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Digital Programming

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

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  • by Bucc5062 ( 856482 ) <bucc5062@gmai[ ]om ['l.c' in gap]> on Wednesday June 19, 2013 @09:01AM (#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.

    • by hazeii ( 5702 )

      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....

      • by rvw ( 755107 )

        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.

        • by Cryacin ( 657549 ) on Wednesday June 19, 2013 @09:49AM (#44049073)
          At least they're not running nuclear power plants in action script. (ducks)
        • by Anonymous Coward on Wednesday June 19, 2013 @10:18AM (#44049371)

          Many of us still can program in macro-11. I got tired of ODT though and built a symbolic debugger with DDT that ran in another task.

          The pdp11 has a number of possible hacks that can be useful in remotely identifying code. Ever try a DIV on SP, which moves the stack and changes
          the program counter all at a go? Mov @offset(r5),pc ? That gives control transfer an extra level of indirection. There are others.
          Note the DIV hack works only for CPU models with the EIS instructions.

          The pdp11/45 has a 300 ns. cycle time though, corresponding to ~3.3MHz clock speed. Current machines have more like ~3.3GHz.
          The larger 11s could address 4MB of memory (a lot in those days). Now a 4GB machine is beginning to look small.
          I recall when we got a 22MB hard drive (size and shape of a clothes washing machine; we put Dymo labels under the lights
          labelled "wash rinse dry" for fun) it seemed vast. Nowadays it is not unheard of for a home machine to have 22TB.

          With all those factors modern machines can be said to have grown by a factor of maybe a trillion.

          Still the pdp11 was versatile and allows significant and useful code to run. It is usually programmed in assembler (macro11;
          nobody uses PAL11R any more I hope) or Fortran or C. (The original pdp11 Fortran was a nightmare of code inefficiency, could
          burn 100 instructions to add 2 integers where the hardware could do it in one. Only the later f4p compiler got half decent code

          I only ever saw mov -(pc),-(pc) used as a fast clear memory; it traps at the end, but won't get any unmapped addresses.

          It was more fun to arrange to handle interrupts in supervisor mode. (Did that too. Needs a lil trick to RTI.)

          • by hughk ( 248126 )
            The original PDP-11 standard Fortran would churn out pseudo code. This would be a list of addresses into the library with a link via R4, something like jmp @(r4)+. This was slow but actually quite elegant (easy to switch amongst the innumerable hardware variants via choice of library), but it was hard work to link because the entire program was external references. F4P cost a relative fortune though and I didn't get to use it until a time working at Digital.
    • by Giant Electronic Bra ( 1229876 ) on Wednesday June 19, 2013 @09:23AM (#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?

      • by Cassini2 ( 956052 ) on Wednesday June 19, 2013 @09:30AM (#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.

        • by Giant Electronic Bra ( 1229876 ) on Wednesday June 19, 2013 @10:10AM (#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: (Score:3, Informative)

          by BrokenHalo ( 565198 )
          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 [] 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 fo
        • by nerdbert ( 71656 ) on Wednesday June 19, 2013 @12:54PM (#44051391)

          Ah, rad hardened PDPs. Those were the days.

          I used to program one and we had one in an accelerator when the PDP11 was state of the art. Every time you injected fresh particles into the beam we'd have to leave the accelerator and hide behind a hill due to the radiation (this particular accelerator was designed to put out a ton of polarized x-rays). We could hide behind the hill, but the PDP11 couldn't. The PDP lasted about 3 years before the CPU died from radiation poisoning. I tried to replace the CPU but DEC wanted more money for the CPU than for an entire replacement motherboard. I tried to explain the AE that I didn't feel comfortable subjecting someone else to a board that didn't have much life left, but they made me return my old board for a new one. I wonder what sucker ever got that nearly-dead motherboard?

          You can get rad-hard controllers these days. The company I worked for a few years back had CERN come in and make a ton of parts in our process. We couldn't figure out why they kept coming to us for parts as we weren't anywhere near the lowest cost provider for such a limited run of parts (our NRE was big to keep the low volume guys out), but it turns out they'd done rad-hard tests on a bunch of different CMOS processes and ours was an order of magnitude better than anyone else's. I can assure you we weren't designing for a rad-hard process, it just turned out that way.

