back to article Huge PDP-11 in a lorry: How I drove computers into schools

Computers in classrooms are so common today, we may forget this was once inconceivably difficult. Computers were very expensive and so large they needed a huge truck to transport them. Nearly 35 years ago, I worked on an ambitious but ill-fated project to bring a minicomputer to rural Iowa schools, a classroom on wheels. This …


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  1. JimmyPage
    Thumb Up

    Oh wow, nostalgia ...

    In 2nd year at poly, our department had a PDP-11 running Unix, which was practically unused, due to the PC (well, BBC B) revolution. I recall the ring-bound manuals which I, and fellow geeks devoured to set ourselves up as sysadmins, and teach ourselves the basics of multi-user computing. we also had a VAX running VMS ...

    those were the days. Gosh, can anyone explain why we had to mount the backup tape as foreign ?

    1. Clive Summerfield
      Thumb Up

      VMS - still my first love

      "those were the days. Gosh, can anyone explain why we had to mount the backup tape as foreign ?"

      The /FOREIGN option was used to mount devices with a file structure other than Files-11. It tells the operating system to make no assumptions as to the file structure on the device.

    2. Mr Larrington
      Thumb Up

      PDP - Aaargh!

      In my first job as a Babbage-Engine driver we had a PDP which was used for word processing, and also by the accounts/payroll bods. Being a curious type who wished to be a 1337 h@xx0r, I discovered that the WP files could be accessed from the command line and were easily legible on a VT100 once you'd stripped away the initial gibberish. After only a couple of months in IT I knew the entire company's salary structure, which was galling as the only person paid less than me was the Wee Work Experience Lackey.

      Twenty-six years later to the day and I'm still driving VMS boxes.

    3. Peter Gathercole Silver badge


      PDP-11 running UNIX. BBC Micros. Polytechnic. VMS.

      I know that all these were quite common in education, but was this Newcastle Poly?

      The PDP-11/34 (in SYSTIME 5000E covers) in the Maths department (which taught the computing courses) there was my pride an joy, and I was instrumental in getting a network of BBC Micros installed there. Was a Golden Period of my working life, and set me up for a life of supporting UNIX systems.

      We were at constant tension with the Polytechnic computer service department, who had a passion for HARRIS systems (strange beasts that were neither Super-mini nor Mainframe), RML 480Z systems and a little later, 1st generation IBM PCs. Eventually, they gave up on Harris systems, and switched their main systems to a VAX 8600 and an 8300 running VMS, and an 8250 running Ultrix.

      All seems a long time ago.

  2. Anonymous Coward
    Anonymous Coward


    Sounds like the Director was a boss of the pointy-haired variety ...

  3. David Kelly 2

    Efficiency. Not!

    File this article under "Government Efficiency: Fiction".

  4. deshepherd

    Re: Oh wow, nostalgia ...

    Well, I remember around that time (late 70s) as a sixth former being able to bootstrap a Data General Nova from front panel switches then install its OS to disk (a single platter 12 or 15" solid disk that probably had capacity measured in kBs) from dozens of trays of fanfold paper tape!

  5. Dicko99

    @JimmyPage Because you were writing raw data to the tape. A normally mounted tape had a file system and from what I remember it was very slow to access.

  6. Version 1.0 Silver badge

    RL01 or RK05?

    Jesus!~ those were bastards to ship anywhere - I'm guessing they had to fit the head-locks each time the truck moved?

    For some reason the DEC engineers were always very paranoid about AC power quality in those days but I ran several PDP-11's in Clearwater, Florida connected to the AC line via an isolation transformer and a dirty great big spike preventive box without any problems - communications were via a 300 baud modem initially then a 1200 baud modem later.

    Most of the DEC field engineers that I ran into had their heads stuck up their rears and every time we got a visit they would shake their heads about the appalling lack of AC line conditioning. Lightning strikes were the biggest threat (I lost several modems, fax machines and the occasional terminal over the years) but I never had any problems with the PDP's over 4-5 years there.

  7. Vladimir Plouzhnikov


    Just starting the thing was like launching a ballistic missle (ours was a Soviet knock-off, SM-1420) - multiple PSUs, fan blocks, disk drives spinning up like jet turbines (with the same sound FX) and my favorite - turning the key to "START" position.

    I could load the bootstrap sequence from console switches from my memory (and was immensely proud of it).

    Run TSX-Plus over RT-11.

    MACRO-11 assembler was the main language I used.

    1. Andus McCoatover


      "I could load the bootstrap sequence from console switches from my memory (and was immensely proud of it)."

      So could I, and so was I.

