An introduction to communications

computerA computer sitting there by itself is all well and good. It is fairly easy to set up and manage a single computer. You can load up new applications on to it. You can do your homework, play games, listen to your CDs and play your films on DVD.  There are some limitations, though. For one, you can't email your friends or contact them in other ways, for example, using Skype or another video chatting application. Not being able to communicate in this day and age is a real downside. Another big problem is that you can't share files or use online software and you can't share hardware. For example, you can't work on your homework in a word processor and then just go to the other computer and get the file back from it (unless you started transferring files on to pen drives, which all takes time). And if you had two 'standalone' computers (ones that aren't connected to other computers), then each one would need its own printer to print out work. Again, you could mess around copying files from one computer to another on a pen drive, or unplug and then plug the printer into the computer you need to print from, but this is a lot of messing around.

It would be much better to be able to connect computers together so they can communicate with each other. If you create a 'network' of inter-connected computers (called 'clients'), you can send and receive email and other communications and you can share files, software and hardware.


A network is simply more than one computer that has been connected together so they can communicate. A computer that is part of a network is often called a 'client' when you are talking about networks. If you had three standalone computers, how would you make a network?

1) You would need to buy a network card for each computer. (They are sometimes called 'network adapters'). You have to fit a network card into a slot inside the computer. A network card gives your computer a unique address on the network, just like a postal address. It also provides a socket so you can connect some network cable to it.
2) You need some cable. You could use wireless, but for the moment, we'll just stick to a simple, traditional network that uses cables.
3) We need a box called a 'switch'. Actually, all this does is act a bit like a postman; it redirects messages to and from the correct computer.
4) You connect the network cards up to the switch using cable.
5) You then get a 'server'. The server is actually just another computer. It's usually very powerful with a big hard drive and lots of RAM because you are going to store all the software on the server and everyone's personal files.
6) You connect the switch to the server using some of your cable.
7) You connect a printer to the server using some more of your cable so that everyone can print out. note that you only need one printer because all the computers on the server can share hardware.
8) Finally, we want an Internet connection, so we connect a modem (or a 'router', a 'modem router', or a 'wireless modem router') to our server using yet more cable.
9) Finally, our network has to be managed and controlled, so we need a 'Network Operating System' or NOS for short. This will manage the computers (the clients), create login accounts for security and take care of all of the communications around the network.

That's it. All networks follow the above design, more or less. you school network will almost certainly be similar to the above. Users with an account can now log in, send each other messages and use other forms of communication and share files, software and hardware.

Networks are more complicated than standalone computers so you might have to employ a Network Manager if your network grows large. you also have to buy extra software and hardware for them like network cards, cable and network operating systems. But the benefits of networks nearly always outweigh these extra costs.

Q1. What is meant by a standalone computer?
Q2. What is an advantage of a standalone computer?
Q3. Describe two disadvantages of standalone computers.
Q4. What is meant by a network?
Q5. What does a network card do?
Q6. What's another name for a network card?
Q7. Describe two jobs a switch does?
Q8. How does a network operating system make sure that only authorised users use the network?
Q9. What is a modem router for?
Q10. What is a disadvantage of a network?

Extension tasks
a) If you want to connect to the Internet, you have to have an account with an ISP. What does ISP stand for?
b) Search the Internet for 'ISP UK'. How much does it cost roughly on average for a household to have an account each month so you can access the Internet?
c) Are all ISPs the same? If you had to decide which one to choose for your household from the hundreds of companies, what kind of criteria might you use?