Motherboard / Mainboard

The motherboard is the single-largest electronic chip in a computer system. Think of it as the nerve centre of the machine. All other key systems and components sends their signals and messages to one-another via the motherboard, into which they are all connected.

The motherboard (or mainboard as it is otherwise known) can be found screwed to one of the internal sides of the case. Being the largest chip, it is pretty hard to miss it when you take the side panel off your computer.

The image below shows a basic computer system with the side panel removed from the case. You can see the motherboard at the bottom of the case. It is the big green electronic chip positioned toward the bottom left of the case and covering about 60% of the total area.

As you can see, there are also various other components all linked into the motherboard. Some are major components like the CPU, the RAM, and the Hard Disk Drive (see articles on these) and other components are minor ones, such as the small cylindrical capacitors, coils and pins dotted across its surface.

The motherboard is home to what is called the BIOS. The BIOS is basically a set of instructions that tells the system what it has to do when it is first powered on. Did you ever wonder how your system can work out what to do after it has been unplugged and plugged back in again?

Going back to the previous image, you will notice a round silver shape toward the bottom right corner of the motherboard - just underneath the two black cables. That is the BIOS battery, which allows the system to remember the vital start-up information it needs, even when disconnected from power. Since this is only a tiny amount of data, it does not require much power to store.

The motherboard also features some things you might be more familiar with if you have ever connected your computer up yourself. Most of the ports and sockets on the back of your computer, into which most other external things such as your monitor, keyboard, mouse, USB devices, speakers or headphones, printers etc. are all connected, all form part of your motherboard.

From the back, a motherboard looks something like this, and this is the side the protrudes through the back of your computer case.

This is a very basic version of the back of a motherboard, and some of the more modern boards have significantly more ports for USB, Ethernet and Audio jacks. However you will probably recognise some of these connections, if you have ever seen the back of your own machine.

Most modern boards will still have the purple and green PS/2 sockets for keyboard and mouse, USB ports (but likely more of them) and the standard blue, green and pink audio jacks. Many modern boards have 6 audio jacks to support 5.1 surround sound.