Digital Fetes the 'Germ' That Began a Revolution
By JOHN MARKOFF
Published: December 16, 1990
MARLBOROUGH, Mass.— The Digital Equipment Corporation held a 30th-birthday celebration here recently for its first computer, a machine with capabilities that today's users of even the simplest computers now take for granted. Among those who gathered were the computer scientists and hackers who as young men helped to shape the computer revolution.
When they set to work on software for Digital's first computer three decades ago, using a computer meant waiting in line to feed in stacks of punched cards, each of which carried a line of instructions. An answer from the machine was often hours or days in coming. And a single mistyped character or misplaced card could ruin the program and require that it be run again.
Digital's first computer, called the PDP-1 and introduced in November 1960, changed everything. It was the first commercial computer to allow a user to type a program on a keyboard, see the program displayed on a screen to make sure it was correct, run the program and receive a prompt answer.
"It was the first time in the history of the world that when you had an idea you could implement it in just a few days," said Ed Fredkin, a professor of physics at Boston University who in the 1960's was a programmer at Bolt Baranek & Newman. "It was fantastic. The PDP-1 was the germ that started the whole thing. It was the world's first fun and interactive computer."
Professor Fredkin hung around with a ragtag band of students, professors and other hangers-on at the Massachusetts Institute of Technology that, working on a machine donated by Digital, came up with software to make the PDP-1 useful. Their software innovations included the first computer graphics systems, the first word processors, the first video games, the first computer music systems and programming tools for the first researchers in artificial intelligence.
Members of this group which almost singlehandedly laid the foundation for the personal computer and work station business commemorated the 30th birthday of the PDP-1, only 49 of which were built.
Among the guests were some who are now among the most famous people in computing. Marvin Minsky, who was and still is a professor at M.I.T., is perhaps the foremost pioneer of research into artificial intelligence, in which computers mimic human functions like vision, speech and decision-making. John McCarthy, a Stanford University professor who was an M.I.T. professor at the time, was an early developer of computer time-sharing systems, which allowed more than one person to use a computer at the same time.
Others included Alan Kotok, a former M.I.T. student who went on to become one of Digital Equipment's leading computer designers, and Richard Greenblatt, another former student, who founded Lisp Machine Inc. and designed Machack, the first chess-playing program that played chess well.
The PDP-1 helped foster the new culture of computer hackers. Before being distorted by news accounts of computer break-ins in the early 80's, the term referred to a group of obsessive young people whose passion was to perfect their programs in all-night sessions at M.I.T.'s Radio Laboratory for Electronics.
The PDP-1 donated to M.I.T. by Digital in 1961 enticed several students who had been members of a model railroad club at the school to experiment with computers.
"It was the first appliance computer," said Steve Russell, a former M.I.T. student who is now a California-based software designer. "It had a switch and you turned it on and you got a satisfying 'clunk' and it started working."
Mr. Russell ultimately used the PDP-1 to develop a two-player video game called Spacewar.
The game, which permitted the user to maneuver a spaceship on a video screen and shoot at another ship, was the first of its kind and almost 30 years later is still the basis of a legal dispute between the Magnavox Corporation and other companies over who invented the first video game.
The PDP-1 was also used for one of the first efforts at time-sharing computing, based on a program written by an M.I.T. professor, Jack Dennis. Although the computer actually ran only one program at a time, it quickly swapped different users' programs, making it appear that each user had the machine to himself.
Time-sharing was a break from the batch-card computing pioneered by the International Business Machines Corporation, and it was controversial when it was introduced.
"Certain people at I.B.M. thought that time-sharing would be a bad thing," Dr. Minsky said. "They believed that it would lead to people writing sloppy programs."
Among the programs written by the M.I.T. group for the PDP-1 was one by Dan Murphy called Teco, or tape editor and corrector. It permitted the computer user to type at a keyboard and search for and replace individual characters in a line of text. Teco was to become the forerunner of word processing.
The computer was then nicknamed "expensive typewriter," Mr. Russell said, because the researchers had managed to turn a $120,000 machine into something that worked almost as well as a typewriter.