      The startup of the two RL01's, as a previous poster wrote, WAS like two jet engines. I daredn't start them at the same time. Either the home fuse breaker would trip, or i'd have to support the rack in case the rotating force made it fall. For 20 megawords of storage??

      The machine (I'd bought it for a tenner in 1990-ish) was at home, I'd wait until wife went out to run it up.

    2. Franklin
      Thumb Up

      A title is optional

      I've actually owned two PDP-11s, an 11/03 and an 11/24, both of which I found for $25 at a Goodwill store. I was going to school at the time, and remember taking them both back to my dorm room, setting them up, connecting an antique VT-52 terminal that had thoughtfully been included with one of them, powering them on...

      ...and watching them just sit there.

      When my girlfriend dropped by for a visit, she mentioned that her uncle had worked with a whole host of PDPs back in the day. I gave him a call, and he had me toggle in the bootstrap sequence for each of them on the front panels (from memory!) One of them had a series of little flip switches, the other had an octal keypad--a rather strange thing to see. We were able to get them up and running, and for a while I explored RT-11 and the wonders of PDP-11 assembly and TECO, which is easily The Single Worst Piece Of Software I Have Ever Used, and possibly The Single Worst Piece Of Software Ever Written.

      The 11/24 was accidentally destroyed a few weeks later when the same girlfriend came for a visit and made the mistake of trying to cook us breakfast with an electric frying pan, tripping the circuit breaker and causing the disk drive to eat itself. Part of the 11/24 lived on for quite some time afterward; a friend of mine disassembled it and used parts of the chassis to make a (very heavy) coffee table and a night stand.

      I kept the 11/03 for a number of years, before finally giving it away when I moved and couldn't find a reasonable way to take it with me.

      1. Anonymous Coward
        Anonymous Coward

        Heretic! Burn him!

        "TECO, which is easily The Single Worst Piece Of Software I Have Ever Used, and possibly The Single Worst Piece Of Software Ever Written."

        Unbeliever! Disconnect his 20mA interface!

        TECO (Text Editor and Corrector) was available and largely compatible on various major DEC operating systems, not just the various PDP11 ones, but also PDP8, VAX, DECsystem 10/20, etc. Also available (not just from DEC) on DOS, Windows, OS-X and doubtless OSes too numerous to mention here (but mentions many/most of them). I'm almost surprised there isn't a POSIX standard or an RFC for it...

        TECO wouldn't necessarily be any sensible person's editor of choice for normal editing, but if you want a universally available, massively programmable, screen or line oriented text editing program, it was (and is) hard to beat.

        My coat's the one with the original (not photocopied, not HTML) TECO Pocket Guide in it.

      2. Ralph B
        Thumb Up


        "TECO, which is easily The Single Worst Piece Of Software I Have Ever Used, and possibly The Single Worst Piece Of Software Ever Written."

        Until Lotus Notes arrived, maybe.

        (I preferred EDT (or was it EDI?) to TECO.)

        1. BoldMan

          EDT was great but not a patch on EVE which was an editor with a very rich programming language!

  8. Anonymous Coward
    Anonymous Coward

    Sounds like a good idea

    But that director's a total dick. I guess nowadays you have enough experience to run like hell in a similar situation.

  9. Rob Daglish Bronze badge

    The Idea Was Reasonably Sound Though..

    We had something called the "SATRO Bus" when I was at school. SATRO was a government funded initiative in the eighties to get more kids doing technology stuff at school, and because we had a lot of small schools in rural locations and not enough staff to train, they went out and bought an old Leyland National bus from the local bus operator (Cumberland Motor Services), and the Leyland factory helped convert it. Originally, it had some whacking huge satellite dishes so they could show you pictures from the weather sats, a couple of computer controlled lathes, routers etc to do technology with, and 16 BBC Model Bs.

    I actually got to help when they upgraded it to 16 Technology for Business 486s...

    After SATRO was disbanded in the 90's, it got bought by Kendal College to do a similar job, but sadly after a number of years with them was replaced by a small minibus in the early noughties.

    It drove all round the county, and worked really, really well - the guy who drove it was my boss for 4 years after he finished with SATRO, and even now staff and ex-pupils remember him as that bus driver with the computers...

    Pint for Jeff the bus, might not even be working in computers if it wasn't for you and your colleagues...

  10. Christian Berger

    Small waste compared to what happens daily in commercial environments.

    In the company I work there are computers.... handed out to people who cannot program, not even BASIC, nothing, nada, zilch. They just sit around and act as expensive paperweights and once every year or so you need to replace the fans on the hugely overpowered graphics subsystems.

