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PDP-11 Still Working In Nuclear Plants - For 37 More Years

Unknown Lamer posted about 9 months ago | from the great-architectures-live-forever dept.

Digital 336

Taco Cowboy writes "Most of the younger /. readers never heard of the PDP-11, while we geezers have to retrieve bits and pieces of our affairs with PDP-11 from the vast warehouse inside our memory lanes." From the article: "HP might have nuked OpenVMS, but its parent, PDP-11, is still spry and powering GE nuclear power-plant robots and will do for another 37 years. That's right: PDP-11 assembler programmers are hard to find, but the nuclear industry is planning on keeping them until 2050 — long enough for a couple of generations of programmers to come and go." Not sure about the OpenVMS vs PDP comparison, but it's still amusing that a PDP might outlast all of the VAX machines.

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336 comments

I cut my teeth on that CPU (5, Interesting)

Bucc5062 (856482) | about 9 months ago | (#44048613)

The PDP-11/45 was the very first computer I ever worked with at College in 1978. God I hate to sound like an old guy with a lawn, but they just don't make like that any more. I learned RATFOR, Pascal, c, and Assembler during that time. Even later on, thanks to my time on the PDP11 I expanded system knowledge working with the HP1000 and its front panel switches.

Good times....good times.

Re:I cut my teeth on that CPU (2)

hazeii (5702) | about 9 months ago | (#44048725)

I still have a bunch of them; every so often I fire them up and program them in ODT. After programming them in assembler (or raw octal), every other instruction set seems irregular. Putting MOV -(PC), -(PC) at the top of memory and executing it was always fun....

Re:I cut my teeth on that CPU (1)

rvw (755107) | about 9 months ago | (#44048951)

I still have a bunch of them; every so often I fire them up and program them in ODT. After programming them in assembler (or raw octal), every other instruction set seems irregular. Putting MOV -(PC), -(PC) at the top of memory and executing it was always fun....

Please explain why it was fun! I know the PDP-11 was still around in 1986, and I have probably worked with it for an assembler assignment once. I do remember being in the terminal room, but that's about it.

Re:I cut my teeth on that CPU (1)

Anonymous Coward | about 9 months ago | (#44048789)

What were you doing chewing on the CPU?

You're supposed to lick them.

Re:I cut my teeth on that CPU (3, Informative)

Cryacin (657549) | about 9 months ago | (#44049081)

What were you doing chewing on the CPU? You're supposed to lick them.

Some like to be chewed, some like to be licked. It depends on the model.

Re:I cut my teeth on that CPU (4, Interesting)

Giant Electronic Bra (1229876) | about 9 months ago | (#44048823)

Hahaha! Yeah, my father designed the original flight information display systems which went into all the big airports in the late 60's/early 70's. I'd go into work with him on Saturday and play around on a TTY with BASIC for the PDP-11/C they had in the office there. In the early 90's we were installing micro PDP-11s at VY to do monitoring of discharge temperatures, that was their state-of-the-art machine at that time! Honestly though, how much CPU do you need to read a DAC and push the data up a current loop? A whole PDP-11/45 must cost $.02 and be the size of a grain of rice today. Why invoke the massive overkill of migrating to a PC?

Re:I cut my teeth on that CPU (5, Informative)

Cassini2 (956052) | about 9 months ago | (#44048871)

The microcontrollers are not rad-hardened. The PDP with core memory and 54-series TTL logic will probably survive a small nuclear blast. There are no highly vulnerable EMI susceptable components in a PDP that I can think of. In fact, I think the military has used (does use?) this and the earlier DTL technologies in its missile computers.

Re:I cut my teeth on that CPU (3, Informative)

Giant Electronic Bra (1229876) | about 9 months ago | (#44049295)

Yeah, I wouldn't be surprised. People nowadays would be surprised at what you can do with low clock speeds, a simple instruction set, and TTL logic. For basic control functions there's no need for anything too fancy and every extra transister is just another thing that can go wrong. Most avionics systems are still using 1970's era 16 bit processors. They've gotten a lot cheaper, but mostly there's just no need for anything fancier when the job is "monitor these 8 DACs and these 5 discrete inputs in a tight loop, apply this filter, write the results to this UART, and close this valve if the state machine reaches this point", lol.

Re:I cut my teeth on that CPU (3, Informative)

BrokenHalo (565198) | about 9 months ago | (#44049315)

Yeah. The only thing the old core-memory processors were not so good at was dealing with excessive heat. My first computer was a Burroughs B3700 a lot like this [google.com.au] but with a teletype master console (which Burroughs called a SPO, for Supervisor Printer Operator).

