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This paper presents a methodology for evaluating text editors on several dimensions: the time it takes experts to perform basic editing tasks, the time experts spend making and correcting errors, the rate at which novices learn to perform basic editing tasks, and the functionality of editors over more complex tasks. Time, errors, and learning are measured experimentally; functionality is measured analytically; time is also calculated analytically. The methodology has thus far been used to evaluate nine diverse text editors, producing an initial database of performance results. The database is used to tell us not only about the editors but also about the users—the magnitude of individual differences and the factors affecting novice learning.

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The Xerox Star has had a significant impact upon the computer industry. In this retrospective, several of Star's designers describe how Star was and is unique, its historical antecedents, how it was designed and developed, how it has evolved since its introduction, and, finally, some lessons learned. What Star Is Star was designed as an office automation system. The idea was that professionals in a business or organization would have workstations on their desks and would use them to produce, retrieve, distribute, and organize documentation, presentations, memos, and reports. All of the workstations in an organization would be connected via Ethernet and would share access to file servers, printers, etc. Star's designers assumed that the target users are interested in getting their work done and not at all interested in computers. Therefore, an important design goal was to make the "computer" as invisible to users as possible. The applications included in the system were those that office professionals would supposedly need: documents, business graphics, tables, personal database , and electronic mail. The set was fixed, always loaded, and automatically associated with data files, eliminating the need for users to worry about obtaining, installing, and starting the right application for a given task or data file. Users could focus on their work, oblivious of concepts like software, operating systems, applications, and programs. Another important assumption was that Star's users would be casual, occasional users, rather than people who spent most of their time at the machine. This assumption led to the goal of having Star be easy to learn and remember. When Star was first introduced in 1981, its bitmapped screen, windows, mouse-driven interface, and icons were unique in the marketplace. They were readily-apparent features that clearly distinguished it from other computers. Soon, however, these features were adopted by others. Today, windows, mice, and icons are more common. However, Star's clean, consistent user interface has much more to do with its details than with its gross features. We list here the features that we think make Star what it is, categorized according to their level in the system architecture, the levels being: machine and network, window and file manager, user-interface, and document editor. Machine and Network Level Distributed, personal computing-Though ViewPoint is available in a stand-alone configuration, Star and ViewPoint were designed primarily to operate in a distributed computing environment. This approach combines the advantages and avoids the disadvantages of the two other primary approaches to interactive computing: time-shared systems and stand-alone personal computers. Time-shared systems, dominant through the Sixties and Seventies, allow expensive resources like printers and large data stores to be shared by many users and help assure the consistency of data that must be used by many. The disadvantages of timesharing are that all users are dependent upon the continued functioning o...

integral to the design process of the Xerox 8010 "Star" workstation was constant concern for the user interface. The design was driven hy principles of human cognition. Prototyping of ideas, paper-and-pencil analyses, and human-factors experiments with potential users all aided in making design decisions. Three of the human-factors experiments are described in this paper: A selection schemes test determined the number of buttons on the mouse pointing device and the meanings of these buttons for doing text selection. An icon test showed us the significant parameters in the shapes of objects on the display screen. A graphics test evaluated the user interface for making line drawings, and resulted in a redesign of that interface.