 |
Abstract
In 1979 Apple began to develop Lisa, a workstation to enhance the productivity
of office workers. The hardware was built around a Motorola 68000, a bit-mapped
display, and a mouse. The user interface is intuitive, using real-world concepts
rather than computer concepts. It is easy to learn, and provides for both novice
users still learning the system and users that have mastered the system. The
user interface is modeless and consistent. The uniformity of the user interface supports
transferrable learning – the ability to learn an operation once and apply
it over and over again in another application in a different context.
The user interface also supports data interchange among documents of the same
or different types. This interchange of data, coupled with the multitasking operating
system and the multiple windows of the Lisa, permits the use of several
tools to perform a task that one tool alone could not accomplish. The
Lisa user interface and its applications provide an environment that allows the user
to concentrate on what is to be accomplished rather than on how
to accomplish it. In this way, Lisa provides tools to improve the productivity of
the office worker.
Introduction
Apple Computer formed the Lisa team in 1979 to develop a personal
computer that would dramatically improve the productivity of typical office
workers (professionals, managers, and their assistants). To accomplish this
goal, a hardware and software solution radically different from current
personal computer offerings was required. At that time, personal computers
had the functionality but lacked the capacity, speed, and ease of use necessary
to reach a market of users who did not want to learn the details of how a
computer worked.
Inspired by SMALLTALK1, the Lisa team developed a system that has the
functionality and speed users require, and additionally has a common user
interface that supports gradual learning and promotes interchange of data
among the same or different applications. The combination of multiple tools
with a consistent user interface and data interchange among applications
permits the user to work with several tools concurrently to accomplish a
particular task.
Lisa hardware
 |  Figure 1: The Lisa |
The Lisa is a Motorola 68000-based personal computer with 512 or 1024
Kbytes of main memory, a memory management unit, a bit-mapped display,
a detachable keyboard, a mouse, a built-in 400-Kbyte floppy disk drive, and a
5- or 10 megabyte Winchester disk (see Figure 1). This hardware provides
the functionality, speed, and ease of use required to support the Lisa user
interface.
The 68000 microprocessor was not the first choice. Development began on a
home-grown bit-sliced system to provide the computing power. When the
68000 became available in sample quantities, we evaluated it and found it had
good performance and was more economical.
The memory management unit (MMU) provides different logical address
space contexts for processes and protection. The protection ensures that an
individual application fault does not damage the rest of the system and
therefore improves system reliability. The MMU also provides for code
segment faulting and automatic stack expansion.
The bit-mapped display provides graphics and text support needed for the
user interface. The display is 720 by 364 pixels and supports quality graphics
and text fonts of different sizes and faces. This permits the word processing
applications to use black on white images, proportional-spaced fonts, and
different type styles including boldface, underline, and italic.
To complement the graphics output, Apple wanted to use a mouse for a
graphics input device, but existing ones were unreliable and had precision
bearings that made them expensive and difficult to manufacture. Apple
developed a mouse that is precise, tracks on almost any surface, and is easy to
manufacture. The original prototypes had three buttons, but we found users
spent too much time looking away from the screen to determine which button
to push; consequently we changed to a two-button mouse. Once we found
alternative ways to implement the functions of the second button, we changed
to a one-button mouse.
Lisa software
Lisa’s desktop model
 | | Figure 2: A Lisa screen showing the menu bar, two windows, and several icons |
The office system software provides the user with a desktop that mirrors the
function of a desk in the office. On the Lisa desktop, icons (small pictures)
depict the office world. In Figure 2 we see a variety of icons, a menu bar at
the very top of the screen, and two windows. One of the windows contains
the contents of a LisaWrite document, and the other contains the catalogue of
a disk.
