Reprinted from CHI ‘98 Conference Summary, pp. 18-19. © 1998 ACM. Copying by permission of the Association for Computing Machinery.

This paper was the introduction to the live demonstration of Lisa.

Abstract

Apple’s Lisa, introduced in January 1983, was the bridge between the first commercial graphical desktop system, the Xerox Star (April 1982), and the Apple Macintosh (January 1984), which popularized it. Although visually similar to current graphical user interfaces, its user model differs substantially. The live demonstration presents a broad view of the Lisa user interface and relates it to other systems. This extended abstract focuses on elements of Lisa’s document-centric user model and context management that made it easier to learn and use than today's systems.

Introduction

Lisa development started in 1979. Intended for general office use, it was to be easy to learn, forgiving of errors, allow for interruptions, robust in the event of failure and, most of all, be fun to use. The user interface design evolved through several iterations [4] and was influenced during development by ideas introduced by the Xerox Smalltalk [2] and Star [5] systems. The Lisa adapted these ideas to a stand-alone personal computer with a smaller screen and an open software environment, and added several new elements common in today’s systems, e.g., the menu bar, trash can, stationery, drag-and-drop, Undo, desktop menu, clipboard, interactive tutorials, and exceptional graphics. For a thorough description of the Lisa user interface see [3], [6], and [7].

Much of the Lisa interface was adopted by the Macintosh but there were significant differences, particularly in their user models. The remainder of this paper describes the Lisa’s document model, document save model, and context switching management, highlighting how they differ from some of today’s systems. For brevity, the following description assumes the reader is familiar with one or more of today’s graphical desktop environments.

Document-centric user model

In the Macintosh document model [1], and that of Microsoft’s Windows [8], a document is a typed disk file where the type determines the icon used to represent it and the application to run, if any, when the disk file is displayed in a window. These systems layer this model on top of a “glass-box” computer model that exposes applications, processes, and disk files in a way that cannot be ignored by users. The Lisa model was based on the single concept of “document,” with two forms of presentation, as icon or window, and the place where it resides, a disk or diskette. It hides applications, processes, and disk files from the user.

Figure 1. Lisa Desktop. Note the lack of Open, New, and Quit commands

A user always began working on a document by selecting its icon and opening it; there was no “Open...” command in any application’s File menu (see Figure 1). New documents were created by selecting a stationery pad and opening it; there was no “New” command in the File menu. Opening stationery created a new document, duplicating the stationery’s content, and automatically named it by adding the date to the stationery’s name. It could then be opened immediately or renamed and/or filed before opening.

When a document was opened, its shape changed from icon to window, leaving only a place holder “shadow” at the icon’s location. When the user “put away” the document, the window changed back to its icon, replacing the shadow. If a user needed to temporarily interrupt working on a document, it could be “set aside” on the desktop. A set aside document was represented by its document icon, but behind the scene it remained active, similar to a minimized window in today’s systems, ready for quick access at a later time. Since users never saw both document icon and window at the same time, a window was perceived as just a form of presentation, not as an independent object with its own edit state.

Hiding processes and applications

Lisa users did not have to manage processes; there was no “Quit” command in the File menu. When a window was put away or set aside, the Lisa activated the next window or the desktop as appropriate. There was nothing left to indicate the presence of a running process for the closed window, e.g., an orphaned menu bar. Behind the scene, when the user opened a document, the Lisa would check to see if the application was already running and, if so, ask the process to open the document – most Lisa applications could manage several open documents. If it could not, or if there was no process running, the Lisa would start a new one. When a process’ last document was put away, rather than automatically quitting the process, the Lisa would keep one application process running for future use until its resources were needed to run something else. This approach to process management removed the need to make processes visible to users so that they could keep frequently used applications running in order to save time when opening other documents of the same kind.

When a user activated a document by opening it, by clicking in its window, or by picking it from the Desk menu, only that document window came forward. Some of today’s windowing systems are process-based. If an application is designed to handle multiple documents within a single process, activating a document will bring forward all document windows managed by that process. This process-centric operation can interfere with a user’s working with multiple documents by potentially obscuring other windows of interest.

A Lisa user’s awareness of an application was limited to the existence of its icon in the “Tools” folder. It was used only to verify the presence of an application on a system and to update it via drag-and-drop replacement. It could not be started directly by the user.

Hiding disk files

Lisa icons represented documents, folders, tools, and applications, not individual disk files. Some icons, e.g., a folder, had no related diskfiles while others, e.g., an application or document, had several. Grouping files in this way reduced the number of icons a user saw. Users could not see or manipulate individual disk files so they were never confused by the sudden appearance of a temporary file, nor could they accidentally corrupt a document or applications by removing, renaming, or discarding one disk file of a document’s set.

Persistent edits, save and revert

In the Lisa document save model, editing changes were persistent. The user did not have to explicitly save changes to protect them from a crash or to turn off the computer. Behind the scene, applications automatically saved changes as needed to an invisible “suspend” file that was part of the document.

Users did specify whether changes were to be saved or discarded when a document was put away. They could also do an explicit save after completing a coherent set of changes. This gave a sense of task completion and set a “save” state that enabled a user to easily remove subsequent changes using the “Revert” command.

This approach to document saving was robust and eliminated the need for precautionary saving and “Save changes?” dialogs. It also provided the user with a simple versioning mechanism: the saved version and the working version.

Context saving

The Lisa preserved the current work context when the Lisa was powered off. It recorded which documents, folders, and tools were on the desktop, the location of each, and if open, the window’s location, size, and scroll position. Similar actions were also performed when a diskette was ejected, though just for those documents, folders, and tools that resided on the diskette.

When the user turned the Lisa on or reinserted a diskette, the icons and windows reappeared as they were, much as some of today’s systems awaken from the “sleep” state. However, to minimize startup time the Lisa did not display a document’s actual content until a user indicated interest by clicking within its window. The user could then resume editing, undo the last change made during the previous session, or revert back to the last save point that may have been days or even years ago.

Conclusion

The Lisa presented users with a user model and interface that was largely free of many of the computer-related artifacts still found in today’s systems. The result was a system that users could learn and use effectively in a very short time. And it was fun to use.

Acknowledgments

Our thanks to Don Gentner and John Tang for their review and thoughtful comments.

Frank Ludolph
Sun Microsystems, Inc.
901 San Antonio Road
Palo Alto, CA 94303 USA
frank.ludolph (at) sun.com

Roderick Perkins
Interval Research Corp.
1801 Page Mill Road
Palo Alto, CA 94304 USA
perkins (at) interval.com

References

1. Apple Human Interface Guidelines: The Apple Desktop Interface. Addison-Wesley, Menlo Park CA, 1987.

2. Ingalls, D.H.H. The Smalltalk-76 Programming System Design and Implementation. Symposium on Principals of Programming Languages. ACM Press, New York NY, 1978.

3. Lisa Owner’s Guide, Apple Computer, Cupertino CA, 1983.

4. Perkins, R., Smith Keller, D. and Ludolph, F. History of the Lisa User Interface, Interactions (January 1997). ACM Press, New York NY.

5. Seybold, J. Xerox’s “Star.” The Seybold Report, 10, 16 (April 27, 1982) Seybold Publications, Inc., Media, PA.

6. Seybold, J. Apple’s Lisa, A Personal Office System. The Seybold Report of Office Systems, 6, 2 (January 24, 1983) Seybold Publications, Inc., Media, PA.

7. Schmucker, K.J. The Complete Book of Lisa. Harper & Row, New York NY, 1984.

8. The Windows Interface Guidelines for Software Design. Microsoft Press, Redmond WA, 1995.