[Matthew Arnoff] built an 8-bit computer around the Motorola 6809 processor. He chose this processor because it seems there are a lot of Z80 builds out there and he wanted to try something different.

When you think of tiny microcontroller boards, you probably think of a modern surface mount processor. Not [Andreas Jakob]. His 5×5 cm keychain computer rocks a 6809 CPU at a blistering 1 MHz or, if ...