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C00011 00003 when he reads their lists or by kickbacks from the publishers.
C00020 00004 sharing service bureaus that will grow into the new information
C00029 00005 over conditioned voice grade lines, and this might be barely
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THE HOME INFORMATION TERMINAL
by John McCarthy
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Visionaries have often proposed that homes be equipped with
information terminals each consisting of a typewriter keyboard and a
screen capable of displaying one or more pages of print and pictures.
The terminal is to be connected by the telephone system to a
time-shared computer which in turn has access to files containing all
books, magazines, newspapers, catalogs, airline schedules, much
additional public information not now kept, and various files
personal to the user.
Through the terminal the user can get any information he
wants, can buy and sell, could communicate with persons and
institutions, and process information in other useful ways. Such a
system has never come about because it costs too much, but with each
advance in technology, it becomes more feasible. I think that the
technology of computers, time-sharing, terminals, and application
programming has advanced to the point where realistic estimates are
possible of the remaining advances necessary to make home consoles
feasible and useful. In this paper, I shall discuss the uses of the
home terminal, some potential beneficial effects on society, estimate
how far we are from a system people will pay for, and advocate some
pilot projects, some standardization efforts, and some laws and
regulations to prevent monopoly and secure adequate competition.
We can start with ordinary reading. To get a newspaper or
book, I type its name or number and the first page appears. The most
obvious benefits are:
1. I can get any document instantly.
2. My house isn't full of paper to be sorted and put on
shelves and dusted or put in the trash. Trees aren't cut down, and
air pollution doesn't result from burning the stuff.
Some immediately apparent disadvantages are:
1. The expense. I'll deal with this later.
2. I can't read in bed. The book size portable terminal will
come later. A household may require several terminals or perhaps we
may have to compromise with sin and provide a hard copy terminal
after all.
There are two other immediate negative reactions:
1. The average citizen is a TV fan and doesn't read anyway.
In the first place, our system doesn't need so many subscribers to be
economical. Secondly, after I have described all the bells and
whistles, you will see that even the TV fan will be tempted, and you
- oh socially conscious reader - may even want to coerce him into
buying one or coerce the government into giving him one for free.
2. How can you think of one more convenience and comfort when
the world will come to an end in ten years unless menaces A, B, and C
are dealt with immediately. In the first place, I don't think the
world is about to come to an end or even that it is getting worse,
and we Americans like new gadgets. In the second place, you will see
that the new information system will make the public more responsive
to the careful reasoning of you good guys and more immune to the
crude propaganda of those bad guys.
In order to see the effects of the new information system,
suppose that all book and newspaper information were so distributed.
What changes would occur?
At present, a newspaper or a book is a package produced by a
large organization. In our new system, the physical production
disappears, allowing a much smaller organization to put out the same
packages of text and pictures. Moreover, the user does not face a
one shot decision to buy Life or Look. He will be able to read the
"cover" or table of contents of each, read such items as strike his
fancy, and the system will bill him for what he reads from each
source. In fact, since the cost of keeping a file of information in
the computer and making it publicly available will be small, even a
high school student could compete with the New Yorker if he could
write well enough and if word of mouth and mention by reviewers
brought him to public attention. What, then, is a publication in
the new information system?
A publication is an organization that puts out a list of
material it has edited and recommends to its readers. It helps its
authors produce material that it thinks will suit the readers, and it
has a financial arrangement with them about splitting the proceeds.
There can be a wide variety of publications of different
standards of writing and editing and different budgets for carrying
out these activities. However, they will all be equally accessible
to all readers, and the only justification for an expensive editorial
organization will be that it can produce a more popular package. The
price of reading a package can be set by the publishers.
A reader may feel that he needs help in finding his way
through the totality of literature available to him. Various people
will be eager to make a living by providing it. A bookstore or
library is a program that when called shows the "covers" of
publications. Reviewers will produce lists for him and make money
when he reads their lists or by kickbacks from the publishers.
"Reading advisers" under some catchier name will offer to generate
lists just for him according to a profile of his interests.
Advertising in the sense of something that can force itself
on the attention of a reader will disappear because it will be too
easy to read via a program that screens out undesirable material.
