[TUHS] Setting Up UNIX—Sixth Edition: An OpenSIMH Laboratory for Reading Lions

[Will Senn via TUHS]

Thanks, Rick. I write the things I wish I'd had and also to remind me 
when I forget :). This latest note is a bit different from the others, 
though it might look the same on surface reading. The others were to get 
the os working for modern folks, this one is to put it closer to the 
state it would have been when Lions was teaching and conducting labs. 
It's not as hand-holdy and it isn't meant to be comfortable, just 
realiably mundane.

In working through it several times and then using it for 
experimentation many times, what strikes me is the luxury of our modern 
era. Where he was constrained by the era, budget, and sheer physicality 
of it all, I can screw up the first stage loader, second stage loader, 
destroy my filesystem completely (don't point two pdp11's at the same 
rk0, it's confusing and nightmarish), and do pretty much anything I want 
to it, it's just a quick cp backup/* . later and I'm back up and running 
pristine.

Oh, yeah, Texas is awesome. I hope your daughter likes it here. One of 
these days, I need to get down under - lots of friends of mine are in 
the southern hemisphere.

Later,

Will


On 7/26/26 12:20 AM, durtal wrote:

>
> Thanks for this update...I found your earlier work very helpful in 
> getting things up and running. I haven't had the time to look at the 
> v7 info.
> Your Apple II assembly work has been much appreciated as well. However,
> I'm still trying to get my head around it % ).
>
> BTW, nine years ago a Texas boy whisked away our Aussie daughter. They
> live in Cedar Hill with two of our grandchildren.
>
> Rick
>
>
> On Fri, 24 Jul 2026, Will Senn via TUHS wrote:
>
>> Date: Fri, 24 Jul 2026 13:23:57 -0500
>> From: Will Senn via TUHS <tuhs at tuhs.org>
>> Reply-To: Will Senn <will.senn at gmail.com>
>> To: "tuhs at tuhs.org" <tuhs at tuhs.org>
>> Subject: [TUHS] Setting Up UNIX?Sixth Edition: An OpenSIMH Laboratory 
>> for
>>     Reading Lions
>>
>> Hi all,
>>
>> I support the proposed IEEE Milestone recognizing John Lions' UNIX 
>> Operating System Source Code Level Six and A Commentary on the UNIX 
>> Operating System. Few works have had a comparable influence on 
>> operating systems education, and it is fitting to see them considered 
>> for formal recognition.
>>
>> With that discussion underway, I thought I would mention a companion 
>> resource I have just completed.
>>
>> For the past several years, I have been working with V6 under 
>> OpenSIMH for a variety of purposes, and I have written up the general 
>> installation and customization process before. This is not another of 
>> those notes. Setting Up UNIX?Sixth Edition: An OpenSIMH Laboratory 
>> for Reading Lions is written in the genre of Thompson and Ritchie's 
>> original memo: a procedure, in their register, addressed to someone 
>> assembling a specific machine and environment. Its scope is both 
>> narrower than theirs and broader. It constructs a modern virtual 
>> counterpart to the laboratory in which Lions' students worked. An 
>> installation guide ends at a login prompt, but this guide goes 
>> further: to a correspondence among the running kernel, the source 
>> tree from which it was built, and the listing Lions annotates, all 
>> resolvable against one another.
>>
>> The original laboratory required a PDP-11/40, controllers, several 
>> RK05 drives, magnetic tape, terminals, a printer, removable media, 
>> and the accompanying source and documentation. In the reconstructed 
>> laboratory, those components take different forms. OpenSIMH supplies 
>> the processor, memory, controllers, and peripheral devices. The 
>> distribution tape and removable disk packs are represented by image 
>> files, while a modern terminal program provides access to the running 
>> system. The cabinets, motors, reels, and 14-inch platters have 
>> disappeared, but the interfaces presented to V6 remain those of the 
>> original machine. V6 does not know the difference.
>>
>> The guide leads readers who want to study Lions in a working 
>> laboratory environment through restoring the original V6 distribution 
>> from tape, rebuilding the kernel, installing the complete source and 
>> documentation filesystems, creating the required device files, 
>> verifying the installation, and producing a restorable baseline 
>> archive. The completed laboratory is configured to match the presumed 
>> model system described by Lions on page 1-2 of the Commentary. It 
>> allows readers to boot the system, examine the installed source, 
>> rebuild the kernel, and move directly among the running system, the 
>> source deployed from the original distribution tape, and the edited 
>> listing published as UNIX Operating System Source Code Level Six.
>>
>> The guide is intended to be used together with my updated and 
>> expanded edition of UNIX Operating System Source Code Level Six, 
>> which preserves Lions' original sheet numbering while adding file 
>> locations, procedure listings, indexes, cross references, and 
>> configured-kernel symbol tables keyed to the delivered source code. 
>> Together, the two resources make it possible to read Lions not only 
>> as a historical text, but against a living V6 system assembled from 
>> the original distribution materials.
>>
>> Guide:
>> https://decuser.github.io/posts/setting-up-unix-sixth-edition-opensimh-laboratory-for-reading-lions/ 
>>
>>
>> Companion source edition:
>> https://decuser.github.io/posts/updated-lions-v6-source-w-appendices-and-helps-v1.4/ 
>>
>>
>> The guide takes me about 15 minutes to work through now, but I expect 
>> a careful first reading and installation will take a couple of hours.
>>
>> I would be glad to hear from anyone who takes a look, even if only to 
>> let me know you had a chance to read it. Corrections, questions, and 
>> suggestions are especially welcome.
>>
>> Regards,
>> Will
>>
>>
>
> durtal at sdf.org
> SDF Public Access UNIX System - https://sdf.org