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Definition: motherboard


Also called the "system board," "main board" "base board" or "logic board," it is the primary printed circuit board in a computer or other electronic device. In a modern desktop computer, the motherboard contains the CPU and RAM sockets as well as the chipset, which houses the control circuits for all the peripheral devices (drives, keyboard, mouse, etc.). A motherboard typically also has a PCI-Express slot for a high-end graphics card and PCI slots for additional peripherals. Laptop motherboards do not have expansion slots for more peripherals.

Wanna Sound Cool?
Every now and then, say "mobo" instead of motherboard, and you will be a "cool geek." See CPU, chipset, PCI Express, PCI and controller.




PC Motherboard
This earlier Baby AT style motherboard required plug-in expansion cards for almost all the peripheral devices. The ISA slots are long gone, and the AGP slot was replaced with PCI-Express.






Expansion Cards
On earlier PCs, expansion cards were required for almost all peripheral devices except keyboard and mouse. Today, enthusiasts may plug in a faster graphics card, but most peripheral control circuits are already on the motherboard.








The Mother of All Motherboards
This is the front and back of the prototype of the first IBM PC motherboard in 1981. The chips are wired together on a "breadboard." (Images courtesy of IBM.) See breadboard.