15 April, 2008

Introduction to PC Hardware

The newspaper ads scream out prices, MHz, ATA, DDR, PCI-e. 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 an office supply store or discount food warehouse it is often treated as a commodity item.

It would be hard to find a vendor with substandard parts. You might buy a washing machine that breaks down just after the warranty runs out, but a computer has few moving parts (some fans and the disk) so there is nothing to wear out. If they built a bad machine, it is just as likely to fail out of the box as two years later. In 2007 some mainboard vendors received shipments of counterfeit capacitors, poor quality parts marked as more expensive components. This is one of the few parts that can overheat, swell and break over time. After those failures the industry added new checks to prevent such things happening in the future, and mainboards today often advertise ďall solid state capacitorsĒ while a few years ago nobody would have thought to even ask.

This is not to say that system builders donít cut corners. Itís just that the corners donít involve substandard components. Instead, they leave out inexpensive upgrades that consumers arenít smart enough to look for. For an extra $20 they can offer a 320G hard drive instead of an 80G disk. For a few dollars they could use less noisy fans. You can get a cheap case (with sharp edges that cut your hands), but if you never open the covers you will never know. So in an era where game consoles cost $600, and you can spend real money on a flat panel TV set, you can still buy the least expensive Dell or HP system for $350 and get a pretty good computer. If that is all the advice you are looking for, read no farther.

The expert or enthusiast will read articles in Tomís Hardware or The Tech Report. The problem with these sites is that even their introductory articles assume some technical background and they really donít explain how things work. That is the purpose of this page and its linked to articles. The background information may have no immediate practical use, but it will increase your comfort level. If the PC is no longer a big investment in money, it is still an important tool in business or education. Knowing more about it should make concerned people more comfortable with their decisions. No technical background is assumed. Even very complex issues will be explained in terms that everyone can understand.

The Most Common Problems are Simple

Backup your files - Every week someone loses their family pictures or their Senior thesis. Every disk will eventually stop working. Some will stop sooner than others. Buy an external hard drive or USB flash stick and make a copy of everything you spend more than 10 minutes creating or editing. As you become more professional (or get burned a few times) you will begin to make two backup copies using either very simply file copy or two entirely different backup programs. Some backups make it easy to recover an entire failed disk, while other backups are better at recovering a single file that you accidentally damaged.

Do not assume that a backup program works unless you have restored something. Lots of people simply check that the backup appeared to work and assume they are safe. Restore the files to another disk or at least a different part of the disk and check to make sure they are all correct.

Malware - Today a lot more computers get discarded because virus programs and other malware have made them unusable than because some hardware has failed. Since most users donít know how to reformat the disk and reinstall Windows from scratch, they buy a new computer. Donít fall into this trap. Buy real software at the store or from reputable online sources. Follow the instructions to turn on automatic updating by Microsoft. After that: Just say No! When something pops up on your screen and tells you that your system is full of disease and offers to install something to fix it, Just say No. When an add promises to clean your registry, or disk, or make network downloads faster, Just say No. When you are offered free porn from Eastern Europe, Just say No.

Vacuum Regularly - The enemy of a computer is heat. Computers have fans to move air around disks and metal heat sinks to cool the components, but the fans and cooling fins can become clogged with dust, dog hair, and any other gunk floating in the air. If you never open the computer, you don't see the problem. To avoid problems, turn the machine off, unplug it, open the cover, and vacuum the screens, fans, and fins. Don't forget the power supply. If there is a filter, clean it.

Who Made It?

IBM invented the modern PC design, but they recently sold that business to a Chinese company. This should not be a big surprise. Often the only American thing in a computer is the name on the cardboard box it came in. Apple assembles systems in Shanghai and ships them overnight to the US.

If you buy a car from Ford, you expect the frame, engine, transmission, generator, and other parts to come from Ford or at least be built to Ford specifications. You do not expect to be able to put a Ford transmission in a GM car.

In a PC, however, the CPU, memory, disk, CD, power supply, and case are all manufactured to industry standards. You can take a hard disk or memory out of a Dell computer and put it into a system made by HP. The brand names you know are the names of companies that assemble, distribute, and support the computers, not the companies that make the parts.

This is an international business. The mainboard almost certainly comes from a Taiwan company (Asus, Abit, Shuttle, MSI, ...). Disks tend to come from Singapore or Indonesia (Seagate, Western Digital, Maxtor). Memory and LCD displays often come from Korea. The external case and the power supply probably come from China (though over time more and more parts will come from China).