If the airconditioning broke down in the machine room, we had about 15 minutes to shut everything down before the temperature hit 50 degrees C. [OT: Why, oh why, can /. *STILL* not manage such simple things as html entities?]

The company I worked for got rid of that machine in 1978 (in favour of a Honeywell DPS7), but I remember reading in some computing magazine in 1988 that NASA (IIRC) had ordered several of these machines. I can't find any reference to it now, so that might have been shitcanned. It wasn't very long after that, in any case, that Burroughs merged with Sperry (another of my earlier platforms) to form Unisys.

Re:I cut my teeth on that CPU (0)

poena.dare (306891) | about 9 months ago | (#44048855)

16 bit... tchka!... you had it easy.

The PDP 8/e was da bomb for:

printing "Hello World"
playing Tic-Tac-Toe
paper tape races

Well, if you're really that old... (0)

Pollux (102520) | about 9 months ago | (#44048931)

How come you have such a high /. ID? Were we "too hip" for you, old man?

Re:Well, if you're really that old... (1)

Anonymous Coward | about 9 months ago | (#44048969)

No doubt he was busy working and providing for his family and future retirement and didn't have time to waste with a bunch of pimply fanboys touting the latest re-invented language.

Re:I cut my teeth on that CPU (2)

kevinT (14723) | about 9 months ago | (#44049059)

Sad but true.

I went to work for a company in 1995 that was still using PDP11 as their primary language on old DEC machines. This was a commercial application suite. They got their spare parts at garage sales in the area (yes that is what they did, literally!). My last project was to read a bunch of old 9 track tapes to try to find the source code for a program that needed to be modified.

I put up with that for 5 months and bailed to a much better, higher paying job using C on AIX. I was never so glad to leave a company!

Re:I cut my teeth on that CPU (1)

kilodelta (843627) | about 9 months ago | (#44049269)

My first brush with PDP-11's was a PDP-11/44. I learned BASIC, PL/I and COBOL on that sucker. Then I got hooked up with a retro computing group and what do they have but a plethora of PDP hardware. It's all based on things called Flip Chips. Tiny boards with discrete components on them.

So diagnosis and repair is pretty easy so long as the parts exist.

Very Cool! (2)

pauljuno (998497) | about 9 months ago | (#44048633)

It's kind of interesting to read these sorts of news articles. You would have thought they would have replaced these relics long ago. I wonder if the PDP-11's used Macro-11 like the VAX-11s. I remember learning to program on a VAX/11-750 in high school. My first real exposure to "real" computers. Up until then I only used TRS-80's. Thanks for the flashback and making me feel old!

Ken Thompson (1)

Anonymous Coward | about 9 months ago | (#44048643)

if they could pull him away from Google.

I just read a story that Ken reported that once he and Dennis Ritchie independently coded an assembly language function. Their implementations were each 20 lines of code, and turned out to be identical line for line! Now that's a good creative partnership.

Re:Ken Thompson (0)

Anonymous Coward | about 9 months ago | (#44048863)

Not surprised. Form mirrors function. A short function, in any language, written to the same specs by several competent programmers, should all be just about the same. 20 lines of assembler == 2 to 5 lines of C code... :-)

That's just cruel (4, Funny)

Chrisq (894406) | about 9 months ago | (#44048645)

... until 2050 — long enough for a couple of generations of programmers to come and go.

By their short lives I imagine that they must make them work in a high-radiation area.

Re:That's just cruel (3, Informative)

msauve (701917) | about 9 months ago | (#44048767)

"Generation" doesn't refer to an average lifetime, it refers to the average childbearing age.

Re:That's just cruel (2)

fnj (64210) | about 9 months ago | (#44048861)

So? A "generation" is commonly held to be 30 years; the average child (note: not first-born) being born when the parents are approximately 30. Secondly, TFA specifies two generations "coming and going", which means two ENTIRE generations pass; not just one passing and the second one beginning.

That is 60 years, not 37 years. TFS, if not TFA, which I didn't read, is officially stupid.

Re:That's just cruel (0)

Anonymous Coward | about 9 months ago | (#44049213)

Maybe they're talking about the total service life of the machine? The things are already 30 years old, so another 37 would more than cover two generations.

Re:That's just cruel (5, Informative)

tgd (2822) | about 9 months ago | (#44049277)

So? A "generation" is commonly held to be 30 years; the average child (note: not first-born) being born when the parents are approximately 30. Secondly, TFA specifies two generations "coming and going", which means two ENTIRE generations pass; not just one passing and the second one beginning.

That is 60 years, not 37 years. TFS, if not TFA, which I didn't read, is officially stupid.

