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1980s Computers Explanation of terms

The Sinclair QL

Sinclair QL


Sinclair Research Ltd (UK)


QL ('Quantum Leap')

Date Launched

Announced January 1984
Limited availability from May 1984



Microprocessor type

Motorola 68008 @ 7.5 MHz
(A version of the 68000 using an 8-bit data bus rather than 16-bit)

ROM size

48 kilobytes

Standard RAM

128 kilobytes

Maximum RAM

640 kilobytes

Keyboard type

Moderate quality typewriter style but based on a flexible membrane

Supplied language

Sinclair Super BASIC
This was an idiosyncratic but powerful version of BASIC.

Text resolution

Normally 42 x 25 characters in low resolution and 85 x 25 characters in high resolution.

Graphics resolution

256 x 256 or 512 x 256 pixels

Colours available

8 colours + flashing at low resolution
4 colours at high resolution

Example Screenshot

Sinclair QL display
This is the business-graphics program Easel, which was supplied with the QL, and could produce bar, line and pie charts very easily. (The actual shape of the QL's display was taller than this screen shot suggests because the QL's pixels were higher than their width.)


Monophonic, output through speaker

Cassette load speed

Used Sinclair microdrives only.
(Two were built in to the right of the keyboard.)

Dimensions (mm)
Weight (grams)

472 x 138 x 46
1200 approx.

Special features

The cheapest computer at the time to use a version of the very fast Motorola 68000 microprocessor.
A very smart and modern appearance.

Good points

Large memory by the standards of home computers.
Was supplied with four highly regarded pieces of software written by Psion: word processor, database, spreadsheet and business graphics.

Bad points

The microdrives were unreliable and of fairly small capacity (only 100 KB per cartridge - less than the RAM size.)
The QL was nowhere near finished when it was first announced and even the first models to ship to customers were missing some features.
Never attracted a huge amount of third party software.
There was no built-in parallel printer port – something almost essential in a 'business' computer.

How successful?

Despite its faults about 100,000 were sold.
One well-known user was Linus Torvalds, who went on to develop Linux.


The Sinclair QL could have been an excellent machine with a little more development time before launch and probably a slightly higher price, to allow fitting of a standard floppy disc drive rather than microdrives.
As it was it never lived up to its promise.

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