Armed with search warrants, the agents came early Wednesday morning to 15 middle-class homes throughout the U.S., peering under beds, pulling out drawers, seizing print-outs and floppy discs. In California, they simulta- neously struck four homes within a 40-mile radius of Los Angeles. Wayne Correia, 17, of Irvine, Calif., looked up at 6:15 a.m. to find a man breaking in through his bedroom window. "FBI," the figure announced. "And that comp- uter's mine." The raids on the homes of young compuer enthusiasts in 13 cities were part of a federal investigation into reports of widespread abuse of computer networks. For months authorities have been waging a quiet war of nerves with the thousands of teen-agers who use their home terminals and telephone hookups to dial into larger systems across the country. Most are careful to do no harm, but for those bent on doing damage, the opportunities are boundless. One 14-year-old brags that he penetrated a computer belonging to a brokerage firm and erased a group of commodity trading accounts. Particularly vulnerable are the 1,200 computer systems that can be reached through a single telephone call to GTE Telenet, a network based in Vienna, Va. Last summer the FBI singled out for investigation a gang of Milwaukee-area youths who had used Telenet to enter a number of different systems, including unclassified Defense Department comp- uters and a machine monitoring the treatment of cancer patients in a New York City hospital. Last week's crackdown was the most dramatic to date. Phone taps and electronic "sting" operations were used to trap the suspects. To prevent them from warning their friends, the raids were carefully coordinated. Indeed, news of the FBI strike was quickly flashed across the country through messages post- ed on computer bulletin boards, and some youngsters reportedly rushed to erase discs and burn files. Though no charges have been filed yet, the Government, by going after the microkids in a style more commonly used for archcriminals, risked turning the youngsters into instant heroes. Nervertheless, while such tamperings may be born of curiosity and high spirits, they have serious con- sequences and are increasingly dangerous. Four of the California youths who were raided held a press conference at their high school to explain how the passwords they used for unauthorized break-ins had been provided by an anony- mous computer-network buddy. "I was kind of naive," said David Hill, 17, of Irvine. "I thought, oh boy, how neat." After the FBI action last week, no one smart enough to get into this sort of trouble should be able to claim such ingenuousness again. Typed by Uncle Fester Presented to you by The Dragon's Lair 10 megs..................516-374-5071