RTS/8 was a real-time system developed by DEC, developed from an earlier system, SRT8, dating back to at least 1974. Curiously, even the last versions of RTS/8 continued to support paper-tape and DECtape. RTS/8 also offered a virtual PDP-8 for background processing, unlike ETOS, this did not require special hardware; instead, software emulation was used to retain control of the machine between the CIF instruction and a following JMP or JMS.