    Yesterday I blew my bosses mind by installing a _wiki_. The poor guy never heard of such a thing.

  11. Steve Davies 3 Silver badge

    There is only one true text editor

    for the PDP-11, and that was 'teco'.

    I saw my first PDP-11 in Sept 1974. IT was a PDP-11/40. 56Kbytes of Core and a single 2.4Mb RK05 disk.

    The evelsting memory of that system was the regular occurrence of the Dos V8 equivalent of a BSOD

    "F342-Odd address or other Trap-4"

    A few years later I went to work for DEC in Reading. 20 years of doing lots of cool stuff.

    Thanks for the memories.

    1. Vladimir Plouzhnikov

      TECO was a nightmare but KED (KEX, K52) was a wonderful editor. I'm sure Brief and Multi-Edit were strongly influenced by it subsequently.

      I remember Trap-4's too! But hardly a BSOD, it would just terminate your program (for trying to access memory beyond the one it has been allocated) and return to KMON.

  12. Kernel

    You youngsters had it easy

    We started off with Portran and pre-punched cards (can anyone say 'hanging chad') and had to wait at least a week for efforts to be sent away, processed and then returned - I well remember the disappointment of waiting all that time, only to see 'Syntax Error' because I'd failed to punch out one chad, or got a card out of order.

    1. seasider

      Same here


      I've still got the punched cards today - I learned nothing from the experience (except that computers were really disappointing - Yep I got the "Syntax error" too often as well) Luckily my old man worked for Plessey and the computing nerds there convinced him that the BBC B was the way forward - they were right ! Suddenly you could see the possibilities from these computer things. Kept me in work for 20 plus years so far.

      Today I look at the homework my kids do on "how to write a letter in Word" or some other such nonsense and wonder how it is that UK education can be so clueless with IT for so long.


    2. JohnG

      I started with Hollerith cards and WATFOR Fortran. I can also remember the long wait followed by a syntax error or a problem with the job control cards. One of the saddest sights of that era was when someone dropped their stack of cards...

      We also had teletypes which gave us access to BASIC, along with Lunar Lander and Star Trek. These also had paper tape interfaces,.which were used much as one might use a USB stick today (I had several paper tapes of ASCII art).

  13. Phil O'Sophical Silver badge

    Christmas project

    Must see if my PDP-11 will boot, haven't tried in years. Only a teeny one, I'm afraid, in the deskside tower, but...

    Now if only I could find RSX-11 for it, instead of the Ultrix it's running. I still have the RSX distribution on RL02, but no drive, and only have RT11 on floppies. Anyone got any ideas?

    Wish I'd managed to find a VAX...

  14. jake Silver badge

    Bloody stupid waste of money.

    In 1977 I had a PDP-11 desktop PC at home.

    Well, an LSI-11 based Heathkit H11, anyway. see:

    She still runs. When siting at the console, my pro-gas dragster is quieter.

    1. Long John Brass

      SimH Software kits for PDP/11 etc

      The SimH project has many software kits available

      not sure you you would go about transfering them to real tin

      But it's a start at least :)

      1. Anonymous Coward
        Anonymous Coward

        SIMH in one direction. In the other direction...

        Do it in hardware. There are a number of FPGA implementations of PDP11s. They need an FPGA card to run on, maybe £100 or so if brand new, depending on the details.

        With this approach, the heart of a PDP11/70 fits in a pocket-sized Spartan 3 FPGA card, for example.

        Then there's the small challenge of IO.

        I keep wondering "why" and "where do they find the time", but hey, it's a free world.

  15. arrbee

    what ?

    Like a previous poster I had a PDP-11 that would comfortably fit on the back seat of the car, together with 3 or 4 vdus if you didn't mind them being on the floor (and no we're not talking about a US car here). Given enough terminals a dozen people or more could use it simultaneously with no problems, although you'd need a TPM to make good use of one of the larger database products around.

    It only really started to suffer if 4 or 5 people tried something like compiling at the same time - especially since there was always one guy who'd worked out how to run several compilations at once from the same terminal. IIRC the bad news message was "dynamic pool exhausted".

    Tell the kids today you could do all that with half a meg of memory in total and they'll just stare at you (*) - although my last 11 had 1.5MB, which was not bad for a 16-bit machine.

    Oh, and 'mainframe' refers to a family of related architectures and has nothing to do with the PDP-11.

    (*) can we have a boring old fart icon please.

  16. John Smith 19 Gold badge

    Extraction, Tranlate and Load

    3 Little words that are often forgotten in migration projects (which *essentially* this was. I'd never heard of this IBM thingy till I read the article. It *sounds* quite impressive. Sort of mult-media and hypertext before those ideas really existed).