    • by kevinT ( 14723 )

      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 leav

      • by dbIII ( 701233 ) on Wednesday June 19, 2013 @10:47AM (#44049717)
        It's 2013 and my workplace has a small storage shed full of stuff on nine track. In theory it's also on other media and the problem of the clients that sent it years ago - in practice people throw stuff out without transcribing and our stuff ends up being the only copy. We didn't have to get anything read last year but a box full of tapes had to be transcribed in 2011. It's hard to know how much was readable because the file format used can handle missing a few bits anywhere outside the headers and seismic data is a bit noisy anyway - either way every file was read in without modification.
        So why is it still on nine track? It's not really our data and the cost of transcribing a few thousand reels of tape is insane, especially since we may need only one or a dozen of them in the future.
    • 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.
    • by ackthpt ( 218170 ) on Wednesday June 19, 2013 @11:48AM (#44050543) Homepage Journal

      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.

      May have cut my teeth on an OSI (that's Ohio Scientific) home computer, with a whopping 4K of memory, later expanded to 12K, but honed my skills on a PDP 11/50. When I was hired as a student programmer I was given an admin account, subscription to a couple DEC magazines (which had some great kernal hacks in them, plus a full color map of Zork GUE, which I still have :o) and the privilege of performing the offline backups of the two RP04 drives each Friday. I learned how to dissemble the kernal, where all the fun bits were, how to peek at various terminals (to see what the very few aspiring hackers were up to), wrote honey pots and generally learned everything there was to learn in Fortran IV, RSTS BASIC, UCSD Pascal and assembler (while still an unpaid student I brought the CPU to its knees with an assembler program to calculate Pi to 1,000 places, one of those Oliver Wendell Jones sort of moves.)

      The one big shock, going from completely nailed down security on a PDP 11 to Windows was how utterly lax and clueless the Microsoft software architects were on dealing with any kind of security - literally babes in the woods, totally unaware of decades of good security practices of mainframe environments. People who think Bill Gates was brilliant need to look more closely at how oblivious he was to threats before unleashing Windows 95 on the world.

      I have a PDP emulator for the PC, but without all my old code, I don't know what I'd really do with it. I once had sources to Mark Turmell's early games written on a PDP, such as Squash, all collision detection peformed with an 80x24 integer array and VT52 cursor controls (I bet nobody heard about those early beginnings before.) Before Atari, C64, Nintendo, etc, we played video games on VT52 and VT100 terminals. :o)

  • 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!
  • by Chrisq ( 894406 ) on Wednesday June 19, 2013 @09:04AM (#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.

    • Why do you think they call it a "half life"...?

    • Re:That's just cruel (Score:4, Informative)

      by msauve ( 701917 ) on Wednesday June 19, 2013 @09:15AM (#44048767)
      "Generation" doesn't refer to an average lifetime, it refers to the average childbearing age.
      • by fnj ( 64210 )

        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 (Score:5, Informative)

          by tgd ( 2822 ) on Wednesday June 19, 2013 @10:08AM (#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.

    • I will be working until 2050, you insensitive clod! :-)
  • by intermodal ( 534361 ) on Wednesday June 19, 2013 @09:06AM (#44048675) Homepage Journal

    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.

    • These days you can probably replace them with Arduinos.

      • by scsirob ( 246572 )

        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)

      • by dywolf ( 2673597 )

        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.

        • by scsirob ( 246572 ) on Wednesday June 19, 2013 @09:53AM (#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.

          • by SJHillman ( 1966756 ) on Wednesday June 19, 2013 @10:12AM (#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.

          • by dywolf ( 2673597 )

            you're not bursting anyone's bubble let alone mine. i have considerable experience in aviation maintenance, primarily military, to back me up.
            even parts for new aircraft, for new civilian light aircraft, have a robustness to them you wont ever find in consumer electronics. its not merely a matter of being hard to get certified due to red tape clogging innovation.

            • by hjf ( 703092 ) on Wednesday June 19, 2013 @12:00PM (#44050721) Homepage

              So what's your point? Want reliability: don't use a PC. Got it.
              But that doesn't mean the PDP/11 is the only reliable system ever and "they don't build them like that anymore". You can get modern machines in MILSPEC if you want to pay for them . But you don't need to go that far. INDUSTRIAL-grade is good enough.
              And honestly, I trust a good PLC, say, Siemens (I have no experience with american brands), to be more reliable than a 40 year old PDP, no matter how well built it was. Siemens has been making automation controls for a LONG time and their products are really good, and I'll guess most of their bugs have been solved in all these years.

              As for PLC programming, remember they're not done in "code", but rather in "Ladder Diagram" so they can be well-understood, and have a graphical representation of the process, which is usually more easy to understand than thousands of lines of code.

        • 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.