Commonly by who?

In virtually all cases, generations are pegged at 20 years. The common "Gen X", "Gen Y", etc are all 20 year spans. In fact, virtually every named "generation" of the last century were equal or slightly less than 20 years.

Even if you go by the average age of first birth, in virtually all of the "1st world", its right around 25. The peak averages are barely 30, and globally its in the low 20's, depending on the source.

So by either definition, there's definitely time for two generations ... and if you're talking about the average time in a given position (which is a more meaningful generation when speaking about engineers), you're looking at more like 15 years -- or time for three.

Re:That's just cruel (0)

Anonymous Coward | about 9 months ago | (#44048829)

... until 2050 — long enough for a couple of generations of programmers to come and go.

By their short lives I imagine that they must make them work in a high-radiation area.

Yeah, but they all eventually get super powers.

If it ain't broke... (5, Insightful)

intermodal (534361) | about 9 months ago | (#44048675)

Honestly, it's a system that works. Everything is seen as disposable today, but really, the only reasons we end up getting rid of systems that works these days are either because of support issues (i.e. Microsoft's end of life abandonment of security updates for older products) or lack of available replacement hardware to swap in for failed or failing units.

Honestly, without the need for protection from security holes related to the Internet (and the accompanying security patches), most office workers could get by on Windows 2000 machines with Pentium III processors with probably less than 1GB of RAM and Office 2000 for the foreseeable future.

Not saying we haven't made advances, but I'm definitely saying that modern closed-source computing (Microsoft, Apple) is a system of planned obsolescence.

Re:If it ain't broke... (1)

Joce640k (829181) | about 9 months ago | (#44048741)

These days you can probably replace them with Arduinos.

Re:If it ain't broke... (2)

scsirob (246572) | about 9 months ago | (#44048867)

Yup, but then someone will eventually be silly enough to hook it up to Internet and all hell would break lose.
Better keep that PDP-11 around to do it's job.
(BTW, PDP-11/05 with paper tape boot loader was my first encounter)

Re:If it ain't broke... (1)

dywolf (2673597) | about 9 months ago | (#44048883)

its not so much what its capable of doing.
its what its capable of surviving.

these systems are extremely robust and reliable. its like when people wonder why aircraft avionics tend to be so big and expensive when an arduino could probably handle those tasks too (and yes ive heard that too)...same thing. vibration, rough landings, random mechanics using a hammer to get the screws to line up, or overwrenched a cannonplug.

Re:If it ain't broke... (4, Insightful)

scsirob (246572) | about 9 months ago | (#44049125)

Sorry to burst your bubble, but that's not how it works in nuclear nor in aviation..

One of the main reasons things are behind in those industries is paper trails. Rules and regulations. It takes forever and lots of money to get this gear certified. Once certified, it takes an act of God to change it.

A PDP-11 isn't much more reliable than any other system. It has unreliable old-style linear power supplies, unreliable backplane connectors and all parts do fail eventually. Just because they weigh a hundred times more doesn't mean they are a hundred times more reliable.

Re:If it ain't broke... (4, Funny)

SJHillman (1966756) | about 9 months ago | (#44049317)

"Just because they weigh a hundred times more doesn't mean they are a hundred times more reliable."

But it is a hundred times more satisfying to shove it off a building when it misbehaves. At least, that's how it works with copiers.

Can doesn't mean should (3, Informative)

sjbe (173966) | about 9 months ago | (#44049045)

These days you can probably replace them with Arduinos.

Theoretically true but not necessarily a good idea. The equipment installed is already known to work and whatever issues it has are probably very well understood. Any installation of new hardware is going to bring new bugs and a nuke plant isn't exactly a place you want to beta test things if you don't have to. Plus there are a host of operational certification issues in play. I get why they haven't "upgraded" the hardware.

On the other hand I'm a little bit surprised (only a little) that doing things this way is the most economical method available, even accounting for the risk involved with updating systems.

Re:If it ain't broke... (0)

Anonymous Coward | about 9 months ago | (#44048745)

I find that argument fascinating. Without the need for protection from security holes related to the internet. . . . That's like saying without the need for oxygen, I could live underwater. It's a terrible argument you're making there.

Re:If it ain't broke... (1)

sjames (1099) | about 9 months ago | (#44049007)

Not really. Some systems really don't need to (and in fact should never) communicate with the outside world.

Re:If it ain't broke... (2)

Karganeth (1017580) | about 9 months ago | (#44048821)

If it aint broke, encourage people to waste their time learning an entire language only to be used once.What a great use of time. Not.

