Robert T. Morris '87-'88, who masterminded the "virus" program that immobilized computers across the country, studied computer security intensely while at Harvard, where he was known as a creative but innocuous prankster, associates said in interviews this weekend.

Termed a "classic hacker," the Dunster House graduate is portrayed by friends as an avid computer buff who spent long hours toying with computers to the exclusion of his studies.

Morris, who was known as "RTM" among his close-knit circle of computer friends, developed a reputation as a friendly practical joker who liked to amuse his colleagues.

"When something went wrong at a work station, people would look at him and he would say, 'No, it wasn't me,'" said Mark J. Nitzberg, a computer graduate student, who knows Morris. "But he's not a criminal."

A typically inventive and nettlesome prank devised by Morris was a program that automatically sent computer users into an adventure game if they made typing errors while trying to enter an electronic mail system, friends said.

The game--dubbed "MIAL" after one of the common spelling errors it exploited--sent the user on a series of adventures from which it was difficult to exit. Morris maintained a file which recorded the moves that players made when they entered the game.

"Some people played it, and some people started cursing at it," said Gregory J. Kuperberg '87, who worked closely with Morris on computer projects while they roomed together in Dunster House.

While many friends declined to label the first-year Cornell graduate student a genius, they said hard work and an incredible enthusiasm for the subject created a potent programming ability. They said, however, that any computer graduate student was capable ofcreating the virus that entered the NationalSecurity Agency's computer system, haltingterminals at many of the premier researchinstitutions in the country and the Pentagon.

Friends said Morris was fascinated by computersecurity and had given several talks on securingsystems similar to the one he broke into.

He had also done considerable work with BellLabs in New Jersey, at the DEC systems researchlab in Palo Alto, Calif., and as recently as lastsummer worked as an assistant in Aiken ComputationLab.

Through his links with Aiken, Morris developeda close circle of friends at Harvard whom hecalled upon when the virus went awry.

Morris, who has remained silent in spite ofheavy national media attention, is a privateperson who would never have run an experiment ifhe thought it would draw attention to him, hisfriends said.

"He's not talking to the press because hedoesn't want to seem like he's taking credit forit or he's proud of it," said Paul Graham, aHarvard graduate student who has worked withMorris. "It was a mistake."

They said he was primarily motivated bycuriosity and never intended any maliciousconsequences to his actions.

"In some sense, it was an experiment, it wastomfoolery," said Kuperberg, now a graduatestudent at the University of California atBerkeley. "If it had worked properly, no one wouldhave noticed it, and he would have seen itprogress and be amused by it."