You can buy the components from CDW or NewEgg and assemble a computer yourself, but you won't save any money. The big computer makers buy parts in lots of a thousand, packaged in bulk to save packing and shipping. Nine screws attach the motherboard to the mounts on the case. Four screws attach the disk to the disk bay. Then the cables all plug into sockets. An unskilled worker can be quickly trained to assemble a computer every few minutes. You can learn to do it from scratch in a few hours, so if you are looking for an electronics project to keep you busy for weeks, go build a shortwave radio.

The advanced technology is in the manufacture of the chips, not the final assembly of the finished product. A CPU chip is constructed in a plant that costs billions of dollars. The building is on shock absorbers because the vibration generated by passing trucks would disturb the process. People wear spacesuits not to protect them from the environment, but to protect the chips from flakes of loose skin or the particles we exhale in every breath.

Then the chip is packaged in plastic and shipped out. There is a socket on the mainboard. One corner of the chip has an arrow, and one corner of the socket has an arrow. Drop the chip into the socket while matching the two arrows, then drop a lever to hold it in place.  It is harder to tie a shoelace than to install a CPU chip on a mainboard.

Technical Trends

There are trends that have developed over the last three years, and strategies that may say something about what computers will look like three years from now. Knowing this stuff makes you informed, but it won't help you to decide what to buy today. These subjects are optional, so you can follow the links to the related articles if you are interested.

Intel and AMD

Duo and Quad

The GPU and Specialized Processors



There are 8 basic parts to a computer:

  1. Case
  2. Power Supply
  3. Mainboard
  4. CPU (and cooling tower)
  5. Memory
  6. Video Card
  7. Hard Disk
  8. DVD Drive


The case is the metal or plastic box that holds the computer. You can get small cases that look like stereo equipment or large cases with room for a lot of disks and add on cards. Enthusiasts may buy a case that is transparent or one that looks sporty.

Things to look for in a case:

If you want an entry level case that comes with a decent power supply, the Antec 44xx series is quite good. It typically sells for $70 but can be had for as little as $40 after a mail in rebate. The Antec Nine Hundred (without a power supply) can be $140 but has been seen on special for as little as $60. It has three 120 mm fans and a gigantic 200 mm fan that is the biggest in any computer system anywhere. All fans have a three speed switch, and while you can run them all on high (if you are really looking for an inexpensive wind tunnel instead of a computer case), on low speed they still move a lot of air. If you are looking for careful design rather than brute force, Lian-Li is the highest quality and most innovative vendor of computer cases.


The mainboard must have a socket for at least one CPU chip, and sockets for typically 2 or 4 memory "sticks". The back panel will expose plugs for keyboard, mouse, USB, Ethernet, and maybe External SATA disks. Some mainboards have integrated video. It will then have slots and connectors for the things you add it: SATA connectors for disk and PCI and PCI-e slots for adapter cards.

Things to look for in a mainboard:

For all the different things that a mainboard does, it is astonishing that perfectly reasonable boards sell for $50. An enthusiast who wants to run two, three, or four video cards for gaming can spend $300, but most of the extra cost supports cooling the chips when you run the board at higher than the standard clock speed.

A mainboard has lots of different functions and connections. While it is possible for something critical to fail, most mainboard problems involve specific functions. A USB port doesn't work, or the built-in audio doesn't work, or the round PS2 connector for the mouse fails. These functions can be replaced with adapter cards or external USB devices. At some point the patches and limitations become annoying enough to buy a new board.


It has been claimed that 93% or more of retail desktop computers have video integrated into the mainboard. Intel has an infamously bad family of integrated video chips, and Microsoft is being sued for misrepresentation when it downgraded its standards for "Vista Compatible" to allow crappy Intel systems to carry that label.

On the other hand, any video integrated on an MATX mainboard is good enough to run all the Office applications, the standard Windows interface, and basic DVD movies. You need more to run Vista in Aero mode, play video games, or show Blu-Ray high definition movies.

The least expensive video cards in any generation of technology typically sell for $45 to $80. They do a fine job for everything except video games, where they are just OK. The most important thing to look for is the connector. The old "analog" 15 pin "D" shaped connector was required by an old CRT monitor, but today everything is digital flat panel. The new larger DVI connector provides a sharper, better picture on such monitors. Most DVI connectors on a video card can be converted to the old analog connector through an adapter plug.

