What is a Motherboard?
Prior to the invention of the microprocessor, a digital computer consisted of multiple printed circuit boards in a card-cage case with components connected by a backplane (a set of interconnected sockets). The CPU, the memory, and peripherals were housed on their own printed circuit boards, which were plugged into the backplate.
During the late 1980s and 1990s, it became economical to move an increasing number of peripheral functions onto the motherboard. In the late 1980s personal computer motherboards began to include single ICs capable of supporting a set of low-speed peripherals: keyboard, mouse, floppy disks, serial ports and parallel ports. By the late-1990s, many personal computer motherboards supported a full range of audio, video, storage, and networking functions without the need for any expansion cards; higher-end systems for 3D gaming and computer graphics typically retained only the graphics card as a separate component.