Introduction to PC Hardware
The newspaper ads scream out prices, MHz, EIDE, and SVGA. Do you know what these buzzwords really mean? Does anyone? The PC may be the single most important tool for researchers and executives, but because it is purchased in a camera store or discount food warehouse it is often treated as a commodity item. It should come as no surprise that most people who use the techno-jargon have no real understanding of any of the terms or issues.
First the good news. There are no bad Personal Computer systems. The least powerful system available today is better than the most expensive system of a few years ago. High quality components are produced in such large numbers at such low prices, that there is no profit building substandard systems. Since the process doesn't stop, the best system you can buy today will be less functional than the cheapest system that will be available in two years.
Two years ago Intel offered one class of processors and both price and performance were measured by the clock speed. Today there are three classes of processors: lower priced Celeron, mainstream Pentium III, and server-class Xeon. You can buy something around a 500 MHz version of each class for $150 (Celeron), $250 (PIII), and $3700 (Xeon with 2M cache). The three chips will probably perform the same on a typical desktop system running typical business or personal applications.
Even within one category, advances in technology are no longer unambiguous. The first generation of Pentium III processors came with 512K of external second level cache. A recent second generation (the "Coppermine" processors, which have nothing to do with copper) are based on higher technology with smaller circuits, faster clock speeds, and less heat. However, they also come with only 256K of internal second level cache. The new chips have half as much cache, but it runs twice as fast. Both versions of the PIII are still available and, when they run at the same clock speed, they have about the same price.
Top performance comes at a price. During February, a Pentium III chip was available at 500 MHz for around $250 or at 700 MHz for around $850. That's 340% more money for a 40% increase in clock speed and a measured improvement in real world benchmarks of only 27%. Although we sometimes say that a faster computer is "smarter", this description does not necessarily extend to the person who purchases the faster machine.
Memory prices have returned to "normal". Memory prices had bottomed out in May, 1999 and then began to jump. Nobody came up with a good reason, but memory prices increased by 300% in late 1999. They have returned to their May levels. This may be a good time to upgrade modern SDRAM machines to 128 megabytes in preparation for Windows 2000. It certainly does not make sense to buy a new machine with less than 128M.
Low-Tech is Important
For the full-time computer user, the most important part of the machine is often the keyboard. This is not an advanced, modern device. The design of today's keyboard is not much different from the electric typewriter of thirty years ago. Good design is still important. A moderately fast typist may press 200 keys each minute, all day long. It is not very difficult to make a keyboard that can record the keystroke. It is much more complicated to make a keyboard that feels good and is comfortable to use.
How far does the key move when it is pressed? What resistance does it provide. How does it feel when it hits bottom? The least expensive keyboards feel soft and squishy. A good keyboard has a substantial feel. In the modern era, where employees complain of hand injuries due to poorly designed keyboards, an extra $100 may be much less expensive than an insurance claim.
The quality of the screen is also important. A larger screen is easier to read. A faster refresh rate reduces flicker. For a secretary, using the system for word processing and casual queries, the keyboard and screen are much more important than anything in the system unit. Performance may be less significant than comfort.
The Q Bridge
In downtown New Haven, CT where I-91 meets I-95, the "Q Bridge" crosses the harbor area. It must be one of the hottest attractions in southern New England, because every morning and afternoon cars line up for miles to cross it. It defines the rush hour commute, and nothing that you do to the other roads or exits in West Haven or East Haven will materially speed things up.
Inside your computer there is an electronic version of the Q Bridge. Depending on the application, some component will become the choke point, and all the data bytes will line up waiting to get through. But while the real Q Bridge never changes, the PC choke point moves as you change use.
A Porche and a Yugo get caught in the backup at the same point in West Haven. Twenty minutes later they cross the bridge at the same time. It doesn't do any good to spend a lot of money on a fast car and a big engine if the limiting factor is traffic moving five miles an hour. Yet customers often select a server with a fast CPU, without first considering what the bottleneck will be.
Database performance will probably be limited by disk speed and cache memory. Windows applications depend on the speed of the display adapter. The CPU tends to get busy only when data is encrypted or compressed. The CPU chip is upgradable, but changing it won't help much if your Q Bridge is located at a different component.
During 2000, the most common performance bottleneck will probably be memory bandwidth. As the CPU chip clock speed for high end machines settles around 1GHz, the memory bus speed for ordinary memory remains at 100-133 MHz. New memory technologies (DDR or Rambus) will be trying to plug the gap.
Topics to discuss include:
Copyright 1998 PCLT -- Introduction to PC Hardware -- H. Gilbert