TV sets and consumer devices use a smaller digital plug called HDMI, and some video cards contain an HDMI socket. Computer standards are more precise than TV standards, and some flat panel monitors will display a sharper picture when connected to a DVI slot than when connected to a HDMI slot on the same adapter card. So always leave DVI available as a fallback position.

Some people hook their PC up to their TV set and operate it using a TV remote control. Others hook their cable up to their PC and watch TV programs in a window on their screen. The DVD has been around for so long that any CPU and video card can handle it. Blu-Ray drives are just becoming available for the PC in the $160 price range. Modern video cards can do most of the processing for High Definition movies, but only if the video card is connected to a monitor that supports HDCP over the digital (HDMI or DVI) connector. Do not assume this is going to work until you try it out. After trying different cards and different connections without getting HDCP to work on my monitor, I e-Mailed the vendor Sceptre. They replied,  "The HDCP is made for DVI-HDMI standalone devices such as up-conversion dvd players or satellite box with DVI output. I'm sorry this was not tested for video card's HDCP protocol." So a monitor, particularly one sold as a TV set, can support HDCP on consumer electronics without successfully negotiating it with PC video card.

If you don't have HDCP support on the monitor that works with the card, then you cannot display Blu-Ray or HD DVD movies on a screen through the DVI or HDMI connector. You can, however, display them on the same screen using the old 15 pin "D" shaped analog connector (the "VGA" connector) because the movie studios allow this. However, in this arrangement the video card does not do the processing, so you need at least a Core 2 Duo CPU running at 2.4 GHz or better to view the movies properly and the CPU will be nearly 100% busy.

There are three main vendors of video chips.

Curiously enough, both Nvidia and ATI have adopted comparable model numbers. The first digit is a generation (1xxx, 2xxx, and 3xxx for ATI and 6xxxx, 7xxxx, 8xxxx, and 9xxxx for Nvidia). Within any generation a x400 or lower card is an entry level device good for watching TV and movies, an x600 card is a middle of the road system that can run some games, and a x800 or x900 card is a high end gaming card that, if you buy two of them, will cost more and use more power than everything else in your computer combined.

Power Supply

The Power Supply is rated by the maximum amount of power it must provide to the rest of the computer. Most business systems will get along with 350 watts, but a system with four cores or high end video cards can require 500 watts or more. The Power Supply is the component most likely to fail sometime during the life of the computer. It may overheat or the cooling fan may fail. As it starts to fail the voltage levels go bad (the 12 volt wires may carry only 11 volts) and that can make the computer unstable and it will start to crash. Or the computer will simply fail to turn on.

There are a lot of "no name" power supplies that together with a plastic computer case sell for $30 or $40. They may work well, or they may fail. Antec is the best known standard maker of cases and power supplies and while they have a good reputation, they also have occasional products. There are some premium brands like SeaSonic.

This is one of the simplest components to replace. Four screws attach it to the case. You have to disconnect all the cables, put in the new unit, and reconnect all the cables. This is fine if the thing dies outright. However, since every other part of the computer draws power, if the power supply doesn't fail outright but just drifts out of its standard operating range, the symptoms can incorrectly point to other components. Experts who deal with lots of computers tend to invest more on the power supply and get higher quality here than on other components. If you are unsure, read the comment section of Newegg to see how other people feel about a particular brand and model. If you have enough machines to stock spare parts, this is the first item where you buy extra and put one on the shelf.


SATA is simpler and faster than the old parallel ATA. There is one high speed disk from WD called the "Raptor" that is at twice as fast as all other disks. Otherwise, you buy disks based on price, capacity, and reliability.

Things to look for in Disk:

All you need is a Phillips Screwdriver

You can buy every part (except the CPU) from a dozen different vendors. There are only two CPU choices. Everything will fit together because there are standards. Lets build the system.

