How Computers Operate
First I think a few introductions are due. Before talking about what each part of your computer does we are going to go over a short list of things we will cover throughout the rest of this piece of writing.
-CPU (central processing unit, or processor for short)
-RAM (Random Access Memory)
-Motherboard, we will discuss how this works.
-Hard Drives
-Video Cards
-Sound Cards
CPU
The CPU in every computer has one purpose, to process data. Basically it does what it is told. Each time you start an application, the application sends information to the CPU to be distributed to the parts it needs to go to. Take a game that has been installed to your hard drive as an example. When you click on an icon to play a game all the programming code goes from your hard drive to the CPU. The CPU is in charge of controlling every aspect of how the game is supposed to be run. The first thing it probably has to do is to distribute the code that important to your graphics card to run what has been coded. All games have an introduction of some sort and it’s usually the first thing you see when a game is loading. After the loading screen, more pieces of code is send from the CPU to handle such things as sound, taking keyboard or mouse commands. Click or typing something will usually get a reaction of some sort out of any game. The CPU is responsible for checking to make sure that what you type or click will result in the required action. The job of the CPU is tough because it is responsible for keeping track of and processing every single thing on your computer.
The CPU assigns all the parts of your computer with an address, or a name. In respect, each device on your computer has a name for itself for when it needs to contact the CPU, the interrupt address.
RAM
Before I get into to much detail about how RAM works there are a few things you should know about how applications and programs work. Programs and applications are put together by computer programmers. They use one of several different types of programming languages. The code they write to make these programs run requires information to be saved to a specific place on RAM. The code they write can do any number of things such as mathematical operations to sorting other data and ultimately running the program. Each and every piece of code they write has to be saved somewhere since all of the code they write will not be used all the time, it will be used only temporarily throughout the length of time the program is running.
Random Access Memory or RAM, as it is more commonly named today, is the CPU’s main helper. A stick of RAM consists of a few memory modules melted onto a circuit board. If you look at a stick of RAM you can see these modules that I am talking about. Most of the time they are black rectangles that go from the top and almost touch the bottom. There can be any amount of these modules on a stick of RAM. Depending on the type of RAM you have the modules can be on only one side or both sides of the circuit board.
Think of these modules as empty bank vaults. Each one of the modules can hold a specific amount of items. As I explained earlier about applications and programs, all application require a certain amount of space on RAM to work efficiently. Now, every time you load an application it takes the needed code and data to the RAM, the CPU assigns the code and data to a dedicated vault somewhere on the RAM. The CPU will keep track of all information that is stored on RAM while it continues running the application. When the CPU needs more code or data that was stored on RAM it knows exactly where it put and simply goes there and gets the information. The code and data on the RAM doesn’t do anything. The RAM just holds this information for when the CPU needs to use it again.
So when any application is running the vault will be loaded with items of code and data. The ‘bank vaults’ on RAM chips are iron clad and cannot be broken into so everything stored in them will remain there until the CPU decides to release it. However, there is one other way for all the items in the ‘bank vault’ to be removed. Most RAM requires an electrical current to keep the vaults closed. If it looses the electrical current (the power goes out or you turn your computer off) the doors will open and cyber bunnies will come and take everything in the vault to the land of forgotten enchantmentâÂ?¦Just kidding about the bunnies, but your information stored on the RAM will be lost!
Motherboards
There are several parts to a motherboard. For now we will only talk about a few specific parts that are directly related to the CPU and RAM. We will stop short of fully explaining the motherboard in its entirety to help you get a better understanding of how other parts contribute to how the motherboard works. Just know that these following items are part of the motherboard.
Chipsets
A chipset is the combination of two different chips that are located in a certain place on the motherboard. The two types of chips are called the Northbridge and the Southbridge. We will first talk about the Northbridge as its main purpose is to work closely with the other two topics we already discussed, the CPU and RAM.
The Northbridge is essentially responsible for controlling the speed of the data flow between the CPU and the RAM. It is often labeled as the memory controller. It also dictates what type of CPU and RAM is allowed. All information that needs to go from the CPU to the RAM, or vice versa, must go through the Northbridge. It is solely dedicated to moving the data to and from the CPU, RAM and the AGP or PCI-Express lanes. We will talk about AGP and PCI-Express a little later.
Think of it as a mailbox for data that is transferred from one device to another. When a device needs to speak with the CPU, if
the CPU is busy the data is stored into the Northbridge until the CPU can get to it.
Before we finish up with talking about chipsets we are going to break away from the motherboard altogether. In order for you to get clear understanding we must introduce you to other pieces of hardware.
Hard drives
The inner workings of hard drives consist of 4 main parts; Tracks, Cylinders, Sectors and Heads. The platters look similar to what a CD-ROM looks like except is a lot slimmer and has a mirror like surface on both sides. Each platter is broken up into 3 parts; Tracks, Sectors and Heads.
