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Run ancient UNIX on modern hardware

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125 pointsdoener39 comments

Robert Nordier's port of v7 to x86 probably didn't get the attention it deserves.

It's what it sounds like: v7 Unix ported to x86. Unix v7 was portable enough and the PDP-11 architecturally similar enough to x86 that almost all the code works without change. (Many of the changes from v6 to v7 were to make Unix more portable; it was already running on at least 4 different architectures by 1980.)

I wonder if the obscurity is because the x86 v7 source was an archive inside an archive? Seems a minor thing but not having it to browse online is likely to be an off-ramp for most.

https://www.nordier.com/v7x86/v7x86-0.8a-all.tar.xz has releases/v7x86-0.8a.tar.bz2 (you'll want to use a -C prefix it explodes in the current directory). Source is in usr/sys and usr/src like normal for v7 Unix.

And yes, your modern Linux system's GNU tar is reading the ancient v7 tar format just fine. Neat, eh?

You might find the modern "file" command can still recognize the v7 a.out binary format too:

    $ file usr/bin/compress  
    usr/bin/compress: a.out little-endian 32-bit executable not stripped

Unix version 7 remains a sort of lowest common denominator almost half a century later.

Wasn't Xenix just Unix V7 ported to x86? (Albeit originally 16-bit x86)

xv6 the MIT 'spiritual port' (so to speak) of Version 6 Unix probably deserves to be mentioned there as well, as while it's not actually a historic Bell Labs Unix it will better meet some people's needs. https://pdos.csail.mit.edu/6.828/2012/xv6.html https://pdos.csail.mit.edu/6.828/2025/xv6.html

Good mention! If one wants to study Unix in an academic sense then xv6 is a great starting point. IIRC, many course studies start with xv6 and gradually adding new capabilities to it.

Videos that go through the xv6 source code: https://www.youtube.com/playlist?list=PLbtzT1TYeoMhTPzyTZboW...

I can't pick up the caper (due to the customary backlog of insane projects), but IMHO someone™ should port RetroBSD¹ to more microcontrollers. There's even a C compiler² running on device!

There's a UNIX shape void in the embedded world. Todays microcontrollers routinely come with several megabytes of RAM.

1: https://github.com/RetroBSD/retrobsd

2: https://github.com/RetroBSD/retrobsd/tree/master/src/cmd/sma...

There's also Fuzix, which is Unix-like. https://fuzix.org/

Supports Arm M0 (Raspberry Pi Pico), ESP32 and a variety of others, including Z80.

At work at the time (I was an intern), in 1993, we ran SCO Unix on a 25 MHz 386sx with 8 MB and another 6 MB on an add-in card on the ISA bus. And while the compilation with Motif was a bear (1 hour for a 1 MB executable), the actual app was reasonably snappy.

I can't imagine how FAST that system would feel with modern hardware.

To quote Scotty: "we going nowhere mighty fast."

Motif? What version of SCO UNIX?

1 MB executable was huuuge in those times, wasn't it?

Inconceivable!

My eval box for my work Xenix deployments was an 80286: an IBM PC-AT with 512 kB of RAM. Everything worked.

> SCO Unix on a 25 MHz 386sx with 8 MB and another 6 MB on an add-in card

OK, SCO Xenix not SCO Unix, but I deployed production Xenix boxes with 4MB of RAM on 80386DX processors.

It ran well and supported 4-6 users no problem. As I recall, one customer had 8 users and they needed a RAM upgrade. I think, dimly now as this wasn't my department, it was eye-wateringly expensive. Something in the region of £5,000 to £6,000 (at the time, $10K+).

We did deploy one box with just 2 MB of RAM, but that didn't work well once a few users on terminals logged in. They had to upgrade the RAM.

FWIW these were 32-bit 386 machines, but with no CPU cache – the lower-end IBM PS/2 Model 80 variants of the time, with 16 MHz and 20 MHz CPUs. (The top-end 25MHz Model 70 had a small SRAM cache for the CPU. It cost over £10,000 with no screen, keyboard or mouse, and my Acorn Archimedes A310, which cost me £800, absolutely smoked it: it was about 4x as fast.)

That's when I knew Arm would eventually eat x86: in 1989. It's finally happening now.

But I was running PC DOS and DOS software in a window on my ARM desktop in 1989, in pure software emulation, and it was sluggish but usable. CPU was equivalent to a 2-2.5 MHz 8086, but disk performance was better than a screaming fast SCSI disk, so it balanced out.

I did the same, but with Tandy 4000s.

>That's when I knew Arm would eventually eat x86: in 1989. It's finally happening now.

I had kind of the reverse feeling: when the 486 came out, I knew those expensive SPARC and MIPS workstations were all doomed.

Ironically Bill Gates was big into UNIX, see his Xenix interview, and had they not gotten lucky with the whole MS-DOS deal, maybe they would have kept Xenix and who knows how that would have turned out.

Xenix was also my introduction to UNIX.

However due to our school resources, there was a single PC tower running it, we had to prepare our examples in MS-DOS using Turbo C 2.0, and API mocks, and take 15m turns at the Xenix PC.

> had they not gotten lucky with the whole MS-DOS deal, maybe they would have kept Xenix and who knows how that would have turned out.

Oh, absolutely, yes. It's one of the historical inflection points that's visible.

My favourites...

