Classic Computer Magazine Archive COMPUTE! ISSUE 167 / AUGUST 1994 / PAGE 80

Totally wired. (data communications technology in the past and future)
by Robert Bixby

Let's take a look at what the future of cable access will be. To see the complete flow, we need to look at the history of telecommunications. (The source for much of this information is Cable TV Technology Information Kit, provided by the National Cable Television Association.)

Once, telephones and telegraphs were very rare things. Information flowed fit-fully and in small packets. The problem (or one of the problems) was wiring. It would take nearly a century just to string wire to every house and to develop a nationwide network of lines. Wireless communication seemed to solve many of these problems. Within a few years of the invention of the wireless (radio), most homes had sets.

When television arrived, it could do more things than radio, but in order to broadcast its more complex set of signals, it had to use a wider band than radio so there could be fewer stations.

When satellites in geostationary orbit came into play, virtually half of the earth was in direct view of any given satellite. Bandwidth was less of a problem, too, since from the beginning, communications satellites could handle hundreds of channels.

Satellite reception is currently in a bit of a muddle. All cable providers use satellite receivers, many homeowners have installed satellite dishes in their backyards, and people will soon receive transmissions using 18-inch receivers on top of their televisions--satellite dishes barely more imposing than rabbit ears. But the big money is on central receivers and distribution through fiber-optic cables.

As you can see, the development of electronic communication has been a continuing battle between distribution (who's included in the net) and bandwidth (the amount of information that can move across the net). Shortwave can distribute a little information to billions of people while television transmissions can move a lot more information but serve at most a few million people close to the transmission tower.

Wire communication faces similar challenges. Twisted-pair wires (used for telephone and some computer networks) can carry only about 1/900 the information a coaxial cable can carry. But coaxial is also prone to problems. Signals are attenuated rapidly along the wire, requiring constant amplification. A coaxial cable must have an amplifier every 2000 feet, or the signal will drop off to nil.

Each time a signal is amplified, a little bit of noise is introduced into the system, so you can't string a cable out indefinitely without making the signal so noisy that it's useless. It's the noise of amplification that limits most cable systems to about 40 channels. If there were a way to feed a clean signal down a cable without amplification, you could boost the number of channels to between 100 and 200.

The key to this is fiber-optic cable, which requires less amplification and can provide a clean signal close enough to your home that an unamplified coaxial cable (called a drop line) can run the rest of the way to your receiver with little degradation in signal and up to 200 channels of infomercials and home shopping networks. But that's not all.

Where cable and computers come together is the point of interest. Think back to the 1980s--those dim days at the dawn of time when people bought magazines and books with type-in programs in order to spend long hours creating software for themselves by typing in code at the keyboard. CompuServe and The Source had some programs available online for downloading, but at 300 bps, who could afford all of the online time?

Disk-based software was available at 80K and 160K at a time. In the blink of an eye, we have moved from those times to the era of CD-ROMs capable of providing 3000--6000 times as much information as the first floppy disks on platters that are smaller and less fragile than floppies. Although CD-ROMs are more convenient, more capacious, and more rugged than floppies, they are on the verge of being supplanted by online technology, which provides far more convenience, capacity, and ruggedness than CD-ROMs provide.

Online connections will make concern over distribution of data a thing of the past. You will be able to access as much data as you need--at least for today's applications--virtually instantaneously. You will pay fees not for collections of disks and manuals but for access to code and text files online. But the key phrase is "for today's applications." Applications will rapidly begin to push the envelope for data transmission. Once, the 600MB CD-ROM full of highly compressed code and data was seen as the answer to distribution problems that made 1.44MB floppies virtually obsolete. A few months later, manufacturers found themselves shipping applications and games on two and even three CD-ROMs. Similarly, I have confidence that the demands of presenting the virtual worlds we will soon inhabit will quickly outgrow the capacity of cable. What will we do then?