This is an Arduino-based emulation of the KENBAK-1, considered by some to be the first "personal computer". It was first advertised for sale in the September 1971 issue of Scientific American (forty years ago!).
I'd been thinking for a while that emulating an old-school switches-and-lamps computer would be a fun Arduino project, but had stalled looking at things like the Altair 8800 with its 30+ lights and 20+ switches. However, when I stumbled upon the Kenbak I thought it was something I could pull off as my first real Arduino project. Naturally I called it the KENBAK-uino.
This is the end-product, it can be programmed via the buttons on the front panel and show outputs on the LEDs. It's a faithful emulation of the original CPU but with a few enhancements thrown in like pre-loaded sample programs and access to a real time clock.
See the set.
See the videos.
Get the Arduino sketch (source code) from here.