[TUHS] LSX issues and musing

Gavin Tersteeg gctersteeg at gmail.com
Tue Jul 12 05:47:11 AEST 2022

Hello, and greetings!

I guess as this is my first post here, I should give some background on
what I have been working on. Last summer I spent a lot of time getting UNIX
V6 working on my PDP-11/23 system. It took a lot of tinkering with the
kernel and drivers to make it work in the way I wanted to, but in the end I
was left with a system that ran well enough to do some demonstrations at

This year I want to do more stuff with 1970s era UNIX, but now with even
more technical restrictions. I have had a Heathkit H-11 (consumer grade
PDP-11/03) for a while now, and I have been looking for something
interesting to do with it. From my research, it seems like there were two
different UNIX variants that could run on a system like this. These
variants were LSX and MINI-UNIX. MINI-UNIX seems to require a decent
mass-storage device like a RK05 and some porting to work on an 11/03, while
LSX is designed to work on exactly the hardware specs that I have on hand.

So on to the actual issues I am having at the moment: I have put together a
SIMH instance to get the ball rolling in building a kernel that will boot
on my EIS-less 11/03, but I am having significant difficulty actually
getting the kernel to build. The first issue is that the C compiler will
randomly spit out a "0: Missing temp file" when attempting to compile
something. This is annoying, but circumventable by just running the same
command over and over until it works. The second issue, however, is much
more of a road block for me. I can't seem to get the kernel to actually
link together once everything is compiled. When the final "ld -X" is
executed, I always get the following errors:

(This is from the build script found in the "shlsx" file)

I am assuming that this is some sort of issue with the object file
orderings, but I simply do not know enough about V6 ld to properly debug
this issue. I am hoping that somebody here has already run into this issue,
and knows what I am doing wrong.

If I can get this working, I have a long laundry list of modifications and
experiments that I want to run with LSX, but as it stands, this is where I
am stuck at.

Thank you,
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