Citizen Bandwidth

# Citizen Bandwidth

Inside the Internet.
Nov. 8 1997 3:30 AM

# Citizen Bandwidth

## Andrew Shuman, boy developer, explains bandwidth to the masses.

How fast can you read this? How fast will your computer keyboard accept the characters you type? How fast does water flow out of your kitchen faucet? The answers depend on bandwidth. Simply put, bandwidth is a measurement of how much, how quickly. The speed at which your brain absorbs words (words per minute), your computer accepts keystrokes (characters per second), or your faucet squirts water (gallons per minute) can be described in terms of bandwidth.

The rate at which computers can send and receive information is expressed in bandwidth, too, as bits per second. Surveys tell us that most readers connect to Slate with 28.8 modems, which, under optimal conditions, deliver a bandwidth of 28,800 bits of data per second. What's a bit? A bit is the smallest unit of data, either a zero or a one. For example, eight bits represent a single letter in the alphabet: The eight-letter word "alphabet" contains 64 bits.

The average Slate article--and I just happen to have one right here, "Booker Snooker"--contains about 800,000 bits of text, images, and formatting information. It takes about 30 seconds to download via a 28.8 modem. (Let's do the math: Eight hundred thousand bits divided by 28,800 bits per second equals 27.8 seconds.)

Software developers like me lust for more bandwidth, and so do civilians like you who only use computers. We all want Slate and ESPN Sportszone and Amazon.com to download faster to our computers. Bandwidth! Bandwidth! Bandwidth! the masses cry. But ever since mankind first took serious notice of bandwidth--ever since the invention of Morse code, that is--there hasn't been enough of it. An average telegrapher can communicate at 20 to 40 words per minute. That's about 16 to 32 bits per second. If your computer operated at Morse code's bandwidth, it would take between a half-day and a full day to download a page from Slate.

The bandwidth bottleneck bugs me because we've seen dramatic increases in performance on almost every other computer front. A 1985 processor (386) ran at 12 MHz. A 1997 Pentium II processor runs at 300 MHz--about 20 times faster. Over that same time, the storage capacity of the average computer has grown by a factor of 250. But usable bandwidth for the home user has increased only about threefold.

Have the bandwidth guys been taking long lunches, or what? Actually, they've been doing a great job--it's the rotten telephone companies that have been lollygagging. Everybody has heard about Moore's Law, named after an Intel founder, which holds that the power of CPUs doubles every 18 months. There's a corresponding bandwidth law, named after its discoverer, right-wing techno-utopian George Gilder, which states that bandwidth triples every 12 months. And it has been tripling every 12 months for the last decade or so.

T he phone companies haven't piped this wonderful bandwidth into most homes yet because they're fairly happy with the quaint technology of copper wire they've installed over the last century. Copper-wire telephone connections have enough bandwidth to transmit voices, but not enough for gluttons like me. Click for an explanation of "Shannon's Limit," which tells you why the bandwidth of conventional telephone connections will never exceed 56,000 bits per second.

If you're lucky, your friendly neighborhood telephone monopoly provides ISDN service in your town. ISDN stands for "integrated services digital network," and the technology moves data to computers at 128,000 bits per second. That's five times faster than a regular modem, which means you can download the average Slate page in about six seconds. The service isn't cheap. In Seattle, the phone company charges about \$100 for ISDN installation and about \$65 a month for flat-rate access. The ISDN modem itself will set you back about \$200. ISDN is the most popular alternative to conventional modems: Slate's Washington, D.C., offices connect to the Web and the Redmond mothership through ISDN.

T he best bandwidth is free bandwidth. For most people, that means a T1 connection at work or school. (In New York City, some Net-savvy landlords are outfitting apartment buildings with T1 service. I wish those landlords would buy my building in Seattle.) Like ISDN, T1 breaks the 56,000-bits-per-second barrier by going 100-percent digital, that is, by transmitting ones and zeros instead of the up-and-down waves of an analog signal. For a more detailed explanation of how ISDN, T1, and other ultrafast technologies work, click.

T1 transmits data at 1.5 million bits per second, delivering Slate articles in about half a second. Of course, your mileage may vary depending on how many users are connected to your T1 line, how busy the Internet or Slate's Web site might be at the moment, and how clogged your local-area network might be. You can only move so much data through the pipe at a time.

But you want faster. Some phone companies are offering test trials of a new technology, ADSL, or "asymmetric digital subscription line." Right now, ADSL is ridiculously expensive--more than \$1,000 for the modem alone. But it's also ridiculously fast. Connection speeds are around 8 million bits per second from the Internet to you and about 800,000 bits per second from you to the Internet. It would take only one-tenth of one second to download a Slate article via ADSL.