Computers have helped humanity since they were invented. From huge installations from the mid-20th century they were gradually improved and developed into smaller and faster versions. When you think of a computer you may think of the laptop you are be carrying. You will also automatically think of technology. The truth is that everything around you, and not just your laptop, is technology.
This essay aims to give you more knowledge about your computer. To do so, a four layer model will be used. It divides the computer and its environment into four layers. These are: the hardware, software, network and people. The higher layers have a broader function, but each layer can't function without all the layers below it.
The Hardware
Computers consists of several components. These are the motherboard, central processing unit (CPU), hard disk drive (HDD), optical disc drive (ODD), the power supply, lots of wires and cables, memory (RAM) and the case.
The motherboard could be seen as, like the name suggests, the 'mother' of the whole computer. This is because every single thing in the case is in some way or another connected to the motherboard, directly by cables.
Another very important part of the computer is the power supply. It supplies the electrical power the computer needs to run. The voltage delivered by the power supply depends on the kind of computer you are using. The power supply in a desktop computer usually gets its power from wall sockets and converts the 230V from the socket into 5V and 12V, the voltages that the components in a PC use to run. The power supply in a laptop is a battery, mostly on 19V.
All other components have a very specific function and aren't as broad as the motherboard.
The CPU (Central Processing Unit) is the brain of the computer. It performs the instructions it gets from the software.
The RAM (Random Access Memory) is one of the determinants of your computer's speed. The more RAM you have, the faster your computer will be able to process information, thus shortening waiting time. RAM is fast but volatile. During the shutdown process your computer sends all information that need to be stored from RAM back to the hard drive, where it will be saved for future use. The harddrive (HDD) has opposite properties to the RAM. It is relatively slow but is like the storage room of the computer as it stores all your software and information permanently. For everything it does, the CPU accesses the HDD and takes the information it needs, lets say Word. It then puts this information to the RAM, and then starts processing it, like editing your Word document. You can then do whatever the installed software allows you to do.
RAM is organised in 'pages': certain blocks of memory. If all this memory is full and you open a new Word document, the computer will write the information of one of the pages back into the HDD. This takes some time, causing the slight delay that many, if not all, computer users are familiar with. When you then want to use that information it will again take some time before everything is back in RAM. The more information has to be send back or restored, the longer the delay will be. The process of throwing out information and restoring it is called swapping.
If you have more RAM, you will have more pages, enabling you to run more programs at a time and spreading the amount of information more, thus making your computer faster. The process of spreading the information out over several pages is called pagination.The less RAM you have, the more frequent information has to be swapped to the HDD, making your computer slower. Unfortunately, RAM is relatively expensive memory, so you can't have as much as you like. The motherboard and operating systems also pose limits to how much RAM they can handle.
The Software
The software is what enables you to actually do something on your computer. To download software on a newly made computer you have to insert a CD in the ODD containing the software. Usually, all software is stored in the HDD. There are different kinds of software. The main groups can be divided into the Operating System (OS) and the applications. There is also a third group called the drivers (which make the hardware work correctly), but some argue that these are part of the OS. The OS is what controls the operation of all the components and make sure your application will work regardless the hardware setup of your computer. The applications are the programs like Word, iTunes and Pages. You will spend most of your computer time looking at one application or the other. The applications are more visual and on-screen programs whereas the OS does all the backstage work.
Examples of different kinds of OS are Snow Leopard, Windows and Ubuntu. Unlike the other two named, Ubuntu is a completely free and Open Source operating system. Open Source software gives you access to all source codes (program lines).
The network
A network is a set of computers linked together so they can communicate with each other. The internet is a network of networks, as it consists out of a huge amount of networks to make one big worldwide network. A kind of ubernetwork. The internet was originally designed to be a nuclear attack proof way of communication for the American army. The army wanted to work around the fact that telephones needed a direct connection to a central exchange. They wanted a communication system that would not be destroyed by the first bomb on the central hub, but would stay intact. If you send something over the internet, it breaks up into packets. Each packet has a number and each has to find its own way to the receiver, hopping across networks. They would always try to find the fastest way to the receiving server. As the packets had thousands of alternative routes they could follow to the destination, it was (and still is) practically impossible to keep it from reaching its destination. The receiving computer would just put the packets back into order. The system that tries to ensure that data makes it from the source to the destination is called Transmission Control Protocol (TCP). The TCP brings the packets to the right Internet Protocol (IP). The IP is the system of addressing computers on the internet. Domains (parts of a network) resolve into IP addresses.
People
These are the people like you and me that use computers. We communicate by chatting, using applications like Skype, or by using social network applications like Facebook, work and entertain ourselves with computer games both off- and online.
But all these good things have a downside. Computers are great tools, but they also pollute the environment. And that doesn't stop when you stop using it and throw it away. When computers or other electronical devices like smartphones and iPods reach the landfill they slowly start polluting the groundwater of the area. Devices with big batteries like laptops are the main polluters. Their battery slowly starts dissolving and leaks acid in the ground. The wealthier parts of the world, like the USA and Europe dump their e-waste in the less wealthy parts of the world, like India, China and Africa. The situation in Gulyu in China is so bad that the groundwater has become undrinkable.
Luckily more and more countries have started to run waste separation and recycling programs, to which many companies are contributing including Apple, Philips Electronics and Dell.
