SA and SD were accompanied by notational methods including structure charts, data flow diagrams and data model diagrams, of which there were many variations, including those developed by Tom DeMarco, Ken Orr, Larry Constantine, Vaughn Frick, Ed Yourdon, Steven Ward, Peter Chen, and others.
DeMarco started working at Bell Telephone Laboratories in 1963, where he participated in ESS-1 project to develop the first large scale Electronic Switching System, which became installed in telephone offices all over the world.
Tom Hanks | Tom Waits | Tom Jones | Tom Jones (singer) | Tom Cruise | Tom and Jerry | Uncle Tom's Cabin | Tom Petty | Tom Stoppard | Tom Clancy | Tom Wolfe | Tom Selleck | Tom Baker | Tom Brokaw | Tom Robinson | Tom Mix | Tom | Tom Paxton | Tom DeLay | Tom Sawyer | Tom Petty and the Heartbreakers | Tom Joyner | Tom Harkin | Tom Green | Tom Brady | Tom Ridge | Tom Berenger | Tom Robbins | Tom Harrell | Tom Morello |
SDM, SDM2, SDM/70 and Spectrum more notably evolved into system development methodologies that were based on the works of Steven Ward, Tom Demarco, Larry Constantine, Ken Orr, Ed Yourdon, Michael A. Jackson and others as well as data modeling techniques developed by Thomas Bachmann and Peter Chen.