Hacker News Reader

Comment by Jerry2 | Hacker News Reader

The 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...

View on HN

This is a good answer to another question: what is the oldest computer family/architecture still in use? I'm sure there are other contenders out there, especially with modern descendants of old architectures and different interpretations of the question. I'd be interested in hearing about others as well.

I believe my employer's PDP-11 ran RSTS/E or some variant, and the software was written in BASIC by my current boss. There were a lot of operating systems available for the PDP-11 for a lot of different contexts (including UNIX).

Depending on how you delineate the families, the origins of x86 date back to 1972 (Intel 8008) and obviously x86 itself dates to 1978 ;)

Z80 also dates back a really long time, and there is a ton of stuff that still uses Z80-family processors in many embedded applications (microwaves, calculators, etc).

I realize neither of those are probably the absolute oldest, but this is going to hinge on what each commenter's exact definition of "families" and "still in use" are. Active development/new chips being released? Still in widespread legacy use? One-off legacy systems still hanging on in an industrial installation somewhere?

In terms of what is the absolute oldest - again depending on your exact definition of "family", z/System is arguably the oldest computer family, you can trace a direct lineage back to punchcard tabulation programs, which date back into the 1880s. z/OS systems can run programs originally compiled for System/360, which was designed to be directly ported from plugboard programs for programmable tabulators, so in a "ship of theseus" sense that is likely the oldest computer family.

The 8008 ISA comes from the Datapoint 2200 which was released in 1971 - although work started earlier. Intel (and TI) were asked to develop single chip implementations which CTC never used.

https://en.wikipedia.org/wiki/Datapoint_2200

Used != 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.

Sufficiently advanced long-term maintenance via patches seems indistinguishable from providing support.

I’d say support is more official than paying a contractor

BSD 2.11 is still getting patched by Steve Schultz, last I saw.

Apropos 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-cod...

I seriously considered applying for that job! I'm probably 30 years younger than anyone with real PDP-11 experience but I got a background in programming tiny embedded systems, with some robotics. And I love computer history with a particular soft spot for the PDP-11. (I've got an LSI-11 in the basement somewhere.) But then I thought about it. Tracing race conditions in PDP-11 code all day seems like the surest way to kill all love for my hobby.

Anyway, the PDP-11 wasn't really an OS but an architecture (like ARM or x86). The robotics software in question probably runs bare metal. It was very, very popular and will indeed remain around in pockets (in emulation) probably until the 22nd century. Ain't broke? Don't fix.

PDP-11 isn't an OS.

What's more, when it comes to computer architectures, even among Digital it's not the oldest nor still supported.

Because you can still buy a new PDP-10 (well, PDP-10 compatible, iirc a lot of I/O is different, but it can run TOPS-20 V7 with patches)

Of course S/360 has longer continuity of hw/sw combination.

> Because you can still buy a new PDP-10 (well, PDP-10 compatible, iirc a lot of I/O is different, but it can run TOPS-20 V7 with patches)

Who is still selling new PDP-10-compatibles? Systems Concepts? XKL?

XKL is still around and makes PDP-10-on-a-chip for internal use, some people managed to get just the PDP-10 part sold.

XKL is still around indeed, but do they still manufacture the TOAD-2 CPUs? Do they still use it in their current products? The TOAD-2 dates from around 2005 or so, it was designed to be used as a service/management processor in XKL's optical routers, although it could run a patched version of TOPS-20. But do XKL's current products still use it? I can't find any information on whether or not they do, but I'd be surprised if they were still using a 15+ year old part in their latest products.

There apparently was no need to update the design, and so TOAD-2 is still in use. At the very least, last year or so I've seen 2 new TOAD-2 boards ending up outside XKL, with caveat that they do not want to make a business out of selling just the TOAD-2 boards (they do not want to deal with providing support etc.)

So various signs on heaven and earth point to still made equipment using TOAD-2s.

> At the very least, last year or so I've seen 2 new TOAD-2 boards ending up outside XKL

I don't think that proves they still include TOAD-2 in new systems. It is equally compatible with all TOAD-2-based systems going EOL: likely they had some new boards set aside as spare parts for the production systems, once all customers stop using the old TOAD-2-based systems in production, the spare parts are no longer required, and so XKL may have decided to quietly give away (or sell) those spare parts to well-connected 36-bit enthusiasts.

Furthermore, there is a good reason to believe they don't use TOAD-2 any more: if you look at the manuals at XKL.com, you'll find recent products are running an operating system called "DXMOS". It appears to be a custom operating system based on *BSD but with a UI inspired by Cisco IOS (so similar in architectural concept to Juniper JunOS, but aiming to be closer in CLI syntax to IOS than JunOS is). The various copyright acknowledgements in their manual (all three of FreeBSD, NetBSD and OpenBSD) support that conclusion (most likely they have picked one of the three as a base, but borrowed some code from the other two as well). It seems rather unlikely a *BSD is running on a 36-bit CPU such as TOAD-2, it seems much more likely it is running on some industry standard 32/64-bit CPU such as x86 (or maybe ARM or POWER or MIPS). Furthermore, the copyright acknowledgements and release notes also show dependence on a number of other software libraries (SSLeay, OpenSSL, OpenSSH, Dropbear SSH – not all at the same time, of course, in recent versions they switched from OpenSSH to Dropbear) which seem rather unlikely to have been ported to run on a 36-bit platform.

You can't buy it from Digital, and TOPS-20 isn't still supported.

a ginormous scripting OS, PDP/11 is.

PDP-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.

Reply on news.ycombinator.com