There are several types of icons: documents, stationery pads, folders, a
wastebasket, a ProFile disk, a clipboard, and one called Preferences. The
types of documents are spreadsheets, business charts, lists, text documents,
etc. These document icons quickly show the user not only that the object
represented is a document, but also what type of document. Stationery pads
permit a user to create new documents, and in addition permit a user to
configure predefined forms or templates. For example, an office usually has
different types of paper stock. One might be used for letters going outside the
office, and another for interoffice memoranda. In the Lisa model, a user sets
up a stationery pad for both types, and then each time the user needs to write
a letter, he simply tears off a new piece of letter stock from the appropriate
stationery pad. Since the pad is constructed from a document, the stock can
be set up with the desired initial format and content. Folders provide a
convenient way of grouping logically related documents together-similar to
the function of file folders in the office. Thus, folders organize the contents
of diskettes, disks, and the desktop.
The desktop supports two icons that represent storage devices. The ProFile
icon represents the Winchester disk drive, and the diskette icon (not shown)
represents a floppy diskette inserted in the built-in drive. These devices are
used for document and program storage.
The wastebasket is used to throw away documents and programs. Just as the
office worker can retrieve something thrown away in the wastebasket, the
Lisa user can retrieve objects thrown in the wastebasket.
The clipboard is used by the editing operations. When a user edits a
document, pieces of information are placed on the clipboard. This
information can be copied into a different place in that document or into a
different document altogether. Thus the clipboard acts as temporary storage
for these scraps of information (more on this later).
The Preferences tool permits the user to customize the Lisa to suit his tastes.
The user can set the screen brightness, the tone generator volume, the key
repeat rate, the mouse click delay time, etc. Using Preferences, the user also
can configure printers and disks.
The menu bar, located at the top of the screen, shows the titles of the
available pull-down menus. The menus are called pull-down because when a
user depresses the mouse button over a menu title, a rectangular area under
the menu title pulls down like a roller blind. The rectangular area is called a
menu and contains a number of labels, which are called menu items. The user
moves the mouse down through the menu items and selects the desired
operation. The menus, in conjunction with the current selection, give the user
the ability to specify actions. For example, one changes a word in a document
to italic type by selecting the word and then choosing the italic item from the
Type Style pull-down menu.
The example desktop also shows two windows. Windows in Lisa show the
contents of disks, documents, wastebasket, etc. Lisa displays up to 20
windows at a time, and windows can overlap or completely obscure other
windows. The user has full control over the size and position of the windows.
The user interface philosophy
The Lisa user interface is much more than just a mouse, bit-map graphics, a
desktop with icons, and overlapping windows. The Lisa user interface is
designed to be intuitive. It uses real-world concepts, not computer concepts,
and provides familiar office objects and ideas. The natural model enables a
user to try things out that would make sense in the real world. In general
they directly transfer to Lisa’s desktop world.
The user interface is designed to work the way you would expect it to work.
In the office, users open documents, move them around, edit them, file them,
etc. With Lisa, the mouse is used to manipulate objects directly. This is one
of the key features of the Lisa user interface and is in stark contrast to
traditional “computerese” of command languages and textual, mode-driven
menus. Because there is no command language, very little typing is required
to perform operations.
To ensure that Lisa is easy to use and learn, Apple developed LisaGuide, an
interactive guide that teaches novices how to use the mouse as well as the
basic principles of selection and menus. Once they have been through
LisaGuide, they pick an application and start learning through actual use.
This seems to be fairly successful; very few users will actually consult the
manual.
The use of a common and consistent user interface provides for transferable
learning. The user interacts with the desktop and all applications in the same
way. For example, titles of documents on the desktop are edited the same way
as text within memos or numbers in LisaCalc. In addition to the editing
model, the filing and printing models are the same across all applications.
The time a user invests in learning the editing, filing, and printing operations
immediately transfers over to the next application. Consequently, the second
application is easier to learn than the first.
One of the features of the user interface is that it addresses those users
learning the system and those that have mastered it. The novice can learn a
few operations, just enough to accomplish his task. As the user becomes more
proficient with the system, he can graduate to the more advanced uses of Lisa
including shortcuts to make his interactions even more effective. In contrast
to other systems, Lisa does not burden the expert user with features intended
for beginners.
