Software for small-memory PDP-11s?

Paul Koning paulkoning at
Sat Nov 14 08:28:22 CST 2015

> On Nov 13, 2015, at 5:45 PM, Josh Dersch <derschjo at> wrote:
> Hey all --
> Now that I have my PDP-11/05 running nicely, I'm curious what others are
> running on small systems like this -- until this point I've only played
> with larger (i.e. at least 28KW memory) systems.  I have only 8KW of memory
> (with no viable options for expansion) and there's not much out there that
> I've found.  There's paper-tape BASIC (which is always fun) and FOCAL, and
> PTS-11 ( which is pretty cool
> if a bit cumbersome.  Any other suggestions?
> I'm also curious if any version of RT-11 that supports the TU58 could be
> made to run on this system -- I have two SLUs in the system so in theory I
> can boot from an emulated TU58. However RT-11 4.0's SYSGEN manuals suggest
> that 12KW is the minimum supported (and experimentation bears this out) and
> I can't find much in the way of manuals for RT-11 V3B -- which I believe is
> the earliest version with TU58 support.  (V3B seems to be different enough
> from later versions that I'm not quite sure how the SYSGEN process works.)

RT11 V2 SJ will certainly fit easily in that size memory.  DOS will fit even in 4K (at least the older versions).  Come to think of it, RT might also; I haven't tried it that small.


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