Re:If it ain't broke... (1)

Infiniti2000 (1720222) | about 9 months ago | (#44048843)

If it ain't broke, then why does it need software maintenance? If it needs software maintenance, then by definition something is broke.

Re:If it ain't broke... (2)

dywolf (2673597) | about 9 months ago | (#44048911)

then by definition something is broke.

No, not at all.
It's called preventative maintenance, and if you have a car you should be familiar with the concept.

Software in critical applications (and what's more critical than running a nuke reactor??) has to work flawlessly. Believe it or not even old critical software can have things identified that need fixed before they become an issue. Or the NRC issues a directive that in the end means the software needs to be updated in order to implement it.

Re:If it ain't broke... (1)

SJHillman (1966756) | about 9 months ago | (#44049341)

Why do you change the oil in your car if it still runs fine? Why do you eat when you're not starving? Maintenance is generally just as much about keeping something running as it is about fixing something that's broken.

Re:If it ain't broke... (1)

fnj (64210) | about 9 months ago | (#44049011)

Basically, abso-damn-lutely. However, the last PDP-11 model was introduced in 1990. I'm not sure when production ceased,but this hardware has to be pretty long in the tooth by now. How long do you reckon the hardware will keep running? How long will repair parts, even down to the IC level, be available? How long will peripherals be available? A PDP-11 still running in 2050 would be like a 1953 computer [google.com] still running today.

Re:If it ain't broke... (1)

Archangel Michael (180766) | about 9 months ago | (#44049087)

I carry a more powerful computer in my pocket.

And you're wrong about the computer needs of today's office workers. Most people don't spend all day in Office 2000. The multitasking needs are much greater than a PIII provides. Not to mention the need for multicore processors doing multiple simultaneous tasks. I currently run about two or three dozen different programs all at the same time. I realize that I am an exception and a geek, but I know people who don't know anything who try to do even more. Office, Accounting, Database, Web, Presentation, Desktop Publishing, Email, Skype ....

I remember trying to run Visio on at Win 2k with a gig of ram on PIII, all I can say "underpowered"

Re:If it ain't broke... (5, Insightful)

intermodal (534361) | about 9 months ago | (#44049171)

You seem to be equating this laundry list of things running at the same time with "need". Frankly, I'm not convinced that present-day "need" gets any more accomplished than was performed by what we had ten years ago in most businesses with the "needs" from then.

I don't measure productivity in the number of bits pushed or number of programs used. I measure it in how useful those bits were and how much was usefully accomplished by those programs. You're simply justifying bloat.

Re:If it ain't broke... (0)

scsirob (246572) | about 9 months ago | (#44049273)

This. "Need' is the most overrated word today.
Where are my mod points when I "need" them.

Re:If it ain't broke... (1)

andy16666 (1592393) | about 9 months ago | (#44049101)

Well, one of the best arguments for upgrading from a system that old is computation power per watt. It costs a lot to run a very old power-hungry system to do something that a tiny micro-controller can do today for fractions of a penny on the dollar in power consumption. You're paying an exorbitant rate per CPU cycle with something like a PDP-11.

That doesn't quite equate to it always being worthwhile to replace a dated system. In some applications, it is critical that a well tested software/hardware combo not be messed with. I suspect this is one of those cases, where the difficulties and cost in maintaining such a system are deemed more economical than the alternatives.

Re:If it ain't broke... (1)

Cyberax (705495) | about 9 months ago | (#44049203)

So what happens once someone accidentally drops a wrench on a PDP machine? How are you going to source replacement parts and where are you going to find expertise to fix it? And what about the price of electricity to power it?

Keeping old outdated equipment just because it works is NOT a good solution.

Re:If it ain't broke... (2)

cardpuncher (713057) | about 9 months ago | (#44049307)

Indeed. I worked on networking products for RSX-11M and there's very little that the '11s didn't do - multi user, memory protection, standard peripheral bus; even Ethernet made it to the PDP-11. And the 11/70 supported more than a dozen development users with 512MB of (core) memory. Nice regular, consistent instruction set. E-mail, chat, even network file access (mostly). Only pain was creating the overlay trees when your application wouldn't fit in 16 bits of address space. It doesn't really take very long to pick up Macro-16 (the assembler language) - there aren't many instructions and they all pretty much work with the same addressing modes. Training people really isn't a problem in this case.

Imagine replacing the systems, though. Apart from the problem of having to recertify all of the software, I imagine there are a lot of sensors connected up to Unibus interface cards which may well have been custom designed. You'd probably pretty much have to redesign the whole thing.

So much easier to keep the kit and adapt the people.

