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I PREFER the quiet of libraries to the whir of computers.

It's more satisfying to hunt a book in lonely stacks than to click the keys of an electronic card catalog. Why run to a computer dictionary, I ask myself, when it's so much easier (and faster) to pull one from the shelf?

But a couple of new software products have forced me to rethink electronic look-ups.

It was October 12, one of those heavy reading days. A scholar, bandying about his knowledge, popped "homoscedastic" into his article. I didn't know what it meant.

On a whim, I had already installed an electronic dictionary and thesaurus from Reference Software International (the same folks who make the grammar-checker Grammatik). So I fired up the program and typed in "homoscedastic." Nothing.

Did I mean "homestead law," the computer asked. Hah! I thought. But my copy of Webster's New World Dictionary didn't have "homoscedastic" either. (The unabridged defines it as "having equal standard deviations.")

The electronic look-ups got better: "argy-bargy" (a noisy discussion) and "global village" (a Marshall McLuhan term). Even more impressive was the program's ability to search phrases. At one point, stuck for a word to describe someone who stays at home, I typed "stay at home" in the definition-search feature. It took several minutes, but up popped "homebody" just 10 seconds after I'd come up with the same word.

I was beginning to glimpse the power of electronic look-ups.

The program is awkwardly titled. Who but a computer company would call a product the "Random House Webster's Electronic Dictionary and Thesaurus, College Edition, Version 1.0?" But for about $99 - in DOS, Windows, and, soon, Macintosh versions - it's worth a look for people who use their computers to write.

Electronic reference works are not just books on computer. They're an entirely new form of publication, says Andrew Rosenheim, director of electronic publishing for Oxford University Press.

This summer, Oxford came out with an electronic version of the world's greatest English-language dictionary, the Oxford English Dictionary, Second Edition. In book form, the only way to search is by word. But with its new software, you can search electronically by anything you like: by etymology, by date ("show me all the words that first appeared in 1780"), or by author. It took one graduate student 18 months to discover that novelist Anthony Burgess was cited 55 times in the dictionary volumes, Mr. Ros enheim says. Electronic searches like that take about 12 seconds.

The use of compact-disk, read-only-memory or CD-ROM for electronic books will grow. These optical disks are slow but they pack so much information they put hard disks to shame. The Windows version of my Random House Webster's dictionary eats up 8.5 megabytes of disk space. Oxford put its 20-volume dictionary on a single CD-ROM. The disk costs a third of the $2,750 asking price of the book.

Compton's NewMedia is another company going into CD-ROM. It fit its entire Interactive Encyclopedia for Windows - pictures, maps, and all - onto one disk, which lists for $395. Compton's is taking the electronic look-up into the age of multimedia.

On a computer wired for sound, you can hear the cluck of a chicken or the roar and shattering glass of an earthquake. The encyclopedia displays a picture of Abraham Lincoln or the text of the Gettysburg Address.

Sometimes this works. The encyclopedia has an animated sequence explaining how the earth's tilt causes seasonal change. It's illuminating. Other times, the multimedia dimension falls flat. The sequence of a spouting whale is small and blurry.

I still don't run to my computer to look something up. But if I'm already working at the machine, it's handier and more powerful to click over to the electronic dictionary-thesaurus than to reach for the book. A multimedia encyclopedia might make sense too, especially for older children already using computers for reports.

Multimedia is only in its first generation. Compton's offers animation but no video. I can't watch an earthquake while I hear it rumbling on the speakers.

But clearly, we're moving into a new era. CD-ROM for library stacks. Multimedia instead of the "Quiet Please" of the reference desk.

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