The QL was a personal computer introduced by Sinclair Research in 1984. QL stands for Quantum Leap, as in the intentions of Sinclair it would have been a major leap in computer technology, offering tremendous power for a relatively small amount of money (399 pounds).
The machine was based on the M68008, the lowest price representative of the Motorola's 68000 32-bit microprocessors' family, and it had a second processor to handle the hardware. The compact and futuristic black plastic box hosted the keyboard, two RS232 serial ports, TV and monitor ports, two QLAN (local area network) ports, two joystick ports, AC plug, a 16KB ROM expansion port, the expansion bus socket, and two Microdrives.
These were the mass storage drives of the QL, in which you would insert little cartridges, containing a long (5 m) loop of magnetic tape running quite fast (70 cm/s) under a head similar to that of a normal tape recorder. Each cartridge carried, and often lost, 100KB of data. Microdrives were never adopted by other manufacturers, partly because cartridges were too expensive and unreliable and partly because floppy disks were becoming the standard.
The QL's hilites were the 32-bit architecture (although the 68008 had only an 8-bit external bus), color display, large 128KB memory, expandable to 640KB, and the operating system, called QDOS.
QDOS supported multitasking, partially implemented windows, and had a built in SuperBASIC interpreter.
As the name suggests, SuperBASIC was a much improved version of BASIC; among the many gems of SuperBASIC I'd like to mention functions and procedures (similar to Pascal), powerful and elegant string and array handling, extendibility, and type coercion, a mechanism which made it possible to enter lines like a="23"+4 and, what's more, obtain in a the result of 27.
The QL was sold with four software packages, written by Psion Ltd.: a word processor (Quill), a database (Archive), a spreadsheet (Abacus), and a graphic presentation program (Easel). This software was powerful, a bit slow, and user friendly.
The QL was launched too early in its development for commercial reasons; the result was a system which was buggy and still unfinished. The first machines were delivered to customers with many months of delay, causing excessive press criticism. Despite its marvellous features, the QL never succeedeed in the mass market. Perhaps it was too expensive for hobbyists and lacked large and reliable mass storage for professionals. Third party hardware add-ons, software, and even some QL compatible computers started to appear in the rapidly growing QL market, giving more than reasonable tools to the users, and often repairing to some original QL's weaknesses, but it was already too late. Forced by the QL's early failure, in March 1986 Sinclair sold its products and technology to Amstrad, which wasn't interested in the QL. Probably about 150000 units were sold in the brief and unlucky QL's life.
More information about the Sinclair QL
Planet Sinclair has a an interesting article about the QL's history, and some more information is available on Wikipedia.
A microdrive cartridge.
The tape inside a microdrive.
Microdrive cartridges are much smaller than floppy disks.
Every QL was sold with a suite of four business applications on microdrives.