Tymnet
TYMNET
(networking, history)In its original implementation, it consisted of fairly simplecircuit-oriented nodes, whose circuits were created bycentral network supervisors writing into the appropriatenodes' "permuter tables". The supervisors also performedlogin validations as well as circuit management. Circuitswere character oriented and the network was oriented towardinteractive character-by-character full-duplexcommunications circuits.
The network had more than one supervisor running, but only onewas active, the others being put to sleep with "sleeping pill"messages. If the active supervisor went down, all the otherswould wake up and battle for control of the network. Afterthe battle, the supervisor with the highest pre-set prioritywould dominate, and the network would then again be controlledby only one supervisor. (During the takeover battle, the netconsisted of subsets of itself across which new circuits couldnot be built). Existing circuits were not affected bysupervisor switches.
There was a clever scheme to switch the echoing functionbetween the local node and the host based on whether or not aspecial character had been typed by the user. Data transferswere also possible via "auxiliary circuits".
The Tymshare hosts (which ran customer code) were SDS 940,DEC PDP-10, and eventually IBM 370 computers. XeroxXDS 940 might have been used if Xerox, who bought the designfor the SDS 940 from Scientific Data Systems, had ever builtany.
The switches were originally Varian Data Machines 620i. TheInterdata 8/32 was never used because the performance wasdisappointing. The TYMNET Engine, based loosely on theInterdata 7/32, was developed instead to replace the Varian620i. In the early 1990s, newer "Turbo" nodes based on theMotorola 68000 began to replace the 7/32s. These were laterreplaced with SPARCs.
PDP-10s supported (and still do in 1999) cross-platformdevelopment and billing.
Tymshare, Inc. originally wrote and implemented TYMNET toprovide nationwide access for their time-sharing customers.
La Roy Tymes booted up the public TYMNET in November of 1971and, as of March 2002, it had been running ever since withouta single system crash.
TYMNET was the largest commercial network in the United Statesin its heyday, with nodes in every major US city and a fewoverseas as well. Tymshare acquired a French subsidiary,SLIGOS, and had TYMNET nodes in Paris, France.
Tymshare sold the TYMNET network software to TRW, whocreated their own private network (which was not calledTYMNET). In about 1979, TYMNET Inc. was spun off fromTymshare, Inc. to continue administration and development ofthe network.
TYMNET outlived its parent company Tymshare and was acquiredby MCI. As of May 1994 they still ran three DEC KL-10sunder TYMCOM-X, although they planned to decommission themsoon.
The original creators of TYMNET included: Ann Hardy, NormHardy, Bill Frantz. La Roy Tymes (who always insisted thathis name was NOT the source of the name) wrote the firstsupervisor which ran on the 940. Joe Rinde made manysignificant technical and marketing contributions. La Roywrote most of the code of the network proper. Several otherswrote code in support of development and administration. Justrecently (1999) La Roy, on contract, wrote a version of thesupervisor to run on SPARC hardware.
The name TYMNET was suggested by Vigril Swearingen in a weeklymeeting between Tymshare technical and marketing staff inabout 1970.
http://cap-lore.com/ETH.html.
[E-mail from La Roy Tymes]