17 ms·
Ask HN: What is the oldest, still supported OS?
I recently discovered that TSOS, an old Univac OS that I used (and loved!) in the mid 1970's and first released in 1968 by RCA, is still supported (although the name has changed) as Fujitsu's BS2000 OS. Unix was released a year after that (1969). Is there something that beats these?
- p_l 5y agoMaster Control Program of Burroughs Large Systems fame was first released in 1961 - latest release is from May 2021
- abrax3141 5y agoOkay, seems like that's the one to beat!
- bombcar 5y agohttps://en.wikipedia.org/wiki/Burroughs_MCP https://en.wikipedia.org/wiki/Burroughs_MCP and there's even a link to the latest release notes: https://public.support.unisys.com/aseries/docs/ClearPath-MCP-20.0/82312182-000/82312182-000.pdf https://public.support.unisys.com/aseries/docs/ClearPath-MCP...
- ElevenLathe 5y agoOS/360 dates to 1966. I believe z/OS in theory still provides compatibility back to applications of that vintage, though AFAIK it is a separate codebase.
- akandiah 5y agoFun fact: z/OS is now emulated on Red Hat Linux nowadays for "new" deployments.
- tgflynn 5y agoWhat exactly do you mean by that ? Are you talking about an IBM emulation product that runs on RH Linux ?
- retrac 5y agoZ/OS is directly descended from OS/360. It's just a renaming. And yes, it continues to have almost complete binary compatibility back to 1966. I know for a fact that the IBM Fortran compiler from 1972 runs unmodified on z/OS today. Just pipe the 80 column EBCDIC data representing punch card images into the virtual punch card reader and off you go.
- p_l 5y agoThere was a big rewrite around MVS, but z/OS to this day executes a lot of code in 24bit address mode of S/360[1], and well, OS/360 code should mostly just run [1] Easy to observe when running z/OS under Hercules, as one of the console modes shows the CPU address size mode. A lot of the time during bootup of basic ADCD you'll see 24, a bit less 31, and rarely 64
- rbanffy 5y ago31 bits ought to be enough for anyone.
- p_l 5y agoAt least on z/OS, executable code still needs to be in lower 31bits space
- monocasa 5y agoIf it ain't broke, don't fix it. And if it's broke just a little, someone probably depends on it for compat.
- gjvc 5y agohttps://www.hyrumslaw.com/ https://www.hyrumslaw.com/
- chefkoch 5y ago> into the virtual punch card reader as someone to young to have seen punch cards live this sounds really strange.
- AnimalMuppet 5y agoIt gets crazier. At least back in the 1970s, you used to be able to emulate 7090 (IIRC) software on System/360. So if you have a 7090 program from the 1950s, you may be able to still run it today on z/OS, because you can probably run the 1970s-era emulator.
- skissane 5y agoFrom what I’ve gathered, the IRS was using IBM’s 7074 emulator in production under z/OS to run some very old applications written in 7074 assembly-they might have finally stopped by now, but they were still doing it as recently as 5 years ago.
- Jerry2 5y agoThe oldest one I know is PDP-11. It's still being used in nuclear power plants and many plants will continue using it until at least 2050 (maybe even longer if they remain working). [1] PDP-11 was released in 1970 so your TSOS find is even older. I'm sure there's something even older than these two that's being used by various gov orgs and industrial systems. There's plenty of small consulting firms that support ancient systems. These contracts provide them with steady and stable income. [1] https://www.theregister.co.uk/2013/06/19/nuke_plants_to_keep_pdp11_until_2050/ https://www.theregister.co.uk/2013/06/19/nuke_plants_to_keep...
- sloaken 5y agoPDP-11 Assembly language is just beautiful, well compared to most other assembly languages. I highly recommend it if you are trying to learn the concept of doing assembly language as a 'trainer' language. Not practical these days but a great way to learn.
- ghaff 5y agoUsed != supported especially for systems that are not network-connected. Also the PDP-11 is a minicomputer series. There were a bunch of operating systems from DEC and others that ran on it. Certainly there are consultants who support ancient system but they probably have limited (if any) access to the OS source code--though they can probably patch to a limited degree.
