Their rallying cry is Operation Sun Devil and other government probes into malfeasance by so-called computer "hackers." These investigations, they assert, smack of hang-em-high justice and all to often become examples of government heavy-handedness. "Some of the government's actions clearly weren't constitutional," said Mitch Kapor, founder of Lotus Development Corp. and a new software firm ON Technology in Cambridge, Mass. Kapor, along with a small group of fellow computer pioneers, recently announced the formation of the Electronic Frontier Foundation, a group dedicated to protecting the rights of computer users. Its ultimate goal is to extend the same First Amendment protection that the print and broadcast media enjoy to digital communications. "Our idea is to get people to understand the issues and not to try and make decisions in a controversial and confrontational atmosphere," Kapor said. Secret Service and U.S. Justice Department spokesmen in Washington declined to comment on Operation Sun Devil or other computer investigations. But they stressed that the federal agencies are mindful of the need to protect civil rights. "We are not just some renegade agency breaking into peoples's computer systems,"said Secret Service Agent Rich Adams. "We would not be investigating if we were not mandated by Congress. That's why we're involved." The foundation is pushing its goals by providing legal assistance to computer users who become victims of what they see as overly zealous law enforcement officials. It also is awarding grants to civil liberties organizations such as the Computer Professionals for Social Responsibility in Palo Alto