Naked Computers

Early computers, like the Colossus and WITCH, were 'naked' and 'open' – their components were exposed to view and there are no cabinets or panels that conceal the works. They were hot and noisy. All the engineering parts were on show. The openness, the smell, and the particular pattern of noise told the engineers that the computer was working correctly.

Colossus had neither sleek panels to hide the internal workings nor commercial logos, like Apple or IBM. It was only later, in the 1960s, that computers were put into boxes and branded.

With the Raspberry Pi, a single-board computer developed in the UK, 'naked' computing has come full circle. This credit-card sized computer has no box and has no input device (keyboard for example) or output device (screen for example) – these need to be supplied by the user.

The Raspberry Pi costs a tiny fraction of what Colossus cost to build.

Valve from Colossus

Valve from Colossus


Glass valves (called vacuum tubes in the US) were a key component of electronic devices, such as computers, TVs and radios right up to the 1960s. In computers the valve controlled the flow of electricity through the device so that it was either on or off. It acts as a switch and this two-state device represented binary 1 and 0 used in computer logic. Valves were large fragile power-hungry devices that had to be heated to produce electrons for the flow of current. Valves made up the logic unit which early pioneers used to create the first generation of computers. Although the hot glass valves were first replaced by transistors and then by micro-chips (also known as integrated circuits), the logic at the heart of a computer remains much the same today.

The Colossus Mark 2 used 2500 glass valves. It used a lot of electricity and got very hot. Keeping it working reliably was a challenge but the engineers did manage to do this and achieved the requirement to break the German codes.