On Jul 2, 2012, at 10:21 AM, Bob Armstrong wrote: ... RSX-11S was the "embedded system OS" of the PDP-11 world (at least as far as DEC's offerings went). That and RT-11. And MicroPower-Pascal, of which I know nothing apart from its name. Was that the RTOS used with the T-11 (the first single-chip PDP-11?) I seem to remember that it was used as the RTOS in the LA-120 printer. Having a real OS allowed it to do fancy stuff like bidirectional printing, the first DEC printer to do so. paul