However, people will still want to know what is for sale and will
still want to see the seller's story about why they should buy it.
Probably, Life will still be able to get money from advertisers; many
people will still want to know what is advertised in Life, but those
who don't want to know will be able to avoid it automatically.
Another effect is the possibility of frequent revisions of
articles and books. An author can take into account new facts or
other people's criticisms, and the revision will take effect
immediately. This raises 1984ish possibilities, so it must be
provided that old versions remain available. Those who suspect the
whole system will keep their own copies of favorite material in their
private files, on microfilm, or even on paper.
Public controversy can be carried out more expeditiously than
at present. If I read something that seems controversial, I can ask
the system if anyone has filed a reply. This, together with an
author's ability to revise his original statement, will lead people
to converge on considered positions more quickly than at present even
if they do not come to actual agreement.
Famous authors will not need publishers because their loyal
readers will have the system find their stuff automatically.
To summarize: the new information system will promote
intellectual competition by reducing the price of entry, will permit
readers to be selective, and will allow authors to revise material
until they are satisfied that it withstands criticism as well as it
ever will. This should make intellectual life more interesting.
The financial aspect of writing would presumably be as
follows: a piece of written material has a price for reading it.
(This price may be zero for amateur writing, political propaganda,
advertising, and for scientific journals). The reader's account is
debited and the account to which the material belongs is
automatically credited. The reader will have the system balk at what
he considers overpriced material.
The new information system will have a profound effect on
buying and selling. Sellers of movies, groceries, automobiles,
plumbing services and cures for baldness will find it advantageous to
list their wares in the information system together with current
prices and availability. The user can place an order through the
system as he can by telephone, but he can do much more:
1. He can call on someone's program to scan the sellers of
sports cars and propose what it considers the best deal. This program
might even negotiate with programs representing the sellers.
2. He can tell the system whether last year's cure for
baldness worked and a get a summary of the opinions of those who
bothered to record their opinions of the cure he contemplates trying
now.
3. He can make an airplane or hotel reservation by
interacting with a program the airline or hotel reservation company
has written to tell him what is available. He need not suffer the
delays you now get when you call an airline or travel agent at peak
hours.
4. Individual design and construction services can be offered
through the system although this requires the development of computer
controlled manufacturing techniques for various types of article. The
idea is that automated design programs can produce designs for
articles meeting individual specifications. Either by himself or in
consultation with an expert, an individual would use the system to
produce a design and display how it would look and possibly how it
would perform. Candidates for individual design include clothing,
furniture, boats, electronic equipment, houses, and even cars. The
system would then produce the instructions for controlling machine
tools, fabric cutters, and also printed instructions for the hand
parts of the operation. In general, it should be possible to make
single objects at little more cost than present mass produced
objects. In some cases, there would even be savings, because mass
production requires estimates of demand that are often wrong
resulting in inventories that are expensive to sell or even have to
be sold at a loss; the cost of this is made up by a general increase
in prices.
There are many more useful services that can be offered
through the new information system and again the system is conducive
to competition. Writing and storing a program and announcing its
availability can be a very low capital operation, and the system can
collect whatever price has been set for its use.
We could go on listing services that would come to be offered
in a fully developed system, but now we shall list some services to
smaller groups of users that are cheaper to provide and which will
help get the system started.
1. Calculation and facilities for writing, running, and
debugging computer programs. This doesn't interest the general
public much, but it is the present bread and butter of the time-
sharing service bureaus that will grow into the new information
system. At present, these service bureaus offer very convenient way
of doing small scientific and engineering calculations, but do not
offer reasonable prices for big computations, and are only beginning
to offer useful services to business firms.
2. Editing. Anyone who writes (writers, journalists,
scientists, advertising men, engineers and students) will benefit
from using an editor program. It allows easy revision, can be made
to check spelling, grammar, and punctuation, and will produce
justified or other forms of elegant output and also indexes.
3. Filing. Keeping personal files in the computer has great
advantages once documents can be entered without retyping them,
either because they have been prepared in a computer readable form or
because a suitable page reader is available. Namely, one can
retrieve any document on the basis of its characteristics without
having taken the trouble to file it properly in the first place.
