a simple essay

Sep28

About the Processor

This article will be the first in a series of informative articles on the fundamentals of computers. I know that it sounds a little intimidating, “fundamentals of computers”, but I’ll be trying my best to make to topic easy to understand. Each article in the series will focus on one or two parts of a computer. I’ll be looking at how these parts work, what do the numbers attached to these parts mean. Additionally I’ll be giving some buying tips, what to look for when buying these parts, and how to add them to your computer systems. Please, don’t let the last sentence scare you; my main intent on these articles is just to give you a little bit more knowledge about these magical “black boxes” so the next time you have a problem, or are out getting a new one because the old one just doesn’t work anymore, you can take a step back, and realize that the computer does not control you.

The Processor/CPU : What is this thing?

When most people think of processors they think of Intel, and Gigahertz; and that it’s best to have higher numbers of the Intel kind. But that’s very deceiving. Let’s start with what’s a Gigahertz? That would be 1,000 million cycles per second. Now if you had a car engine that ran at 1,000 million rpm I’m sure it would be pretty loud, but as you can tell sitting next to your computer that little box is barely making any noise. So what cycles are we talking about then? Electronic cycles - waves of electricity run through the CPU, another name for processors, at the rate of 1,000 million per second or more! That’s it. And this is supposed to make computers faster?

Let’s think of this realistically. Electricity alone is not going to do any fancy thinking for you. Behind the scenes of processors are some very abstract concepts and notions, which I’m not going to talk about here, that transfer electricity to useful processor instructions. Processor instructions are the building blocks for any other complex action that happens in a computer, it takes hundreds of these basic instructions just to draw the desktop, and the programs you are running, one time. Every new cycle the processor gets new instructions and runs them through the processor’s “assembly line”, where the processor executes the instruction.

So, if electricity is flowing faster through the CPU, then more instructions are fed to CPU per second, getting more work done. Simply stated, bigger numbers do make computers run faster, but it’s still not that easy. Take for example the difference between gasoline and diesel engines. Both can make a car go relatively fast, say 100km/h, but both work at different RPMs, diesels run in the hundreds while gasoline engines run more rapidly at thousands of RPMs. It’s the same with processors.

Like I said earlier, processors get work done by executing the processor instructions. Processors with slower cycles per seconds are still capable of getting as much work done as those with 1,000 million Hertz. This is because every processor has a base number of instructions it can completely execute per cycle. That means that a processor that did 4 IPC (instructions per cycle) and ran at 8 Hz, will do as much work in the end then a processor that did 1 IPC but ran at 32 Hz. The actual power of both of these processors would be 32 instructions per seconds (or the IPC x Hz). Regrettably, because processors and programs are incredibly complex, it is very difficult to obtain a processor’s exact IPC number, and furthermore processors rarely ever work at a constant IPC.

What you need to know when looking at sales tags

Now, having gone through a general description on processors and how they work lets see how it stands up to what you’ll find at the local electronics store. When looking at the numbers for a computer sitting in an isle on a shelf, one of the first points on the label will be something akin to:

“Intel Pentium 4 3.2GHz, 1MB Cache, 800MHz FSB”

Look at all those numbers and acronyms. Having already read up to this point, we can definitely say that this processor is fast, to the tune of 3.2GHz. What can that do for you though?

The first thing you may have noticed in the processor name example was “Intel Pentium”. These are names that everyone seems to throw around without really knowing what they mean. It’s a lot like saying Dodge Hemi, really. The Hemi engine powers many of Dodge’s as well as other car company’s cars and comes in different shapes, sizes, versions, types, and so forth. As such, the words Intel Pentium don’t say a lot about the processor, other than the great amount of branding Intel has done. What’s really important in the example above is “Pentium 4” as this actually describes what type of processor it is.

Like I pointed out earlier, processing power is not necessarily derived from MHz or GHz, but rather a combination of speed and instruction computing. Processors can either excel in one or the other, but not both. Each type of processor has a different design, or architecture. Think of these architectures as the designs of a factory with actual assembly line, as that is what they emulate. Small manufacturing companies have small assembly lines, but each step in the assembly line does more work on the object then longer assembly lines. Factories can also have several assembly lines. When talking about why there are different processors, such as Pentium 4, or Pentium III, or Athlon, it is because each of these processor types have different a different design in their assembly lines.

