The Durham adaptive optics real-time controller

The Durham adaptive optics real-time controller was initially a proof of concept design for a generic adaptive optics control system. It has since been developed into a modern and powerful CPU based real-time control system, capable of using hardware acceleration (including FPGAs and GPUs), based primarily around commercial off the shelf hardware. It is powerful enough to be used as the real-time controller for all currently planned 8~m class telescope adaptive optics systems. Here we give details of this controller and the concepts behind it, and report on performance including latency and jitter, which is less than 10~$\mu$s for small adaptive optics systems.