4. Education. Computer aided instruction (CAI) has advanced
to the point that a number of courses or aids to traditional courses
have been developed and have been shown to be useful. The main
obstacle to the widespread use of CAI is economic, but new
developments in display technology and communications give a
reasonable probability of cost-effective systems within this decade.
There is no special problem in having these systems available in the
home as well as at school. This would be aided by standardizing
course writing languages. Again, we should try to stimulate
competition by encouraging the offering of courses in particular
subjects independent of the schools.
The development of such a system is probably inevitable
(unless it is forbidden by law) as soon as costs come down to the
point where it is profitable for time-sharing service bureaus to
offer services to individuals. However, favorable policies will
bring this about sooner and will make the effects better.
The main danger to be avoided is the creation of services of
limited scope that through some avoidable feature cannot be expanded
to provide the services mentioned here and many more. Another
problem is to avoid monopolies; the intrinsic nature of the system
permits any person who can write computer programs to compete with
large organizations in inventing and offering imaginative services,
but one can worry that the system might develop commercially in some
way that would prevent that. In general, we should try to develop
information services in such a way as will enhance the individuality
of its users.
Between us and the home information system lie a number of
problems, some in developing suitable low cost terminals, some in
programming technology of time-sharing, some in the economics and
politics of communication systems, and some in the attitude of the
public and government towards innovation. In the following sections
we shall discuss these problems.
How we get there from here.
1. Consoles.
The quality and price of display consoles is rapidly
improving. At present, one can add a display console with keyboard to
our laboratory system for about $700, but to add another port on the
system so that the number of consoles active at one time is increased
by one costs about $2500. A reasonable display console that can be
located at the end of a telephone line now costs about $10,000. These
consoles are adequate for any of the services mentioned in the
previous section, although for reading purposes, it would be
desirable to be able to display more than 35 typed lines at a time.
In my opinion, the cost of an adequate display terminal that
can be located at the end of a telephone line will be in the $500 to
$1000 range by 1975 even without a market of the size of the
potential home terminal market. The business, engineering and
science, and government markets will be large enough and price
sensitive enough to bring this about.
Another contender as a terminal is the plasma panel, but the
above estimates are based on CRT terminals with a mini-computer and
an integrated circuit memory.
2. Communications.
In the United States, the facilities for digital
communications are growing rapidly but in a rather disorderly way
because of the multiplicity of requirements of the different
applications. Some applications such as credit verification require
very low cost short communications with turn around times of seconds.
Others require very low cost per bit but can stand delays of minutes
and hence are candidates for low performance store and forward
systems. The terminal systems require long holding times, short
response times, and much higher transmission rates from the computer
to the user than in the other direction.
For the purposes of the home terminal, the speeds of
transmission over present unconditioned voice grade circuits are a
bit too low for such applications as reading. 1200 bits per second
would take 20 seconds to transmit a typed page and about four times
that for a page of a dictionary. Eight times this rate is obtained
over conditioned voice grade lines, and this might be barely
adequate. Perhaps a better bet is the transmission facility planned
for the Picturephone service now being introduced experimentally, but
the cost of this service for long holding times is not yet
determined. The most economical system might be a specially designed
store and forward system configured to give fast turn around for
short messages.
Whether such a service will be made available depends on
political as well as technical factors. For example, if on the basis
of present plans, the digital communication market is divided by
regulatory action among AT&T and its potential competitors, it might
turn out that no-one is obliged or even allowed to offer the service
required for home terminals at a reasonable cost.
3. Computer technology.
At present, computer technology can offer the services
required for the home terminal at a reasonable cost, provided
computer configurations are optimized for the purpose, provided
reasonable load factors can be obtained, and provided there are
reasonable economies of scale. Unfortunately, IBM computers are
organized in such a way that time sharing is very expensive because
of their interrupt structure, their expensive terminal multiplexors,
and their dedication to the archaic half duplex method of
communication. The other major computer manufacturers such as CDC,
General Electric, and Univac are not in much better shape since they
offer for time sharing, machines that were optimized for other
purposes. Smaller companies like DEC are in a somewhat better
position. However, none of these difficulties are permanent, and
better organized computers may be expected once the factors in
computer design that make for good cost-performance in time sharing
become clearer to the manufacturers.
