Welcome to the first of what may be a series of articles on the home computer.  It is not a technical article and makes no pretences at converting the reader into a computer wizard.  It is aimed at the people who have bought a computer for educational or recreational purposes but who would like to know a little more about their machine. 

In this article, I’ll be describing what goes on inside the ‘tower’ of your computer – please remember that the home computer is an electrical device and you shouldn’t attempt to dismantle it for safety reasons!  If you do ever need to look inside your PC for whatever reason, always refer to the instruction manual for safety instructions.

With that off of my chest let us begin.  As you are reading this I can safely assume that you have in front of you at least a screen, a keyboard, a mouse, a modem and a box packed full of hard drives, floppy disks, CD's and various electronics.  It will come as no big surprise to you that we "in the trade" call this a computer. 

See, it's not rocket science so far is it? Let's begin our trip around your computer.

We are first going to take a look at what's inside the case.  I will take it step by step working outwards to the "flashy stuff" such as the monitor and keyboard.  The first thing we need to do is switch the darned thing on so the number one item on the tour has got to be the power supply.  This is usually fixed at the top rear of your computer and can easily be recognised (from the outside) by the fan grille.  The power supply is rated in watts.  A typical wattage is 250 watts to 300 watts.

Now we move on to the motherboard.  Looking from the front of your computer case the motherboard is usually fixed vertically to the right hand side of the case. 

The motherboard is the centre of your computer’s universe. Everything plugs into this board, all the bits and pieces of electronic wizardary live here.  All these parts, apart from the Central Processing Unit (CPU) or chip, may be classed as a peripheral. 

So what is a peripheral?  Well, the dictionary defines it as something of importance but not of major importance.  So the motherboard is of major importance and is the device through which every single action is routed to the appropriate peripheral.

We now come to the brain of your computer, the chip.  The chip is known as the Central Processing Unit (CPU) and if you have a sticker on the case announcing that you have "Intel Inside" then this is the little monster to which it refers.  This device plugs into the motherboard and makes everything happen.  Nowadays its speed is measured in Megabytes per second and is the figure we like to use when describing our machines to others.

Now we need memory.  The memory type is Random Access Memory (RAM), which means that it only holds data whilst the data is required or the computer is switched on.  RAM comes in various flavours but has one thing in common: it comes as a long thin printed circuit board roughly six inches long by one and a half inches wide.  It is usually referred to as a "stick" of memory.  Most motherboards allow two sticks to be plugged in side by side. 

A stick varies in memory size from 128 Megabytes to 512 Megabytes and can be easily upgraded.  Upgrading the memory in your computer is one of the best (and cheapest) ways to make your machine run quicker if it’s getting a little sluggish.  Remember – RAM is not used to save data.  That is the job of the hard disk drive (HDD), which gives me a good lead into the next section.

The hard disk drive (HDD) is usually bolted into a slot or tray beneath the floppy disk drive at the front of the computer case.  The hard drive can be thought of as a very advanced tape recorder.  You can record and play back but instead of music you record computer programs.  The operating system (usually Windows) is stored on it.  Every program or game you use is stored on it.

Let's take a simple example using the tape recorder analogy.  You wish to write a note in (say) Notepad. You double click the Notepad icon and "play" the Notepad program.  You write your short note.  You can “record” (save) the note you have written in Notepad onto the hard disk.  You close Notepad and there it remains on the HDD until called again.

So, just to clarify between RAM and a HDD.  The HDD is where you permanently store your program.  RAM is the memory used by the computer as and when it needs it – to run the programs that are stored away on the HDD.

We move now to the three and a half inch floppy disk.  You can see the disk input slot at the front of your computer case.  Again this connects to the motherboard.  Some computers may have two floppy drives, and increasingly these days, some may have none at all.  The floppy drive is known as a ‘removable’ drive for pretty obvious reasons; you can use a floppy disk in any computer but try removing your fixed HDD to another computer - difficult. 

The floppy drive is now somewhat obsolete due to the large amount of computer data you may wish to share with others.  Alternatives to the floppy drive are read/write CD's or the more convenient USB plug in memory sticks such as the Disgo.  A floppy disk will hold 1.44Mb of data whilst a CD 640Mb and a memory stick 125Mb to 256Mb.

Just a quick mention of your CD, CD-RW or if you are up to date CD-DVD's. These also plug into the motherboard in exactly the same way as your HDD. These devices are again designated as removable data drives.

We finish our tour of the innards of your computer case by mentioning the cooling fans, information lights or LED's (Light Emitting Diodes) and the internal speaker used as a warning device during computer boot up.  Like everything else these are controlled by the motherboard.

Now we move outside your computer case.  At the back of your computer you will find various sockets to connect the external peripherals.  By now it will come as no shock to learn that all these sockets are connected to the motherboard.

Apart from the keyboard and the mouse sockets, which are colour coded, all the other sockets are designed to take only the appropriate plug from the appropriate peripheral.  Thus the monitor plug will only fit into the monitor socket.  Likewise the printer, modem, USB devices will only fit the correct sockets.  Of course this does not exclude the over enthusiastic from trying to force something to go where it should not but reasonable people will have no problems. 

I don't need to explain what the 'outside' peripherals do as you have already proved you know that by connecting to this site using your mouse and keyboard!

I hope the above has not proved over simplistic and that you have found it of some use.  As I said at the beginning this article it is not written for the computer graduate.  It is a very simple tour for the computer owner who simply uses the machine as a tool but wishes to gain a little knowledge for when he/she replaces or upgrades.  Depending on the interest a future article will explain what to look for when buying or upgrading a computer.