[TUHS] LSX issues and musing

Noel Chiappa jnc at mercury.lcs.mit.edu
Tue Jul 12 07:24:13 AEST 2022

    > From: Gavin Tersteeg        
    > 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

You must have made a lot of changes for it to take "a lot of tinkering".
Bringing V6 up on the /23 has been done several times, and when I did
it, it only took about 2 dozen lines of code in about 2 files. What all
did you wind up changing?

    > 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.

Bringing up MINI-UNIX on the /03 has been done at least twice; once
historically (now lost, AFAIK), and again recently:


I'm not sure what you're basing the "MINI-UNIX seems to require a decent
mass-storage device like a RK05" on - it should run as well on whatever
you're running LSX on as LSX does.

I haven't run LSX myself, but from what I've seen, the only significant
difference between the two is that LSX will run with less main memory than
MINI-UNIX (which really kind of needs 56KB; LSX you can probably get away
with 40KB).That was a significant issue when the LSI-11 was originally
released, but these days one has to really work to have a QBUS PDP-11 with
less than 56KB.

    > my EIS-less 11/03

EIS chips can be found on eBait for not much money (I just bought a couple
myself), and it's worth investing in one, so on can dispense with the
emulator, which takes real memory for which a better use can be found.

    > 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.

Schaeffer's Law (from Larry Niven): anything you don't understand
might be dangerous. I'd track down why this is happening.


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