While newer Arduinos and Arduino compatibles (including the Hackaday.io Trinket Pro. Superliminal Advertising!) either have a chip capable of USB or rely on a V-USB implementation, the old fogies ...

But what if the Arduino Uno was released in 1980? You’d probably get something like [ElectroBoy]’s 8051-based Arduino Uno. The board itself also has some differences from the original Arduino Uno.