1980s (1)

Beorytis (1014777) | about 9 months ago | (#44048685)

I remember one at my high school (1982-1986). I didn't get to do any assembly programming on it. IIRC we had the timeshare OS, RSTS.

The never ending death of programming languages... (0)

Anonymous Coward | about 9 months ago | (#44048707)

Every time I read an article about supposedly dead languages which are never dead and will never be, I wonder if the only reason is because the big companies depending on those languages just want new juniors to focus in the relics of the past in order to avoid paying annoying ciphers to the senior people.

But then again, I may just be a paranoic looking for his foil cap.

Clones (0)

Anonymous Coward | about 9 months ago | (#44048713)

Actually in Soviet Russia there was a personal computer named BK-0010 [wikipedia.org], popular in the beginning of 1990s. It has a compatible CPU instruction set, and even came with a FOCAL interpreter, similar to the one you could find on a real PDP-11.

Assembly programmer. (4, Interesting)

morto (525092) | about 9 months ago | (#44048721)

Just a small correction. The language is Assembly. Assembler is the tool. Best regards.

Re:Assembly programmer. (0)

Anonymous Coward | about 9 months ago | (#44048775)

Good point. It's probably just a detail that was lost on the Indian programmers GE has hired to maintain the assembly for these systems.

Re:Assembly programmer. (1)

Anonymous Coward | about 9 months ago | (#44048807)

But but but... Linux is written in compiler!

Re:Assembly programmer. (0)

Anonymous Coward | about 9 months ago | (#44048889)

Oh, I though they were looking for people to program a new assembler.

Re:Assembly programmer. (1)

tgd (2822) | about 9 months ago | (#44049293)

Oh, I though they were looking for people to program a new assembler.

Considering most of the PDP-11 coding I did, my fingers, a pencil and some paper was the only assembler ... there was definitely a time I would've been in support of programming an assembler.

DEC (1)

barista (587936) | about 9 months ago | (#44048735)

Nice to see the Digital logo get used again. While the PDP predates my experiences, several family members worked for DEC during the 80s. I assume Ken Olsen is laughing in his grave at HP's boardroom misfortunes of the past several years.

Re:DEC (1)

Virtucon (127420) | about 9 months ago | (#44049067)

HP? HP threw DEC a lifeline after Compaq drove it into the ground because when they bought DEC out in the late 90s they couldn't absorb the operations. DEC was ripe for acquisition and had a ton of customers but those customers weren't the typical PC folks that Compaq was dealing with. As a result DEC products suffered and lost share. It was a $9 Billion blunder and they took on a lot of debt and responsibility that they weren't ready to handle. That's what eventually led HP to buy them out. To be sure though, DEC products under HP haven't fared well because of the competing lines of hardware, i.,e, HP9000s, 3000s and software (HPUX). It is valid business strategy to buy a competitor and dismantle it or milk it vs. letting it be bought by another competitor.

You go old timer! (4, Interesting)

NormHome (99305) | about 9 months ago | (#44048751)

My high school got a DEC PDP-11 in my junior year (like 31 years ago) with dual 8inch floppy's which replaced the PDP-8 with dual DEC tapes.

Glad to see that they're still going but after all these years where do they get parts for them? Didn't Compaq buy DEC and then Compaq merged with HP, does HP still support hardware this old?

Re:You go old timer! (2)

RobKow (1787) | about 9 months ago | (#44048879)

When you have all of the schematics it isn't too difficult to support the hardware yourself, assuming you're running one of the older TTL CPUs. That, and/or a huge storeroom of spares, and you're set.

Re:You go old timer! (0)

Anonymous Coward | about 9 months ago | (#44049185)

As an army technician we learned how to gate chase and use logic analyzers. A valuable experience as to how machines really work indeed.

A real file system (1)

invid (163714) | about 9 months ago | (#44048759)

My first real programming job was on a VAX system. The file system and scripting language were so extensive we were able to use them to create a working configuration control system for our source code. DOS was a toy operating system by comparison.

Security? (0)

Max DollarCash (2874161) | about 9 months ago | (#44048815)

Am I the only one worried about security of such an ancient system running a nuclear power plant? How long before...

Re:Security? (2)

thoriumbr (1152281) | about 9 months ago | (#44048897)

If the system is running fine for decades, what is the chance that it would suddenly die for no reason next week?
It's a very good hardware platform, made to last for centuries. Is different from your brand new GPU card that will fail and die in 4 years. Mine have not failed yet, but will soon.
Almost all the banking business in the world runs on COBOL, compiled almost 40 years ago, and that keeps running and running. Why replace the core COBOL with Java or .NET, if they are working just fine?

