[3] Tymshare was restructured, split up and portions were resold, spun off, and merged with other companies from 1984 through 2004 when most of its legacy network was eventually shut down.
Consequently, rights to use technology developed by Tymshare are currently held by Boeing, British Telecom (BT), Verizon Communications, and AT&T Inc. due to the acquisitions and mergers from 1984 through 2005.
Tymshare was founded in 1964[4] by Thomas O’Rourke[3][5] and David Schmidt, two former employees of General Electric's Computer Department.
IBM Stretch programmer Ann Hardy rewrote the time-sharing system to service 32 simultaneous users.
[6] In 1968, LaRoy Tymes[7] and Norm Hardy developed the idea of creating a network with minicomputers to communicate with the mainframes.
The minicomputers started off as an inexpensive 12-bit computer from General Automation and soon became a more capable 16-bit Varian 620i—would serve as the network's nodes, running a program called a "supervisor" which routed data, performed diagnostics, and kept network statistics; a local program at each node, dubbed a "leprechaun," handled log-in, security, and diagnostics.
The supervisor was written in assembly code by Tymes for the SDS 940, with architectural design contributions from Hardy in late 1969.
Additional acquisitions included United Data Centers, Alan-Babcock Computing, Bancard of Rhode Island, and TeleCheck.
In 1972, Joseph Rinde joined the Tymnet group and began porting the Supervisor code to the 32-bit Interdata 7/32, as the 8/32 was not yet ready.
The OS work was done by a group of eleven people: Bill Weiher, Vance Socci, Allen Ginzburg, Karen Kolling, Art Atkinson, Gary Morgenthaler (founder of the company that produced INGRES), Todd Corenson, Murray Bowles, Randy Gobbel, Bill Soley, and Darren Price.
Tymnet II ran in parallel with the original network, which continued to run on the Varian machines until it was phased out over a period of several years.
In 1976, Tymnet Inc. was spun off from Tymshare Inc. and became an FCC "common carrier" which allowed it greater latitude as a communications service but placed its rate-setting under regulatory review.
McDonnell Douglas acquired Microdata and created McDonnell Douglas Information Systems Group (MDISC), expecting to turn Microdata's desktop and server systems along with Tymshare's servers and Tymnet data network into a major player in the Information Services market.
After five years, peace was breaking out in many places in the world and McDonnell Douglas sold off MDNSC and MDFSC at a profit for much needed cash.
British Telecom (BT) wanted to expand and the acquisition of Tymnet which was already a worldwide data network helped to achieve that goal.
BT brought with it the idea of continuous development with teams in America, Europe, and Asia-pacific all working together on the same projects.
Another project begun a few months before the BT purchase was to migrate the Tymnet code repository from the PDP-10s to Sun systems.
After the migration, these servers managed source code and binary images for more than 6600 nodes and 38,000 customer interfaces worldwide.
Tymnet was still growing, and at several times reached its peak capacity when some of its customers held network intensive events.
Tymnet usage statistics showed AOL's call capacity was greater than its maximum volume for the duration of the event.
Times were changing and the Internet and World Wide Web were becoming a practical and even important part of corporate and personal life.
However, the Tymnet network was still bringing in considerable cash — in some cases more than current IP based services—so both BT and MCI needed to keep their customers happy.
With the alliance gone, BT and MCI WorldCom began the process of unraveling and separating their extensive voice and data communications systems.
Sometime in early March 2004, without ceremony, BT Americas disconnected the last two remaining Tymnet supervisors from the network, effectively shutting it down.
WorldCom executives were involved in a financial scandal resulting in the CEO, Bernie Ebbers, to be ousted and later charged with violations of federal statutes.