You can go retro by using an old video game console or a PC from the 1980s, but why stop there when, like one man, you can build your own vacuum tube computer using 75-year-old recycled components?

A UK resident who identifies himself only as “Mike” has done just that, as detailed on his tube computer website and accompanying Hackaday project page. Mike’s tube computer is primarily made up of 460 recycled, Soviet-era 6N3P vacuum tubes, which were common enough in their age to be readily and cheaply available online. //

“Many were used and then stored for over 50 years, so life expectancy may be questionable,” Mike explained on Hackaday. A new 6N3P tube is supposed to have around 500 hours of life, but because each has been used, its current condition is essentially a mystery. Throw in manufacturing inconsistencies of mid-century Soviet Russia, and each tube had enough variability to necessitate extensive testing, Mike explains in the technical writeup on his website. //

It takes between 10 and 15 minutes for the entire system to stabilize once switched on, Mike said, resulting in a “warm and cozy computer room.” The tubes all power up in random states, requiring the machine to be reset each time it is switched on, but then it’s ready for the fun part: computing.

The entire thing uses NOR (i.e., not OR) gates, just like the Apollo guidance computers that got humans to the Moon, which allows it to be a bit smaller than some of the other classic tube computers of yesteryear. As for what it can do, well - 16-bit math is a possibility, as well as anything else that can be done with a limited set of 16 instructions on a 4-bit instruction register.