          I think it's more of a matter that A, when things are mission-critical, you become conservative and don't swap stuff out every month and B, a large, standardized object is easier to swap out than one of an incompatible collection of newer odd-sized smaller things. Some people could also say C, repairability, but there are limits to what's repairable in-flight anyway, and there are fewer things that need repair when everything's on a single chip that's so small that you could pack 3 primary and 2 spare units

      • by sjbe ( 173966 ) on Wednesday June 19, 2013 @09:46AM (#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.

    • 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.
    • If it ain't broke, then why does it need software maintenance? If it needs software maintenance, then by definition something is broke.
      • by dywolf ( 2673597 )

        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.

      • 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.

    • by fnj ( 64210 )

      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 [] still running today.

      • Considering you can still buy a brand new 486 today (although it's a little more difficult at the consumer level), I don't think it will be a problem as long as there's demand. Sure, prices might go up as you become the only customer for those parts, but someone somewhere will gladly take your money for them.

        It's actually not too hard to keep stuff running for decades as long as you can still source replacement parts. The main reason there's not a lot of Model T's and Model A's on the road is because newer

    • 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, A

      • by intermodal ( 534361 ) on Wednesday June 19, 2013 @09:58AM (#44049171) Homepage Journal

        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.

    • by Cyberax ( 705495 )
      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.
      • by jkonrath ( 72701 )

        If you dropped a wrench on a PDP machine, you're probably going to need to buy a new wrench.

      • by rnturn ( 11092 )

        ``So what happens once someone accidentally drops a wrench on a PDP machine?''

        That's easy: buy yourself a new wrench.

        In a former life, I've built, disassembled, and rebuilt PDP-11s (34s, 44s, 70s, and a their Q-bus equivalents) more times than I care to remember. You rarely needed an actual wrench for anything... Oh, wait... yeah, you used a wrench to adjust the feet on the racks to keep them level. But that was pretty much it.

    • 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 lon

    • by jonwil ( 467024 )

      If you need a modern "system that just works" in the vein of these old systems, IBM and others will sell it to you.

      Comparing a PDP to a modern desktop PC is like comparing a big-rig truck to a Toyota Corolla.

  • 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.
  • Assembly programmer. (Score:4, Interesting)

    by morto ( 525092 ) on Wednesday June 19, 2013 @09:11AM (#44048721)
    Just a small correction. The language is Assembly. Assembler is the tool. Best regards.
    • by dpbsmith ( 263124 ) on Wednesday June 19, 2013 @10:20AM (#44049391) Homepage

      If you want to get technical: the language was MACRO-11. Which is an example of an assembly language. I program in "C#", not in "compiler."

      In the Digital world, the name "MACRO" stuck because there were very early assemblers for the PDP-1 that did not have macro capability. So "MACRO" was the name for the assembler that did. In subsequent machine generations, "the" assembler was usually called MACRO even though as far as I know there weren't any assemblers without macro capabilities.

      And perhaps I should add: the reason that it's called assembly language is because of drum memory. The usage dates back AT LEAST to the IBM 650 and Symbolic Optimal Assembly Language (SOAP). "Assembly" was short for "optimal assembly." Each instruction contained within it the address of the next instruction--they weren't sequential--and "optimal assembly" was the process of calculating how long each instruction would take so that the next instruction could be placed at the right location on the drum that it would be almost under the head when the last instruction had completed. "Optimal assembly" was the memory placement aspect of it.

      The symbolic optimal assembly program added to that the advanced capability of allowing programmers to refer to instruction codes by convenient, easy-to-remember mnemonics like UFA and STA, as well as the capability of giving your very own names to instruction locations.

      For some reason, the category name got abbreviated to "assembler" rather than "symbol-" um... symbolizer? Symbolic? OK, maybe THAT reason... and it stuck, even after advanced computers like the IBM 704 started to have random-access memory.

  • by barista ( 587936 )
    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.
    • 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 sur

  • You go old timer! (Score:5, Interesting)

    by NormHome ( 99305 ) on Wednesday June 19, 2013 @09:14AM (#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?

    • by RobKow ( 1787 )

      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.

    • by bellers ( 254327 )

      I have 3 VAXen at work that are still on 4-hour hardware support contracts. HP has achieved legendary status among my team for being able to show up in less than 4 hours with parts in hand for them, every single time.

  • 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.
  • 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 setti
    • by kevinT ( 14723 )

      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!

      • Something well made will last for many generations... a fact we've forgotten in modern society with throw-away everything and a new model every year. My neighbor purchased a circular saw in 1946 after he got back from WWII. When he passed away a few years ago, his widow gave it to me and I still use it regularly. I wouldn't be surprised if it still works when it turns 100.

  • 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.

  • 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.

  • 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.
  • 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.