  1. The Power Supply is a metal box with cables that dangle from it and connect to devices inside the case. You slide it into place and attach it to the back of the case with four Phillips screws (that come with the Power Supply).
  2. The mainboard sits on screw holes on top of nine "standoffs" that keep the bottom of the board a quarter inch away from the metal of the case trey. Standoffs and the screws that attach the mainboard come with the case. In almost every case these are the same size screws as the ones that hold the Power Supply.
  3. A modern power supply has a 24 pin connector that plugs into a slot on the mainboard. There is a second 4 pin connector. There is a latch on one side of each plug that attaches to a plastic notch on one side of the mainboard socket, but the plugs have shapes so they cannot be plugged in upside down.
  4. The CPU drops into the socket and clamps in place. A cooling tower (heat sink and fan) clamps on top of the mounting assembly on the mainboard. Plug the fan into the little 3 pin power connector on the mainboard.
  5. Plug memory into the memory slots. If they don't go in at first, you may be trying to plug them in backwards.
  6. Plug the video card in the long PCI Express slot.
  7. The hard disk and DVD drive connect to the case with four screws, typically two screws on each side. These screws also come with the case, but they are slightly smaller than the screws that hold the mainboard to the standoffs. There are only the two sizes of screws.
  8. Now plug the long thin SATA cable to SATA socket number 1 on the mainboard and connect it to the back of the disk. There is an L shaped connector so it cannot go in wrong. Connect a power cable from the power supply to the back of the disk.
  9. Now there is a block of pins on the mainboard and some little cables from the front panel of the machine. Typically you connect the power switch, power light, disk light, and speaker cables. There will be a diagram in the manual for the mainboard. The power and disk light connectors are the only things in the computer that you can plug in backwards. If either light does not go on, open the case later and flip the connector around.
  10. Connect the monitor, keyboard, and mouse. Plug the power cable in the wall and turn the machine on. It is time to install an operating system.

The first time you do all this you may spend hours checking and rechecking everything. When you get used to it, the whole process can take as little as 20 minutes. On an assembly line, a worker probably builds a system in 3 minutes.

For another description with pictures (but oriented to more powerful high-end systems), read this step by step guide from The Tech Report.


There are only a dozen different components in a PC. Some like the keyboard or mouse are obvious, and if they break you can replace them for $15 to $30. It turns out that this applies to the components inside the computer as well. The CPU, mainboard, disk, DVD drive, memory, video card, power supply, and the cables that connect them are all standard components with standard shapes and connections. Each component is inexpensive and is mass produced in complex factories. If one breaks, you replace it rather than trying to repair it.

You can get a three year service contract with Dell. This simply means that someone else will replace the broken component. Disks are generally sent back to the manufacturer to be reconditioned and sometimes reused. Everything else probably ends up as electronics trash. If you have a laptop you are probably stuck with the service contract. Each system is different. If you have a desktop computer, however, all the parts are standardized.

Sometimes the problem is obvious. In most cases, the only way to troubleshoot the problem is to replace one component at a time until the problem goes away. This is only practical, however, if you have a complete set of spare parts (unlikely) or a second machine. Therefore, if you only have access to one computer, get the service contract. If you have a second computer purchased at roughly the same time and therefore with compatible components, you can do it yourself.

Memory is easy because you almost always have more than one memory stick installed (for performance) but the system will run with only one stick of memory installed. So you can run with first one stick and then with just the other, and if the system only fails when a particular stick is installed that is the bad part.

Disks should be easy, because everyone should have two disk drive and should backup their system onto the second drive. Then if the primary disk fails you can swap cables and start using the backup. Remember, before you toss a "bad" disk out, first change the cable that connects it to the mainboard, the mainboard connection the cable plugs into, and the power connector. Alternately, take the "bad" disk out and plug it into spare connectors as an extra disk on a second system to see if it is still unusable.

In general, you can either replace components in the good system until changing one thing makes the problem go away, or you can move components to a good system until one of the items causes the problem to move with it.

Swapping one power supply for another takes about 10 minutes, especially if you don't take a lot of time to pretty up the cables. If the system previously did not power up, and now it does, then you know the old power supply was bad. You can buy a power supply tester for $20, but typically you have to do this sort of thing a lot before you get one of them.

To swap components, they have to be based on the same technology. You cannot swap a SATA disk for a old parallel ATA. You can't swap an AGP graphics card for a PCI-e card. You can replace DDR 2 memory with old DDR memory. That is why the other computer has to be roughly contemporary.

