To forestall dissatisfied-customer hassles, most software publishers offer altered versions of their programs so prospective buyers can sample them beforehand. But because such demos aren't fully functioning, it's still "Let the buyer beware" at the software store, even for programs costing hundreds of dollars.

The risk of blind investment in a shrink-wrapped product will shrivel, however, if a just-launched distribution scheme succeeds. This month TestDrive, a Silicon Valley start-up, begins quarterly release of a CD-ROM platter onto which are crammed as many as 100 software programs. Each is the complete off-the-shelf version, not a demo. By downloading one of the programs from a CD-ROM drive (at $250 or so, a worthwhile investment on its own), a shopper can give that package -- Quattro Pro or Lotus 1-2-3, for example -- a head-to-toe workout.

What's to prevent a user from simply going on using the programs? A "counter" encrypted in each one limits the number of times it can be run. If, after a few trials, the user wants to keep a given product, he or she dials an 800 line, provides a credit-card number to pay for it, and is given a code that disables the counter. The program's manual and ancillary material follow by express mail.

TestDrive CD-ROM is $9.95 quarterly; an introductory annual subscription is $19.95. PC and Mac versions are available. Call 800-788-8055.

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