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What's inside your PC

Here's a guide to help you sort through all the techno terminology.

By JOHN TORRO

© St. Petersburg Times, published November 13, 2000


You stare at the advertisements for new computers and scratch your head: What does that mean? You stand in the store, listen to the sales rep make his pitch and wonder: What's he talking about?

Buying a new computer isn't like buying most other consumer appliances. The computer industry has a language all its own, and for first-time buyers it can be a challenge to figure it all out.

So let's take a look inside today's computers to understand the most important elements, as well as my recommendations of what to look for when you shop:

Central processing unit (CPU): It's the main processing chip and plays a large part in how fast your computer will run. The speed is measured in megahertz (MHz). Now, more than ever, the types of CPU chips and speed options are numerous and potentially confusing. However, you don't need to understand terms such as "pipelining" or "branch prediction." You just want to know how fast it is and, more important, whether it will be sufficient for your computing needs.

Intel and Advanced Micro Devices (AMD) are the two main companies that produce CPU chips for most IBM-compatible computers.

L2 level cache: Cache memory is high-speed memory built into the CPU chip, designed to accelerate processing of data and instructions by the chip. (L2 is the second level of cache available on a chip. All of today's chips come with the first level called L1.) Without cache, the full speed of the CPU chip isn't utilized. It also is one of the most expensive areas of chip production, which is why less L2 cache equals lower prices. What separates Intel's high-end Pentium Xeon chips from the rest is that the L2 cache on the chip can be as large as 2 megabytes (MB), or 2,096K.

Intel's CPU chips: Intel's entry level CPU chip is the Celeron. It is Intel's price leader and likely will be part of any Intel-powered sub-$1,000 PC available. It comes in speeds ranging from 366- to 700MHz.

Don't let the fact that the Celeron doesn't carry Intel's better-known Pentium name fool you. Architecturally, the Celeron is very similar to the Pentium II that came out about three years ago, including the MMX instructions that permit jazzed-up multimedia. The newer Celerons at the 533A-MHz level and up even include SIMD (single instruction-multiple data) extensions, the more than 70 instructions added to the Pentium III line when it was introduced. SIMD instructions help boost the performance of advanced games featuring 3-D graphics, image manipulation, voice input and other audio/video tasks that have been written to take advantage of these instructions.

The Pentium III comes in speeds up to 1.13 gigahertz (GHz), but that power comes at a higher cost.

Here's the real difference between the Celeron and the Pentium III: The Pentium III has more Level 2 cache (256K versus 128K). The Pentium III also has a faster system bus (133MHz versus 66MHz). Think of the system bus as a road used to transfer data between the CPU and main memory and other components.

One of the biggest changes in the newer Pentium III chips has been the inclusion of what is referred to as Advanced Transfer Cache. The first wave of Pentium III chips included 512K of Level 2 cache. However, this cache transferred data at only half the speed of the processor. Although the newer chips mostly come with cache amounts of 256K, the Advanced Transfer Cache technology has all 256 kilobytes of Level 2 cache running at full processor speed and connects to the processor via a new, 256-bit wide data path.

The Pentium III Xeon is currently Intel's top-of-the-line chip. The Xeon chip is available with Level 2 cache in amounts up to 2 megabytes. Its capabilities are important for applications such as digital content creation, 3-D visualization and mechanical design automation, as well as database server applications. But unless you run these types of applications (if you're not sure, then you probably don't), you'd be wasting the considerable extra money you'd pay for a Xeon-based PC.

Not yet available is Intel's newest chip, appropriately named Pentium 4. It will be geared to improved performance for Internet, imaging, streaming video, speech, 3-D, multimedia and multitasking applications. The usual architectural improvements are part of this new chip. However, the most significant change I saw was a system bus speed increase to 400MHz, three times the current speed. I can't wait.

AMD chips: AMD is the other major manufacturer of CPU chips. Its main offerings are the Athlon, AMD Duron, AMD-K6-III and AMD-K6-2. They are about equivalent to Intel's high-end Pentium III, low-end Pentium III, high-end Celeron and low-end Celeron respectively. The 3DNow technology is AMD's version of Intel's SIMD instructions. Software applications need to be written to take advantage of this technology. Machines with these chips generally will cost less than PCs with Intel chips, but their performance is comparable for most computer users.

