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How the new DAT recorder works

technofile  by al fasoldt

Columns and commentaries in a life-long dance with technology

Simple gray rule

How the new DAT recorder works, and why Sony capitulated

By Al Fasoldt

Copyright © 1987, The Syracuse Newspapers

Two weeks from tomorrow, Sony will introduce its most significant new product in years. With suitable hoopla, the Japanese giant will begin selling a digital tape recorder that uses tiny cassettes.

Sony's new recorder is not the first to reach the market, but it is the trendsetter. Without backing and participation from Sony, the new digital taping system would have no chance of success.

Called DAT for "digital audio tape," the new recording format was ready for introduction many months ago, but a political battle held up its premiere. The Reagan administration sided with recording companies and proposed a law that would require all digital cassette recorders to have an "anti-piracy" chip built in. The chip would prevent the recorder from working if it were dubbing a compact disc's digital output.

Although such a measure has not become law, Sony took no chances. Its new recorder includes the chip, and if Sony's leadership in other product areas is a guide, the rest of the audio component industry is likely to climb on the anti-piracy bandwagon.

Aiwa, which is a company owned by Sony, and two other manufacturers - Sharp and Matsushita (parent of Panasonic) - have also announced digital audio cassette recorders. All of them are being sold in Japan first, with U.S. introduction not expected until this fall at the earliest.

When the DAT recorders arrive here, they will start out at prices much higher than standard cassette decks - about $1,000 to $1,400 would be a good guess. But prices are likely to fall to the $500 range within two years.

DAT recorders do not use the same cassettes as regular decks, and the recording technique is entirely different, too. The DAT machines actually work like small video recorders, employing a spinning head drum to lay down helical tracks on an 8mm-wide tape.

With a standard 8mm tape, recording time is two hours. This could be increased if thinner tape or slower recording speeds are used, although a two-hour maximum seems well suited to most recording needs.

Efforts to keep DAT recorders from being used to make pirate copies of compact discs started when the recording industry realized that the digital circuits of DAT recorders could be hooked up directly to the digital outputs of some CD players. (Most CD players do not have digital outputs, but some of the more expensive models do.)

When a CD player and a DAT recorder are connected directly in this fashion, the digital signal that goes into the DAT recorder will be indistinguishable from the signal on the CD - and the result is a perfect clone on tape. Copying the normal way - by recording the standard audio output of the CD onto a DAT recorder - yields a good copy, but not a digitally perfect one.

So circuit designers proposed adding the chip that Sony adopted. It allows the recorder to work in the normal mode, but if it detects a "copy prohibit code" in the digital bit stream of a compact disc player, the recorder's circuits are disabled.

The anti-pirating code, of course, would have to be placed in the digital signal of a CD by record companies. No CDs have such signals now, so the anti-piracy chip would have no effect on the thousands of CDs already produced.

If Sony had decided to produce a DAT recorder without the anti-piracy chip, the rest of "Japan Inc." might have been encouraged to defy the threats of the U.S. trade regulators, who had talked about slapping quotas on the Japanese or even blocking the importation of DAT machines that could be used for direct digital copying.

But the significance of Sony's decision extends beyond the reaches of audio recording. Digital audio recording makes use of computer-type data, and any scheme that prohibits copying of digital audio data could be used in a modified way to frustrate piracy of computer data also.

Even the medium is the same in both cases. Compact discs are used in audio to record sound, and in computer storage to hold hundreds of megabytes of information. Computer-data CDs, called CD-ROMs, are already on the market, and it now seems likely that software publishers will find ways of making their CD-ROMs resistant to piracy, too.

If it is done properly, theft-proof software may at last become common, and software publishing could become as profitable as any other business. For those who spend their working hours (and working capital) writing tomorrow's computer programs, that could be good news indeed.

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