I plan to make an fpga mining device for bitcoin mining just for the fun of it. I thought understanding bitcoin as whole would be the first step to take. However I realize that understanding the whole verification and transaction process in bitcoin would take a lot of time. Time that I really dont have. So I just wanted to know what would be the most important things to know related to bitcoin before getting started as only solving the nonce would be the part that I write in verilog/vhdl. The remaining part related to understanding how bitcoin uses Script and processes transaction would be quite unnecessary to know since I am not going to use it for the project. Having said that knowing how the whole system works is important and I will do it but from the point of view of an fpga mining device I would like to know on what to really focus on?