Rest assured, the trusthy PDP-11 will keep the nuclear plant running safe, as it has been done in the past couple decades.

Re:Security? (1)

AlphaFreak (646767) | about 9 months ago | (#44048901)

Those things are probably not networked. Will Adama would have no trouble having them on board of Galactica.

Re:Security? (2)

Bucc5062 (856482) | about 9 months ago | (#44048935)

Horrible CompSci Movie scene

Evil Guy (EG) to young hacker (YG): Okay, here's the terminal. get to work
YG: What's a terminal, this thing got a usb port for my S6 to access?
EG: This thing is a PDP11. They didn't have USB ports when it was made. Can you get in?
YG: Get in? How the hell to I even log in? This thing was old before my father was born
EG: Get in or Die!
YG: Then it's been a good life for they had actual security on these old systems. Now if it was a PC we'd be done
                No way can I hack into this system. Its just too damn old.
EG: , okay then we just blow it up.

Re:Security? (1)

scsirob (246572) | about 9 months ago | (#44048937)

With nothing more than RS-232 console lines, if at all, there will be little to worry about. If by chance there is a network connection on it, it will be Thick Ethernet (drilling a hole in the cable to attach a new system), and running a network stack that is nothing close to TCP/IP

Re:Security? (0)

Anonymous Coward | about 9 months ago | (#44048997)

Why should you be worried? The PDP-11 is a fine 32-bit computer, fully capable of real-time operations (with the appropriate operating system). In truth, with some exceptions (64-bits, ARM, VLIW systems such as the defunct Wave Tracer, newer bus architectures, etc) it is up to par with most modern systems.

Re:Security? (1)

Virtucon (127420) | about 9 months ago | (#44049143)

Oh hell no! I'll tell you something, those Real Time systems that were built around a PDP-11 were great technology and were state of the art. A whole bunch of process control, nut just for the nuclear power industry, was driven by PDP-11 technology. It was reliable, parts were readily available and there were more options for controlling other devices with off the wall interfaces. Think about it though, the nuclear power industry has heavy regulation and if you start changing components, like control systems I'm sure the red tape will get heavy and thick quickly. Look at the whole San Onofre debacle and you'll see what I mean. Yes, if you were building a new plant you'd look to newer architecture to support it but not one designed or built back in the 70s, Which in terms of architecture is where the PDP-11 was in it's prime.

That is government for you. (1)

140Mandak262Jamuna (970587) | about 9 months ago | (#44048831)

It is not surprising. Nuclear industry is very heavily regulated. These regulations are not updated regularly. The regulations were laid with whatever was the state of art and they never paid any attention to cost, upkeep or updates. It leads to quite ridiculous situations like maintaining old bugs as is. I don't know why or how. But I hear stories about nuclear customers demanding some buggy behavior to be reproduceable after the software update, even if the update was about that very bug. "Give us a setting/env switch to reproduce the old buggy answer!". Same way the Air Force is still flying B-51 bombers that are older than their pilots, older than their commanding officers, now getting to be older than even their commander-in-chief.

The cost of a reactor meltdown can be high (0)

Anonymous Coward | about 9 months ago | (#44048949)

If there is a nuclear meltdown, tens of square miles of real estate will become uninhabitable, and can contaminate groundwater for hundreds of years. ie, very very expensive. So, there is very strong economic incentive to avoid a major failure in a nuclear power plant.

Re:That is government for you. (1)

kevinT (14723) | about 9 months ago | (#44049031)

The Air Force is flying B-52 bombers. Minor typo, but important to those that care.

Recently I read about a pilot that looked in the older logs of the plane he was flying and noticed his Grandfathers signature as pilot in some of the entries!

DEC (1)

Lawrence_Bird (67278) | about 9 months ago | (#44048837)

made some amazing equipment. It was sad when they were sold to Compaq. I never worked on a PDP-11 but did work on a DEC2060 during college. This was a 36 bit machine and used an improved version of the KL10 processor originally used in PDP-10s. IIRC there are a few TOPS20 (twenex) enthusiast sites on the net too.

Re:DEC (0)

Anonymous Coward | about 9 months ago | (#44048943)

"If you don't have 36 bits, you aren't dealing with a full DEC." ... :-)

I loved the PDP-11 (1)

Richard Rankin (2956843) | about 9 months ago | (#44048841)

I remember writing code for a bare machine (no OS). I'd set up the code to come in through the serial port and then use the front keypad to key in the instructions in octal to get the code, load it into memory and execute it. It was a little easier with UNIX, even with a dozen people on it.

