A motherboard is the center board in all-in-one systems and many other expandable devices. It holds and facilitates communication between all the key electronic components of the system, including the central processing unit (CPU), main memory, hard drives, random access memory (RAM), and video display output port. The motherboard also controls the other peripheral devices, such as printers, keyboards, USB devices, video card, ISA cards, and others. Motherboards can also be integrated with a computer's operating system to provide a complete means of input and output for computing devices.