Arduino Altair 8800 simulator

For a long time I have thought it would be cool to have an Altair 8800 computer to play around with. But working vintage Altairs are rare and therefore expensive, easily costing $1500-$2500 if available at all. There are some other options, such as but that still costs $600 which for me is too much to spend on a computer that - while very cool - will be of limited use. At some point I was looking at the specs for the Arduino Mega 2560 and started wondering whether it would have enough I/O pins to just hook up the LEDs and switches from the Altair front panel and write my own emulator software. Turns out the Arduino Mega has exactly the right number of I/O pins. So I just had to make my own Altair clone.”