NEW YORK — Lawrence Tesler, a pioneering computer scientist who in his work at Xerox and with Steve Jobs at Apple devoted himself to making it easier for users to interact with computers, died Sunday at his home in Portola Valley, Calif. He was 74.
His wife, Colleen Barton, said that there was no known cause of death, but that in recent years Mr. Tesler had suffered the effects of an earlier bicycle accident.
During his career Mr. Tesler worked at a number of Silicon Valley’s most important companies. But it was as a young researcher at Xerox’s Palo Alto Research Center in the 1970s that he did his most significant work, helping to develop today’s style of computer interaction based on a graphical desktop metaphor and a mouse.
Early in his Xerox career (he began there in 1973), working with another researcher, Tim Mott, Mr. Tesler developed a program known as Gypsy, which did away with the restrictive modes that had made text editing complicated. For example, until Gypsy, most text-editing software had one mode for entering text and another for editing it.
Mr. Tesler was passionate about simplifying interaction with computers. At Apple he was responsible for the idea that a computer mouse should have only one button. For many years the license plate on his car read, “NO MODES.”
At Xerox PARC, his first breakthrough came when he took a newly hired secretary, sat her in front of a blank computer monitor, and took notes while she described how she would prefer to compose documents with a computer. She proceeded to describe a very simple system, which Mr. Tesler then implemented with Mott.
The Gypsy program contained such innovations as the “cut and paste” analogy for moving blocks of text and the ability to select text by dragging the cursor through it while holding down a mouse button. It also shared with an earlier Xerox editor, Bravo, what became known as “what you see is what you get” or WYSIWYG printing, a phrase Mr. Tesler used to describe a computer display that mirrored printed output.
And it implemented the idea of opening a computer file by simply clicking on a screen icon while pointing at it with the mouse cursor. Before that, files had to be opened by typing the file name into a command line.
“At Xerox he pushed a lot for things to be simpler in ways that would broaden the base of users,” said David Liddle, a veteran Silicon Valley venture capitalist who worked with Mr. Tesler at Xerox PARC. “He was always quite focused on users who weren’t also PhDs in computer science.”
Mr. Tesler later joined a small team of researchers run by Alan Kay, a visionary computer scientist who had pioneered the idea of a so-called Dynabook, which would become the inspiration for today’s laptop computers. The group was developing a software environment called Smalltalk, and Mr. Tesler developed a system for searching for software components, which he named the browser.
“He can be hailed as one of the true pioneers of many important aspects of personal computing,” Kay said.
After attending a demonstration of the Altair, an early hobbyist personal computer, at a Palo Alto hotel in 1975, Mr. Tesler returned to PARC to alert his colleagues to the arrival of low-cost systems. His warnings were largely ignored.
He continued to advocate for less costly computers. In 1978, with Adele Goldberg and Douglas Fairbairn, he designed a portable machine called NoteTaker, a forerunner of luggable computers like the Osborne, Kaypro, and Compaq machines of the early 1980s. But Xerox declined to commercialize the NoteTaker; only a few prototypes were made.
It was Mr. Tesler who gave Steve Jobs the celebrated demonstration of the Xerox Alto computer and the Smalltalk software system that would come to influence the design of first Apple’s Lisa personal computer and then its Macintosh.
Mr. Tesler left Xerox to work for Jobs at Apple in 1980.
“The questions the Apple people were asking totally blew me away,” Mr. Tesler was quoted as saying in a profile that appeared in IEEE Spectrum, the magazine of the Institute of Electrical and Electronics Engineers, in 2005. “They were the kind of questions Xerox executives should have been asking but didn’t.”
Mr. Tesler left Apple in 1997 for a startup and later went on to work for both Amazon and Yahoo. He left Yahoo in 2008 and spent a year as a product fellow at 23andMe, the genetics information company. He was most recently an independent consultant.
Lawrence Gordon Tesler was born in the Bronx on April 24, 1945, to Isidore and Muriel (Krechman) Tesler. His father was an anesthesiologist.
At Stanford, where Mr. Tesler studied mathematics, he was involved in a number of early projects that prefigured personal computing.
Mr. Tesler’s first startup venture was a programming consulting company located in a mall adjacent to the Stanford campus. He also used a mainframe computer to build a system to permit the Stanford football student rooting section to program elaborate card stunts. It was, Kay said, a forerunner to the ways in which modern graphical displays would be programmed.
In addition to Barton, a geophysicist, and his daughter, Lisa Tesler, he leaves two brothers, Charles and Alan.