Computers: Pranksters, Pirates and Pen Pals

In 1980 four 13-year-olds from Dal ton, a private school in New York City, used the school's computers for a silicon-chip joy ride through the stored riches of several corporations. Over a period of six months, the Dalton Gang eavesdropped on private data banks, juggled accounts and mischievously erased 10 million bits of data from a Canadian cement company's computer. Tracked down and thoroughly chastised, the youths promised to go straight. But since then, electronic pranksterism by other teen-age sorcerers has only grown more sophisticated—and diabolical.

In his pin-neat, Northern California bedroom, a...