On Jul 2, 2012, at 11:47 AM, Johnny Billquist wrote: On 2012-07-02 16:40, Paul_Koning at Dell.com wrote: 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. I'm not sure how practical the other ones were as embedded systems. The big point with RSX-11S is that it's all just one binary for the whole system. There are no disks. In fact, you can't even have things on disk in the sense that you think for other systems. Without disks, you could put this all on PROM, flash, or whatever. Or (which I think was more common), download from the net, and then run. As far as I know, RT likes a disk, or something disklike, such as DECtape (real or even the fake "DECtape II"). But Micropower, I'm pretty sure, is a deep embedded system that runs from ROM/RAM. paul