Early Computers
The earliest calculating engines, such as Charles Babbage’s Difference Engine were all mechanical. It wasn’t until the invention of the thermionic valve (commonly referred to nowadays as a vacuum tube) that electrical computers were possible.
After the second world war, electrical computers began to slowly displace mechanical calculating engines in the corporate world. These were very slow by modern standards, and required a lot of maintenance due to the relatively short life of the valves. They were also very expensive and only large companies could afford a computer. Towards the end of the ’60s, they began to be replaced with designs based on germanium transistors, which allowed much cheaper (and smaller) computers to be built. While still expensive, these were affordable by a much larger number of organisations.
Early computers were very simple machines and a number of companies sprung up in the UK, including Wales, to build them.
Further Reading: Simon Lavington, Early British Computers, Manchester University Press, 1980.
Early Home Computers
From the early ’80s, a large number of manufacturers were creating cheap computers built around off-the-shelf 8-bit CPUs, typically the MOS 6502, Intel 8080 or 8085, or the 8085's derivative, the Zilog Z80. Competition was fierce; one manufacturer cut their margins so fine that they needed to keep the money from their customers in their bank account earning interest for a month before they could afford to buy the components.
Many of these machines were used primarily for gaming, but machines of this class introduced a generation of school children to computer use and programming. In Britain, this was encouraged by the Government of the time, through initiatives such as “Micros in Schools” and “IT82: The Information Technology Year”.
