Talk:VAX-11/780

I split up the 11/780 & the 11/785 because the formatting was all broken with the two info boxes on the same page...

Booting VAX-11/780

I'm currently trying to boot DEC Ultrix 1.1 on SIMH, using the vax780 (11/780) emulator - however, I am used to the 'vax' (MicroVAX 3900) emulator, which has its console environment in ROM (possibly EEROM). The VMS - before it was 'OpenVMS'! - documentation for the 11/780 mentions a console floppy and SIMH's vax780 source dir has a file named 'vmb.exe'; I think that this might be the minimal console environment that I need to carry out disk maintenance tasks to get Ultrix running, but I am unable to load it ('Invalid argument'). I have tried the 'fload' command and 'load -o vmb.exe 0' and 'run 2' - but the simulator just hangs.

Can anyone explain how the VAX-11/780 boots? Any hints would be appreciated!

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It's... complicated.

and not 100% by any stretch, look at 4.2 BSD, and 32v for some hints... Odds are Ultrix being a 4.2BSD derived OS, it'll work better with forced bootblock injection... I bet you can even use BSD 4.2's bootblocks. I'm assuming you can extract the miniroot from the tape? I don't have access to Ultrix 1.1 so I can't spell it out..... neozeed 12:50, 12 June 2011 (PDT)

Thanks Neozeed, and yes, I may be able to get the miniroot off the tape image as I have had some success in just poking around the Ultrix dist and separating various sections. Part of this is me learning how to use such an old OS, and also working out what translations need to be done to get SIMH to work with these files. I have 4.2 BSD working, and 4.3 BSD too, thanks to the tutorials gunkies.org. The bootblock injection stuff is a little (well, a lot) beyond me at this point. lexthehex 01:25, 13 June 2011 (GMT)

Honorable Mention

In this article: https://news.ycombinator.com/item?id=27758962 This article got mentioned:

"I remember reading an old paper on some funky experimentat user-interface that used a pair of PDP-11s (possibly, might have been event older) essentially wired together at the busses, with extra instructions added with new logic in TTL silicon, I think it was for doing the maths for the vector graphics. It was amazing the amount of hardware hackery that was necessary to build these experimental systems."

"Actually I think those were Vaxen

https://gunkies.org/wiki/VAX-11/780#Dual-CPU_experiment "

Turns out the "experimenter" was none other than George H Gobel, BBQ/LOX and web server overloading fame. ForOldHack 07:44, 9 July 2021