The present magnetic disk storage units are a bit marginal in
cost effectiveness for use with home terminals. Thus storage on the
new IBM 3330 disk would cost a user about $.03 per month to store a
typewritten page making storage of extensive personal files expensive
and private copies of books at $5 to$10 per month prohibitively
expensive. This would not be too expensive for national libraries,
but it would be economically very difficult to get enough readers to
support the storage of books on magnetic disk files in the near
future.
Fortunately, much larger files are becoming available. The
laser file made by Precision Instruments Inc. is claimed to store a
trillion bits and costs $1,000,000. This comes to about $4 per book
which is reasonable even for single copies. Mass production of such
files will reduce the cost even further.
4. Computer programming.
The basic technology of writing time sharing technology is
reasonably well developed in that cost effective systems have been
written, but there is still a lot of chasing of willow-the-wisps and
quite bad time-sharing systems are often produced by otherwise
competent firms. Before the programming required to offer the
services mentioned in the first part of this paper can be
accomplished some further advances need to be made including at least
the following:
1. The interactive and file reference aspects of programming
languages and time sharing systems need to be standardized so that an
interactive system written in one system can be used in another that
uses different hardware and a different time sharing system. Without
this it will be very expensive for new user services to get large
markets unless some particular time sharing system gets a monopoly.
2. A system needs to be developed for representing text in a
computer that will include the full variety of alphabets, type fonts
and character sizes and also be adaptable to diagrams, drawings and
photographs. The consoles also have to be adapted to this variety of
styles. This is an ultimate requirement; much can be done with texts
that are just regarded as sequences of latin letters.
3. The biggest task, however, is the application programming
itself.
5. Commercial organization.
From a social point of view, one of the attractive features
of the provision of time-sharing services is that it is not a natural
monopoly. Communication is cheap enough for teletype based
time-sharing so that with local multiplexors, time-sharing bureaus
can compete all over the United States. In principal, it should be
possible to have world wide competition. The major force that might
tend to reduce competition is the exclusive possession of proprietary
programs or files. Therefore, it is desirable to separate the
ownership of programs performing services from the ownership of the
service bureaus themselves and to encourage enough compatibility
between different time-sharing systems so that the owner of a service
program could provide it on a number of machines. It is also
important that important files be accessible and modifiable with
suitable protections by actions initiated on other machines than the
one that maintains the file.
6. Needs for research and development.
The hardware required for home consoles will be too expensive
for extensive systems for probably another five years. In the
meantime, research and development should be undertaken in the
following areas:
1. Standardization of the interfaces of time-sharing systems
and their languages.
2. Experimentation with services. At present, it is very
difficult to get support for development of generally useful services
unless either it can be claimed that disaster will result from
failure to support the activity or that the supporting organization
will itself make a profit. This political fact is one of the reasons
for the concentration on military technology in the recent past.
3. Research aimed at devising ways of co-ordinating the great
variety of time-sharing services into a mutually communicating
network. Neither sufficient understanding nor sufficient political
or commercial force is available to cause the development of
time-sharing services to proceed according to a unified plan.
Nevertheless, computers are flexible enough so that originally
incompatible systems can be made to communicate and use each other's
services. Experiments with the ARPA network that provides
communication between U.S. Government sponsored research computers
will provide useful information.
7. Comments on the conference.
In general, the conference showed a poor situation in the
scientific and technological community and also the public affairs
community regarding technology and the human future. There were a
few technically competent but rather narrow surveys of the state and
prospects of particular tool areas of technology. There was much
random doom-saying and denunciation of currently fashionable whipping
boys. There was a fair amount of opinion that certain things should
not be done. There was an almost total lack of imaginative
discussion of the opportunities technology offers us to improve human
life. This lack was especially notable in those individuals and
organizations that are supposed to be professionally concerned with
the matter.
This essay is part of an effort to correct the imbalance.