During the late 1960s, interface design made additional leaps. In a famous 1968 lecture, Doug Engelbart, a scientist then working at the Stanford Research Institute, unveiled a prototype of the modern graphical interface. Rigging up a television set to the computer and adding a pointer device which Engelbart dubbed a " mouse," the scientist created a system even more interactive than the time-sharing system developed a MIT. Treating the video display like a high-speed printer, Engelbart's system gave a user the ability to move the cursor around the screen and see the cursor position updated by the computer in real time. The user suddenly had the ability to position text anywhere on the screen.
Such innovations would take another two decades to make their way into the commercial marketplace. Still, by the 1970s, video screens had started to replace teletypes as display terminals, creating the potential for full-screen-as opposed to line-by-line-editing capabilities.
One of the first programs to take advantage of this full-screen capability was the MIT AI Lab's TECO. Short for Text Editor and COrrector, the program had been upgraded by hackers from an old teletype line editor for the lab's PDP-6 machine.ccording to the Jargon File, TECO's name originally stood for Tape Editor and Corrector.
TECO was a substantial improvement over old editors, but it still had its drawbacks. To create and edit a document, a programmer had to enter a series of software commands specifying each edit. It was an abstract process. Unlike modern word processors, which update text with each keystroke, TECO demanded that the user enter an extended series of editing instructions followed by an "end of command" sequence just to change the text.Over time, a hacker grew proficient enough to write entire documents in edit mode, but as Stallman himself would later point out, the process required "a mental skill like that of blindfold chess."See Richard Stallman, "EMACS: The Extensible, Customizable, Display Editor," AI Lab Memo (1979). An updated HTML version of this memo, from which I am quoting, is available at http://www.gnu.org/software/emacs/emacs-paper.html.
To facilitate the process, AI Lab hackers had built a system that displayed both the "source" and "display" modes on a split screen. Despite this innovative hack, switching from mode to mode was still a nuisance.
TECO wasn't the only full-screen editor floating around the computer world at this time. During a visit to the Stanford Artificial Intelligence Lab in 1976, Stallman encountered an edit program named E. The program contained an internal feature, which allowed a user to update display text after each command keystroke. In the language of 1970s programming, E was one of the first rudimentary WYSIWYG editors. Short for "what you see is what you get," WYSIWYG meant that a user could manipulate the file by moving through the displayed text, as opposed to working through a back-end editor program."See Richard Stallman, "Emacs the Full Screen Editor" (1987). http://www.lysator.liu.se/history/garb/txt/87-1-emacs.txt
Impressed by the hack, Stallman looked for ways to expand TECO's functionality in similar fashion upon his return to MIT. He found a TECO feature called Control-R, written by Carl Mikkelson and named after the two-key combination that triggered it. Mikkelson's hack switched TECO from its usual abstract command-execution mode to a more intuitive keystroke-by-keystroke mode. Stallman revised the feature in a subtle but significant way. He made it possible to trigger other TECO command strings, or " macros," using other, two-key combinations. Where users had once entered command strings and discarded them after entering then, Stallman's hack made it possible to save macro tricks on file and call them up at will. Mikkelson's hack had raised TECO to the level of a WYSIWYG editor. Stallman's hack had raised it to the level of a user-programmable WYSIWYG editor. "That was the real breakthrough," says Guy Steele, a fellow AI Lab hacker at the time.
By Stallman's own recollection, the macro hack touched off an explosion of further innovation. "Everybody and his brother was writing his own collection of redefined screen-editor commands, a command for everything he typically liked to do," Stallman would later recall. "People would pass them around and improve them, making them more powerful and more general. The collections of redefinitions gradually became system programs in their own right."
So many people found the macro innovations useful and had incorporated it into their own TECO programs that the TECO editor had become secondary to the macro mania it inspired. "We started to categorize it mentally as a programming language rather than as an editor," Stallman says. Users were experiencing their own pleasure tweaking the software and trading new ideas.
Two years after the explosion, the rate of innovation began to exhibit dangerous side effects. The explosive growth had provided an exciting validation of the collaborative hacker approach, but it had also led to over-complexity. "We had a Tower of Babel effect," says Guy Steele.