The Altaids Computer Kit is a small single board computer, same as the Raspberry Pi, BeagleBone Black, and Arduino. It uses parts that would have been used in the late 1970s/early 1980s (so, no surface-mount!). When connected to a monitor it has the ability for program development.
The Altaids Computer shows that retro-computing doesn't need to take up a lot of space. If you want to relive the early days of computing with a small 8085 computer board, go out and build your own Altaids Computer.