    The answer the manager seems to have come up with in *each* of these cases was "We'll think of something."

    *Heroic* effort but icon for the plan being well, stupid..

  17. OziWan
    Thumb Up

    Ueber Cool

    Nothing more to say. Brings back nice memories I am sure for many of the old gits on the register. Loved reading it.

  18. nitsedy

    ....and with the magic of Google here's a June 1980 news report about the crazy mobile thing being deployed: Apparently this was the kind of project that just wouldn't die. By 1980 the schools in our rural state had Apple II's and TRS-80's for teachers to use. Honestly, the whole thing looks like one of those higher-ed stunts where some career climber writes a grant so they can trumpet to the world how progressive they are with their ideas and pad their CV. Then they get a bunch of lowly undergrads to do the grunt work while they go off to conferences to receive the praise of people who don't know any better.

    Yes.......yes, I am bitter.

  19. Mage Silver badge

    Apple II

    First and last Apple product we had.

    it eventually spent most of its time running CP/M on 1Mbyte 8" floppies using a Z80 card. A Research Machine 380Z or S100 system would have worked out cheaper.

    The next computer was an ACT Sirius 1 (Victor 9000). Then PCs. It took 4 years for the PC to catch up with Sirius 1.

    We got a contract service/maintaining TRS80, BBC Micros, Apple II, Research Machine 380z etc in schools. Most of the computers in Schools in early 1980s a sheer waste of money. They should have bought the teacher one for home first.

    Even in the mid 1990s teaching trainee secretaries about PCs, Computer Filing, Word-processing and Spreadsheets the easiest ones to teach and best students came from schools with no computers.

    Computers in schools could have achieved so much more. Even today the "tool" is badly taught and under utilised.

  20. Herby

    But one has to learn somewhere...

    Back in the 60's I did some work on both IBM1620s (I had access to several) and an IBM1130. Both were programmed with punch cards, and I became VERY familiar with IBM keypunches (both 026's and 029's). Since the IPL sequence was normally reading a specific "cold start" card for both machines, knowing the sequence wasn't commonly done. An exception was if you wanted to control the IBM1620 via its console typewriter (one had a old model b electric typewriter, the later model had a modern Selectric). In that case keying in the IPL sequence was easier than getting out of the chair and going to the card reader to put the card in. I still remember the sequence:


    The things you remember from high school.

  21. Morten Bjoernsvik

    AC power and computers

    I recall my days at SGI, During 1997-2000, Every year end of May we had to replace 3-4 powersupplies in the University of Bergen HPC. On the 3rd year we found this to be a travelling circus/tivoli connecting to the same power source nearby. It showed up yearly for the national holiday.

  22. Graham Hawkins

    A-Level Computer Science - happy days...

    ... in 1974 at the local High Wycombe technical college (now of course a uni).

    Punching BASIC to tape, then loading and running the program on a mainframe at the OU in Milton Keynes, via 300baud modems. All on on proper teletypes! Instant results, great fun!

    Then off to uni to program in batch processed Fortran via punched cards - what a disappointment!

  23. John Styles

    IBM 1401 in Vietnam

    There was a story about an IBM 1401 on a trailer in Vietnam during the Vietnam war.

    This mentions them being on trucks

    and this mentions them being in Vietnam

    Neither is quite the story I was looking for, if I remember correctly, but both are worth a read

    1. disgruntled yank Silver badge

      don't know about trailers

      A guy I shared a house with years ago had been a computer operator at a base in Vietnam. I wouldn't be surprised to learn that it was a 1401 he tended--I think he was running payroll or other personnel applications. As far as I know, the only danger he ran was from MPs, officers, and unpleasant infections.

  24. The Askylist
    Thumb Up

    Any MGS alumni will remember...

    The PDP-11 that occupied the computer lab from 79-81. Great fun learning BASIC and filling our 256KB allowance with not very good Star Trek text adventures and moon landing simulations....

    Happy days, and all driven by Neil Sheldon, who was a hell of an inspirational maths teacher and form tutor. Not a bad pool player, either.