Using Lisa
Wherever possible in Lisa, the user moves the mouse to manipulate objects
directly. For example, to move a document from one diskette to another, the
user moves the mouse over the icon representing the document, depresses the
mouse button, moves the mouse (and the document icon) over the appropriate
container, and releases the mouse button. The mouse moves windows around,
sizes them, scrolls the contents of a window, and uses the elevator to jump to
a position in the document. The elevator is a rectangular white icon in the
scroll bar found at the bottom and right of the active window.
Another aspect of direct operation is the modeless nature of the user
interface. A modeless system is a flat, non hierarchical model, permitting
virtually any operation at any time. Thus the user need not remember what
mode to enter to perform a function, nor what command to use to exit the
mode. This flat command structure also permits the user to peruse the menus
to find the most suitable operation.
 | | Figure 3: A Lisa screen showing a pull-down menu |
When the user wants to operate on objects in the Lisa environment, the model
we use is to select the objects and then operate on them with an action
selected from a menu. We call this the noun-verb model, and it permeates all
the applications as well as the Desktop Manager. For example, to open a
document, the user moves the mouse over the icon of the document (named
NCC paper in Figure 3), and clicks the button once to select the document.
Then the user moves the mouse up to the menu bar and depresses the mouse
button over File/Print, which causes the menu to pull down (see Figure 3).
The user moves the mouse (with the mouse button down) over the “Open
NCC paper” menu item, and then releases the mouse button.
In addition to a single click to select an object, several objects can be selected
with single-click drag. This operation proceeds as follows: First the user
positions the mouse to one side of the object, then the user depresses the
mouse button and moves (drags) the mouse through the objects. When the
selection includes all the objects, the user releases the mouse button. The
selection of objects with single click and single-click drag, combined with
menu commands can be used to perform every operation.
Two types of shortcuts are provided for the expert user multiple clicks of the
mouse button (in quick succession) and Apple keys. Double- and triple-click
operations substitute for selecting an object and operating on the object with a
specific frequently used command. For example, a double click on a
document icon opens the document. For less frequently used operations some
menu commands have Apple key sequences. For example, text-editing menu
commands like cut, copy, and paste have Apple key sequences that cause the
command to be invoked. Apple key sequences involve holding down the
Apple key along with an alphabetic character. Thus, multiple click shortcuts
are used for the most frequently used operations on the selection, and the
Apple key shortcuts are used for frequently used menu commands.
Error handling
A good user interface has good error handling. There are three aspects of
error handling in Lisa: error prevention, error notification, and error
recovery.
With many personal computers the contents of diskettes can be damaged by
ejecting a diskette or turning off the machine at an inopportune moment. To
protect against such errors, Lisa has software-controlled mechanisms for the
diskette eject and on-off button. To eject a diskette, the user selects the eject
menu item, the software then suspends the processing of all the documents
that reside on that diskette and writes out those suspended documents to the
diskette. Once all the I/O has been completed, the diskette is ejected. Pushing
the on-off button causes suspension of all documents, the ejection of all
diskettes, and finally the power down of the Lisa. These controls help to
ensure the integrity of the user’s data.
 | | Figure 4: A Lisa screen showing an alert |
Error notification in Lisa is handled with a special window called an alert
(see Figure 4). An alert appears whenever the user must be notified that an
error has occurred, a requested operation cannot be performed, or an
explanation must be given. There are several kinds of alerts: stop, caution,
note, ask, and wait. Stop alerts are used when the requested operation cannot
be performed. Caution alerts inform the user that an operation has
ramifications, and gives the user the opportunity to change his mind. Note
alerts notify the user of something, ask alerts solicit input from the user, and
wait alerts tell the user to wait until a lengthy operation completes. Alert
messages that inform the user that an error has occurred have three parts.
First, the user is told the nature of the problem; second, the user is told how
to work around the problem; and finally, the user is told where to refer in
the manual for more help.
Another level of recovery is provided by the Revert to Previous Version
menu command. Sometimes a user makes several changes to a document and
then changes his mind. In this event, the user can invoke the Revert to
Previous Version command to return the document to the state when the
document was last saved.
In the event of a program failure in Lisa, an alert message appears informing
the user that the tool failed. The user is given the option to redisplay the
document and if he chooses to do so, the document is shown, usually with the
last changes intact.
