What's a C.P.U.?

My intention with this article is to dispel some myths and help people stop wasting money when buying a new computer or getting an upgrade.

In the early days of the personal computer CPUs where very slow and powerless. 1978 saw a huge leap forward with the introduction of the Intel 8086 at just 5MHz, however, being a 16bit processor it was a revolution at the time...

In those days dinosaurs roamed the earth, Michael Jackson looked more like his brothers than his sisters, "nobody would ever need more that 640KB of RAM" <--- Bill Gates --->, and the most critical specification of a computer was the speed of the CPU.

A 16bit processor can really only address 64KB of memory, but additional 'control pins' allowed the 8086 to address just over 1MB, via a 20bit external address bus. Unfortunately this slowed memory operations.

The 8086 was the basis of IBMs first 'Personal Computer' and despite the fact that any computer one can personally own and have private access to could be considered a personal computer, it is the 'IBM compatible' that the term PC is associated with.

This first personal computer from IBM also marked the beginning of Microsoft's meteoric rise, even though it was via software piracy... OMG what?
Yes, that's right, the first Microsoft operating system (MS-DOS) used for the first IBM PC was a relabelled copy of SCPs Q-DOS, obtained by less than legitimate means... they sold it to IBM before they bought it from SCP...

This article is not supposed to be a history lesson, but, as the ancestor of today's CPUs, I thought it worth mentioning the 8086, the majority of today's CPUs still bear the 'x86' tag. I'm only talking 'IBM-compatible' PCs, however even Apple Macintosh has begun using x86 Intel CPUs, with this switch many Apple owners are running Microsoft Windows on their Apple, the only advantage I can see for the extra premium paid for an Apple is the pretty box... (Many more Apple users do run the mighty Mac OS-X, but discussion of operating systems is a subject for another article)

Today's CPU is so much more powerful than most people need, but people continue to consider it the most important aspect of their purchase, and waste their money on a system with the fastest processor and end-up with a slow machine because it has too little RAM, they only realise it has a rubbish graphics adaptor (probably 'on-board' the motherboard and sharing the system RAM) when they try to play a game and it only dawns on them that 'size DOES matter' when they fill up their tiny hard drive with photos, video and music... so it's back to the shop for an upgrade... (PC vendor smiles knowingly $$$).

A much better machine could have been designed in the first place with a CPU of half the cost (and yet still adequate performance) and more spent on other components... but then it's the BIG NUMBER associated with the CPU that sells computers. So this superior, balanced machine would be passed-up in favour of a lesser machine with a Pentium4 core2 quad extreme 3.0GHz coupled with 256MB RAM, tiny hard disc and on-board graphics... (the scary thing is, I'm not making this up!)

There are some users who do need the extra processing power, for these users today's market offers plenty of choice. BUT, always remember that although the CPU does the work, it does its work in the RAM... remember seeing pictures of Einstein working on huge blackboards? Even with his towering intellect he would not have got much done if he had to work on a small board. It's the same with a computer; CPU power needs to be balanced with RAM capacity and other components.

Another important factor is known as 'cache' (pronounced; 'kaysh') this is a small piece of very high speed (and expensive) memory located inside the CPU itself. Cache runs at the same speed as the CPU and stores data that the operating system or program thinks may be useful again soon. In the same way that you or I might spend an hour or two doing some calculation for the tax department; add this, this, this and this, subtract that, divide by pi, multiply by the square root of the weight of the cat... we get our answer and write it on a piece of paper because we know that we're going to need that figure again soon... and we don't like doing math.

Cheaper CPUs often have less cache and this affects their performance more than the slower clock speed. The trick is to ignore the Megahertz (MHz) or Gigahertz (GHz) (the clock speed) and just get the best CPU you can afford, a Celeron D550 (2.13Ghz / 1MB cache) is better than a Celeron D341 (2.93Ghz / 256KB cache) and half the price...
A CPU designed for a server or a very 'high-end' machine has a very large cache to enhance performance. Similarly a CPU designed for a laptop or PDA often has a large cache, this is to allow the use of a CPU with lower clock speed and therefore lower power consumption, and yet maintain their performance.

Multi core CPUs are becoming popular these days, however they are only going to give a performance advantage if the operating system AND the program you are running are written to utilise them, and of course, only if you have sufficient RAM

Multi core CPUs (Intel's core2 duo and core2 quad and AMDs X2, X3 and X4 processors) are like having multiple CPUs, an extension on the old "two heads are better than one" cliché. To the best of my knowledge, all modern operating systems are designed to take advantage of multiple processors, but not all programs are. So it depends on what you intend doing with your PC as to whether your multi core dollars are going to be well spent or not. You'll have to ask the software vendor.
Similarily 64bit CPUs offer a performance advantage... if you have software designed to take advantage of the extra processing power. A 64bit CPU and OS can address 16EB (ExaBytes) of RAM
If you're the type of user who tends to run multiple programs simultaneously (like me) and have 20 or more windows open simultaneously (like me) if you do digital video editing (like me) play 'high-end' 3D computer games (like me) have heaps of RAM and a top-notch graphics adaptor (yes, like me) and your software was written for it, then a 64bit and/or multi core processor is a good investment.

If you're the type who uses email, word, chat and a web browser, opens one program uses it then closes it before opening another program, your money would be wasted. Similarly, if your other hardware is below par you're only lining the pocket of the 'oh-so-friendly' local PC vendor.

For computer users who fit the last category, a single core, x86, 32bit CPU is more than enough. A 32 bit CPU can address 4GB of RAM which is at least 4 times what most people need. The SLOWEST single core 32bit CPU produced by intel today (for desktop PCs) runs at 1.60 Ghz, coupled with 1 GB of RAM this will be quite adequate for MS Word etc. Spend your money on a faster internet connection, printer, HDD, or something you actually need instead...

I hope this article is of some use to someone, if anyone spots an error please let me know, if anyone needs more information on some point or another, also feel free to contact me.

By the way... the pic is of a Celeron 333 (CPU) with a water-cooling system I made coupled with a "peltier device"... they told me that a 333 could not be overclocked to 500Mhz... they were wrong...circa; 1999