Sinclair QL

The Sinclair QL consists of a large as a home computer and personal computer of the company Sinclair Research, which decreed in the original 1984 version first marketed on a Motorola 68008 processor, 128 KB RAM and two Microdrive tape drives. The QL in the name stands for quantum leap ( English: quantum leap ).

Despite his sometimes extremely advanced concept, such as a simple graphical user interface with windows, high-resolution graphics, a very powerful BASIC and then advanced microprocessor, the device was not a commercial success for Sinclair. This was, among other things attributed to the fact that the QL less suitable for professional applications due to the slow Microdrive tape drives, on the other hand oversized for a pure gaming and hobby - oriented home computer and was too expensive. At the same time the launch was delayed again and again, and the first units had technical problems, which caused damage to their image. Due to the long delay of the sales launch of the QL was also exposed after a short time with its competitors such as the Atari ST and the Commodore Amiga, which were superior to the device in many aspects.


The Sinclair QL is constructed in the form of a panel with two integrated Microdrive drives. Microdrives are tape storage, using a miniature -loop tape as a storage medium and thanks to sector -oriented data storage provide similar functionality as floppy drives. The RAM basic equipment of 128K was upgraded by original expansion modules up to 896 KB. The Sinclair QL has connections for both RGB and then more common (F) BAS monitors in order to make its graphics resolution of 512 × 256 pixels in four colors or four gray levels visible can.

Also an RF modulator is built so that the QL can also be connected to a TV. Available, especially in, via the RF modulator in graphics mode of 512 × 256 pixels can be expected depending on the quality of the analog electronics of the TV with limitations of image size and quality. As in the 1980s, when home computers usually televisions were used for image display, Sinclair had therefore implemented an alternate display mode of 256 × 256 pixels in eight colors with an enlarged edge of the image, which still offers even on poor televisions a complete and relatively clear display.

On the left side of the QL provides a module for expansion modules. Smaller specimens, such as floppy disk controller, disappear completely in it, others protrude out from the unit. The most common extension modules were memory upgrade. In addition, the QL has a slot on its back side, can be placed in the ROM modules.

Operating system

The QDOS this operating system with integrated shell and Basic interpreter ( called in distinction to the ZX- series " Super Basic" ) is located in a 48 KB ROM. It supports standard - unique for its time - true preemptive multitasking. The BASIC QL is very extensive and powerful, it supports comfortable string manipulation, and similar to Pascal nested statements, functions with multiple parameters, local variables and recursive procedures.

The user interface offers a simple windowing technique with any number and any windows arranged, which, however, all lie in the same plane - Expenditure in overlapping windows can overwrite each other, therefore, (which can be collected from the applications ). All windows are like the concurrently released Apple Macintosh " bitmapped " and thus full graphics capability, that is, each pixel is individually controlled. The operating system is different output-only window and windows that can be used both to discretionary spending as well as for the input. As for the text output window each individual character sets can be mapped, even spending in exotic fonts are realized.

The QL is also standard network capability; QLAN called the network is running at 100 kbit / s and may take up to 63 Sinclair QL together. The two RS232C ports, however, can only be operated with up to 9,600 baud, in Send Only mode (eg to a printer ) with 19,200 baud. For game two joystick ports are available.


When software facilities also very powerful for its time programs Quill (word processing ), Abacus ( spreadsheet ), archives ( database with its own programming language) and Easel ( business graphics) have been included. These programs came from the British company Psion, which had previously been producing a series of software titles for the predecessor of the QL ( ZX80/81, ZX Spectrum). This early Office package was evaluated very positively by the press and was long considered one of the principal arguments for buying a QL at all. A few years later, the program package appeared incidentally in a slightly different form under the title XChange for IBM - compatible computers ( it alone cost more than a Sinclair QL, including the Psion software).

Apart from Sinclair " house suppliers " Psion QL software manufacturers, however, was little support. In particular, games that would have made it attractive for the typical home user, there was significantly less than for the former main competitors C64. For many office users the supplied Psion package would have been a sufficient incentive to buy because of its undoubted quality, if they had not been deterred by the then appeared in many magazines negative reviews, which related to the premature QL deliveries and the unfamiliar Microdrives.

After the end of production of the QL insider continued the development of the QL and especially the operating system QDOS continued arbitrarily. Among other things, QDOS was transferred and adapted to the more powerful hardware of the Atari ST.


