The Sinclair QL, QL for Quantum Leap, was a personal computer system launched by Sinclair Research in January, 1984. A successor to the ZX Spectrum, the QL was designed with the hobbyist and small business market in mind.

The computer used a Motorola 68008 processor running at 7.5 MHz, came with 128 KB of RAM, and could be connected to a monitor or TV for display. It used a multitasking operating system (OS), Sinclair QDOS primarily designed by Tony Tebby , and was bundled with an office applications suite (wordprocessor, spreadsheet, database, and graphics) written by Psion. It had a built-in advanced BASIC Interpreter named SuperBasic designed by Jan Jones . Physically, the QL resembled the contemporary Sinclair Spectrum, including the Spectrum's non-standard plastic keyboard.

The QL was the second 680XX-based personal computer to be released, following the Apple Lisa but beating the Apple Macintosh by a month, and the Atari ST by several. While clock speeds were comparable, the 75% cycle stealing of the ZX8301 integrated circuit crippled the QL.

The QL was plagued by a number of problems from release, particularly bugs in the QDOS operating system ROM, which lead to multiple releases of the firmware. Indeed, the first issue of the machine had to be shipped with a plug-in 'dongle' which contained parts of the ROM, without which the machine did not work. The QL also suffered from reliability problems of its built-in "Microdrive" tape-loop storage systems (first seen as add-ons for the ZX Spectrum). Although the computer was hyped as being advanced for its time, and relatively cheap, it failed to sell well during its peak and was eventually discontinued. Apart from its reliability issues, the intended business market was becoming wedded to the IBM PC platform, whilst the majority of Sinclair owners were uninterested in a machine which had a minimal library of games. Sinclair's persistence with the non-standard Microdrive and uncomfortable keyboard did not endear it to the business market; coupled with the machine's resemblance to a Sinclair Spectrum, led many to perceive the QL as something akin to a toy. Although in hindsight the new directions set by the Macintosh, Atari ST and others prevailed - most notably a GUI, which the QL lacked - the core concepts of the QL's Operating System appeal even today.

The QL was also available for a short period of time in the guises of International Computers Ltd's One Per Desk (OPD) and British Telecom Merlin Tonto . Based around the same platform as the QL, but with a different case and keyboard, the OPD and Tonto had the intruiging addition of a telephone handset on one end of the keyboard, and rudimentary Computer-Telephony Integration (CTI) software. The BT machine had limited success.

After Amstrad abandoned the QL concept, several companies stepped in to fill the market void. These were CST and DanSoft that created the Thor line of machines, Miracle Systems creator of a series of QL expansions such as the Gold Card and Super Gold Card and QXL PC based hardware emulator and finally Qubbesoft with the first replacement multi-colour/multi-resolution QL mainboard called the Aurora.

Today the QL is present in the guises of two self-contained mainboards named Q40 and Q60 (collectively referred to as Qx0) created by Peter Graf and marketed by D&D Systems . The Qx0 machines bring immense power to QL computing and have the ability among other things (such a multimedia, high resolution modern graphics, Ethernet networking etc.) to run the Linux operating system.

Hardware add-ons are still being produced for the original QL mainly by TF Services who supplies the RomDisQ , the Minerva replacement Operating System, I²C bus based peripherals and MPlane buffered backplane systems.

It is a little known fact that Linus Torvalds, creator of Linux, owned a Sinclair QL in his youth and was inspired by both the shortcomings and advantages of the QDOS Operating System to create Linux.

External links

• QL clones Q40/Q60 – QL compatible machines which can even run Linux

Emulators and support are still available for the Sinclair QL from:

• RWAP Software
• QBranch
• Jochen Merz Software
• Sinclair QL Homepage
• TF Services (Tony Firshman)
• Davide Santachiara web page

General QL information and software downloads are available from:

• Dilwyn Jones's QL pages