1. A computer system, comprising: a central processing unit; main memory accessed by the central processing unit; a video system for driving a video monitor in response to the central processing unit; and an accelerator receiving input data from and providing output data to the central processing unit, the accelerator comprising: at least one graphics processing unit; accelerator memory for the graphic processing unit; and an accelerator controller for moving the input data into the accelerator memory, moving output data from the accelerator memory, and supervising data exchange between the accelerator memory and at least one graphic processing unit.