Have you noticed that it is almost Christmas? I have and as I sit here writing this I'm thinking that I should have bought the Christmas presents, even if it is only the middle of November. The trouble is I have two sons, which makes Christmas rather expensive. The youngest, Jason is not really a problem, since he is still at the toy cars and trains stage. The eldest, Matthew, however, has discovered Duke Nukem 3D. And, worse still, the level editor of Dukey. Now I have no problem with Matthew writing levels for DN3D but I would like to get a go on my computer occasionally :-) Come to think of it so would Jason.

Matthew has a solution. All I have to do is buy him a new PC for Christmas. “A Pentium Pro with 64 Mb of Ram, a couple of gigabytes of hard disk storage, a 10 speed CD Rom, a modem, a Matrox Millennium graphics card with 8 Mb on board and a 21 inch monitor would just about do, Dad”

I offered him my old 486 instead but “It's to slow. The picture is too jerky. And so on. And so on...” So I suggested that he upgrade it gradually. “But I don't know how to do it dad”. At that point Matthew swears he saw a light bulb appear above my head and switch itself on. Personally I think he's been watching to many cartoons. But he is right in that it did give me an idea for this months column. Which is called:-

Open Heart Surgery on Your Desktop PC

The PC is not by any means the best possible microcomputer. Even when it first came out it could be argued that other machines were better. But the PC does have one major advantage over a lot of other breeds of microcomputer; It can be upgraded. By that I mean that if a component is not suitable for a new task you can just take it out and put in a new better one. For example, if the graphics card is not good enought for the new game you have, throw it away and put in one which does. Assuming of course you can afford to buy a new graphics card :-) And assuming you do not have a laptop or a portable. This article, by the way talks about desktop machines not laptops.

Those of you who have been reading Game-Over from the beginning may have noticed that the machine I used for reviews has changed from a 386 with a bottom end of the range Trident video card and 10 Mb of RAM to a Pentium clone with a Matrox Millennium graphics card and 16 Mb of RAM. Now the thing is I didn't buy this new machine, if only because I couldn't afford it. What I did was upgrade the 386 a bit at a time. The advantage of that is you can afford much better components. I found it much easier to find less than £200 for the Matrox Millennium graphics card, for example, than the £1000 odd pounds a new Pentium machine would have cost.

The problem with upgrading is you have to take the machine apart and that is difficult, isn't it?

Well, no it isn't. It's very easy to take it apart. It's putting together again that causes the problems. :-) But even that is easier than you might think.

WARNING - you must remember that the inside of your computer is a delicate piece of electronics. It is possible to damage it if you are not careful. While none of the things described in this article should cause any damage I can take no responsibility for it if it does. Sorry.

When you first look at a couple of PC's you might think they are all the same. After all they all have a box that sits on your desk, a keyboard, a mouse and a VDU. Then you notice that some them don't have a box on your desk but one under it instead. The you see some with bigger VDUs. Then some with CD readers. And so on. At this point you are probably thinking that all PC's are different. And you would be right. But the basic layout of the components and the way they work is very similar. In fact most people when presented with the insides of a computer, the motherboard, graphics card, memory simms etc., have difficulty in telling the make of the PC. This means that I can talk about these things in general, but please note that in practice any component may be different from what I describe here so don't take this article as being true all the time.

OK the first thing to do is get your self an anti-static strap. This is a wrist band with a lead which usually has a clip of some sort on the end. You wear the strap and clip the other end on to your PC. This prevents any static electricity you may have build up from damaging your PC.

Now you can take the lid off. Usually there will be a number of screws at the back, or on the side holding the case in place. The manual which came with your PC should tell you where they are. Once you have removed the screws the case should just lift or slide off. If it doesn't do not force it. You have probably missed a screw.

Once the case is off you should be able to see the motherboard. The trouble is it is usually hidden below the disk drives and the cables and the add on cards and the power supply and so on. If you can't spot the motherboard don't worry about it just yet, instead we will look for the more obvious and easy to find bits first. For example the power supply. This is a big box at the back of the case, usually the top right. It's easy to find cos the power cable goes in the back and a lot of coloured wires come out the front. Another thing that is easy to find is the floppy disk drive. You can track this down by looking for the hole you put the diskettes in. The other side is the disk drive.

Wow this is easy. :-)

OK. So far we have found the power supply and the floppy diskette drive. Now out of the back of the diskette drive you will see two cables. One has four coloured wires. This is the power supply. The other is a flat ribbon cable. This cable carries the data to and from the rest of the system. Carefully follow this cable back from the diskette drive. You will eventually come to the Input/Output or I/O controller. On modern machines this will be on the motherboard itself but on older machines it will be a card plugged into the motherboard. Either way there should be another ribbon cable next to the floppy diskette one. Follow this one from the I/O controller and you should come to the hard disk. Note you can have two drives on both the floppy diskette drive cable and the hard drive cable. One drive will be at the end of the cable and one in the middle.

Now the hard disk drive will also have a power cable. Note that this is identical to the one in the back of the diskette drive. You may well have some spare power cables. To see if you have follow the coloured wires coming out of the power supply. If you do have a spare one have a look at the plug on the end. You will notice that it is shaped. On one side the two ends are angled. This means that you can only insert it one way. At least in theory. I have seen a machine in which the power cable had been inserted upside down. Needless to say the disk drive did not like it. So always check that you have the connection in the correct way.

When you were following the power cables you may have followed one to the motherboard itself. If not find it now.

Got it?

