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4.2BSD on SIMH vax with networking (plover.net)
78 points by beefhash 7 months ago | hide | past | web | favorite | 14 comments

SIMH is one of the things that got me into embedded programming. I'm still very fond of this thing, and it's one of the first things that I install on any machine that I have.

I am not old enough to have used those machines in real life. I have seen some of them in real life, but only as a child. However, I was interested in computer history -- and I had been for quite some time (after stumbling upon ESR's edition of the Jargon file) when I ran into SIMH.

This was back when documentation was pretty scarce, and Internet images slow. I got SIMH on my home computer by relying on floppy disks and a very understanding internet cafe operator. Shortly after, I got a dial-up connection, and managed to lug a few of the historical UNIX images, and boot them in a PDP-11 machine.

I remember being astonished at how much could be achieved in (what seemed to me, back in the late 90s/early 00s) so little memory and with so little computational power. It's what got me interested in the whole "doing less with more" business. Many years later, it turned out to be useful knowledge; when I got my first job writing device drivers for a really tiny RTOS, 48 KB of flash and 4 KB of RAM seemed like a reasonably comfortable space to write code in.

A few years later, I also got a hold of an OpenVMS copy -- which was actually pretty complicated because it involved signing up for DECUS Munchen (I still have my membership card!), which was not very easy considering that I was well under 18 and all the German words I knew were "Danke", "Gutten" and "Tag". I don't remember if SIMH or another emulator already had pcap-based networking support back then, but in any case, I ran a small OpenVMS machine and offered shell accounts to a few curious folks. The whole thing didn't really take off since the machine doing the hosting was the one I used every day for general computer stuff so...

I think the other emulator I had tons of fun with back then was GXemul ( http://gxemul.sourceforge.net/ ). Warmly recommended, even today. It's a glimpse into interesting times -- I'm tempted to say "better times", but nostalgia is a little treacherous.

There is also a writeup on how to run OpenVMS on SIMH VAXserver 3900, a more obscure thing than older Unix installations: https://vanalboom.org/node/18

Spun up 4.3 BSD Unix on SIMH a few years back -

Definitely puts things in chronological perspective to boot up something from that era (1986) and find it to be just about as functional as the base system today..

This is in contrast (imho) to v7/32v from only a few years prior which feels very 'incomplete' as compared to a modern system.

Reminds me a bit of my writeup here:


(I figure if you enjoy this tutorial you'll probably enjoy trying that one out too.)

To OP: The networking is a really nice touch. I didn't even attempt anything like that so kudos to you.

For networking, if necessary, one can use slirp.

"Another alternative to direct pcap and tun/tap networking on all environments is NAT (SLiRP) networking. NAT networking is limited to only IP network protocols so DECnet, LAT and Clusting can't work on a NAT connected interface, but this may be the easiest solution for many folks."

source: https://github.com/simh/simh/blob/master/0readme_ethernet.tx...


Nice writeup.

But if you do this don't you get 4.3?


There are some more obscure systems of interest for which emulators are also available -- Multics (see http://multicians.org/sim-inst.html), the Burroughs 5500 and MCP (http://retro-b5500.blogspot.com/), old mainframe environments via Hercules, and so forth.

Ok, that's interesting. I'd seen the Multics source was made available a few years ago. Has anyone tried this?

Oooh, a Multics emulator?

I am going to have to try that one over the weekend! ;-)


I've always felt SIMH was pretty cool. I haven't done anything with the VAX emulators, but a few years back I had a PDP-11 simulation running on a Raspberry Pi with RSTS/E 7.0.

This was roughly equivalent to the system I used in high school, and I laughed out loud when I discovered that 7.0 wasn't Y2K-compatible. The math teacher who taught the computer classes was warning us about two-digit year values back in 1981!

Can you actually use the Web on this? A couple of years ago I installed NetBSD on a Vaxstation 3100, and white it ran fine, and even networked over the AUI port, I couldn't get Lynx to run. I'd love to have a less-anachronistic BSD on my VAX.

You will have to rewind to 5.9, but lynx should work on openbsd. Not sure why it wouldn't work on netbsd, though.

Thank you. It looks like my 3100/38 is supported. Should be a fun winter project.

Really impressive. One question though - back in 1985, when I first logged in to a real VAX 11/780 running BSD 4.2, it was on a VT220 terminal connected through a terminal on a DZ11 (I think). Is that also available in the simulation?

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