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NEWMEDIA

READER

Decision/Creativity Systems [Thinkertoys]

Theodor H. Nelson

19 July 1970

It has been recognized from the dawn of computer display

that the grandest and most important use of the computer

display should be to aid decisions and creative thought. The

work of Ivan Sutherland (SKETCHPAD) and Douglas

Engelbart have really shown how we, may use the display to

visualize and effect out creative decisions swiftly and vividly.

For some reason, however, the most important aspect of

such systems has been neglected. We do not make important

decisions, we should not make delicate decisions, serially and

irreversibly. Rather, the power of the computer display (and

its computing and filing support) must be so crafted that we

may develop alternatives, spin out their complications and

interrelationships, and visualize these upon a screen.

No system could do this for us automatically. What design

and programming can create, however, is a facility that will

allow us to list, sketch, link and annotate the complexities we

seek to understand, then present “views” of the complexities

in many different forms. Studying these views, annotating

and refining, we can reach the final designs and decisions

with much more in mind than we could otherwise hold

together in the imagination.

Some of the facilities that such systems must have include

the following:

Annotations to anything, to any remove.

Alternatives of decision, design, writing, theory.

Unlinked or irregular pieces, hanging as the user wishes.

Multicoupling, or complex linkage, between

alternatives, annotations or whatever.

Historical filing of the user’s actions, including each

addition and modification, and possibly the viewing

actions that preceded them.

Frozen moments and versions, which the user may hold

as memorable for his thinking.

Evolutionary coupling, where the correspondences

between evolving versions are automatically

maintained, and their differences or relations easily

annotated.

In addition, designs for screen “views,” the motion,

appearance and disappearance of elements, require

considerable thought and imagination.

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Here’s how simple it is to create and edit text with the JOT system. Since your typewriter is now a JOT machine, not every key does what it

used to. [When Nelson wrote much “word processing” was through modified typewriters, wihtout graphic displays—eds.]

CREATING TEXT: just type it in.

You type: The quick brown fox jumps over the lazy dog.

It types:  The quick brown fox jumps over the lazy dog.

REVIEWING A SENTENCE YOU JUST TYPED: the back-arrow takes you back, the space bar steps you through.

You type:

←

sp

sp

sp

sp

It types:

(bell)

The

quick

brown

fox

DELETIONS AND INSERTIONS: the RUBOUT key rejects words you don’t want. To insert, merely type.

You type:

←

sp

sp

RUBOUT

lithe

sp

sp

sp

sp

sp

sp

It types:

(bell)

The

quick

/brown/

lithe

fox

jumps

over

the

lazy

dog.

REARRANGING TEXT: first we make three Cuts in the text, signaled by free-standing exclamation points.

You type: sp

!

sp

!

sp

!

fox

It types:

The !

quick

!

lithe

!

fox

TO REARRRANGE IT, YOU TYPE: LINE FEED key. This exchanges the two pieces between the cuts.

CHECK THE RESULTS:

←

sp

sp

sp

sp

(bell)

The

lithe

quick

fox

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The object is not to burden

the user, or make him aware

of complexities in which he

has no interest. But almost everyone in intellectual and

decision pursuits has at some time an implicit need for some

of these facilities. If people knew they were possible, they

would demand them. It is time for their creation.

A full-fledged decision/creativity system, embracing both

text and graphics, is one of the ultimate design goals of

Project XANADU.

This user-level system is intended to aid in all forms of

writing and scholarship, as well as anywhere else that we

need to understand and manipulate complex

clusterings of text (i.e., thought). It will also

work with certain animated graphics.

The parallel Textface, as described here,

furnished the initial impetus for the

development of the Xanadu™ system (see p.

335).  Xanadu was developed, indeed,

originally for the purpose of implementing

some of these functions, but the two split

apart. It turned out that the Parallel Textface

required an extremely unusual data structure

and program techniques; these then became

the Xanadu system. As developed in the final

Xanadu design, they turn out to handle some

very unusual kinds of screen

animation and file retrieval. But

this grew out of structuring a

system to handle the functions described here.

Thus the Parallel Textface basically requires a Xanadu

system.

It is hoped that this system can be sold complete

(including a minicomputer or microprocessor—no

connection to a large computer is required) for a few

thousand dollars by 1976 or 1977. (Since “business people”

are extremely skeptical as to whether anybody would want

such a thing, I would be interested in hearing expressions of

interest, if any.) 

As shown here, the screen presents two panels of text;

more are allowed. Each contains a segment of a longer

document. (“Page” would be an improper term, since the

boundary of the text viewed may be changed instantly.)

The other odds and ends on the screen are

hidden keys to control elements which have

been made to fade (in this illustration), just to

lessen the distraction.

Panel boundaries and control graphics may

be made to appear by touching them with the

lightpen.

Roving Functions

The text moves on the screen! (Essential.) The lower right

hand corner of each text panel contains an inconspicuous

control diagram. The slight horizontal extension is a movable

control pip. The user, with his lightpen, may move the pip up

or down. “Up” causes the text to move smoothly upward

(forward in the material), at a rate proportional to how far

you push the pip; “down” causes it to move back. (Note that

we do not refer here to jerky line-by-line jumps, but to

smooth screen motion, which is essential in a high-

performance system. If the text does not move, you can’t tell

where it came from.)