- cptnapalm 5y agoBSD 2.11 is still getting patched by Steve Schultz, last I saw.
- paulmd 5y agoApropos of nothing but this is one of the fun bits about FreeBSD, you can trace a lineage back through the AT&T Research Unix days. The oldest (known) surviving code in FreeBSD dates back to November 1974, committed by Ken Thompson. https://www.researchgate.net/figure/The-oldest-surviving-code-in-a-2016-version-of-Freebsd-Unix-lines-114-118_fig12_306070534 https://www.researchgate.net/figure/The-oldest-surviving-cod...
- nix0n 5y agoPossibly Burroughs MCP[0] from 1961, currently Unisys ClearPath MCP. Not to be confused with Encom MCP[1], which was defeated by Flynn and Tron in 1982. [0]https://en.wikipedia.org/wiki/Burroughs_MCP https://en.wikipedia.org/wiki/Burroughs_MCP [1]https://www.imdb.com/title/tt0084827/ https://www.imdb.com/title/tt0084827/
- rbanffy 5y ago> Not to be confused with Encom MCP MCP is the most user hostile OS I've ever seen. It may be less intelligent, but shows the same contempt for users as its fictional counterpart.
- pjmlp 5y agoSafety first has a price.
- rbanffy 5y agoYou can't hack an OS you can't use.
- annoyingnoob 5y agoI worked on an HP3000 in the early 90s. It had a software package that changed all of the error messages to resemble IBM360 error messages, just to throw would be attackers off.
- gnu8 5y agoWas that package really intended to be a security feature? To me that seems like a low effort way of landing a contract with an over-specific requirement. But security practices used to be way different so that explanation is also plausible.
- annoyingnoob 5y ago
- Animats 5y agoUNIVAC 1108 EXEC-8, now OS-2200. Still in use, 55 years later, with mostly the same API and commands. [1] https://en.wikipedia.org/wiki/OS_2200 https://en.wikipedia.org/wiki/OS_2200
- kragen 5y agoBurroughs MCP was released in 01961 and seems to still be supported. The latest release was 20.0 in May. That's probably the oldest. z/OS was released in 01966. BOS/360 made it out the door earlier, in 01965, thanks to the disastrous delays in z/OS, but it's no longer supported; DOS/360 (z/VSE) also beat z/OS out, is still supported, and is arguably the continuation of BOS. https://en.wikipedia.org/wiki/DOS/360_and_successors https://en.wikipedia.org/wiki/DOS/360_and_successors Unix wasn't released in 01969. I think it wasn't released until Fifth Edition in 01974, though Thompson and Ritchie described the Fourth Edition in CACM in 01973. Fourth Edition had "over 20" installations, but I think all within AT&T. https://en.wikipedia.org/wiki/Research_Unix https://en.wikipedia.org/wiki/Research_Unix
- alexvoda 5y agoI find it interesting that you write years using 5 digits with leading zeroes. Can you tell me more about that choice?
- tenebrisalietum 5y agoY10K problem: https://simple.wikipedia.org/wiki/Year_10,000_problem#:~:text=The%20Year%2010%2C000%20problem%20(also,five%20digits%20for%20a%20year https://simple.wikipedia.org/wiki/Year_10,000_problem#:~:tex....
- aluminum96 5y agoThis is slightly off topic -- it's about an old supported microarchitecture -- but Linux still supports DEC Alpha, despite no chip with that architecture having been developed since 2004. DEC Alpha has extremely weak memory ordering. [1] In fact, it's the weakest ordering of any arch supported by linux, which includes extra fence instructions to support it. The memory model is crazy weak, but it apparently allows for extra speculative execution parallelism. [1] Awesome Raymond Chen post, totally worth a read: https://devblogs.microsoft.com/oldnewthing/20170817-00/?p=96835 https://devblogs.microsoft.com/oldnewthing/20170817-00/?p=96...
- Klonoar 5y agoOne question: why? Is this still used en masse somewhere and needs updates? Consider me 100% ignorant.