• MS wanted to go with Xenix but DOS proved a hit so it changed course.

• DR had multitasking Concurrent DOS on the 80286 in 1985, but Intel's final released chip removed the feature CDOS needed, so it pivoted to FlexOS and RTOSes, leaving the way open to MS and OS/2 and Windows.

• MS wanted OS/2 1.x to be 386-specific but IBM said no. As a result, OS/2 1.x was cripped by being a 286 OS, it flopped, and IBM lost the x86 market.

• Quarterdeck nearly had DESQview/X out before Windows 3: a TCP/IP enabled X11-based multitasking DOS extended that bridged DOS to Unix and open systems... but it was delayed and so when it appeared it was too late.

* GNU discussed and evaluated adopting the BSD kernel for the GNU OS, but decided to go with Mach. Had it gone for the BSD kernel, there would have been a complete working FOSS Unix for 386 at the end of the 1980s, Linux would never have happened, and Windows 3 might not have been such a hit that it led to NT.

I got whole series of articles out of this, titled in honour of Douglas Adam's fake trilogy about god...

https://www.theregister.com/2024/08/28/where_computing_went_...

https://www.theregister.com/2024/08/29/where_computing_went_...

https://www.theregister.com/2024/09/04/where_computing_went_...

With apologies to Oolon Colluphid. ;-)

> I did the same, but with Tandy 4000s.

Never saw one of those. Tandy computers did exist in the UK, and even here on the Isle of Man there was a single Tandy's store. (They weren't called "Radio Shack" here.) But while they sold lots of spares and components and toys, they didn't sell that many computers.

> I had kind of the reverse feeling: when the 486 came out, I knew those expensive SPARC and MIPS workstations were all doomed.

Well, yes. Flipside of the same coin.

Expensive RISC computers were doomed. Arm computers weren't expensive back then: they were considerably cheaper than PCs of the same spec. So for a while, they thrived, then when they couldn't compete on performance they moved into markets where they could compete on power consumption... which they then ruled for 30 years.

I tried EMWM with Motif based tools (from Vim to Emacs, EMWM, XFile, Ximaging, Classic-Colors (and even tried to write a simple UI for Mplayer) under a 10-15 year old n270 based netbook.

https://fastestcode.org/emwm.html

It ran really fast. Also, if Dillo ran snappy under a 486 (today so-so except for a slight delay because of TLS, but bearable once the page it's rendered), Dillo today runs at light speeds. This on my n270 netbook under OpenBSD. With NetBSD, it would run slightly faster.

simh deserves the credit here

Simh can still run modern NetBSD under Vax. Go figure.

Is 'ancient UNIX' a term of art, or should I be offended?

While exact definitions vary, it's a term of art for Research Unix ≤ V7, perhaps plus or minus a version, perhaps including contemporary derivatives.

Relatively speaking, any operating system from the 70s is "ancient".

What about from the 60s? Archaic?

https://www.unisys.com/product-info-sheet/ecs/clearpath-mast...

Anything with non keyboard input = prehistoric.

Is it at all possible to get a peak into that world as a curious person?

http://ibm1130.org/emu/

https://opensimh.org/simdocs/ibm1130_doc.html

Unisys not, but the one predating UNIX,

https://multicians.org/simulator.html

With Multics i'm familiar enough, i meant unisys specifically.

Not for free,

https://www.unisys.com/client-education/mcp-clearpath-server...

However you can get into the documentation for free,

NEWP manual, the systems language,

https://public.support.unisys.com/aseries/docs/ClearPath-MCP...

Overall documentation,

https://public.support.unisys.com/aseries/docs/ClearPath-MCP...

The original system back in 1960's,

https://en.wikipedia.org/wiki/Burroughs_Large_Systems

I'm a Stargate fan, and I call everything created before 1980 Ancient Technology. I like how it sounds.

The Ancients had cool tech. Probably all running on Unix :P

I’d call basically anything before the mid 90s ancient, even though I was there and using it at the time, just because of how much of the way we use computers now has changed so drastically.

Amiga WB, Macs, Atari GEM, RiscOS... not that different.

How many of the operating systems that you listed remain as ways we use computers?

Even Macs were an entirely different codebase that didn’t even have memory protection or preemptive multitasking, which very much changed how you used it.

Some of us are ancient enough to have been born before the last person walked on the moon.

Some of us are working day jobs in tech and remember the first guy.

Severo Ornstein called his memoir of the 1950s - 1970s Computing in the Middle Ages. Ornstein worked on SAGE, TX-2, LINC, and the Arpanet IMP among other things, before moving on to Xerox PARC.

https://worrydream.com/refs/Ornstein_2002_-_Computing_in_the...

Great read, but he undersells the weight of von Neumann's EDVAC report. If you haven't read that (which I imagine you have), it's crazy how prescient some of the lesser-known ideas are. He seemed to assume that we'd end up with some kind of neural architecture, and it's easy to imagine him being surprised that it took us this long to get serious about the idea.

Apropos of that, I couldn't resist telling Gemini 3 to run with your story prompt from the earlier thread: https://gemini.google.com/share/ac122aba6f7f. Thanks for the inspiration, apologies for following it. :-P

(Also thanks for posting the material you wrote back in the 1980s on the SCP initiative. I had heard of it as an SDI connection or component, but that was all. Reading through it now.)

Thanks! -- Jon

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