How Computers Work – Part 4 – The Motherboard III [Mega Series]


No, you didn’t get off the hook. The motherboard portion of the “How Computers Work” series actually needs a third part to fully encompass the beauty of the works of this complex piece of hardware. In this part of the motherboard chapter in my mega series, I’m going to describe the rest of the motherboard, and try to keep it simple. If you got lost in the previous part of the series, don’t hesitate to ask questions. It offers a learning opportunity for those who might wonder the same thing. Remember, the question might be simple, but that doesn’t make the person who asks it simple-minded.


The RAM Controller

If you don’t understand the concept of a bus on the computer, I suggest you read part 3 of the mega series (part 2 of the motherboard chapter). To the right of the CPU socket, you’ll notice a series of long slots that support a certain type of random access memory (RAM) card. We’ll go through this a bit later, but it’s important for you to know that the RAM controller bus holds all the physical memory cards of your computer. See the picture below to get an idea:

The RAM slots sit below the CPU socket in this image.

It might be important for you to know that the typical motherboard can have anywhere from 2-6 RAM slots.

The Chipset

The motherboard’s chipset manages the communication and message queue from different parts of the motherboard. Near the CPU socket, you have the northbridge chip, which manages the most important interactions, such as those with the CPU, the RAM, and any dedicated graphics.

Towards the bottom of the motherboard, you have the southbridge chip, which manages all other interactions, such as the PCI bus, the drives, and USB ports. Of course, the chipset can be more complex than this, but I prefer to give you a simpler description. It’s not like you’re going to make your own motherboard, right?

Here’s an example of the locations of a motherboard’s bridges.

The IDE Controller

IDE stands for Integrated Drive Electronics, which represents the standard which all new drives use. Instead of having a circuit board separated from the drive, manufacturers now integrate them just below the body. It took them a decade or so to realize they can do this, when it takes a 3-year-old only a few minutes to realize that sticking a fork in a wall outlet isn’t a good idea. Both realizations require the same level of intelligence.

Besides gathering power from the PSU, a drive also needs a link that helps it communicate with the rest of your computer. The IDE controller helps make this happen with a couple of connectors. Depending on how old your computer is, the IDE controller could have some long and fat connectors with many teeth (ATA), or it could have a set of small and thin connectors that look much less scary (Serial ATA, or SATA).

Compare this…

ATA: The interface your grandfather used.

To this…

SATA connectors on motherboard

SATA: Nice, small, and sexy, until it’s replaced by something smaller than a cat’s… you know…

These connectors serve but one purpose: They help drives communicate with the rest of the computer.

The Back Panel Connectors

You can go your whole life without opening your computer and still see the back panel connectors, for as the name implies, they’re located on the rear end of the computer. The motherboard always manages the back panel connectors using a series of on-board chips.

On-board graphics are managed by the motherboard’s graphics chip. The USB ports on the back where you connect your USB humping dog are also controlled by the motherboard’s USB interface, and so on.

This is what I’m talking about. Perhaps you recognize it better when you see it.


Since there’s a lot of material on this, I’m not going to bore you with details. The Basic Input/Output System (BIOS) on the motherboard is a chip that tells the computer how to enter the boot sequence. The boot sequence is everything your computer does from the moment you turn it on until the moment it’s finished loading up.

This is the chip I’m talking about.

The complementary metal-oxide semiconductor (CMOS) on the motherboard helps the computer remember things like the hour, the date, and many other system settings related to hardware on your computer. No, it’s not a chip planted by the CIA to determine if you’re engaging in Communist activity.

The motherboard remembers all these settings when you unplug the power through a battery known as the CMOS battery, shown below.

This battery will last you a very very long time.

You’ll know that this battery died if your computer’s date & time keeps resetting every time you remove the power cable. A dead battery makes a computer get Alzheimer’s disease.

I’m now proud to announce that you’ve read all the rudimentary information you need to know about the motherboard. See you on part 5!


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The Tech Guy

Miguel has been working with computers back when the latest processor could print "Hello World" on the screen a couple of times and everyone was going nuts about that. From the days of DOS to the days of 'dows, he's been exploring every minute detail about computers, banging his head against the keyboard until he got it. Now he's blogging about it on his dedicated server until it breaks down, he repairs it, and just keeps on blogging.

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