- crest 5y agoWhy support real hardware? Old as Alpha AXP CPUs are they are still orders of magnitude faster than emulating the instruction set. Why care about the instruction set? It a very good regression test for the kernel locking primitives and data structures. Something "boring" like x86 with its TSO memory model will hide bugs.
- zamadatix 5y agoIs there something special about Alpha that makes it hundreds of times harder to emulate? X86 Windows XP on my M1 MacBook runs CPU bound workloads faster than my XP machine in 2004 did and that's not even using the extra X86 emulation specific parts of the M1 cores, just bog standard QEMU.
- skissane 5y agoProbably because a lot of effort goes into optimising x86 emulation to be as efficient as possible, whereas I doubt anyone is motivated to make the same investment in DEC Alpha emulation. In practice that will make Alpha emulation slower than x86, quite apart from any technical features of their respective architectures which may impact the efficiency of emulation.
- deleted 5y ago[deleted]
- codazoda 5y agoTHEOS might be a contender. I don’t know when it was created, but I ran into a user 15 years ago. They were old then and still providing active support to customers. http://www.theos-software.com/ http://www.theos-software.com/ Edit: Looks like it died in 2014 or 2016 or, at least, that’s the latest update I see. Update: Yup, it’s now listed as suspended. Looks like it was started in 1983.
- avar 5y agoWhat does "oldest" OS even mean? I haven't used TSOS/BS2000 but its Wikipedia article suggests that while the OS lineage dates back to 1968 that anyone using it currently is using some currently maintained developed version of it. In my mind supporting an old OS means e.g. that someone is still running old terminals that still run actual Windows 95 (emulator or not), DOS etc. It wouldn't be meaningful to say "this runs on an OS from the mid-80s!". Only to find that it's all C# code targeting last year's release of Microsoft Windows (which has its eventual origins in the mid-80s).
- abrax3141 5y agoWell, the exact same built-in text editor, called EDT, and he exact same basic command language (like what is "ls" in unix is "fstat" in TSOS) is still nearly exactly the same as I remember it from the 70's. (Of course, there have been improvements and additions, like, say, the internet! .... although, actually, we were on the early internet (arpanet) then too! In fact, my summer job just before college was tinning wires that did the local arpanet interconnect! :-)
- eatonphil 5y agoAlong these lines I was curious what the oldest running program is. Found [0]. In use since 1959(ish). [0] https://www.technologyreview.com/2015/08/06/166822/what-is-the-oldest-computer-program-still-in-use/ https://www.technologyreview.com/2015/08/06/166822/what-is-t...
- abrax3141 5y agoA (literally!) orthogonal question: What's the most knocked-off program -- that is, has the widest family tree. My off-the-top-of-my-head (OTToMH?) guess would be ELIZA.
- eatonphil 5y agoNot "print 'Hello World!'"?
- abrax3141 5y agoHmmm. I'm not sure that Hello World actually counts as a program. It's usually just a code snippet. And anyway, it was created (coined?) way after ELIZA.
- kevin_thibedeau 5y agoXmodem
- geoffeg 5y agoSometimes I think it would have been cool to have gotten into supporting something really obscure like that at an early stage in my career. A near-guaranteed contract renewal as long as the system wasn't replaced. If it was to be replaced, you'd likely have a good amount of warning. You'd be one of a very small handful of people in the world able to support and maintain the system. You could become a deeply knowledgeable expert about the system over dozens of years likely without having to learn a new language, framework or system more than a few times in your career. Of course, the downsides are huge, especially if you limited yourself to that one system. If the contract didn't renew, finding a new job would likely be incredibly difficult. I could see it getting mind-numbingly boring, I guess that might be a plus for some people, but would likely drive me crazy.
- walrus01 5y agoThe OS for IBM system/34 and system/36 mainframes is currently virtualized on their z/os POWER systems.
- tyingq 5y agoPossibly TPF, if you consider it's predecessors to be just TPF with different names. https://web.archive.org/web/20041204030934/http://www.blackbeard.com/tpf/tpfhist.htm https://web.archive.org/web/20041204030934/http://www.blackb...