1 Jan, 1998

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.

Therefore, you measure the quality of your decision in months. My 233 MHz system is three months better than yours. At the same time, not everyone wants to be on the leading edge. The big brand names like IBM, Compaq, and HP redesign their systems less frequently and test them more agressively. This matches the needs of large corporations, who want large numbers of identical systems. Lower support costs are more important than modest technological improvement.

At the other extreme, Gateway 2000 sells computers over the phone. They do a large volume of business, but do not maintain massive inventories of spare parts. Customers have come to expect the latest technology. So if Intel releases a new mainboard chipset, Gateway is selling computers that incorporate the chips two weeks later and has stopped selling anything else within a month.

There are changes in the CPU. However, a new CPU chip gets lots of publicity and is hard to miss. Everyone knows, for example, that the Intel Pentium II is sold door to door by people dancing in pastel spacesuits.

Fewer people know that during the second half of 1997 a new generation of mainboards was phased in. In the third quarter, the Pentium MMX system boards were upgraded. Older boards used EDO memory packaged on 72 bit SIMM boards. The new boards used SDRAM memory packaged on 168 pin DIMM boards. The new boards also supported a faster disk transfer mode (Ultra DMA), some USB ports (useless at this time since there are no USB devices to connect to them), and some central management features useful to corporations. In the fourth quarter the same technology was phased in for Pentium II mainboards, and a faster video card connector called AGP was added to PII systems.

SDRAM is a bit faster than EDO. A 233 MHz processor will be a bit faster than a 200 MHz CPU. However, anyone who uses their computer to do useful work will probably not notice the difference. This article is being written on an old 90 MHz Pentium (non-MMX) chip with EDO RAM, and that system is fast enough to do almost anything. Today, a $700 system unit has the same power. If you need a faster system, it is probably to play 3D blast-everything-in-sight games.

If you buy one of the lowest price systems, the best upgrade is probably memory. Given the requirement of modern software, 32 megabytes are always useful and a serious user can benefit from 64. All modern operating systems use "virtual memory." When the applications fill up available RAM, some of the program and data is moved to disk. When you switch from one program to another, the system pauses and the disk becomes active as Excel moves out to disk and Word comes back in. This is not a problem when programs are used alternately, but if more programs are running simultaneously than can fit in memory, then the system begins to "thrash." The disk light comes on all the time, and the system slows to a crawl. It takes about 90 nanoseconds (billionths of a second) to fetch some data from RAM. If the data is on disk, then it takes about 10 milliseconds (thousandths of a second) to read the record in from a fairly fast modern disk. The disk is 100,000 times slower than memory.

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.

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.

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PCLT

Copyright 1998 PCLT -- Introduction to PC Hardware -- H. Gilbert