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Computer System Components: Computer Parts & Functions

Desktop or Laptop?

I typically refer to the computer I use as my laptop. The one my son uses is our desktop, even though it doesn't sit on the desk!

How about we go shopping for a new computer system for you? First we'll have to figure out if a desktop or a laptop is going to be best for you. One thing that I'll use in terminology is the system unit. This is the case that contains all of the components needed for your computer to work. The two constructions available to you are the desktop (or tower) or a laptop.

Laptops are for the user who prefers portability. This unit is common for someone like you - a college student, consumers who travel frequently and business people who find themselves working in places other than their office.

The desktop, or tower, is intended for a user who doesn't need a computer that is portable. They are larger in design and often have more features and computing power.

Now that you know for sure what the differences between the two are, which system seems like it would be best for your situation? Let's talk about the details of how computers we're looking at are put together. Many of the components I'll show you will have more than one choice for you. Your budget is going to be what drives many of the decisions that you make.


Now, the first thing is the motherboard. It's the basis of your computer. It's the first component installed in the system unit, and it holds all of the circuitry that ties the functions of the computer components together.

You can think of it like your car (which has many computer systems of its own). If you have a frame and tires, you've got a car (or you've got a system unit), but it won't take you very far! Now, add your engine - the motherboard - where all the systems tie in one way or another, and you've got the start of a working vehicle.

Central Processing Unit

The motherboard and circuitry need to have power. There is a power box included with your system unit, and you'll see a cord coming out of the back of your computer for that. The central processing unit, or the brains of the computer, sits on the motherboard and does actually have its own cooling fan. The processors now are so fast they need to be cooled down. All the instructions you give the computer - like a click of a mouse - go through the CPU, which processes in billions of cycles per second. Commonly installed processors have quad-cores, or four separate processors in one component. There are six-core and eight-core available, and the more advanced the technology the higher the cost. That's one of the choices you might need to make.

Memory, Cache, RAM, ROM

Next to the CPU sits the cache, or the temporary memory where things you are working on sit for quick interpretation by the CPU. The RAM chip is also near this location. Random-access memory is volatile, or temporary, memory. Whenever you turn on a program, its instructions are stored in RAM while the machine is on. Once you shut the machine down, both the cache and the RAM are completely cleared out. RAM storage is common at eight, ten or twelve gigabytes.

ROM, or read-only memory, is located here as well. This is a permanent, or non-volatile, memory. As soon as you turn on your computer, the start-up instructions that are stored in ROM begin to execute. Even when you turn it off, the instructions stored in ROM remain. So if you have a machine that runs Windows, as soon as you hit the power-up button, you'll get a short screen that might give you a message from the manufacturer. Then in the background you'll just see black and the Windows logo come through, and it will say 'Starting Windows.' What's going on there is that as soon as you hit the power button, your ROM is kicking in and starting up all those instructions for systems checks.

The part attached to the motherboard you're most likely to recognize is the hard drive. The hard drive doesn't sit directly on the motherboard, but it is connected to the circuitry by electrical wire. The hard drive stores software you've put in there like Firefox, WordPad or a music player. It also stores the data files those programs have created and used. Hard drive storage commonly begins at one terabyte now and goes up to two and a half terabytes.

The hard drive stores all the software programs you load onto your computer. Hard Drive Picture

Video and Sound Cards

Let's take a peek at the video card, or the graphics card. This card is used to process images so you can see them on your computer. As a standard computer user, the video card included with the system you are looking at will suffice. If you are a gamer, or really into working with photos or digital art, you may be looking for higher-end cards. These cards are more expensive, but typically have their own CPU for better and faster processing of images. Many video cards now allow for more than one monitor to be hooked up to the system.

I don't know about you, but I really like that I can listen to music with my computer when I'm working or cleaning the house. The sound card on the motherboard lets us hear from an internal speaker. We can also plug in peripheral devices such as speakers, microphones or headphones. You should think about where you will be using your computer. If you're going to end up needing to use headphones most of the time, or speakers that are included with your system, the stock sound card will work just fine for you. If you want something that jams, you may need to upgrade.

Network Connections

A part of the system unit most of us take for granted these days is the wireless local area network card, or the LAN card. This is the card you actually don't see signs of from the outside of your unit, but it is what lets us connect to our wireless internet.

Another way to connect to a network is by hardwire, or the plugging a jack into the network interface card (NIC). This looks like a telephone receptacle, but is slightly larger.

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