What does a bus do in computer systems?

A bus in computer systems serves the purpose of transferring data between different components such as the CPU, memory, and input/output devices. This orchestrated movement of data is crucial for the overall operation of the computer, enabling communication and coordination among its various parts. Buses can be categorized into data buses, address buses, and control buses, each playing a specific role in managing this exchange of information.

The other options describe functions that are not directly related to the primary role of a bus. For example, storing data and instructions for the CPU pertains to memory units rather than the bus itself. The connection of external devices to the main system is typically managed by interfaces or ports, not solely by the bus. Similarly, providing a video output interface relates to graphics cards and display outputs rather than the data transfer role of a bus. Hence, the role of a bus is fundamentally about facilitating communication within the computer system.