The Valve.Computer
A modern 8 bit design, built using 1950s thermionic valves that glow and heat the entire room.
The prototype first ran on 28th May 2021 whist perched on our dining room table, chairs and surrounding floor space.
The Valve.Computer is now firmly nailed to the study wall,
and is almost safe to touch.
Almost!
Thermionic valves, (aka vacuum tubes), can switch several hundred million times a second, and in the 1950s were the basis for all computer designs. To work efficiently they require high voltages and are not for the faint hearted.
The Valve.Computer is an 8 bit computer, with the usual 12 bit address and data buses plus the rather unusual current demand of over 200 Amps. It can play a decent game of PONG using its valve and relay RAM, or run a 32 bit Fibonacci sequence using modern NVRAM.
After switch on you have to wait a while for the last thermionic valve to warm up. If you look from the side you see a few start to show a red glow. After about a minute the Valve.Computer has the pleasant homely aroma of 560 double valves, quietly burning off their dust.
When all the valves are glowing, I check the fire extinguisher is full, and run the code.
It has been a ridiculous amount of soldering
and a fantastic amount of fun.