TYMNET

A United States-wide commercial computer

network, created by {Tymshare, Inc.} some time before 1970,

and used for {remote login} and file transfer. In its

original implementation, it was made up of a number of fairly

simple circuit-oriented {nodes}, whose circuits were created

by one central network supervisor writing into the appropriate

nodes' "permuter tables". The supervisors also performed

login validations as well as circuit management. Circuits

were character oriented and the network was oriented towards

interactive character-by-character {full-duplex}

communications circuits.

There was a clever scheme to switch the echoing function

between the local node and the host based on whether or not a

special character had been typed by the user. Data transfers

were also possible via "auxiliary circuits".

The network had more than one supervisor running, but only one

was active, the others being put to sleep with "sleeping pill"

messages. If the active supervisor went down, all the others

would wake up and battle for control of the network. After

the battle, the supervisor with the highest pre-set priority

would dominate, and the network would then again be controlled

by only one supervisor. (During the takeover battle, the net

consisted of subsets of itself across which new circuits could

not be built). Existing circuits were not affected by

supervisor switches.

{Tymshare, Inc.} originally wrote and implemented TYMNET to

provide nationwide access for their {time-sharing} customers.

When Tymshare started using {Interdata 8/32} {minicomputers}

as nodes they started developing TYMNET on {PDP-10}. The

Tymshare hosts (which ran customer code) were {SDS 940}, {XDS

940}[?], {DEC} {PDP-10}, and eventually {IBM 370} computers.

The switches were originally: {Varian Data Machines} 620 [?]

and {Interdata 8/32}. PDP-10s supported (and still do in

1999) cross-platform development and billing.

Tymshare sold the TYMNET network software to {TRW}, who

created their own private network (which was not called

TYMNET). In about 1979, TYMNET Inc. was spun off from

Tymshare, Inc. to continue administration and development of

the network.

TYMNET was the largest commercial network in the United States

in its heyday, with nodes in every major US city and a few

overseas as well. Tymshare acquired a French subsidiary,

{SLIGOS}, and had TYMNET nodes in Paris, France.

TYMNET has outlived its parent company Tymshare and is now

owned by {MCI}. As of May 1994 they still ran three {DEC

KL-10}s under {TYMCOM-X}, although they planned to

decommission them soon.

The original creators of TYMNET include: Ann Hardy, Norm

Hardy, Bill Frantz. Laroy Tymes (who always insisted that his

name was NOT the source of the name) wrote the first

supervisor which ran on the 940. Joe Rinde made many

significant technical and marketing contributions. Laroy

wrote most of the code of the network proper. Several others

wrote code in support of development and administration. Just

recently (1999) Laroy, on contract, wrote a version of the

supervisor to run on {SPARC} hardware.

The name TYMNET was suggested by Vigril Swearingen[?] in a

weekly meeting between Tymshare technical and marketing staff

in about 1970.

{(http://www.mediacity.com/~norm/ETH.html)}.

(1999-03-17)