Since the theme of this issue is "Computing on the Road," let's take a look at the current crop of processor chips that power today's notebook computers. The processor chip is the main central processor unit (CPU), which performs all the calculations that makes the computer work. In other words, it's the computer's brain, which does all its "thinking." The newest processors are all designed to overcome some inherent problems with notebook computers: speed, power consumption, and connectivity. Notebook processors have typically lagged behind desktop processors due to slower clock speeds and slower memory buses. Increases in processor speed not only consumes more power (shortening battery life), they also generate more heat. Finally, connecting notebook computers to the external world has gotten easier as wireless networking becomes more popular. As we look at each type of processor, we'll consider how it deals with these factors.

The Pentium 4-M was Intel's first attempt to adapt its Pentium 4 to notebooks. Its design focused on saving power, which it does well. But it lacks the speed of the desktop Pentium 4, and costs more. The fastest Pentium 4-M has a 2.5 GHz clock.

The Mobile Pentium 4 is very similar to the desktop Pentium 4, but consumes about 25% less power. Its fastest version has a 3.06 GHz clock, the same as the fastest desktop Pentium 4, but without the hyper-threading feature that adds considerable speed to the desktop model. And the Mobile Pentium 4 chip costs more than the desktop Pentium 4.

Intel's most recent, and highly advertised new processor chip is the new Centrino. Although its name sounds like a sub-atomic particle, the Centrino is actually a suite of three chips. The processor chip is the Pentium M, which is designed from the ground up as a notebook chip. It uses a 1 MB cache to fetch data from the notebook's memory faster. That gives its 1.6 GHz version performance equal to a 2.4 GHz Pentium 4-M. The fastest Pentium M chip has a 1.7 GHz clock speed.

But Centrino includes more than the Pentium M chip. A new chipset called the Intel 855 takes care of the essential functions on the motherboard. Supporting up to 2 GB of RAM, the Intel 855 also provides highly desirable USB 2.0 support. Running 40 times faster than a USB 1.1 bus, the USB 2.0 bus is essential to adding high-speed accessories, like printers, scanners, DVD burners, and today's high-speed CD burners.

Finally, Centrino includes built-in support to 802.11b wireless networking (sometimes called WiFi) via an Intel PRO/wireless 2100 network connection chip. This chip reduces power required to run a wireless connection, and lets a notebook manufacturer build in the wireless network circuitry. That means you don't have to give up a PCMCIA expansion port to the WiFi card.

Intel's main rival, AMD, is not ignoring the notebook market, either. It recently announced Athlon XP-M processors designed for notebook computers. There are three versions of the Athlon XP-M processor: 1900+, 2000+, and 2800+ models. Remember, the numeric rating of Athlon processors is intended to designate equivalent performance in an Intel processor, so the 2800+ processor should be roughly equivalent to a 2.8 GHz Pentium 4. The 1900+ and 2000+ chips are designed for use in slim, lightweight notebooks, while the 2800+ chip is designed for high performance notebooks.

Although AMD chips are compatible with WiFi networks, there is no direct support akin to the Intel PRO/wireless 2100 chip.

Listen to Your Laptop
Many modern notebook computers include DVD drives, which can play standard DVD movies that you can rent (or buy) at your local Blockbuster Video. My notebook computer keeps me entertained during trips on which I have lots of free time (e.g., on airplanes) and few recreational opportunities. But when I watch a movie, the notebook's tiny (and tinny) speakers don't do justice to the sometimes spectacular soundtracks on many DVDs. So I pack a set of headphones in my notebook case. Plugging those into the speaker output jack on my notebook yields much better sound, although it's far from audiophile quality. Similarly, when I want to listen to music CDs, I can pop one into the notebook DVD drive, and play music through the headphones. But increasingly, I have become dissatisfied with the quality of sound through the headphones. So I did what many audiophiles do: I consulted the HeadRoom Corporation, a company that specializes in amplifiers and other accessories for headphones.

HeadRoom offers two amplifiers designed for mobile listening. The HeadRoom AirHead amplifier is only slightly larger than a cassette tape, and runs about 40 hours on three AAA batteries. You can get an AC adaptor at most electronics shops (e.g., Radio Shack). According to HeadRoom, it produces "clean, clear, massively enjoyable audio reproduction." The price is $120. For a little more money ($200), HeadRoom offers the Total AirHead amplifier (Figure 2), with upgraded internal components. In its refreshingly direct manner, HeadRoom acknowledges that the Total AirHead will make a difference with only the best headphones, so unless your headphones cost in the neighborhood of $300 or more, the basic HeadRoom amp is probably the better choice. Plug the AirHead into notebook's audio output jack and your headphones into the AirHead. As a final enticement, HeadRoom includes its proprietary circuit that creates a more believable stereo image from headphones, instead of the common sound-in-the-middle-of-your-head image. This circuit should make music sound more like it's coming from speakers than headphones.

So what if you don't have headphones, but would like to try some? When you visit any electronics or music store, you'll see there's an enormous choice. For notebook users, space is at a premium, since they have to store headphones in their notebook case. For that reason, I recommend considering headphones that fit into the ear like earplugs. Prices start at around $10, but for more money, you can get some decent headphones. The Etymotic ER-4 in-ear headphone sells for $269, and is one of the best headphones you can get. If you're like me and not ready to spend that much on headphones for occasional use, Etymotic makes a lower cost ER-6, and Shure (maker of phono cartridges and professional audio equipment) makes an E2C model, both of which cost about $100. That's still a lot of money, but way less than $269. The in-ear headphones also provide better isolation (around 20db) from the outside environment, which provides sonic comfort in noisy environments like airplanes. HeadRoom sells all these headphones, and offers package deals if you buy headphones and an amplifier at the same time.