 The Unix operating system also became popular, but lacked the real-time features and extremely small size of RT-11.RT-11 ran on all members of the DEC PDP-11 family, both Q-Bus- and Unibus-based, from the PDP-11/05 (its first target, in 1970), to the final PDP-11 implementations (PDP-11/93 and /94).In addition, it ran on the Professional Series and the PDT-11 "Programmed Data Terminal" systems, also from DEC.