We have a family friend, Glen, who was an important NASA scientist on the Apollo project. As a mathematician, he invented the idea of using a Fourier Transform to filter data on a digital computer. This was used to filter out signals coming back from in-flight rocket sensors and reduced the data processing time and increased the volume of usable data substantially. Reducing data processing time meant more flights could be scheduled and more adjustments could be done per flight and more things learned from each flight. Processing turnaround was the main bottleneck in the moon program at the time and solving it was the key element in not only winning the race to the moon, but doing it far more safely than would otherwise have been possible.

Glen built his own computer from TTL logic chips back in the early 70s. You programmed it initially by flipping nice thick metal toggle switches. He toggled in an assembler to bootstrap it, and eventually worked his way up to a keyboard and CRT for it. While visiting him one summer, I played an adventure game on it.

Today I read about a teacher in Portland who built a computer not out of TTL logic chips, but out of physical relay switches. He teaches computer architecture and if you want to understand that topic, watch his 1 hr video.

Then visit the web ring of homemade CPUs, linked from the bottom of that page. What fun!

Among the links is this web page:

http://www.magic-1.org/

Yes, that web page is being served to you by a webserver running in Minix, a small Unix, on a computer designed and built by hand using discrete logic units wirewrapped together.

Details of that computer and a photo:

http://www.homebrewcpu.com/