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

Posted by Unknown on from the great-architectures-live-forever dept.

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.

61 of 336 comments (clear)

  1. I cut my teeth on that CPU by Bucc5062 · · Score: 5, Interesting

    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.

    --
    Life is a great ride, the vehicle doesn't matter
    1. Re:I cut my teeth on that CPU by hazeii · · Score: 2

      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....

      --
      All your ghosts are just false positives.
    2. Re:I cut my teeth on that CPU by Giant+Electronic+Bra · · Score: 4, Interesting

      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?

      --
      "Malo periculosam, libertatem quam quietam servitutem." -- Jefferson
    3. Re:I cut my teeth on that CPU by Cassini2 · · Score: 5, Informative

      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.

    4. Re:I cut my teeth on that CPU by kevinT · · Score: 2

      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!

    5. Re:I cut my teeth on that CPU by Cryacin · · Score: 4, Funny

      At least they're not running nuclear power plants in action script. (ducks)

      --
      Science advances one funeral at a time- Max Planck
    6. Re:I cut my teeth on that CPU by Cryacin · · Score: 3, Informative

      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.

      --
      Science advances one funeral at a time- Max Planck
    7. Re:I cut my teeth on that CPU by Giant+Electronic+Bra · · Score: 3, Informative

      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.

      --
      "Malo periculosam, libertatem quam quietam servitutem." -- Jefferson
    8. Re:I cut my teeth on that CPU by Sique · · Score: 2

      That might get flashy.

      --
      .sig: Sique *sigh*
    9. Re:I cut my teeth on that CPU by BrokenHalo · · Score: 3, Informative

      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 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.

    10. Re:I cut my teeth on that CPU by Anonymous Coward · · Score: 5, Interesting

      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
      generation.)

      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.)

    11. Re:I cut my teeth on that CPU by swalve · · Score: 4, Insightful

      Yeah, but ironically fancier is cheaper. And now we have printers that take two minutes to boot up.

    12. Re:I cut my teeth on that CPU by Giant+Electronic+Bra · · Score: 5, Interesting

      Yeah, I know what you mean. A lot of newer technology is just less good. Verizon 'improved' my phone service so now they 'back up' my contact list. Its great, every month or so they restore some old worthless crap over the top of my contact list on my phone. Ain't progress great? Now I carry around an actual physical address book.

      --
      "Malo periculosam, libertatem quam quietam servitutem." -- Jefferson
    13. Re: I cut my teeth on that CPU by Anonymous Coward · · Score: 2, Interesting

      anything with a feature size at or under 0.25 um is more or less rad hard. that's what we use at the LHC. ESD is another story though.

    14. Re:I cut my teeth on that CPU by rochrist · · Score: 2

      I sill fondly remember the 5MB disk drives with the removable platters the size of manhole covers. Those were the days.

    15. Re:I cut my teeth on that CPU by ackthpt · · Score: 4, Interesting

      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)

      --

      A feeling of having made the same mistake before: Deja Foobar
    16. Re:I cut my teeth on that CPU by nerdbert · · Score: 4, Interesting

      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.

    17. Re:I cut my teeth on that CPU by hazeii · · Score: 2

      >Mov @offset(r5),pc
      Ah, the calling convention for Fortran. I spent a while recoding the hotspots in a Fortran program into Macro 11 - the runtime dropped from several minutes to a few seconds.

      --
      All your ghosts are just false positives.
    18. Re:I cut my teeth on that CPU by hughk · · Score: 2

      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.

      --
      See my journal, I write things there
  2. Very Cool! by pauljuno · · Score: 2

    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!

    1. Re:Very Cool! by Nutria · · Score: 2

      The VAX uses the 32-bit MACRO-32 assembler.

      --
      "I don't know, therefore Aliens" Wafflebox1
  3. That's just cruel by Chrisq · · Score: 4, Funny

    ... 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.

    1. Re:That's just cruel by msauve · · Score: 3, Informative

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

      --
      "National Security is the chief cause of national insecurity." - Celine's First Law
    2. Re:That's just cruel by fnj · · Score: 2

      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.