Random access memory (RAM): As your computer runs programs and works with data, it uses RAM to hold this information. Measured in megabytes (MB), RAM is often the most important factor of overall system speed. When Windows runs out of physical RAM, it starts using space on the hard drive to create what is referred to as virtual memory. When this happens, even the fastest CPU will slow to a crawl. Some systems come with only 32MB of RAM. Be clear about this: That's not enough. Windows Me, the newest version of the Microsoft operating system, and the Internet Explorer Web browser alone will consume this amount, and the computer will immediately start slowing as Windows uses your hard drive as virtual memory.

If your operating system is Windows 2000, the industrial strength operating system, don't even think about running with less than 128MB.

The bare minimum for RAM these days is 64MB, with 96- to 128MB highly recommended. Even 256MB in a Windows 2000 Professional environment is not excessive. Without a doubt, RAM is the area where you'll get the most performance bang for the buck. RAM prices have leveled off from last year, even decreasing in some cases to about $1 per megabyte. Upgrading a new computer from, say, 32- to 96MB of RAM should cost less than $80. It will be money well spent. Don't skimp.

Hard disk: Here is where you store your programs and data. It's measured in gigabytes (GB) -- each equal to 1,024 megabytes -- and bigger is better. Sizes as large as 40GB are becoming common in newer systems, and 7.5GB should be the absolute minimum. If you work with graphics, photo editing or music, you'll want the larger sizes. Most of the new drives are UltraATA/66 or UltraATA/100 drives. As its name implies, the transfer rate of an ATA/100 disk drive is 100MB per second. Again, if you do a lot of graphics/photo-editing work, the UltraATA/100 type drives will provide much better performance.

Monitor: The window into your computing world, I consider this one of the most important parts of your computer purchase. However, sometimes it's better to consider it separately from your main computer purchase. Good monitors can last through a couple of computer lifetimes, so you don't necessarily have to buy a new one when you upgrade. You can look at it as an investment beyond just your first (or next) computer purchase.

I recommend buying the best quality you can afford. A general rule is the flatter the screen, the better the quality. Flat screens of all sorts, not just the very expensive LCD models, cost more to produce, and they offer much less distortion and bend in the corners. If those problems show up, it usually is a sign of an inferior monitor. Some other things to look for:

Size: A 17-inch screen (measured diagonally) is probably the most popular size and works well for most types of applications. Serious graphic designers and game players will want at least 19 inches.

Resolution: Most computers use a screen resolution of either 800 X 600 on smaller monitors and 1024 X 768 on larger (17 inches or above). The resolution is the number of pixels in the horizontal and vertical directions. The higher the resolution, the more information you can see on the screen at once, and in more detail.

Refresh rate: This refers to the number of times a monitor redraws the screen each second. Higher refresh rates mean less flicker on the screen and less strain on the eye. Refresh rate is irrelevant on LCDs, which are usually optimized for a fixed resolution. Regardless of which size you choose, make sure your monitor is capable of at least 1024 X 768 resolution and a 75MHz refresh rate.

Dot pitch: The distance between the physical phosphors that make up a pixel, measured as a fraction of a millimeter. Again, this does not apply to LCD displays. In general, the smaller the pitch, the sharper the image. Look for a horizontal dot pitch of 0.25mm or less.

Flat LCD displays: You pay at least $600 above what you'd pay for a conventional CRT monitor of the same size. If the extra money is not a factor, this is definitely the recommended path. The clarity and brightness far surpass even the best conventional monitor, not to mention the loads of extra room you pick up because it takes so little space on a desk compared with the giant CRTs. Keep in mind that a 15-inch LCD is nearly equivalent to a 17-inch CRT screen in viewable area.

Video card: All new computer systems come with an Accelerated Graphic Port (AGP). AGP was introduced a couple of years ago as a new interface for the home computer platform that dramatically improves the processing of 3-D graphics and full-motion video. Video cards have their own RAM (measured in megabytes). The more RAM a card has, the faster it can process and display information, as well as produce higher resolutions. Here, 4MB is the minimum. If you don't do much with graphics or games, it will be sufficient. Otherwise, look for one with at least 16- to 32MB. If you do a lot of photo editing, play 3-D games or plan on adding a TV-tuner card (which lets you watch TV on your monitor), look for one with 32MB of RAM and 3-D acceleration capabilities. If you plan to use the higher resolutions (1280 x 1024), then get a card with 32MB of RAM. Note whether the video RAM is "shared," which means it borrows from the RAM for the rest of your PC's operations, reducing what's available.

