Regarding PDP-11/ and rt11 too

Earlier I poionted out that RT-11 has a hobby license... after rereading the License it's clear that's not the case it's only available free for the Supnik Emulator. This doesn't help most people. Now, the problem is for those people that have an -11 and want to use it somehow what is there in the way of OSs? RT-11 legal restrictions exist... RSX-11 No idea, but I'd expect licensing again RSTS Licensing again? Unix... AVAILABLE via PUPs support group as free binaries and 100$ license for sources. Initially this seems good but not all PDP-11 configurations can run unix and not all versions of Unix have the drivers to interact with some PDP-11 hardware. So it may take a lot of work with limited tools or none to get it going. Xenix, available free as binaries for the PRO... Canned version OF V6 by appearance and if you have other than an RD51 it doesn't work. So what else is there that is free (or very low cost) and can be run on most of the LSI-11, PDP-11/23 or 11/73 series? IE: can be run on a 11/03 with RX01 floppy or a 11/73 with RQDX3 MSCP disks (hard disks). There is fuzzball but I know far to little about it or it's applicability to various hardware configs. Allison