    3. Re:That's just cruel by tgd · · Score: 5, Informative

      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.

  4. If it ain't broke... by intermodal · · Score: 5, Insightful

    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.

    --
    In SOVIET RUSSIA... erm...NSA AMERICA, the Internet logs onto YOU!
    1. Re:If it ain't broke... by Karganeth · · Score: 2

      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.

    2. Re:If it ain't broke... by scsirob · · Score: 2

      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)

      --
      To Terminate, or not to Terminate, that's the question - SCSIROB
    3. Re:If it ain't broke... by dywolf · · Score: 2

      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.

      --
      The guy who said the election was rigged won the presidency with the second-most votes.
    4. Re:If it ain't broke... by scsirob · · Score: 4, Insightful

      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.

      --
      To Terminate, or not to Terminate, that's the question - SCSIROB
    5. Re:If it ain't broke... by intermodal · · Score: 5, Insightful

      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.

      --
      In SOVIET RUSSIA... erm...NSA AMERICA, the Internet logs onto YOU!
    6. Re:If it ain't broke... by cardpuncher · · Score: 2

      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.

    7. Re:If it ain't broke... by SJHillman · · Score: 4, Funny

      "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.

    8. Re:If it ain't broke... by jkonrath · · Score: 2

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

    9. Re:If it ain't broke... by dywolf · · Score: 2

      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.

      --
      The guy who said the election was rigged won the presidency with the second-most votes.
    10. Re:If it ain't broke... by RabidReindeer · · Score: 2

      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 into the same-sized space as the older discrete or TTL circuitry with plenty of spare room for shock padding and radiation/pulse shields.

      Even the Shuttle gradually migrated to electronic controls. Long after the astronauts' watches packed more computing power. But a whole different dynamic applies to stuff like that. Some things can muddle by for a long time without the latest and greatest.

    11. Re:If it ain't broke... by hjf · · Score: 4, Informative

      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.

    12. Re:If it ain't broke... by cangrejoinmortal · · Score: 2

      This actually answers a question I was making myself about this sense of reliability of old equipment, In my experience its a nightmare to service and maintain old equipment. One of my first job was in the manufacturing (machining) industry, it was a small operation and it needed old computers with old software that controlled some old (~6 years back then) but very expensive quality control and milling equipment; those were all old PC's, with old ISA buses, old and insanely expensive RAM (that eventually failed), I eventually convinced my boss to replace those things with cheap assembled PC's, we had to buy PCI expansion cards for all the serial and parallel ports that the measuring table seemed to need but it worked out just fine. There was a kind of sentiment that those machines were somewhat magical and no new PC's would ever be able to connect successfully and run the aging software (the equipment was second hand, out of support, software update was in the thousand dollar range), they depended on them so the things had to be reliable, right? If we add regulation to this attachment that management has with old 'working' equipment we get the nightmare that it is to deal with medical equipment and (now I know) nuclear facility equipment.

  5. Assembly programmer. by morto · · Score: 4, Interesting

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

    --
    "Think globally, act locally".
    1. Re:Assembly programmer. by dpbsmith · · Score: 4, Interesting

      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.

      --

      "How to Do Nothing," kids activities, back in print!

  6. You go old timer! by NormAtHome · · Score: 4, Interesting

    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?

    1. Re:You go old timer! by RobKow · · Score: 2

      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.

    2. Re:You go old timer! by bellers · · Score: 2

      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.

      --
      This space for rent.
  7. Re:Security? by thoriumbr · · Score: 2

    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.

  8. Don't Freak! Prolly A PCI Card Emulator by cmholm · · Score: 2

    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.

    --
    Luke, help me take this mask off ... Just for once, let me butterfly kiss you with my own eyes.
  9. Re:Security? by Bucc5062 · · Score: 2

    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.

    --
    Life is a great ride, the vehicle doesn't matter
  10. awesome by lkcl · · Score: 2

    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.

  11. Re:Well, if you're really that old... by mrr · · Score: 3, Funny

    Okay, noob.