Platters are made up of concentric circles. To help you understand what that means we are going to make a little drawing, don’t worry you don’t have to be an artist. So grab a sheet of paper and a writing utensil! Start by drawing a fairly large circle. Inside the circle draw a smaller circle inside the first circle. Inside that circle draw a smaller circle, continue doing this until you can’t fit anymore circles inside the first circle you drew. The whole drawing is what you would call a platter. Now, the spaces between all the circles are called Tracks.
Now image a yummy apple pie. When you go to get a piece of that pie you cut a small triangular piece out of the pie. On your drawing draw a line from the top of the circle all the way down to the bottom of the outer circle. Then draw another line from the left side of the outer circle to the right side. Continue drawing line until it looks like pieces of a pie. Don’t make to many slices because it will be difficult to talk about the next part if you don’t leave yourself enough room. Four slices should be enough. Each ‘slice’ is what you call a sector.
Hard drives usually consist of several platters stacked on top of each other. For example let’s say there are 8 platters in your hard drive. Take any one sector from the top platter and continue to take a sector from all the platters beneath the first platter until you get to the bottom platter. With 8 platters you should have 8 ‘slices’, or sectors. These 8 sectors are what you call a cylinder.
All the information on your computer is usually stored on sectors, cylinders and tracks. The hard drives uses two tools called an actuator arm and a read/write head to imprint all the information on sector, track and cylinder. The actuator arm moves back and forth across the top platter as the platters are spinning at really high speeds.
On the back of the card drive there is a small circuit board on the drive. It contains the card drive memory controller. When information comes into to hard drive, the memory controller will receive the data that was sent to it and save it to the hard drive at its own speed. This way the CPU doesn’t have to wait for it to finish if it needs to do something else with the hard drive. This, in turn, takes a lot of strain off of the CPU.
Video Cards
If you are into video editing, games, 3d modeling or 3d art than this could be the most important part of your computer. The video card is responsible for making all the eye candy on your computer come to life. Without a graphics card everything on a computer would still only be made up of 8 colors. Graphics cards can vary in size. The older ones can be a small as a pamphlet and the larger ones can be as big as a paperback novel.
All the program code and data that the graphics card needs to do its job comes with the application or program you are running. The information is sent out from the application to your graphics card. Graphics cards are so advanced these days that they simulate what a computer does. It has a CPU, it’s called a GPU (graphics processing unit) which is responsible for doing just about the same thing the CPU of your computer is. The only exception is that the only devices you can hook up to them are video related.
Sound Card
The sound card is responsible forâÂ?¦yeah, you guessed it, sound! Without it we would still be in the days of using the sound form small motherboard speakers. Beep, Beep! Without the kind of sound we have today computer wouldn’t be nearly as interactive as they are now.
Piecing it all together
Here we go, this is it! You may have been wondering when all this data is sent and received, where it was going to or coming from and how it was getting there. Located on your motherboard there are tiny lines that all this information travels called the system bus, lets call these highways for the sake of simplicity. Each piece of hardware sits at in its home (its place on the motherboard) and stares out the windows constantly looking at the highway outside. Almost constantly there is a lot of traffic on the highways zipping up and down at speeds faster than you can imagine.
Each device is looking for its specific name that the CPU gave to it. If you remember me talking about it early I called it an address. Let’s say that you double click on a music file for it to play. The electrical pulse goes from your mouse to your motherboard. It just on the highway and immediately makes a run for the Southbridge.
The Southbridge is the second part to the chipset we were discussing in the motherboard section. It is responsible for maintaining the flow of data between all devices connected to your motherboard, aside form the graphics card.
Once the pulse reaches the Southbridge the Northbridge takes the information from it and sends it to the CPU. The CPU looks at the data and can tell that it’s a sound file. After it figures out what type of data it is and gives it a name (or address), it sends it back to the Northbridge which in turn sends it to the south bridge and it then hops on the highway. As it is traveling down this highway and it comes close to the sound card, the eager waiting sound card quickly nabs the information off of the highway and does its own thing. The sound card can identify that it belongs to him because of the address the CPU gave to that information. After the sound card is finished with the data he puts his name on it (or interrupt address) and throws it back onto the highway. It works it way back to the Southbridge then the Northbridge.
The Northbridge holds this information until the CPU is ready for it. The CPU can see what is on the Northbridge with a quick glance. The Northbridge is trying desperately to get the CPU’s attention by holding up the name that the sound card sent back with the data. The CPU will decide if the information is relevant at this point or not. If it is, it quickly nabs it, if not the data is left there. Obviously since we were trying to listen to a sound file the CPU is waiting for that information. So it takes that information and processes and sends the required sound data back through the bus and out to your speakers.
This happens when your do anything with your computer. All data goes through the bus system on your motherboard and meets up at key places. All parts work together while the CPU is the main driving force behind it all. You should now have a general idea of how a computer really works.
