Many people don't know the history of the Kenbak-1 Digital Computer, but it's considered to be the world's first commercially available personal computer -- and one is going up for sale in just a few minutes. John Blankenbaker introduced the $750 machine in 1971 -- years ahead of the more well known Altair 8800 and Apple I, but after the Datapoint 2200 -- hoping to sell it to schools as a way to introduce people to computer programming. It didn't have a microprocessor at all, and contained only 256 bytes (you read that correctly) of RAM. No more than 50 units were ever made, although a few have been popping up for sale in the last few years. One recently sold for about $31k, and another model is going on sale via German auctioneer Breker within the hour. It's certainly a piece of history, but if that's a little too rich for your blood, then hide your credit card details and just read our Time Machines article to catch up on the history of this groundbreaking device.