We had one in our house (1)

Stele (9443) | about 9 months ago | (#44048881)

I lived with 4 other guys in a big old house in Blacksburg, VA (VA Tech) in 1991. One guy had a knack for finding computer surplus, and brought home *two* PDP-11s, along with a bunch of other "vintage" equipment. One sat out in the garage, while the other adorned a landing in our stairwell.

Re:We had one in our house (0)

Anonymous Coward | about 9 months ago | (#44049303)

How did you dispose of the spent nuclear material?

VAXen are still around (1)

AlphaFreak (646767) | about 9 months ago | (#44048885)

... but the PDP-11 had (has) better interrupt latency so it was preferred for realtime applications. It is not (so) surprising it is still around...

The legacy of the PDP-11 (1)

Anonymous Coward | about 9 months ago | (#44048891)

The design of the PDP-11 was quite elegant. It should be feasible to implement it in a single chip these days, including memory and I/O... :-)

Compare the 68K (1)

tepples (727027) | about 9 months ago | (#44048965)

The design of the PDP-11 was quite elegant. It should be feasible to implement it in a single chip these days

When you take a PDP-11 and redesign it to be partially 32-bit, you get a 68000.

including memory and I/O... :-)

Like the 68K-driven SOCs in Palm PDAs.

Compare the 360 (1)

fortunatus (445210) | about 9 months ago | (#44049099)

Note, too, that the IBM 360 instruction set is 32 bit and highly orthogonal, very much as is the PDP-11, and later the Motorola 68000, in fact the 360 instruction set pre-dates the PDP-11 by several years.. Both DEC and IBM were heading in the same direction over some of the same years that way. It's hard to really claim that DEC (Gordon Bell) copied IBM there, but it's also really hard to claim he didn't.

Re:Compare the 360 (1)

fortunatus (445210) | about 9 months ago | (#44049139)

PS - yes, I know the PDP-11 is 16 bit, while the 360 and 68000 are 32 bit - I meant to refer to the "orthogonality" of the instruction sets, and structure of the instruction words, rather than the bit widths when I made the comparisons above...

Whatever (1)

sunking2 (521698) | about 9 months ago | (#44048893)

Unless they aren't teaching assembly anywhere anymore there is nothing special about PDP-11 assembly. In the late 80s it's what we learned it on, and I'd venture that it's pretty simple in comparison to anything modern.

Don't Freak! Prolly A PCI Card Emulator (2)

cmholm (69081) | about 9 months ago | (#44048899)

This doesn't surprise me. Back in the day, Huge Aircrash had a big investment in PDP-powered test bays, and didn't want to incur the risk/cost of replicating the functions of the assembler software libraries on a new platform/language. So, the PDPs slid out, and rack-mount PCs slid in, featuring a hardware emulator on a PCI card. Minor bonus: a bit more speed. Obviously, Huge wasn't the only customer. Google "PDP hardware emulator", and you'll find a number of vendors.

Re:Don't Freak! Prolly A PCI Card Emulator (1)

K. S. Kyosuke (729550) | about 9 months ago | (#44049053)

And if you want to learn the assembly dialect, just fetch SIMH [trailing-edge.com] - the greastest thing since the bit-slice microprocessor.

Re:Don't Freak! Prolly A PCI Card Emulator (0)

Anonymous Coward | about 9 months ago | (#44049175)

Careful, not a lot of people will actually remember Hughes Aircraft. It's been a while now.

Exceptions (0)

Anonymous Coward | about 9 months ago | (#44048913)

We've to go to nuclear power plants to get exceptions like this. It's sad.

Most of the IT industry is focused on switching every few years to something different (rarely new).

Only the very best for the nuke stuff... (-1)

Anonymous Coward | about 9 months ago | (#44048915)

For the nuclear industry, we spare no expense!

/sarcasm

And people still believe it's cheap, clean energy! LMFAO. Nuclear Power is right as a temporary, short term solution for our energy needs. But it cannot be permanent... for the obvious reasons (it is very dirty, the dirt stays effectively forever, and the actual true cost of everything (including development, construction, special materials, worker education, operational requirements, safety requirements, etc. etc.) is and has always been really, really outrageously fucking high.

Dave Cutler's work lives on (1)

cohomology (111648) | about 9 months ago | (#44048953)

Obsolete? Not the ideas.

