It is a 4 bit binary counter to decimal display decoder. It uses a lot of AND gates and comparators. Instructions on how to get to it are above. It took me about a week to make, I started by designing the display and the counter itself, then I moved on to the decoder. The decoder took the majority of the time. Most of the time was not designing it but just building it. It was very tedious to work my way up all the way to 15. Considering that it was my first large scale redstone creation, it isn't too bad!