Like Woody Allen's 1983 movie character, Zelig, who appears at every significant historical event of his era, [see sidebar, "Larry Tesler"] has had a hand in major events making computer history during the past 30 years. When the first document-formatting software was developed at Stanford University in 1971, Tesler was coding it. When a secretary first cut and pasted some text on a computer screen at Xerox Corp.'s Palo Alto Research Center (PARC) in 1973, Tesler was looking over her shoulder. When the first portable computer was turned on in an airport waiting area (and on an airplane), Tesler had his fingers on the keyboard. When Steve Jobs went to PARC in 1979 to see the legendary demo that is purported to have set the stage for a revolution in computing, Tesler had his hand on the mouse.

And when Apple Computer Inc.'s infamous Newton handheld computer failed spectacularly in the early 1990s, taking millions of dollars of investment and a few careers down with it, Tesler was there, too. Hey, nobody gets it right 100 percent of the time.

So why haven't you heard of him? [see sidebar, "Larry's Lexicon"].

"Larry generated a lot of the basic ideas for the work we were doing," says Douglas Fairbairn, a former colleague at PARC. "But he doesn't have a big ego, so his name didn't get attached to things. He wasn't the one guy who did one big thing you'll remember him for; he was a collaborator on many things."

This past May, Tesler joined Yahoo Inc., in Sunnyvale, Calif., as vice president of user experience and design. At Yahoo, Tesler has perhaps his biggest opportunity yet to shape the way hundreds of millions of people interact with technology as they search the Web, watch and listen to media, share things they've created or found, correspond with family and friends, and even find love through the Internet.

When Tesler was a child, his parents couldn't quite figure him out, so they had him tested by a career counselor. The counselor told them that the results were unusual—Tesler registered a strange combination of sensitivity to people and fascination with math. The best career choice the counselor could suggest was working as an architect or maybe becoming a certified public accountant.

The field of computer usability did not yet exist. At the time, people had to learn arcane codes to communicate with computers, typically via punch cards and printouts. The idea of making a computer easy for the average person to use was still a new one when Tesler came along.

"I was born to do it and feel very lucky to have been in the right place at the right time," he says.

It's a recurring theme in his career, starting with Stanford University, in California, in the early 1960s. Computer time was available free of charge to anybody who wanted it, and Tesler, a math major, wanted it very much. He wrote a few little programs for his own amusement, and he programmed enhancements to the software that created graphic patterns for the 3465-seat card section at Stanford Stadium.

Soon he got a paid job in Stanford's computer laboratory developing software that would make strings of computer code easier for humans to read, by formatting the text into either fixed-width columns or free-form lines. It wasn't a new idea, he says, just a nicer implementation of an old idea.

But this was the first bit of computer code Tesler wrote that was meant to be used by large numbers of people. And he was hooked, by programming in general and by text formatting in particular. Text formatting—the ability to display or print out type in different sizes and with different fonts, spacing, and so on—doesn't generally get much attention in treatises on how the computer has transformed civilization. But it is actually one of the most common computer functions and the foundation of such programs as Microsoft Word. After college in the early 1960s, Tesler spent a few years working as a computer consultant. As one of only four listed in the Palo Alto, Calif., area phone book, he got a lot of calls. He wrote programs that scheduled classroom use for the San Jose school district and that simulated the distribution of nuclear fallout for the Stanford Research Institute (now called SRI International).

When the Silicon Valley recession of the late 1960s dried up consulting contracts, he managed to find a job at the Stanford Artificial Intelligence Laboratory, where he considered how computers might be made to understand natural human language and even to express simulated human thoughts and feelings.

"This work was technically fascinating," Tesler recalls, "but one day I woke up and realized that this stuff wouldn't be practical for decades."

And he had bigger woes, too: by 1970 his brief marriage to his college sweetheart had broken up. He packed his 5-year-old daughter and her favorite toys into his aging Dodge Dart and moved to Oregon, joining a wave of Vietnam-era dropouts. There, he and a group of friends bought land and began building their own houses. Eventually, he had a nice house but no savings. That was when he noticed that there was only one computer within a 60-kilometer radius, at a bank.

The bank wouldn't hire him, so Tesler called his former colleagues at the Stanford AI laboratory for help. He hadn't been in touch with them for six months.

"Did you know that Xerox started a computer research center in Palo Alto?" one asked Tesler. "About a week after you left for Oregon, Alan Kay, who planned to go to Xerox himself, came here looking for you." Kay, now a senior fellow with Hewlett-Packard Co., in Palo Alto, recalls that he even went to Oregon to try to track Tesler down. Kay had worked briefly at the Stanford AI lab and had considered Tesler "one of the most interesting intellectuals and one of the best programmers there."

Tesler immediately contacted Robert Taylor, director of the computer science laboratory at PARC, asking for a part-time job, so he could continue to live in Oregon. But PARC would consider Tesler only for full-time positions; Tesler wasn't interested. A month later, still jobless, he reconsidered, but by then Xerox had instituted a hiring freeze. The opportunity was gone.