Dave Cutler designed and wrote much of the popular RSX-11M operating system for the PDP-11. He went on to design the OS for the Vax (VMS). Programmers observed that it was just like RSX-11M, but better. Microsoft hired him to lead a team that designed Windows NT. That kernel lives on in modern versions of Windows.

awesome (2)

lkcl (517947) | about 9 months ago | (#44048955)

the PDP-11 is awesome. i believe its instruction set was the inspiration for the 6800 (http://en.wikipedia.org/wiki/Motorola_6800#MC6800_microprocessor_design yes it was) which then resulted in the 68000 all the way up to the 68040, processors which both commodore and amiga used to great effect up until the early 90's. at imperial college we didn't write a compiler for 68000 or even x86, we wrote a compiler for the PDP-11 instruction set.

the other thing is: if they're still running PDP-11's in large geometries (.35 micron or even bigger) then chances are it'll be much more robust and less prone to random radiation hits/changes. the kind of thing you really really REALLY want to be still working and under computer control is the "emergency shutdown" procedures in the event of a radiation leak. the LAST thing you want is one of the bits changing a floodgate to "open" instead of "shut" due to a random gamma ray flipping a bit somewhere.

I cut my teeth on PDP/11s and 8s (1)

Virtucon (127420) | about 9 months ago | (#44049005)

I started out programming on PDP 11s and it still amazing that those systems are still in operation especially in Real Time applications. I remember just before DEC was bought out by Compaq, the PDP 11 business was still doing a billion dollars a year. I guess that much value to Compaq for some reason even in the 90s. They sold the rights off to Mentec. I think Mentec is out of business or out of the PDP-11 business anyway. There are still lots of third party hardware solutions still keeping the architecture alive. It's been awhile though since I needed to find an enclosure or parts for a QBUS system. Maybe I should dust off some of that old code I have and install an emulator.

List of great Assembly language programs? (1)

WillAdams (45638) | about 9 months ago | (#44049027)

One of my favourites was WriteNow, a word-processor for the Mac OS, and later NeXTstep, ~100,000 of assembly language.

PDP-11 is the basis of modern non-x86 CISC (4, Interesting)

Trailer Trash (60756) | about 9 months ago | (#44049093)

This CPU is an excellent 16-bit CISC CPU, and it's the forerunner to not only the VAX-11 architecture, but also the Motorola 68000 series and the TMS9900 series. My only gripe with the assembly language was that it required octal instead of hex. The CPU had a lot of addressing modes, 8 registers (6 GP) and even floating point capabilities.

My first actual programming job was in 1988, making minimum wage, working for a physics professor - translating a PDP-11 assembly library that provided a programming interface to a Grinnell graphics processor into VAX-11 assembly. Part of that was turning the various IO calls on the PDP-11 into QIO calls on the VAX.

The Grinnell was incredibly capable for the time. It produced a 512x512 display with the capability for either 8-bit monochrome or 24-bit color. It also had a monochrome camera attached to it. The display had 5 memory "planes", so you could configure red, green, and blue to whichever planes. Writing an image to a plane took a few seconds. Reading an image from a plane took around a minute. It also had hardware 2D graphics commands for lines and squares which were hella-fast for the time.

The professor had just upgraded from a PDP-11 to a MicroVAX II (not sure it was an upgrade) and had 1800 fortran programs that used this library to do various graphics things. A lot of them were throw-aways written by students, but he had some cool stuff for the time to do histogram stretches, change contrast, etc. Yeah, stuff we do with a slider in photoshop now, but then we would run the program and wait for a couple of minutes.

Amazing longevity (1)

sjames (1099) | about 9 months ago | (#44049117)

The PDP-11 is amazing in it's long life. Most actual PDP-11s are long gone now, but the platform lives on in the form of PDP -on-a-card products like the Osprey [strobedata.com] or an emulator.

Guaranteed a Job for 37 More Years... (0)

Anonymous Coward | about 9 months ago | (#44049157)

Ha, ha, beat that, you young 'uns! I'll be stepping through code with ODT and living high on the hog 25 years from now when you'll be an expat begging for a job rewriting Java web apps in New Delhi! And livin' in a van down by the river (Yamuna)! Bwahahahaaaaa!!

Only bad side is my ass is sitting atop a nuclear reactor. Note to self: buy lead-lined jockey strap. Or maybe the women like balls that glow in the dark - must check out.

Oh, wow ... (1)

gstoddart (321705) | about 9 months ago | (#44049197)

Most of the younger /. readers never heard of the PDP-11

Then, seriously, get the hell of my lawn.

My introduction to assembler was PDP-11 assembly on a VAX, and when I got to C the language made a lot of sense since that's the platform C was originally written on.

In the pantheon of Things You Should Know About Computers, the PDP-11 is up there as being hugely important to be aware of.

Where do they buy these PDP-11s? (0)

Anonymous Coward | about 9 months ago | (#44049297)

Where does one buy a new PDP-11s?

Did they just buy a pile of them years ago and stash them in a warehouse somewhere?

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