Excerpts from The Xerox "Star": A Retrospective

Jeff Johnson and Teresa L. Roberts, U S WEST Advanced Technologies
William Verplank, IDTwo
David C. Smith, Cognition, Inc.
Charles Irby and Marian Beard, Metaphor Computer Systems
Kevin Mackey, Xerox Corporation
See http://www.geocities.com/SiliconValley/Office/7101/retrospect/index.html

The Reactive Engine

While Engelbart et al were developing ideas, some of which eventually found their way into Star, Alan Kay, then a graduate student, was doing likewise. His dissertation, The Reactive Engine, contained seeds of many ideas that he and others later brought to fruition in the Smalltalk language and programming environment, which, in turn, influenced Star. Like the designers of NLS, Kay realized that interactive applications do not have to treat the display as a "glass teletype" and can share the screen with other programs.


Alan Kay had been one of the main advocates of the Alto. His Learning Research Group (LRG) began using the Alto to build prototypes for a personal computing system "of the future": a portable machine that would provide -- rather than a canned set of applications -- the building blocks necessary for users to build the tools and applications they need to solve their own information processing problems. The technologies needed to build a lap computer with the power of the "DynaBook" (as the envisioned system was called) were unavailable at the time, and still are. The prototypes developed by Kay's group evolved into the Smalltalk language and programming environment. They further promoted the notion of personal computing, pioneered complete, interactive programming environments, and refined and solidified concepts of object-oriented programming that had been extant only in vestigial form in previous systems. Most importantly for Star, they demonstrated the power of graphical, bitmapped displays, mouse-driven input, windows, and simultaneous applications. This is the most visible link between Smalltalk and Star, and is perhaps why many people wrongly believe that Star was written in Smalltalk.


The first large program to be written in Smalltalk was Pygmalion, the doctoral thesis project of David Smith. One goal of Pygmalion was to show that programming a computer does not have to be primarily a textual activity: it can be accomplished, given the appropriate system, by interacting with graphical elements on a screen. A second goal was to show that computers can be programmed in the language of the user interface, i.e., by demonstrating what one wants done and having the computer remember and reproduce it. The idea of using icons -- images that allow users to manipulate them and in so doing act upon the data they represent -- came mainly from Pygmalion. After completing Pygmalion, Smith worked briefly on the NLS project at SRI before joining the Star development team at Xerox.

Influence of systems


Star has had an indisputable influence on the design of computer systems. For example, the Lisa and Macintosh might have been very different had Apple's designers not borrowed ideas from Star, as the following excerpt of a Byte magazine interview of Lisa's designers shows:

Byte: Do you have a Xerox Star here that you work with?

Telser: No, we didn't have one here. We went to the NCC when the Star was announced and looked at it. And in fact it did have an immediate impact. A few months after looking at it we made some changes to our user interface based on ideas that we got from it. For example, the desktop manager we had before was completely different; it didn't use icons at all, and we never liked it very much. We decided to change ours to the icon base. That was probably the only thing we got from Star, I think. Most of our Xerox inspiration was Smalltalk rather than Star.

Elements of the Desktop metaphor approach can also be seen in many other systems.

The history presented here has shown, however, that Star's designers did not invent the system out of nothingness. Just as it has influenced systems that came after it, Star was influenced by ideas and systems that came before it. It is difficult to inhibit the spread of good ideas once they are apparent to all, especially in this industry. Star was thus just one step -- albeit an important one -- in an evolutionary process that will continue both at Xerox and elsewhere. That is how it should be.