Fault Tolerant Unix
(FTX) Stratus's own Unix System V Release 4 multiprocessor operating system. In 2016, FTX is supported but no longer developed.
FTX was one of three operating systems supplied by Stratus on their hardware, the other two, HP-UX and VOS, were the more common choices, FTX was only sold on an exceptional basis.
Early FTX 3.x releases used an in-house virtual disk layer (VDL) driver, but later releases switched to a version of Veritas VxVM.
FTX supported many of the proprietary communications boards (ISDN, serial, parallel, X.25, etc.).