Sound card: If you're not into playing games or music CDs, almost any sound card will do. Otherwise, make sure your sound card uses Wavetable technology rather than FM Synthesis. Wavetable technology produces a clearer, more lifelike sound. Some of the better cards simulate 3-D surround sound. No matter how good your sound card is, the quality of the sound will be determined in large part by the quality of the speakers. Speakers that include a subwoofer will be able to greatly enhance the deep bass sounds. A little extra money usually goes a long way in getting better quality sound from PC speakers.

CD-ROM and alternatives: Lower-end systems will come with a CD-ROM (compact disc, read-only memory). Its speed is measured in spin rates, with higher numbers being faster. They change almost daily, and most are in the 17X to 48X or higher range.

DVD-ROM is the latest compact disc technology. It can hold much more information than a normal compact disc (up to 8.5 gigabytes versus 650MB). This will allow software titles that previously used multiple CDs to be contained on one disk. Movies also are available in DVD, but unless you want to watch a feature-length movie sitting around your PC, get one with jacks that will connect to your TV. DVD is backward compatible with CD-ROM and audio CDs, so your existing CDs will work.

For the higher end, you may want to consider creating your own CDs. With a CD-RW (compact disc, rewriteable) device, you can record data on a CD, erase it and then re-record it up to 1,000 times. CD-RW can use two different type of compact discs (also called media). CD-R, or write-once, media can sell for as little as 33 cents each, while CR-RW, or reusable, media sell for as little as $1 each. Both will work in a CD-RW drive. Recordable CD devices are good for making music CDs or saving photos or other data that won't fit on a regular floppy disk. It's also a good alternative for backing up what's on your computer's hard drive. (DVD-RAMs for recording DVDs also are available, but are expensive.)

Backup: Although today's hard drives have become very dependable, you need to provide for some kind of backup media. A CD-RW drive or Iomega's 2GB Jaz drive are great alternatives for large amounts of data, and 250MB Zip drives could be sufficient for smaller systems. Remember, you don't need to back up your whole system, just whatever can't be reproduced from original media.

Modem: To hook up your computer to the Internet, most new systems include a modem that claims speeds up to 56 kilobits per second (what's known as a 56K V.90 modem). Actual transmission speeds don't reach that level, though, because of phone line limits. Some modems also can send and receive faxes at 14.4Kbps. But these traditional modems soon will be considered about as useful as old 5.25-inch floppy disk drives. High-speed Internet access is becoming more popular and more widely available for home use, either through your TV cable or through your phone lines as a digital subscriber line (DSL). The specialized modems for such connections are provided by the cable or phone companies offering the service.

Universal Serial Bus ports (USB): These are included on all new PCs. The list of equipment that uses the USB connections has grown to include almost any peripheral you'd care to hook up to your computer, such as printers and scanners. Low-price USB hubs allow you to string together a number of devices once you use up the two connections that come with most computers. Soon to come, but not yet available, will be USB version 2.0. This next generation of USB will extend the speed of the peripheral-to-computer connection from the current 12 megabits per second to 480Mbps, or 40 times faster. When evaluating sub-$1,000 PCs that have fewer expansion slots, keep in mind that many of the peripherals you would normally use expansion slots for, such as network cards, modems and TV-tuner cards, are available in USB format.

FireWire: It's also known as IEEE 1394 (IEEE stands for the Institute of Electrical and Electronics Engineers) and is a serial interface similar to Universal Serial Bus. Both offer "hot plug" capability, eliminating the need to restart the computer when a new peripheral is attached. However, FireWire is much faster. The current FireWire standard transfers at rates up to 400 megabits per second, while USB tops out at 12Mbps. Future versions of FireWire may reach speeds up to 3,200Mbps. Similar to USB, FireWire devices provide their own bus power, which means that no power plugs are usually needed. FireWire devices include disk drives, CD-RW and DVD-RAM drives, printers, scanners and digital editing equipment. FireWire is the preferred interface for serious digital video editing users.

Mouse: Not usually worthy of mention, the lowly mouse has undergone its first real technology change since its introduction 18 years ago. The new optical mouse uses a tiny digital camera to take 1,500 pictures per second of the surface beneath the mouse. A digital signal processor then analyzes these pictures and translates movement of the mouse into crisp movement of the cursor on your computer screen. What this means is no more mouse pads or moving parts on the mouse that need to be cleaned. Its movements also are much more precise. The optical mouse often is not standard equipment, though, and prices start at around $50.

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