This project is a hard drive emulator for your Atari ST using an inexpensive STM32 microcontroller and a SD card. The aim of this project is to be very easy to build, extremely cheap, reliable and ...

So you've already outgrown Arduino's most beginner-friendly board, the Uno, and are looking to move on to bigger, more exciting projects. In that case, the Nano family might just be what you need.