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.
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Originally published 5 December 2004