The final area of error recovery is recovery from external errors such as
power failures. If power goes off while using a computer, the disk is likely to
be inconsistent; some of the current data are in memory but not on the disk.
To protect against failures of this kind, the Lisa file system has redundant
information permitting reconstruction of files on disk. The Desktop Manager
and the LisaList tool also detect such failures and repair and reconstruct their
information. When the user powers up the Lisa after such a failure or opens
a damaged LisaList document, he is informed that repair is needed. When the
user confirms that the repair operation should be started, the repair begins.
Lisa applications
Apple offers seven Lisa applications (also called tools): LisaCalc
(spreadsheet), LisaWrite (word processing), LisaGraph (business graphics),
LisaDraw (graphics editing), LisaProject (project scheduling), LisaList (list
management), and LisaTerminal (terminal emulation). Lisa is an open system
that permits third parties to develop Lisa applications, hence additional Lisa
applications also are available.
The Lisa tools have effective user interfaces for their applications. LisaCalc
and LisaGraph use the spreadsheet user interface developed by VisiCalc,
further improved by the addition of the mouse. LisaList builds upon the user
interface techniques developed in OBE2. LisaWrite uses techniques found in
several word processors.
The unique Lisa applications are LisaDraw and LisaProject. LisaDraw is a
structured graphics editor that permits the user to draw lines, circles, ovals,
rectangles (both square and rounded), polygons, freehand curves, and text. It
is used for such diverse applications as preparing diagrams for presentations
and architectural drawings.
LisaProject is a PERT/CPM project-scheduling tool. It uses a graphical
PERT chart representation to enter a project schedule. The user draws the
schedule using rectangles for tasks and circles for milestones. The user
specifies the task, the resources needed to accomplish it, the duration of the
task, and its relation to other tasks. As tasks are added, durations changed, or
scheduled dates specified, the schedule is recalculated.
The user interfaces of LisaDraw and LisaProject have opened up these tools
to a much greater audience. Just as VisiCalc and QBE opened up spreadsheets
and databases to those who were unable to use other offerings, LisaDraw and
LisaProject have done the same in their application areas. Both these tools
magnify the capabilities of the user. For example, people like myself who are
totally inept at drawing are assisted by LisaDraw to the extent that very
respectable results are easy to achieve. A similar result occurs with
LisaProject. Administrative assistants unable to use conventional
project-scheduling tools are now using LisaProject to make very large
schedules.
During the development of the Lisa applications and the application libraries,
we found that application development was not as easy as we would like it to
be. The library structure was very hierarchical and was hard to use.
Consequently we were determined to make it easier for third parties to
develop Lisa applications. This led to two ways to develop Lisa applications,
QuickPort and ToolKit.
QuickPort permits a third-party software developer to run standard PASCAL
programs (ones that use standard PASCAL I/O) in a window in the Lisa
office system. In addition, QuickPort permits cutting, copying, and pasting of
information from the QuickPort window to other Lisa desktop windows. The
modifications the third-party developer must make to the application to use
QuickPort are minimal. The developer must use a few new units, and
possibly make name conflict changes. This process can be accomplished in an
afternoon.
QuickPort is the easiest way to get an application operational in the office
system, but such a program cannot use all of the capabilities of the Lisa.
ToolKit is used to write an application that fully uses the features of the Lisa.
ToolKit is essentially a generic application that calls application-specific code
to implement application-specific functions. This permits the sharing of
common control structure code across several different ToolKit applications.
Because different applications have different needs, the ToolKit generic
application had to be extremely flexible. The flexibility required, along with
the need to call application specific code, led to the use of classes similar to
those in SMALLTALK3. The classes provide the ability to call the
application-specific code while also permitting the developer to override or
subclass a class to modify its behavior.
Both QuickPort and ToolKit promote the development of Lisa applications.
This open nature of the Lisa office system permits third-party developers to
develop a specific application, yet leverage off other Lisa applications. These
third parties can develop applications that target specific markets while
relying on the standard tools such as LisaWrite and LisaDraw for
presentation of the results.