These architectures try to get the best balance of speed and instructions. The Intel Pentium III and AMD Athlon processors are designed to do more work per cycle, while the Intel Pentium 4 processor was designed to run faster. Because of this, a Pentium 4 2.4 GHz is actually comparable to an AMD Athlon XP running at 1.8GHz. Knowing the processor type, will let you know the difference in styles which guides how important speed is to that processor.

What about the other numbers and acronyms in the example though: 1MB Cache, 800MHz FSB? The Cache and Front Side Bus (FSB) are very important to the total performance of processor, which is why you’ll see these numbers on labels. The Cache of a processor is the size of the memory that is resident in the processor. This isn’t regular RAM or Hard disk memory though; these small little pieces of memory, which are anywhere from 128KB to 1MB or more, is strictly used to store processor instructions or data for these instructions. It is a small reserve that runs at or close to the speed of the processor and can be accessed almost instantly, as opposed to RAM and hard disk memory which takes a lot of time to retrieve from. Like the general consensus, more cache memory tends to increase general performance up to a point. Unfortunately, doubling the cache, does not mean a doubling in performance, it’s actually close to 5%-10%.
A Small processor compared to a penny

The front side bus, or FSB, is the connection the processor has to the rest of the computer. While this is very dependant on the processor type, while the AMD Athlon processor ran fine at 333MHz FSB, the Pentium 4 was originally offered at 400 MHz FSB. The FSB speed is there to help you determine a faster processor within the same family.

Taking a look at the following processor descriptions:

Intel® Celeron® D Processor 330 (2.66 GHz, 533 FSB)
Intel® Pentium® 4 Processor (2.80GHz, 533 FSB)

You can now make a more in depth analysis of the difference between the two. Starting off, we can tell that they are different families; one is a Celeron D while the other is a Pentium 4. One is faster than the other, though marginally so, and both have similar FSB speeds. The best way to decide the better processor from the two is by knowing the difference between Celeron’s and Pentium’s. This particular Celeron, the Celeron D, is identical to Pentium 4’s except that they have half the cache that a Pentium 4 would have. Which is the better processor?

Consumer Processors

The following is a list of the current consumer processors, with some details on their architecture and features.

AMD Athlon, Athlon XP
The original athlon was an equal performer to the Pentium III, while it has gone through some revisions, the Athlon processor was designed to do more work per clock cycle. It is a versatile processor that handles all tasks equally well.

AMD Athlon 64

The Athlon 64 is almost identical in design as the Athlon. Major changes include added instructions for security and multimedia, as well as the ability to run 64bit programs.

AMD Duron, AMD Sempron

Duron was the original value processor for AMD. The main difference between a Duron and an Athlon, include halved cache size, and only a 200MHz FSB. The Sempron is AMD’s new value processor, which follows after the Athlon 64 design, except with only 256KB of cache and no ability to run 64 bit programs.

Intel Pentium I, II, and III

The design of the first three Pentiums was very similar. Each new version included more cache and a set of new instructions to help in multimedia programs - this was the original Pentium’s low point.

Intel Celeron A, B, C

A “crippled” version of the Pentium II and III models. The Celeron has been considered a crippled version in that it contained half the cache as the Pentium models it was designed after.

Intel Pentium 4

Designed to run at extremely high speeds, the Pentium 4 was originally released at 1.4 Ghz. Unfortunately, its design at this speed made it less powerful then a Pentium III or Athlon running at 1GHz. The Pentium 4 has gone through several revisions so far, that have made the design more efficient. It is greatly suited for several multimedia programs.

Intel Celeron D

A crippled version of the Pentium 4.

Intel Pentium M

Intel designed this processor to be run in portable computers and laptops. With this in mind, the Pentium M gives laptops running it longer battery life than most other Mobile processors, at least 25% more battery life. While it does have many power saving features, it runs at slower speeds than the Pentium 4. Still, a 1.6 Ghz Pentium M is comparable to a 2.4 Ghz Pentium 4 while yielding better battery life.

About Computers

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