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A technological turning point

technofile  by al fasoldt

Columns and commentaries in a life-long dance with technology

Simple gray rule

Tandy's THOR recordable CD, and reflections on a technological turning point

By Al Fasoldt

Copyright © 1988, The Syracuse Newspapers

When I was a boy I used to dream of space travel on the long walk to school.

Down the hill past the cattails, up the side road, down the street near the pond, I imagined I was captain of a space cruiser. I could press a button and shift into overdrive and travel instantly to Alpha Centauri or any other place in the universe.

That was 35 years ago. By the time I discovered girls and cars, I had almost forgotten about intergalactic travel. But the memory of all those childhood fantasies came back to me this spring in a curious fashion, as I was reading the announcement of a new recording system.

I had picked up a public-relations release from Tandy Corp., the parent company of Radio Shack and the maker of Tandy computers. Tandy said it was going to sell a compact disc player that would record as well as play back.

Tandy said the erase-and-record CD system would cost about $500. The company made it clear that no one will be able to buy the device for quite a while - probably not until 1990 - because it's still being developed.

Tandy didn't mention that other companies are coming out with their own versions of erase-and-record CDs, too, possibly even before the Tandy CD recorder reaches its stores. The other ones probably won't work the same as Tandy's version.

I figure Tandy announced its new system so far ahead to ambush its rivals. It wants to line up backers for its own way of turning a compact disc player into a recorder, because it can't afford to do it all by itself.

But all's fair in love, war and business, and Tandy can do whatever it wants.

What intrigued me was the effort by Tandy and the other manufacturers to create record-and-play compact disc machines at the same time that many companies are about to introduce tape recorders that do the same thing.

Digital audio tape machines, which have the same sound quality as CDs, are almost certain to be sold in the United States by late this summer or early autumn. These DAT recorders have a clear advantage over recordable compact discs - they'll play for a much longer time. CDs can play for only about 70 to 74 minutes, but DAT recorders can play for 120 minutes. And older style digital recording systems, which use special adapters hooked up to VCRs, can play for up to six hours.

Surely the record-and-play CDs must have a compelling advantage. What could it be?

Some writers have suggested that a big advantage of erasable CDs is that they will be cheaper than tape. That's probably not true. Blank CDs are likely to cost as much as blank tapes, at least for a while. (And if you compare cost per minute, CDs might even be more expensive.)

As for the machines themselves, CD recorders probably will cost less than digital tape recorders because they will be easier to mass-produce, but the prices are likely to be too close to make much of a difference to consumers.

Then, too, a minor advantage of CDs is their ruggedness. Much has been made of the fact that a CD can be stepped on and even tossed around the room without affecting the sound. However, digital audio tapes are rugged, too. Many manufacturers have already chosen DAT players over CD players for use in cars, where rough treatment is a way of life.

The answer lies elsewhere. Recordable CDs are superior to tapes because of the most elemental reason - the way they are shaped. CDs are discs and tapes are ribbons. Tape is fine for sequential operations - when you want to do one thing at a time, without changing the order of events. Tape is like a conveyor belt in which items come off at the end in the same order that they went on at the beginning.

But a disc has a special property that sets it apart from every other object: When it is spinning fast, every point on its surface can be reached almost instantaneously by an arm that travels across it in a simple back-and-forth motion. You can play a disc - in other words, take information out of it - in any order, regardless of the order in which it was recorded. You can also record onto a disc at any point, any time you want to.

This principle is well known in the computer world. It's called "random access," and it's used billions of times a day around the globe in computer disc drives. It's also used in many regular CD players whenever the user programs the player's microprocessor memory to play the musical tracks in a non-standard order.

By pushing the development of a digital disc recording system rather than digital tape, Tandy is looking beyond audio applications to computer data storage. Digital audio signals are actually computer bytes, which means that CDs are perfect for computer use. That is, they could be perfect, as soon as CDs are developed that can be recorded and erased just like computer floppy discs are now.