Integration in Lisa
Several components of integration in the Lisa system have already been
mentioned. There is a consistent user interface that is common across all
applications and the Desktop Manager. If the user wants to enter text and
makes a mistake entering it, he can fix it using the standard text-editing
model. The user does not have to remember which tool he is in, nor does he
have to run an editor tool.
The editing model used by Lisa is the cut-and-paste model. Just as an editor
might cut up a paragraph with scissors and paste-up sentences or paragraphs
to improve an article, the Lisa user can cut and paste with the Clipboard. The
editing model also includes the ability to copy to the Clipboard and undo the
last edit operation. When a user copies or cuts an object, the object is copied
onto the clipboard, a repository for scraps of information. The Paste
command pastes the information from the clipboard into the active window
replacing the current selection. This model is used for all objects; e.g., text
within textual documents, numbers and formulas within LisaCalc, and
graphics within LisaDraw. A user can cut or copy information from a
paragraph and paste it into the same document or a different document. The
is copy and paste model is also the mechanism for data interchange between
documents.
This data interchange is illustrated by the following example. Let us assume
that a user has data in a LisaGraph document (a bar chart) and wishes to
move them to a LisaDraw document to annotate and customize the chart for a
presentation. To do this the user selects the entire graph in the LisaGraph
document, and then uses the Copy command in the Edit menu to copy the
graph to the Clipboard. Next the user opens the LisaDraw document and
selects Paste from the Edit menu. The user can then use the capabilities of the
LisaDraw tool to add labels, change patterns, etc.
The direction of software integration that we see for Lisa in the future is
presented in the following scenario. Lisa provides an environment where one
can use LisaTerminal and gather data from a mainframe, copy the data to
LisaList and subset them, copy the result to LisaCalc and perform some
arithmetic manipulation to analyze the data, copy the resulting data to
LisaGraph to make a chart, then copy the chart to LisaDraw to further
customize it, and finally copy that customized chart to LisaWrite for
inclusion in a report.
This type of integration permits the user to choose the best tools for his task.
The user is free to concentrate on his task, not on the mechanics of typing the
data or mastering the commands of the application. The model permits the
tool's developer to concentrate more on the functionality that has to be
provided, and not on extraneous features. For example, the LisaGraph tool
can concentrate on drawing the best pie charts, without having to provide all
the presentation flexibility (e.g., detached pie segments), since the chart can
be copied to LisaDraw where the chart can be customized.
The open nature of the Lisa office system further expands the integration
possibilities, The power of an open system becomes apparent when
third-party tools can be used as equals in conjunction with the standard tools.
This permits the Lisa to be used by a broader range of customers for a wider
variety of applications. This is in contrast to closed systems, which are
typically one large program, and do not permit integration of other
components.
The clipboard
The clipboard provides a common interchange form between documents.
There are three distinct interchange forms-text, tables, and graphics. In most
cases, the user is unaware of what type of interchange form is employed. The
user merely selects the object, and copies or cuts it. The type of object
determines the form of the data on the clipboard. In cases where a particular
selection is ambiguous, the user is required to further specify his intent.
The cut, copy, and paste model does require that it be easy to move data from
one tools document to another. In the Lisa environment, this is provided by
the multitasking operating system4. Lisa uses a multitasking operating system
to permit the concurrent operation of processes. For example, this permits
LisaGraph and LisaDraw documents to be both on the screen and in memory.
When the user switches from one document to the other, the operation can
complete rapidly (one or two seconds if both are in memory already).
The clipboard provides for rapid exchange of data to and from the same or
different documents. It also provides the ability to undo the last cut or copy.
In this way the user can undo a cut operation and then paste the previous
clipboard contents. The astute reader will realize that only the last operation
is undoable; undo of an undo undoes the undo.
Productivity enhancement
Integrated software of almost any style enhances productivity5.
Just as word
processors improve productivity by minimizing retyping, integrated software
has reduced the time it takes to perform tasks that require the use of several
tools.