If you have eliminated all the other easy to swap components, then what is left is the CPU and mainboard. Although these are two components that can be swapped separately, removing the heat sink and CPU can be a lot of work. Besides, it is almost always the mainboard because it is more vulnerable and has more parts to fail. If that is the only remaining possibility, swapping mainboards from a good system is more likely to cause a second problem and not of much diagnostic benefit. Go online and buy a new mainboard for $50 to $80, and maybe a new CPU to go with it.

If you donít want to be bothered, buy the service contract.

Carburetor or Cup Holders?

Back in the 1950's, before fuel economy and pollution controls, people judged a car by the power of its engine. Today, however, cars are sold to the mass market based on a quiet smooth ride, side air bags, a nice sound system, and Cup Holders.

There is a "hot rod" market for custom computers today. As with the automotive hot rod, the target audience for high performance computers are young males playing games. They have even borrowed a word from automotive customization, buying "modding" hardware for their systems. Cases have transparent panels and low heat internal lights to show off the electronics. The CPU is "overclocked" (run at a speed higher than that recommended by the manufacturer) and the extra heat is removed with exotic cooling systems. As with cars, this is a specialty market.

Maybe itís the lower speed limits, or maybe the boomers are just getting older. Big engines are less important than they used to be. Some people even dream of zipping through town on a Segway. The same thing may happen with computers. The 55 to 65 miles per hour boundary for computers may correspond to 700 MHz to 1 GHz. That is fast enough to run Windows, browse the Web, read E-Mail, listen to MP3 files, and run all the Office programs. Faster speeds are only useful if you play computer games, convert video files, or run a server.

This is not a message that the computer makers want you to hear. It might suggest to people that they keep their old computer for another year rather than replacing it with a new model. However, technology continues to evolve across the board, and CPU may not be the most important thing. You didn't buy your last new car because the speed limit increased on the highway.  Consider some other issues:

High performance computers run games that appeal to the teenager. For the rest of us, a comfortable keyboard, easy to read screen, and quiet room may be more important.

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.

If you play video games or edit video, then the speed of your computer depends on the speed of the CPU. If you record TV shows on your computer and then edit out undesirable material periodically inserted into the program, processing may be 10 times faster if you read from one disk and write to another than if you use a single disk. The performance of a database is typically determined by the amount of memory you have. Copying files from one machine to another depends on the network speed.

Summary and Links to Topics

Each main point will be summarized here. The summary is then linked to a secondary page where you can learn more about a particular topic. Readers are urged to follow each such link to get the full story, but you can make your own decision.

Circuit Size, Voltage, and Heat

All the electronic components of a computer follow some basic design principles. To make a computer circuit operate faster, you have to make it smaller. Smaller circuits can run at a higher speed, using less voltage, and producing less heat. By analogy, if the only question is 0 or 1, empty or full, then it is much faster and requires much less work to fill a shotglass with water than to fill a bathtub. These four factors (size, speed, voltage, and heat) are always in balance. You can increase speed on a given chip by increasing the voltage, but that produces more heat and requires more expensive cooling. For more information ...

Clocks and Cycles

Components of a computer (the CPU, memory, adapter cards) are coordinated by a "clock" signal measured in Megahertz (millions of ticks per second) or Gigahertz (billions of ticks per second). Generally we say that speeding up the clock makes the computer run faster, but that is slightly misleading. The clock tells all the components when they should all be done with their previous operation and when they should begin the next step. Components all run at whatever speed their design permits. If all the components can complete their longest operation with lots of time to spare, then there is room to speed up the clock, shorten the periods, and get more work done in the same amount of time. Set the clock too fast ("overclock") and it ticks before one of the components is quite done with its last operation. Then the system crashes.  For more information ...

CPU, Instructions

A computer chip can do simple arithmetic, compare numbers, and move numbers around in memory. Everything else, from word processing to browsing the Web, is done by programs that use those basic instructions. CPUs get faster in three ways. First, better designs can do the simple operations faster. Second, better design can do as many as six simple operations at the same time in different areas of the CPU. Thirdly, since a lot of time is lost if the CPU has to wait for data from slower memory, techniques that reduce the memory wait time appear to speed up the CPU. For more information ...

Hyperthreading and Multi-Core

The processing steps of a computer program can be decomposed into a set of independent "threads". To display a Web page, the Browser has to read in the page itself plus each individual file representing the pictures and ads displayed within the page. Then the text has to be arranged on the page and each picture has to be decompressed. Finally, the page has to be arranged and displayed on the screen. Each of these operations can be assigned to a thread. If a computer has (or appears to have) two CPUs, Windows will assign a separate thread to each processor and the computer will process two different streams of data at the same time.