  12. Re:The legacy of the PDP-11 by AlphaFreak · · Score: 2

    Indeed. There are several projects around to implement a full PDP-11 in single FPGA. For example:

    http://opencores.org/project,w11

  13. Can doesn't mean should by sjbe · · Score: 3, Informative

    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.

    1. Re:Can doesn't mean should by LWATCDR · · Score: 3, Interesting

      Really which micro? You have the advantage of 20/20 hindsight.
      Maybe go with an IBM PC based system? What RTOS would you use? What hardware interface would you use ISA? EISA? MicroChannel?
      Then you have the problem of revalidating the software when a new CPU comes out. Remember the Pentium Bug?
      Or you could have gone with VAX.... Dead.... Alpha? Dead, 68k? Still kicking around but mostly dead, 88000, PowerPC, MIPS, Spark?
      And yes you can get new PDP-11 hardware. http://www.logical-co.com/dec-replacement-systems/

      --
      See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
  14. Re:Security? by AlphaFreak · · Score: 2

    The PDP-11 is a 16 bit computer...

  15. PDP-11 is the basis of modern non-x86 CISC by Trailer+Trash · · Score: 4, Interesting

    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.

    --
    Do you have ESP?
  16. Re:Dave Cutler's work lives on by Anonymous Coward · · Score: 5, Informative

    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.

  17. Re:Well, if you're really that old... by Anonymous Coward · · Score: 2, Funny

    How come you have such a high /. ID?

    Ever tried running a web browser on a PDP-11?

  18. Nine track 1995 - how about now? by dbIII · · Score: 3, Interesting

    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.

  19. What it anything breaks inside? by aglider · · Score: 2

    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.

    --
    Sent as ripples into the electromagnetic field. No single photon has been harmed in the process.
  20. Recruiting PDP-11 people should be easy... by swb · · Score: 3, Funny

    ..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.
     

  21. predecessor to PDP11 by gordona · · Score: 2

    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.

    --
    "Gentlemen, you can't fight in here! This is the War Room!" -- Dr. Strangelove
  22. Coroutines... by AliasMarlowe · · Score: 2

    JSR PC,@(SP)+
    We always put a comment at the top of such code saying "only experienced programmers should attempt to modify coroutines". We meant it...

    Before the PDP-11 (I used at least the 23, 34, 44, 70, and 73 series, later the Pro series), I used a couple of PDP-8 machines. Now booting those 12-bit wonders was a real lark, involving magic incantations, thumps, and a load of toggled-in instructions. Once you got it going, the paper tape reader worked like a charm (of the malevolent variety).

    Almost forgot the IBM-360 and its card-punch and programs spanning several boxes of cards. BTW, although I chase kids off my lawn, I'm not actually retired yet.

    --
    Those who can make you believe absurdities can make you commit atrocities. - Voltaire
  23. Re:The legacy of the PDP-11 by emt377 · · Score: 2

    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... :-)

    It was indeed elegant, often in very clever ways. For instance, most OS installs came on tape. The boot loader for tape was supremely simple, and consisted essentially of "tell the tape controller to read one block", "jmp .". I forget if it was 2 or 3 instructions, but it took only a few seconds to enter them on the front panel switches. After a full reset the block would the first on the tape, DMA to location 0, caches disabled, I/D space unified, etc. This then caused 256 words (512 bytes) from the first block on the tape to overwrite the code entered, and in particular the "jmp .". And so the secondary boot loader from the tape would start at that location (4 or 6 or something like that).

    I had a pdp-11/05, a nice little toy useful for training. It came with a microcode dump, and extender boards permitted single-stepping the microcode. It basically took the source addressing mode, shifted it, jumped to that location in the microcode and computed the source address. The exact same code was then used for the destination address. It would then proceed to the instruction implementation. I forget off hand but I think the entire instruction set fit in 256 words of microcode. It was supremely elegant, clever, neat, and to me as a young kid interesting in all things computer architecture, positively brilliant. Of course, microcode is inherently inefficient. But it was an amazingly elegant exercise in factoring.