ATing system> (TORTOS) An operATing system developed from MVTAT Health Sciences Computing, UCLA by Dr. PATrica Britt from the lATe 1960s to the mid 1970s. Dr. Britt was a senior scientist ATIBM, who become the Assistant Director of HSCF. TORTOS pre-dATed TSO and provided bATch, real-time and time sharing on an IBM 360/91. (2004-07-02)