    1. Dr Zmic
      Thumb Up

      Around a little longer than that

      Seconded, yay for RSTS/E, though it was at least there until 85 since a friend and I wrote the library book management program for it (him doing the majority). Not just BASIC, but BASIC-PLUS-2, whose "foo if bar" qualifier inspired the same Perl syntax and whose code grew large enough to require overlays and the TKB Task Builder to produce the executable, taking hugely longer and hammering the system something rotten during each build. Mostly used FED as editor (local homebrew?) though occasionally TECO. (I later had a TECO version on Ultrix and later yet used DEC's MIPS->Alpha binary converter to have it running on Digital UNIX years after). All that (30 concurrent users at times) in 128KB (or was it 256KB?) of memory. A Systime (*cough*) rather than a PDP. Still have a mini-magtape backup of the code somewhere. Taught by both Neil Sheldon and Alan Pickwick whose ICL 1902T in the chemistry lab has also been commented on in the The Reg, IIRC. Being taught by those two and "sysopping" both those machines was a formative part of my education and current career.

  25. Anonymous Coward
    Anonymous Coward

    PDP's in strange places

    Try replacing the passenger seat of an Army Landrover and putting a non mil spec PDP-11 in a slightly rugged enclosure in its place

    Then drive it around West Germany on excercise with the Brit Army.

    Software was loaded from 1/4in Tape on Cassette. (Qic drive)

    The software was RSX-11S and did message store and forwarding over military radio nets.

    Date: 1978

    Project Wavell if anyone remembers.

    Then getting shouted at by an RSM for snappingthe gear lever off of our support rover when it was in 4WD reverse and blocking a whole convoy from making camp. A huge pair of mole grips came to the rescue.

  26. David Haig


    Late seventies Aldermaston replaced their PDP4/7. They couldn't sell it, for obvious reasons, so they gave it to a school outside Reading - but all the manuals were 'unavailable' under the official secrets act (they let us have lead boxes with 1/2 inch tapes in that had 'Danger - exposed in irradiated area' on the box but didn't give us the pin out for connecting the D-Type connectors from teletype to CPU).

    It arrived on a flat bed in two CPU / core memory towers, a teletype, light pen & screen, a startup unit with flipper switches similar to the PDP11 and a 1inch bootstrap reel to reel, with two 1/2 inch tape drives all at 110 volts (with the most dangerous 110/120 - 230/240 transformer I have ever seen). Luckily, the PDP team at Digital in Reading wanted a look at the machine - they'd been denied access whilst it was in a British military establishment. - and we got it fired up as a bunch of 15 -18 year olds running Fortran 77.

    May not have got it to do as much as our PDP11 (argghhh moon landing sim on papertape) or Apple II (god knows how we got hold of that) but learnt a lot about computers from one that needed a whole room to work in.... Best time in my computer life, and that core memory - fix it with a wire wrap tool!

    Mind you, typing up a lighting plot on a telex machine - some other bugger had nicked the Lisa - was another highlight of necessity over technology....

    And they don't know how good they've got it now!

  27. Naras

    Ah - CourseWriter!

    In 1979, my first project was to develop CourseWriter on an EC-1033 (IBM/360 Clone). It ran IBM OS/MFT. We were team of 7, and the customer was the Soviet manufacturer of these clones (!).

    The language we developed it was called Assembler/360. We prepared punched card decks in our office at South Extension, New Delhi and sent it through "courier service" to the data centre at Lodi Gardens. Before sending the decks, we would carefully check the printed letters on top of each card for errors, and correct them with new cards. We would get one "run" and the results would come back the next day in the form of printed output.

    The first hurdles would be JCL errors. After correcting them for about 3-4 runs, we would get compilation errors. Correct them again to get programming errors. While doing so, introduce new JCL, compilation or programming errors. After doing this the first few months, some of us got tired of it. We started going personally to the data centre to wheedle out more runs from the EC-1033 mainframe. It was necessary to offer Chai (tea) to the operator to get more runs.

    We estimated the project to be 6 months for our team of 7. The design was done by my colleague, who had an year's tenure in the industry. We had 3 core modules, Task Control (KCM), file control (FCM) and a terminal control (TCM). I wrote the TCM. The display would be IBM 3270 terminals. The actual language parser in Course Writer would use the services of these modules for its interpret-and-render cycle. This cycle had to use "pseudo-reentrant" code for its calls to the services i.e. no local data storage between calls to any service.

    As months passed, and the core modules got into some shape, we were all doing late nights at the data centre, and sleeping off in the mornings. The bio-rhythms changed, and so did our toilet usage patterns. The saga lasted for 18 months, and took 144 person months. But we did complete the project and delivered it to the customer.

    It was a partly painful, wholly exciting lesson in software projects, Assembly language, design and project management. When I first started using 3270 terminal with the TSO editor to write card decks, submit jobs and see the results immediately, I thanked my lucky stars.

  28. Anonymous Coward
    Anonymous Coward

    This is mobile computing for real men.

    iPads are for those who speak with a lisp and are limp of wrist. Give me a trailer with a PDP-11 any day.

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