failed to sell well, and UK production was suspended in 1985, due to lack of demand.

Clive Sinclair later maintained that the Microdrive was "a marvellous approach", also claiming that he had really wanted to base the QL on the Z80, that others in the company had persuaded him to use the 68000, and that "there was nothing you could do on the 68000 that you couldn't do on the Z80".

This is reputed to have been due to the timing constants in the ZX8301 chip being optimised for the flat-screen CRT display originally intended for the QL.

[24] The QL is bundled with an office suite, consisting of a word processor, spreadsheet, database, and business graphics written by Psion.

The result of a three-year collaboration between Sinclair Research, ICL and British Telecom, the One Per Desk adds a telephone handset at one end of the keyboard, and rudimentary Computer-Telephony Integration (CTI) software.

[27] Linus Torvalds has attributed his eventually developing the Linux kernel, likewise having pre-emptive multitasking, in part to having owned a Sinclair QL in the 1980s.

[28] In part, his frustration with Minix on the Sinclair[29] led years later to his purchase of a more standard IBM PC compatible on which he would develop Linux.

"Like any good computer purist raised on a 68008 chip," Torvalds "despised PCs", but decided in autumn 1990 to purchase a 386 custom-made IBM PC compatible, which he did in January 1991.

[23] In the late 1990s, two partly QL-compatible motherboards named Q40 and Q60 (collectively referred to as Qx0) were designed by Peter Graf and marketed by D&D Systems.

The Q40 and Q60, based on the Motorola 68040 and 68060 CPUs respectively, are much more powerful than the original QL and have the ability among other things (such as multimedia, high resolution graphics, Ethernet networking etc.)

Patched or reengineered versions of QDOS were produced, most notably Minerva which gradually evolved into a completely rewritten operating system, offering improved speed, with multitasking SuperBASIC interpreters.

Tony Tebby went on to produce another updated operating system, SMSQ/E, which has continued to be developed for the Sinclair QL and emulators, offering many more features.

[36] Several emulators and virtual QLs became available over time, of which Q-emuLator (Windows/Mac),[37] QPC2 (Windows),[38] SMSQmulator (Java),[39] ZEsarUX (Windows/Mac/Linux)[40] and sQLux (Windows/Mac/Linux)[41] are actively maintained.