Mark Wilson of New Zealand created an Arduino-based emulation of the KENBAK-1, one of the first, if not THE first personal computer, released 40 years ago.

Fully assembled and powered on. The LED indicates that the INPUT register is being displayed, pressing the 8 buttons on the left will toggle the corresponding bits and LEDs. The four contol buttons provide for setting the address, reading/writing memory etc.

Flickr set and source files.