Controllers

The CPU also contains a number of interfaces or controllers to access devices and busses. On of the primary functions of a controller is to free up control unit time by performing routine or clearly identified tasks. A typical microprocessor will have a controller interface to slow-speed devices such as serial data connections, high-speed interfaces connected to a computer bus, and connections to dedicated registers containing report status. These controllers will also typically interface to other controllers on a bus for specific types of operations. The details of this are not important for the A+ exams, but they have a huge impact on system performance because they relieve the control unit of unnecessary work.