The QL brought some major changes: He was the first home computer, its operating system have been multitasking. The QL based also on a Motorola 68K CPU to the series, so a very progressive for his time as a microprocessor core. However, the smallest variant was selected with the Motorola 68008; In this processor, the data bus is reduced to 8 bits and the address bus to 20 bits, which simplified the hardware technical effort strong. Compared to an identically clocked 68000 runs about 15% of the 68008 because of the increased memory access cycles slower; the QL with its clocked at 7.5 MHz 68008 CPU so ran about as fast as a computer with a clocked at 6.5 MHz 68000 CPU. As a second processor of the QL had an Intel 8049 for control of the keyboard, sound, interfaces and Microdrive; thus data transfers could take place already in the background.

In other respects, the QL brought little progress: If you add to bought an expensive floppy drive, data storage was carried out on the standard built in-house developed endless cassettes " Microdrive " (from the development of the Spectrum borrowed ), which only offered slow data accesses and used a fatigue- prone endless belt. Although it is still much slower tape drives were in other home computers used at that time, but at the professional CP/M- and MSDOS computers were faster but expensive 8-inch and 5 ¼ -inch floppy drives standard. The around the same time as the QL published Apple Macintosh already contained even one of the all-new 3.5 -inch drives from Sony ( 400 KB). Only 5 ¼ -inch drives were initially available for the QL, in the fall of 1984, finally, 3 ½ -inch drives with 720 KB memory capacity. Beginning of 1985, prices for disk drives began to fall heavily, thus appeared increasingly standard on home computers on and let the Microdrive QL appear more exotic.

For some countries, Germany and France, localized QL were produced. The German version deviated in some details from the English. In addition to a QWERTY keyboard and the operating system was Germanized, such as the error messages. Moreover, who had " German " QL other joystick and serial connectors. Moreover, the housing was better interference suppression by a metal vapor and the installation of a choke.

Market success

A number of factors contributed to the fact that the QL was a commercial failure compared to its predecessors ZX 81 and ZX Spectrum. First elapsed between the announcement and delivery of a relatively long time; the British Computer Press therefore interpreted the abbreviation " QL " as quite late ( " quite late "). Unfinished QL were still delivered in spring 1984. Since the operating system was not ready in time (on ROM), it had in these early samples in the form of a projecting from the housing dongles (also " kludge ", dt: called " Workaround " ) are supplemented ( whereby the planned 32 KB ROM were extended to 48). Later QL were strikingly often claimed as defective. Thus the image of the computer was damaged early on.

When he was finally shipped in late 1984 in large numbers and working copies ( now with 48 KB built-in ROM), the QL was suspended in view of the rapid development in the mid -1980s, a much stronger competitive pressure. Although the QL supported multitasking, color raster graphics and an early version of the windowing technique, but has been operated exclusively by keyboard commands. A graphical user interface with desktop metaphor, icons and mouse control, as they developed in the early 1970s at Xerox and 1984 with the appearance of the Apple Macintosh was state of the art, there was not.

Sinclair's American competitor Atari and Commodore introduced in 1985 with the Atari ST and Amiga also models before, who possessed as the Apple computer with a graphical user interface with mouse control and also powerful were there it the Motorola 68000 processor with 16- bit data bus used. Thus, the QL was not competitive as an office computer.

Another aspect to which the QL falling behind, was the use of the proprietary Microdrives as an integrated mass storage. Microdrive cartridges were compared to floppy disks, the ousted the still widespread in the home user area cassette tapes as storage devices, in more ways than one at a disadvantage: they were undercut in price from the initially more expensive floppy drives shortly after the appearance of QL, were slower than those in the access, were considered to be susceptible to interference and preconceived only about 110 kilobytes. Although external floppy drives could be connected to the QL, but first had a floppy controller from a purchase of several third-party, while the later competing models of Atari (Atari ST) and later also by Commodore (Amiga) with ready built-in 3.5 - inch drives waited on.

All user groups of the QL had to buy expensive hardware, respectively. For the first time since development of the ZX80 was the concept to offer at an affordable price for everyone, no longer. The QL really could not address the core target groups.

These factors led to sluggish sales of QL, which brought Sinclair into financial difficulties. Making matters worse was that the Sinclair C5 electric vehicle had proven itself in 1985 as a complete flop. In this situation, we sat down again on the rapidly obsolescent, but popular ZX Spectrum, from the 1986 extended version with 128 KB RAM appeared. However, this was already too late: in April 1986, Sir Clive Sinclair did eventually forced the troubled company to the British competitors Amstrad for sale, which set the QL production and the rest of the computer had to sell below book value.


  • The British computer manufacturer ICL was based a on the QL, but are provided with another operating system office computers called OPD (One per desk ) finished.
  • The Linux inventor Linus Torvalds made ​​his first serious programming experience with a QL, so he analyzed the QDOS and wrote software for a floppy controller.