Larry Tesler, who has died in California aged 74, was among the chief architects of the way we now use computers. Those in the industry knew him as the creator of design features such as cut and paste. Yet his true impact was in helping turn computers from business machines aimed at skilled technicians into appliances easily operated by anyone.
In 1973, Tesler took a job at the Palo Alto Research Centre (Parc) of Xerox, the copier company. He worked on Gypsy, a program for creating text documents on Xerox's pioneering but hefty word-processors. Although these were the first to use on-screen graphics for functions instead of typed commands, the obligation to switch between modes for different operations such as editing and inputting was off-putting, especially to novices.
Tesler was so keen to get rid of this that he had a T-shirt and number plate bearing the words 'NO MODES'. His solution was to make all modes always available, so that text could be inserted by simply clicking with a mouse at the chosen point on the screen.
Next, he took a secretary, Sylvia Adams, seated her in front of a screen and asked her what she would like to be able to do with a document.
From this came such innovations as selecting text by dragging a cursor and cutting and pasting. Another term which Tesler created was 'WYSIWYG' - what you see (on the screen) is what you get (on the page).
He later worked on Xerox's project for a portable computer, developing for it a system to search software that he called a browser. But Xerox's attention was focused on the threat from Asian manufacturers of cheap copiers and the idea foundered. Somebody else, however, was interested: Steve Jobs.
In 1979, in return for Xerox having an option to buy shares in Apple, its staff were shown around Parc. Jobs was astonished not only that its engineers had created features such as WYSIWYG and cut-and-paste but also that Xerox had not appreciated their potential.
The following year, Tesler made a speech at a conference revealing Xerox's innovations. With no trade secrets to protect, he was subsequently able to join Apple, which he realised was about to revolutionise personal computing.
He worked on the Apple Lisa, which incorporated much of Parc's development of windows, icons and, at Tesler's suggestion, a mouse with a single button. Although it was a relative failure, Lisa led to Apple's first success, the Macintosh.
The second of three children, Lawrence Gordon Tesler was born in New York on April 24, 1945. His father was an anaesthetist.
Larry Tesler is survived by his second wife, Colleen, and by his daughter. He died on February 16, 2020.