Several studies have been performed by outside groups that substantiate the
assertion that Lisa enhances productivity. Seybold Publications Inc. did a
comparison of Lisa, SuperCalc 3, Context MBA, and Lotus 1-2-3. The task
was to prepare an operating budget, which included spreadsheet calculations,
making graphs, looking up information, and preparing a report. The timings
did not include set-up time for the model, nor thinking time, consequently the
timings do not represent the total time to complete the task, but only the time
necessary to perform the four specific tests. The article reports that the total
time it took was 27 minutes for a SuperCalc 3 user, 33 minutes for Context
MEA, 47 minutes for Lotus 1-2-3, and 59 minutes for a Lisa user.
We couldn’t understand how it took them so long to do the tasks using Lisa,
so we looked into it. It turns out the users were experienced IBM PC users,
and the users were inexperienced in using Lisa. We retimed the tests with an
experienced Lisa user and found that it took 19 minutes. So the study should
have shown it took 19 minutes for an experienced Lisa user, 27 minutes for a
SuperCalc 3 user, 33 minutes for Context MBA, 47 minutes for Lotus 1-2-3,
and 59 minutes for an inexperienced Lisa user. The disparity of time between
the experienced Lisa user and the inexperienced Lisa user is that the
inexperienced one was unaware of a mechanism for transferring data from
LisaCalc to LisaGraph, and cut and pasted the data cell by cell. Another
reason for the disparity was that the inexperienced user did not take
advantage of background printing.
This study was chosen because it illustrates several things. The fact that an
inexperienced Lisa user was in the ballpark for these tests shows that an
inexperienced user can effectively get the job done (especially when the
combination of set-up time and thinking time dominates). The other
important point that this study illustrates is that a simple user interface leads
people to some incorrect conclusions. People wrongly conclude that simple
user interfaces are good only for simple things, and that features are not
implemented. In the case of this study, the simple user interface led the users
to believe that they had mastered the system, so they failed to look up
functions in the manual.
Summary
Lisa achieves integration in a variety of ways. It uses an intuitive model using
familiar objects that permit direct interaction as opposed to indirect
interaction with a command language. In contrast to some systems that always
prompt for individual steps, Lisa’s user interface supports users at every
point on the learning curve. The uniform user interface also provides for
transfer able learning; the user needs to learn how to edit, print, and file only
once, and then can apply that knowledge throughout all applications. The
combination of gradual and transferable learning results in a system that is
many times easier to use. This ease of use has made it possible for individuals
to use tools to accomplish tasks that they could not before.
The editing model provides not only for editing information within a
document, but also promotes the interchange of data among documents of
similar or different types. This interchange is fostered by the ability to have
several windows displayed concurrently. The ability to use documents
concurrently and interchange data among them makes it possible to use
several tools in a cooperative manner to perform a task that one tool alone
could not accomplish. Since one of these windows can be connected to a
remote computer, this permits exchange of data between mainframes and
Lisa documents. In contrast to some systems, Lisa is an open system,
permitting third parties to develop additional applications. Third-party
developed applications function in a manner that is similar to other Lisa
applications with the uniform user interface, and are able to interchange data
as well.
The combination of the uniform user interface coupled with multiple tools
that operate concurrently, each of which can interchange data with others,
provides an environment that increases office worker productivity. Workers
are free to concentrate on their tasks, not on how to accomplish them.
by Edward W. Birss
Apple Computer, Inc.
Cupertino, California
References
- Goldberg, A., and D. Robson. “SMALLTALK-80: The Language and its Implementation.”
Reading, Mass.: Addison-Wesley, 1983.
- Zloof, M. “Query by Example.” AFIPS, Proceedings of the National Computer
Conference (Vol. 44), 19175, pp. 431-437.
- Smith, D.C., C. Irby, R. Kimball, and E. Harslem. The STAR User Interface. AFIPS,
Proceedings of the National Computer Conference (Vol. 51), 1982, pp. 515-528.
- Daniels, B. Lisa’s Alternative Operating System. Computer Design, 22 (1983), pp.
159-166.
- Uttal, B. “The Best Software for Executives.” Fortune, December 26, 1983, pp.
136-142.
|  |
Home 
