What are the minimum hardware requirements for mining in a bitcoin pool? Note that I'm not looking for profitability, this has been answered numerous times. I'm more into setting up an old computer to learn how things work. But I guess there are minimum hardware requirements to be able to  mine at all, e.g. being able to transfer blocks when a hash is found and a new block gets the attention. Are there any limits in the pools? Pools might not want participants that are so weak that they just create administration? If so, what is the minimum hash rate level, or is there another figure limiting pool access?