Sinclair QL (1984)
The Sinclair QL (for Quantum Leap) is a personal computer launched by Sinclair Research in 1984, as an upper-end counterpart to the ZX Spectrum.
Based on a Motorola 68008 processor clocked at 7.5 MHz, the QL included 128 KiB of RAM, which is officially expandable to 640 KiB and in practice, 896 KB.
It can be connected to a monitor or TV for display. Sinclair recommended the "SINCLAIR VISION-QL" RGB monitor for usage with the QL. When connected to a normally-adjusted TV or monitor, the QL's video output overscans horizontally. 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.
Two video modes are available, 256 × 256 pixels with 8 primary RGB colours and per-pixel flashing, or 512 × 256 pixels with four colours: black, red, green and white.
Development
The QL was conceived in 1981 under the code name ZX83 as a portable computer for business users. It had 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 overambitious, and the specification was reduced to a conventional desktop configuration.
The electronics were primarily designed by David Karlin, who joined Sinclair Research in summer 1982. The industrial design was done by Rick Dickinson, who already designed the ZX81 and ZX Spectrum range of products.
The QL was designed to be more powerful than the IBM Personal Computer, and comparable to Apple's Macintosh. While the CPU clock speed is similar 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.
Sinclair had commissioned GST Computer Systems to produce the operating system for the machine, but switched to QDOS, developed by Tony Tebby as an in-house alternative, before launch. GST's OS, designed by Tim Ward, was later made available as 68K/OS, in the form of an add-on ROM card. The tools developed by GST for the QL would later be used on the Atari ST, where GST object format became standard.