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NEWMEDIA

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DERIVATIVE MOTION: when links run sequentially,

connecting one-after-the-other on both sides, the contents of

the second panel are pulled along directly: the smooth

motion in one panel is matched in the other. This may be

called derivative motion, between independent text (being

handled directly with the lightpen) and dependent text

(being pulled along). The relationship may be reversed

immediately, however, simply by moving the lightpen to the

control pip of the other panel, whose contents then become

the independent text.

Irregularities in the links will cause the independent text

to move at varying speeds or jump, according to an average

of the links’ connectivity.

If no links are shown, the dependent text just stops..

Collateral links between materials in the two panels are

displayed as movable lines between the panels. (Text omitted

in this diagram; panel boundary has been made to appear.)

Some links may not have both their endpoints displayed at

once. In this case we show the incomplete link as a broken

arrow, pointing in the direction of the link’s completion.  

The broken arrow serves not merely as a visual pointer,

but as a jump-marker leading to the linked material. By

zapping the broken arrow with the lightpen, the user

summons the linked material—as shown by the completion

of the link to the other panel. (Since there has been a jump in

the second panel, we see that in this case the other link has

been broken.)

When such links lead to different places, both of these

destinations may nevertheless be seen at once. This is done

by pointing at both broken links in succession; the system

then allows both links to be completed, breaking the second

panel between the two destinations (as shown by dotted line

across panel).

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*Oddly, this has the same logical structure as time-travel

in science-fiction.

There are basically three alternative premises of time-

travel: 1) that the past cannot be changed, all events

having preceded the backstep; 2) that the past can be

changed; and 3) that while time-travelers may be deluded

into thinking (2), that (1) is really the case—leading to

various appointment-in-Samarra plots.

Only possibility (2) is of interest here, but there are

various alternative logics of mutability and time-line

stepping. One of the best I have seen is in The Man Who

Folded Himself by David Gerrold (Popular Library, 1973):

logic expounded pp. 64–8. I am bemused by the parallel

between Gerrold’s time-controls and these, worked out

independently.

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Fail-Safe and Historical Features

In systems for naive users, it is essential to safeguard

the user from his own mistakes. Thus in text systems,

commands given in error must be reversible. For

instance, Carmody’s system requires confirmation of

deletions.

Another highly desirable feature would allow the

user to view previous versions, to see them collaterally

with the corresponding parts of current versions, and

even go back to the way particular things were and

resume work from the previous version.

In the Parallel Textface this is all comprised in the same

extremely simple facility. (Extremely simple from the user’s

point of view, that is. Inside it is, of course, hairy.)

In an egregious touch of narcissistic humor, we use the

very trademark on the screen as a control device (expanded

from the “X” shown in the first panel).

Actually the X in “Xanadu™,” as it appears on the screen, is

an hourglass, with a softly falling trickle of animated dots in

the lower half, and Sands of Time seen as heaps above and

below. These have a control, as well as a representative,

function.

TO UNDO SOMETHING, YOU MERELY

STEP “BACKWARD IN TIME” by dagging the

upper part of the hourglass with the lightpen.

One poke, one editing operation undone.

Two pokes, two operations.

You may then continue to view and make

changes as if the last two operations had

never taken place. This effectively creates an

alternative time-line.* However, if you decide

that a previously undone edit operation

should be kept after all, you may step

forward—stepping onto the previous time-line—by using

the lower half of the hourglass.

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We see this clarified in a master time diagram or Revision

Tree which may be summoned to the screen, never mind

how. In this example we see that three versions are still

“current,” various other starts and variations having been

abandoned. (The shaggy fronds correspond to short-lived

variations, resulting from operations which were then

reversed. In other words, “excised” time-lines, to use Gerrold’s

term—see footnote.)

The user—let’s say he is a thoughtful writer—may define

various Versions or Drafts, here marked on the Revision Tree.

He may, indeed, define collateral linkages between

different versions defined at various Times in the Tree . . .

. . . and see them displayed collaterally; and revise them

further.

Materials may be copied between versions. (Note that in

the copying operation of the Parallel Textface, you actually

see the moved text moved bodily as a block.)

Getting Around

The user may have a number of standby layouts, with

different numbers of panels, and jump among them by stabs

of the lightpen.

Importantly, the panels of each can be full, each having

whatever the contents were when you last left it.

The File Web™ is a map indicating what (labeled) files are

present in the system, and which are collaterated..

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The File Star™ is a quick index into the contents of a file. It

expands as long as you hold the lightpen to the dot in the

center, with various levels of headings appearing as it

expands. Naturally, you may jump to what you point at.

Editing

Rather than giving the user anything complicated to learn,

the system is completely visual. All edit controls are

comprised in this diagram, the Edit Rose™. Viz.:

Separate portions of the Edit Rose invoke various edit

operations. (You must also point with the lightpen to the

necessary points in the text: once for Insert, twice for Delete,

three or four times for Rearrange, three times for Copy.)

Generality

The system may be used for comments on things,

for organizing by multiple outlines or tables of contents;

and as a Thinkertoy, organizing complex alternatives. (The

labels say: “Conflicting versions,” “New account of conflicts,”

“Exposition of how different accounts deal with objections,”

“Improved, synthesizing account.”)

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In other words, in this approach we annotate and label

discrepancies, and verbally comment on differences in

separate files or documents.

In ways this may seem somewhat obtuse. Yet above all 

it is

orderly, and the complex of collateral files has a clarity that

could be all-too-easily lost in systems which were

programmed more specifically to each problem.

The fundamental strength of collateration, seen here, is of

course that any 

new structure collateral to another may be

used as a table of contents or an outline, taking the user

instantly to parts which are of interest in some new context.

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