1980s Computers Logo



Explanation of Terms


A photograph of the computer is shown, obtained from various sources, mostly old magazine advertisements.
In many cases clicking on the picture will load a larger version.

Manufacturer

The maker or brand name.
The country of origin is shown in brackets.

Model

The model name. There were often variants such as '16K' and '48K'.

Date Launched

The approximate date this model went on sale. It may have been announced months earlier.

Price

UK price when first sold. The cost of components, especially memory, fell rapidly in the 1980s so the price may have been reduced later.

Microprocessor type

The microprocessor manufacturer, model number and speed in Megahertz.
By far the most common were the '6502' sold by MOSTEK and the 'Z80A' sold by Zilog. The Z80A was theoretically faster than the 6502.
In principle a higher speed processor should mean the computer runs faster, but the processor's internal design and the way programs are written are just as important.

ROM size

The ROM or Read Only Memory held information such as the built-in programming language and operating system. In general a larger ROM size meant the computer could do more. A limitation though was that in many designs a larger ROM resulted in a smaller maximum RAM.

Standard RAM

RAM or Random Access Memory stored the program the computer was currently running. The more RAM available the more sophisticated games could be. RAM was always quoted in units of kilobytes (1024 characters worth). Standard RAM is the amount of memory in the machine as sold.

Maximum RAM

Many computers came with a relatively small amount of RAM to keep the price down. It was usually possible to add more, either internally or via a pack which plugged into the back of the computer. Each design of machine imposed a limit on the total amount of RAM possible, normally less than 64 kilobytes.

Keyboard type

In the beginning of the 1980s good quality, typewriter style, keyboards were expensive and might add as much as £100 to the price of a computer. A much cheaper alternative was a flat sheet of flexible plastic with keys printed on the top and an electrically conductive coating on the back. When the 'keys' were pressed they bridged contacts on a printed circuit board underneath, acting as a switch. It was impossible to type quickly on such a keyboard.
Other models had moving keys but with a poor tactile feel. The type and quality of keyboard was one of the most varying attributes of home computers up to the mid 1980s.

Supplied language

Since at first there would be few or no commercially available programs for a new model of computer, the only way to use it was to write one's own. 1980s computers thus almost invariably came with a programming language built into the ROM (in fact taking up most of the ROM). By far the most common was BASIC, either bought from Microsoft or the manufacturer's own version. Although the core commands in BASIC tended to be common to all, each manufacturer would add extensions to enable use of the particular hardware features of their machine, to a greater or lesser extent.

Text resolution

This is the number of characters per line x the number of lines per screen.
Early computers used monospaced text so all characters were the same width and there was a fixed number of characters per line.
This was significant for use as a word processor since an A4 page normally has 60 or more characters per line and if the computer's limit is less than this it cannot produce a 'WYSIWYG' display.

Most early desktop computers were intended to be connected to a domestic television rather than a dedicated monitor.
The limited resolution of a TV meant that if there were too many columns or lines of text it could become very difficult to read.

Graphics resolution

The earliest home computers could only display text but it was a definite advantage to be able to also produce pictures on-screen. The higher the resolution (pixels horizontally x pixels vertically) the more detailed the pictures could be.
Unfortunately high resolution pictures needed quite large amounts of RAM to store them, leaving less available to the program.
A restriction in some designs was that they could display either text or graphics, but could not show text with graphics.

Colours available

The very earliest models were monochrome. If a screen was supplied with the computer it usually had green phosphor rather than white, intended to be easier to read. However most home computers were fitted with a UHF modulator to allow them to be connected to the owner's existing television set.
Colour capability was soon added but generally in a limited range of colours, typically 16, or there might be a limit of 16 different colours on the screen at one time but they could be chosen from a larger palette.
The colour display hardware of some earlier machines was less than ideal and it was common for adjacent blocks of colour to 'bleed' into each other.

Example Screenshot

An example of the kind of screen output possible with the computer, to give an impression of the resolution and number of colours available.
Mostly these are actual screenshots obtained from emulators running on more recent hardware, but a few have been 'simulated' where no direct VDU ouput could be obtained.
Some displays are shown at twice their original size (but still the correct number of pixels) to make details clearer.

Sound

The majority of early computers had some means of generating sounds, but they varied enormously.
Some could only produce simple beeps while others had three note polyphonic synthesisers.
A further difference was whether the sound came through a built in speaker or was sent through the television, the latter generally giving more volume.

Cassette load speed

In 1980 even a floppy disk drive cost a few hundred pounds, more than the price of most home computers, and a hard disk drive cost over £1000. A much cheaper alternative was to store programs and data on an audio tape cassette. Some computers needed a special cassette recorder only available from the manufacturer (at a special price), but most could use an ordinary domestic mono recorder.
The main disadvantage of audio cassette storage was the slow speed of transfer between the computer and tape. This was limited by the maximum frequency response of the recorder.
Speed was measured in 'Baud' which roughly equates to 'bits per second'. Typical speeds ranged from 250 baud to 1500 baud, with faster speeds sometimes being unreliable. To load a 16 kilobyte program would take about 10 minutes at 250 baud or less than 2 minutes at 1500 baud. It was therefore much more convenient to have a computer which loaded at a fast speed, so long as it was reliable.

Dimensions (mm)
Weight (grams)

Width x Depth x Height in millimetres
Weight of the unit in grams

Special features

Each manufacturer added its own design features. These might include a particularly good version of BASIC, a wide range of interfaces to plug in extra equipment, advanced graphics or sound capability, a built-in joystick, etc.

Good points

Almost every model had some reason to choose it over its numerous competitors.

Bad points

Unfortunately most models also had some 'misfeatures' which made them difficult to use or limited their abilities. These might be a very poor keyboard, too little RAM, unreliable cassette loading...

How successful?

Each manufacturer always claimed its products were selling very well. This was important because a model with low sales volume was not likely to attract much third-party software development, and lack of software would harm sales. Only a general guide to the popularity of the model can be given here.

Comments

A place to expand on information in some of the other sections.


Close window

1