On 07/02/2012 10:58 AM, Bob Armstrong wrote: 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. Did the LA120 have a T11 in it? Wow - makes me want to go take mine apart and look :-) I just picked up four more LA120s with some 11/84s and a bunch of RA90s. (very happy!) I will check tonight if you don't look at yours by then. For example, the RFxx drives (all of 'em, I think) used a T11 and I'm pretty sure ran some variant of RSX-11S. Wow, I didn't know that, that's neat! The HSC controllers had PDP-11s in them, didn't they? I don't remember which model but I bet the OS was another RSX derivative. The HSC50 uses an F11, the HSC70 and HSC9x use J11s. Some of the bigger DECserver terminal servers were PDP-11 based (not T11, but an 11/53 for example). Don't know if the little ones (e.g. DECserver-100, 200, etc) were T11 or 68K based. The -200 is 68K-based. I don't know about the -100. The -550 is the one that's basically a PDP-11/53 with different EPROMs. -Dave -- Dave McGuire, AK4HZ New Kensington, PA