UNIX on PDP-11s (was Re: PDP 11/73 on the Internet)

Ethan Dicks ethan.dicks at gmail.com
Thu Jun 4 11:20:03 CDT 2009

On Thu, Jun 4, 2009 at 11:42 AM, John Floren <slawmaster at gmail.com> wrote:
> Interesting, I didn't know a /23 could run V7--all I know for sure is
> that it works on /45s and /70s. Do you know any other machines it runs
> on? I'd like to try installing on my 11/73 (KDJ11-A) if possible.

I think it would come down to disk drivers.  If the kernel will run on
an 11/70, there's no difference I can think of off the top of my head
why it wouldn't run on a KDJ-11, unless there's something about the
22-bit Unibus mapping on the 11/70 vs no mapping on the Qbus.

Disks, though... a 11/73 is likely to have an MSCP disk controller,
but the 11/70 has quite a number of supported disk controllers.

I'd look at the 7th Ed. sources and the install process to see what
7th Ed. is expecting to load onto.

It's all part of the joy of vintage gear - you used to have to know
exactly what you had and exactly what the software was looking for to
have a successful install experience.  More than once, I had to
install on machine A, then either move the disk or the data on the
disk to machine B because I couldn't install directly on machine B
(most often due to tape drive/boot ROM issues).

You might be able to scope this out with simh prior to gathering
genuine hardware, but if you have the hardware lying around, you might
as well try it.


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