The rover computer is inside a module called "The Rover Electronics Module" (REM). This lies inside the rover body. The communication interface that enables the main computer to exchange data with the rover's instruments and sensors is called a "bus". Bus communicates with all controls of the rover motors.
The computer contains special memory to tolerate the extreme radiation environment from space and to safeguard against power-off cycles so the programs and data will not accidentally erase when the rover shuts down at night.