Good. Notice that the connector is different to the one for the disk drives. Also note that there are actually two connectors. [Unless you have the very latest design of board. In which case there will only be one connector.] It is very important that these two connectors go in correctly. Put them in the wrong way round and you could destroy your motherboard :-( The problem is that both connectors are identical so it is very easy to get them the wrong way round.

Right, have a look at the motherboard now. At the back of the motherboard will be a number of slots into which cards can be inserted. If you have a slim line case then you will probably have a card in one of these slots which has similar slots in it. Any cards you have in your machine will be plugged into this daughter card. That is the cards in a slim line cae will be horizontal rather than verticle.

There are a number of different types of slots these days, including:-

ISA    Industry Standard Architecture
EISA    Extended Industry Architecture
VLB    VESA Local Bus
PCI    Peripheral Component Interconnect

ISA was the original type but a few years ago IBM realised that it could be improved. IBM, being IBM decided to redesign the whole motherboard so as to make it better. This new design was called Micro Channel Architecture, or MCA for short. In my personal opinion MCA was a lot better than ISA. The trouble was that it was not compatible. You had one or the other. So if you upgraded your PC to and MCA one you had to buy new cards as well. For various reasons which I will not go into now, all the other PC manufactures decided that ISA had to be kept, which ment it had to be improved. So they came up with Extended Industry Standard Architecture. This gave the benefits of MCA but was still compatible with ISA. Thus your old ISA cards would work quite happily in an EISA slot. This proved much more popular than MCA and now you rarely see an MCA machine.

The trouble was that EISA, even though better than ISA and arguably as good as MCA, just isn't good enough. It is far too slow, espically for graphics cards. There are a number of ways round this problem but the one adopted was to add a Local Bus to the system. A Local Bus is just a means of rapidly moving large quantities of data between the CPU and the add in cards. But, PC's being PC's there was, at first no standard. Each motherboard manufacture had its own design. Since the add on cards would only work with the motherboard they were designed for this was not a very pratical solution. To solve this problem Intel, designed the PCI bus technology. Needless to say some other people came up with a different 'standard' loacal bus, VLB. The VLB system was ready first and a number of motherboards were built and sold using it. However, VLB is not as popular as PCI so most, if not all, modern motherboards are now PCI.

While you can use an ISA card in a EISA slot you can only use EISA, VLB and PCI cards in the appropriate slot. In fact all three slots are different enough that you should not be able to insert a card into the wrong type of slot.

So what else do we need to find?

Well the Random Access Memory (RAM) chips are something you may want to upgrade, so lets find them.

The most common type of memory chips, these days, come on SIMMs, which stands for Single Inline Memory Module. These are small circuit boards slightly over 4 inches (11 cms) in length and about 1 inch (2.5 cms) in height. There will be a number of gold coloured connectors at the bottom, usually 72 but some older ones have 30. There will be a number of chips on the board, these are the actual memory. The chips may be on both sides of the board or just on one.

Prior to SIMMs we had SIPs. These are similar to SIMMs but instead of the gold connectors along the bottom they have a number of pins.

Before SIPs the memory chips plugged directly into the motherboard or a separate daughter board.

The actual location of the memory chips varies from motherboard to motherboard, so look around until you can locate them. Better still have look at the manual for the motherboard. Most of you will have SIMMs, although a few might have SIPs, so look for one or more small boards sticking up from the motherboard. When you find them have a look at the 'slots' into which they have been placed. The actual number of slots varies from board to board, although 4 seems to be a common number. Hopefully, you will have some empty slots. You should be able to see if you have SIMMs or SIPs just by looking at the chips and/or the empty slots.

Now count the number of SIMMs. I'll assume that you have SIMMs rather than SIPs, but what follows is applicable to both. You should know how much RAM you have in total, if not look at the numbers which count up in the top left of the VDU when starting. This is the total amount of memory. You can now work out the size of the SIMMs, by dividing the number of SIMMs into the total memory. So if you have 16 Mb of memory and 4 SIMMs each SIMM is 4 Mb in size. Well, probably. It is possible to mix and match different size SIMMs on some motherboards but this is pretty unusual.

Right you now know what sort of size memory chips you need if you want to add more. If you have some spare memory slots than you can add more of the same size. For example if you have 4 memory slots, two of which are empty and the other two have 4 Mb SIMMs in, then you need another two 4 Mb SIMMs.

“Two. Why can't I put one in and have 12 Mb of RAM?”

A good question. And the simple answer is “Because the CPU is accessing 32 bits instead of 16 bits at a time.” If you don't understand that then just think of it as the CPU grabbing twice as much memory as a single SIMM can supply.

The problem with upgrading memory comes when all your memory slots are full. The only way to upgrade then is to replace all your SIMMs. So if you have 4 slots and 4, 4 Mb SIMMs you will need to get replace all 4 SIMMs with 8 Mb or larger SIMMs. This can work out expensive. So what I recommend is that if all your memory slots are full then think about replacing the lot with just enough larger ones to give you the same amount of memory. For example in the above case replace the 4, 4 Mb SIMMs with 2, 8 Mb SIMMs. Then when you need to upgrade you only need to by two SIMMs not 4.

The only other thing to find is the CPU it self. This will be a fairly large square chip. In fact it will be the biggest chip on the motherboard and is usually at the front of the board. In the case of a newer chip, Pentium, Pentium Pro, Cyrix 6x86 etc. it will probably have a fan on it, which will help find it. If it doesn't have a fan on it you should be able to see the name printed on it.

OK I've found everything. Now what?

Well now you can think about upgrading.

And next month I'll tell you how to do it.