Tymshare's operating system which ran for many years on Tymshare's PDP-10s. It was a descendent of TOPS-10 but had many of the important features of TOPS-20 such as real paging and controllable/spawnable processes. TYMCOM-X, one of the best kept secrets in the PDP-10 folklore, was written by Bill Weiher, Vance Socci <email@example.com>, Allen Ginzburg, Karen Kolling, Art Atkinson, Gary Morgenthaler (founder of the company that produced IDRIS), Todd Corenson and Murray Bowles. Some copies still run today. Most TYMNET development was done under TYMCOM-X and Tymshare sold a TYMCOM-X system to TRW to use in their credit reporting network, which was based on a purchased copy of TYMNET circa 1979.
[E-mail from Vance Socci 1994-05-20].