    • And if you want to learn the assembly dialect, just fetch SIMH [] - the greastest thing since the bit-slice microprocessor.
      • by SIGBUS ( 8236 )

        The first computer I actually used was a PDP-11/34 running RSTS/E at my high school. A few years back, I decided to throw SIMH on one of my PCs and bring up my very own RSTS system. I laughed my ass off when I discovered RSTS wasn't Y2K compliant, since my high school CS teacher (in 1980!) was warning about the Year 2000 issue even then. I wound up calling the RSTS system "sgtpepper" since I set its clock back exactly 20 years.

        SIMH is pretty amazing - but the hilarious thing is that a modern CPU emulates th

  • 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.

    • by Anonymous Coward on Wednesday June 19, 2013 @10:24AM (#44049435)

      Microsoft hired him to lead a team that designed Windows NT.

      Wow. Way to re-write history. No, I'm afraid that's not how it went down. Dave Cutler developed what ultimately is NT while working for Digital Equipment Corporation. DEC wasn't interested in Dave's creation. Dave unethically and possibly illegally shopped it around. Microsoft was interested. Dave and his entire engineering team left DEC, and went to work for Microsoft, and actually, literally stole DEC's intellectual property and eventually released it as Windows NT. Yes, I am saying that Windows NT is the intellectual property of Digital Equipment Corporation, and Microsoft never paid DEC a red nickel for it.

      On a personal note, I am divided about Mr. Cutler. Windows NT might have been the best Windows ever, and NT itself isn't a terrible platform. What Microsoft did to it is unfortunate for users and administrators everywhere, but it essence, NT wasn't terrible. Cutler is an impressive developer... quite amazing... yet it sickens me that what he and Microsoft did was insanely unethical, and no one noticed. Microsoft's main flagship product was STOLEN, and no one noticed, and this is hardly ever acknowledged.

  • by lkcl ( 517947 ) <> on Wednesday June 19, 2013 @09:37AM (#44048955) Homepage

    the PDP-11 is awesome. i believe its instruction set was the inspiration for the 6800 ( 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 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 arc

  • by Trailer Trash ( 60756 ) on Wednesday June 19, 2013 @09:51AM (#44049093) Homepage

    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.

  • 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 [] or an emulator.

  • 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.

  • However, this development, or should I say lack of development, the article details bodes well for those looking for new definitions to the phrase, "a blast from the past", in the event of an accident.
  • Most of the younger /. readers never heard of the PDP-11

    I was about to complain about the accuracy of that statement... and then I realized I'm not one of the younger readers any more.
    /me cries.

  • by aglider ( 2435074 ) on Wednesday June 19, 2013 @10:53AM (#44049811) Homepage
    Like serial lines, 16KB memory banks, power supply or the CPU itself?
    Do they have spare parts? Do they know those parts really work now and will work when needed?
    I think the plastics around the chips will start degrading much earlier than 2050 ...
    I foresee another nuclear incident quite soon... this time triggered by laziness and stupidity.
  • by swb ( 14022 ) on Wednesday June 19, 2013 @11:15AM (#44050093)

    ..unless MBAs get involved.

    Find some CS grads, offer them PDP-11 training and assembler training and a job paying slightly-above-average wages & bennies and tell them the job is guaranteed for the next 30 years.

    Right now that sounds pretty good to me --- guaranteed employment on a well-understood platform for 30 more years (although I really only need about 20-25 more years..)

    Sure, some guys would rather slave away 80 hours a week to develop iPhone apps, Metro tiles or Web X.0 apps because that's what all the cool guys are doing and it's "the future" (until those jobs are shipped off to the next up-and-coming third world country).

    Of course, MBAs would manage to fuck this up by deciding that because it's an "obsolete" technology, you don't need to pay anything.

  • by gordona ( 121157 ) on Wednesday June 19, 2013 @11:34AM (#44050313) Homepage
    The predecessor goes back to the MIT machine in the 60's, the Link-8 which became the PDP-8. It had two DEC tapes, 4KB ram. We programmed it in LAP-4 and had to key in a bootstrap loader on the front panel to load in the OS. At the time we wrote a 64 point FFT and a routine to output the results to a Calcomp plotter. It took 5 minutes to run the FFT. Memory was divided into 2 2KB segments, one for data and one for program. We used one page (512KB) as an executive routine and the other 3 pages to program the FFT which kept the DEC tapes spinning as different segments of the program were shuttled in and out of those 3 pages.

"Probably the best operating system in the world is the [operating system] made for the PDP-11 by Bell Laboratories." - Ted Nelson, October 1977