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48. Gauging speed, memory of processors

By Mark Alberstat

Computer speeds have changed immensely over the years. Not only have computers gotten faster, but they also come with a confusing array of numbers and letters that sales staff at many computer stores think their customers know and understand.

In fact, most people don't understand the ins and outs of memory cache and clock speed and all too often leave the store bewildered and frustrated.

There are two main computer chipmakers, Intel and AMD (Advanced Micro Devices). There are also, of course, Macs, but more on their speed later.

Intel has two classes of processors, generally called chips, for desktop computers, the Pentium and the Celeron. Currently, Pentium is on version No. 4, so if you are out looking today you will be seeing Pentium 4 or P4 computers or Celerons. Pentium is the premier brand, while Celeron is the economy model, and the difference is reflected in the pricing of the PCs.

In the consumer marketplace, the fastest P4 computer you can buy right now is about 3.2 gigahertz. This means the chip can cycle 3.2 billion times a second - that's fast! This 3.2 number is what is known as clock speed or clock rate.

Chips with a higher number work less than slower ones.

Related to these chips is their memory cache, also called Level 2 or L2 memory. In Pentium-class chips, this memory can range from 256 kilobytes to one megabyte. This memory holds common processor commands that the chip can call up right away. The more of this type of memory, the less the computer has to go to the system memory, thus speeding up the whole process.

Celeron processors, as mentioned, are economy models. They contain only 128 to 256 kilobytes of L2, and their clock speeds are lower. Generally, the fastest Celeron on the market today is about 2.8 gigahertz, which is still fast for most people's home use. The important difference is that drop in L2 cache.

AMD is Intel's main competitor, and its Athlon chip is up against the Pentium chip. One of the main differences, however, is that the AMD is a 64-bit chip, while Intel is a 32-bit chip. This means that the AMD chip can handle 64 bits of information at any one time. This may sound like a big advantage but, realistically it isn't, as there are very few programs that are written for this high bit-rate.

The clock speeds of the AMD chips are often slower than those found on the Intel side of the line, but that needn't worry consumers. AMD and Apple tend to focus research and development more on the number of instructions their respective chips can perform per cycle and not purely clock speed. This is why the slower AMD chips often outperform the faster clocking chips from Intel.

The L2 cache on the Athlon and the Pentium chips are similar.

For various reasons, one of which seems to be to confuse the computer-buying public, the naming of the chip speeds are different between the companies. AMD features numbers like the 3000+. For rough estimating, you can compare this to an Intel 3.0 gigahertz. The AMD competitor to the economical Celeron chip is called the Sempron. This chip has lower L2 memory and is a 32-bit chip.

On the Apple processor cart, you will find chips called G5. These are found in both Power Macs and iMacs. As already mentioned, they run at lower clock speeds but can complete many instructions per cycle. All G5 chips have 512 kilobytes of L2 cache. The main difference between the two varieties of Mac is that the Power Mac features dual processors and has plenty of power and speed. That, however, comes at a cost to the consumer.

The next time you walk into a computer shop, you might know more about processors than the sales staff.

The Mousepad runs every two weeks. It's a service of Chebucto Community Net, a community-owned Internet provider. If you have a question about computing, email If we use your question in a column, we'll send you a free mousepad.


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Originally published 5 December 2004


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