No matter how fast Intel makes its chip, a modern CPU spends 50% or more of its time waiting for data to arrive from main memory. This is only getting worse, because CPU speed increases much more quickly than memory speed. A larger cache provides some help. Another idea, however, is for the CPU to have some way to switch from the instruction and thread that is blocked waiting for data to another thread that is ready to execute. This is the idea behind "Hyperthreading". Each CPU pretends to be two processors. The OS assigns a thread to each pretend processor. When one thread is blocked waiting for data, the CPU can switch over to the other thread and get more work done. For more information ...

Memory and "Burst" Speed

Technology has been applied to increase memory speed only when it can be done without reducing size or increasing cost. Current mass market designs favor Double Data Rate SDRAM. When a CPU instruction requires data from memory, it presents the address and then has to wait several cycles. Once the first block of data has been located by the memory hardware, the 32 bytes immediately surrounding the address can also be transferred in a "burst" of activity. DDR memory transfers the data at twice the ordinary speed of the memory bus by transferring bytes on both the tick and the tock of the clock. For more information ...

The Mainboard (Motherboard)

The mainboard contains slots for the CPU, memory, and I/O devices. In current designs, one chip called the Northbridge  sits between and connects the three high speed devices: CPU, memory, and AGP video port. It is then connected to a second chip called the Southbridge that provides logic for all the slow speed devices: the keyboard, mouse, modem port, printer port, IDE controller, PCI, USB, and any other devices. For more information ...

Hard Disks and CD Drives

Apple adopted an industry standard technology called SCSI for its Macintosh computers. It was a standard that applied to desktops, servers, and even mainframe computers. PC makers, however, followed a path of tricks and gimmicks to design the lowest cost disk attachment. The simplest possible electronic interface was a chip that duplicated exactly the mainboard I/O bus available at the time. A simple 40 wire cable connected this chip to logic chips on the disk. The mainboard bus had been introduced on the IBM PC AT in 1985, so the disk connection became knows as AT Attachment or "ATA". It is also popularly known as "IDE" but some manufacturer claimed that as a trademark barring its use as an official name. Then a dozen years passed, and each year the chips got twice as smart as the year before. ATA evolved from an 8 MHz connection to a 133 MHz connection and became smart enough to handle other types of devices. However, the physical connectors and programming interface had to build on and remain compatible with an idea that some engineers developed to build the lowest cost possible interface based on the primitive electronics available at that moment in time. Today computers are transitioning to a new simpler and higher speed interface called Serial ATA. For more information ...

Video and Monitors

The video adapter requires higher data transfer speeds than any other device. While the disks and network plug into the PCI bus or Southbridge mainboard chip, the video adapter is connected at high speed to the CPU and memory. For a decade, the video connector has been an AGP slot rated by speed (2x, 4x, or 8x). In the last few months, Intel has begun to offer a new slot design called PCI-Express that on paper can operate four times as fast as the fastest AGP slot. However, at the currently available technology, no video adapter card requires that much extra speed. For more information ...

PCI and PCI Express

For a decade starting in 1985, PC adapter cards all plugged into the "ISA" bus. Then Intel came up with a better, faster PCI bus, which has dominated the last decade. The good news from such a long period of stability is that there are lots of fast, cheap, compatible adapter cards to upgrade your computer with an extra disk controller or a better audio system. The bad news is that ten years are up and it is time for a new I/O bus. The only part of PCI-Express that is similar to the old PCI bus is its name. It provides a much higher speed in a much smaller socket. However, although there are a few PCI-Express video cards available, there are no PCI-Express adapter cards. Systems will continue to need PCI slots for at least the next few years. For more information ...


An Ethernet adapter card connects an office PC to the corporate network. At home it connects several computers to each other for file sharing, and it allows all the computers to share a single high speed Ethernet connection over a DSL or Cable modem.  For more information ...

USB and FireWire

To connect external devices (printers, scanners, disks, CD or DVD writers) to a computer there are two popular connection standards. USB 2.0 and FireWire provide full speed support for large numbers and a broad variety of external plug and play devices. For more information ...

Copyright 1998, 2005 PCLT -- Introduction to PC Hardware -- H. Gilbert