That's Tandy's real aim. More than anything else, it wants to be a world leader in computer technology, especially at a time when other aspects of electronics, such as audio and video, are becoming merged with the science of computing.

Tandy was also following the same kind of path that my reveries led me on when I dreamed of instant travel on my way to school. The route I took from the back porch of my home to the schoolyard was as unfailingly sequential as any tape recording.

But my notion of hypertravel was like that spinning CD: Leave one spot on the disc and drop down to any other in an instant. The difference, of course, was that I was hoping such a thing could be done by people and not just by lasers. But at least the little boy in me can always say we're part way there.


Tandy calls its new compact disc recording system Thor-CD, but computer hobbyists have another term for it: Vaporware.

Unlike hardware or software, vaporware exists only in the minds of product planners and company presidents. Tandy announced its Thor-CD at least a year and a half before it will be able to sell the first sample, and it is even possible that unless Tandy wins support from other manufacturers, the Thor-CD won't be sold at all.

Tandy is taking its chances with vaporware to steal the spotlight from Japanese companies that have been working on the same type of system - a compact disc player that can erase and record as well as play. The combined Japanese research effort is undoubtedly bigger than Tandy's, and may even be further along toward a working consumer version.

Tandy's hope is that by announcing its own type of CD recording system, it can persuade researchers who have not yet lined up with the Japanese to help it surmount the major design obstacles.

Those barriers are, in brief:

  • The possibly limited lifetime of the medium. Tandy's technique creates the pits that are read by the CD's laser in playback and smoothes them out during its erasing operation. Smoothing out the pits is a physical process, and no one knows how many times the medium can be reshaped before it literally wears out.
  • The permanence of the recorded signal. Even CD recordings that are never subjected to repeated record-erase cycles may not be as stable as normal CDs. From descriptions offered privately following Tandy's announcement, it appears that Tandy's method is yet unproven in this area.

To Tandy's credit, it has insisted that record-and-erase CDs be compatible with current CDs in every way. This means that someone who makes a CD recording on a Tandy Thor-CD machine can send it to a friend with a regular CD player without worrying whether it can be played properly. This is similar to the situation that is finally evolving in home video, where nearly all regular VCRs are of the VHS type, and tapes can be swapped easily.

But Tandy may be wasting much of its time concentrating on compatible CDs. The biggest use for a CD recording system won't be in home audio - where, after all, digital audio tape and regular cassette tape recorders will reign for many years - but in computer data storage.

It's much less important in computer usage whether a recordable CD follows the audio-CD format. A computer record-and-play CD drive makes different demands on the medium, including the need for more precise error checking than Tandy has designed into its Thor-CD.

Adding to the confusion over Tandy's announcement is the recent development of another kind of computer CD, called CD-ROM (for "read-only memory"). A dozen companies will be selling CD-ROM players this year, with some of them already on the market.

CD-ROMs contain vast amounts of computer data, placed on the discs by companies that specialize in data recording. They can't be erased, and they are as permanent as audio CDs. A single CD-ROM can hold all the printed information (although not the pictures) of two or three encyclopedias.

And then, to muddy the issue even further, there are laser-based systems that allow the user to record computer data onto a CD-type disc. These are called WORM drives, for "write once, read many" (the name is a strained acronym, but the computer world is stuck with it).

WORM discs, which are usually larger than CDs, can be recorded, but they can't be erased. This is a major liability, but since they usually can hold huge quantities of data - 2,000 times as much as a computer floppy disc in some cases - they work well in applications where information is unlikely to be changed, such as financial records at the end of each day.

CD-ROMs, WORM drives and Tandy's Thor-CD face a common competition from an older technology, the magnetic disc. Breakthroughs in magnetic technology have already raised the capacity of the most common type of disc, the floppy, to 6 megabytes, and researchers in Japan say they have designed floppies with capacities of two or three times that figure.

This is far below the 630-megabyte capacity of a CD, but parallel developments in hard magnetic discs are promising to raise their storage limits in affordable consumer versions - to the CD range within the next year or two.

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