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←Communicating by DIALNET
←%3John McCarthy and Les Earnest
←%2Computer Science Department
←Stanford University
.end
%1Electronic mail and other communications can be sent between computers
using ordinary telephone lines.
Even though this would be a very valuable service for many people and organizations,
it is not yet widely available.
The primary barrier to development appears to be the lack
of suitable standards for inter-computer communication.

Beginning in July 1977, a project called %2Dialnet%* was organized at
Stanford University to tackle this problem, under sponsorship of the
National Science Foundation.
The Dialnet goal is a set of protocols
enabling a computer user at a terminal attached to his own computer
to send messages to users of other
computers, to transmit files between his own and other computers,
and to use other time-shared computers directly--all using
the existing dial-up telephone network.
His computer will need an automatic dialer and a suitable modem
and must implement the Dialnet protocols in its operating system.
No formal network administration will be required.
The users of any computer implementing
the protocols will be able to communicate with the users of any
other computer implementing them--anywhere in the world.

Services very similar to these are available in
the %2Arpanet%*, which was developed by the Department of Defense and
links hundreds of computers around the world.
These services have proven valuable in aiding
collaboration among computer scientists at different sites and in
permitting nationwide access to unique facilities such as the Macsyma
system for computing with algebraic and analytic expressions at
M.I.T.  They permit a new form of publication in which documents are
kept in the computer, are continuously updatable, are immediately
accessible throughout the country, and in which comments from readers
are accessible to other readers.

The usefulness of the Arpanet has prompted many non-defense
installations to try to connect to it. In some cases this has
been possible, but often the institutional and financial
obstacles have been insuperable.  The main financial obstacles are
the need for a dedicated computer at each site called an IMP, costing about $80,000,
and the need for dedicated communication lines rented by
the Department of Defense at great expense from the telephone companies.
Other networks have been started, some for particular user populations
and others as common carriers.  However, they have higher base
costs than can be achieved with direct use of the telephone system
and they don't presently offer general message, file transfer and login services.

The Dialnet protocols will make network services available to any
time-shared computer installation
or single user computer system without having to join any formal network.
The hardware cost will be from $500 to $5000, depending on the type of system
and how difficult it is to connect devices to the computer.
For time-sharing systems, an automatic telephone dialer
will allow the system to initiate calls.
For small single-user systems where economy is paramount, the user can do his
own dialing.
There will be programs to transmit signals and information according
to the protocols.  Any installation implementing the protocols will
be able to communicate with any other.  The only disadvantage compared
with the Arpanet will be generally lower speed.

Like Arpanet, Dialnet will be most useful with %2full
time-sharing systems%1 that operate 24 hours a day
and have file systems.  In such systems, each user has named disk
files that are kept in the system even when he is absent,
and new files can be created by file
transfer from other machines and on receipt of messages.
Efficient use of the message facilities normally requires that users
habitually log in each working day and are most beneficial when users
have individual display terminals in their offices.  Further benefits
accrue when reports are normally prepared at terminals and when
secretaries use terminals for letters and messages.

While the first users of Dialnet are likely to be
regular computer users, the corresponding Arpanet facilities have
been much used by non-programmers.  Users of Dialnet need not
know how to program, and increasing use by non-programmers is expected as
terminals become more widespread.

The economics of sending messages and file transfer by
Dialnet are quite favorable within a single country.  Using Dialnet
for remote login is economical only within a local area, because longer
connect times are generally involved.

Preliminary protocols may be available as early as Spring
1978, and a "final" version will be available by the end of 1978.
Anyone interested in implementing the preliminary protocols or in
influencing them is invited to communicate with the authors.