The PDP-1: The Machine that Started Hacker Culture

One of my bucket list destinations is the Computer History Museum in Mountain View, California — I know, I aim high. I’d be chagrined to realize that my life has spanned a fair fraction of the Information Age, but I think I’d get a kick out of seeing the old machines, some of which I’ve actually laid hands on. But the machines I’d most like to see are the ones that predate me, and the ones that contributed to the birth of the hacker culture in which I and a lot of Hackaday regulars came of age.

If you were to trace hacker culture back to its beginning, chances are pretty good that the machine you’d find at the root of it all is the Digital Equipment Corporation’s PDP-1. That’s a tall claim for a machine that was introduced in 1959 and only sold 53 units, compared to contemporary offerings from IBM that sold tens of thousands of units. And it’s true that the leading edge of the explosion of digital computing in the late 50s and early 60s was mainly occupied by “big iron” machines, and that mainframes did a lot to establish the foundations for all the advances that were to come.

At the time, computing was Very Serious Business Indeed. Big iron cost big bucks, and even a modest mainframe system was a huge capital investment for a company. So deep-pocketed customers dominated the market, and their needs shaped the hardware. More often than not, the primary need was to deal with big accounting problems, like running weekly payroll or quarterly profits. Computers of the day were primarily operated in batch mode, where stacks of punch card containing the programs and data were fed into the machine, outputting results hours or even days later. A computer operator was someone to move stacks of cards around and gather output, and the idea of sitting at a terminal was unthinkable. But DEC founder Ken Olsen had a different vision:

“We had a dream of interactive computing. Normal computing was considered big, expensive, awesome, beyond ordinary people. Interactive computing was exciting and fun, and people could interact directly with the computer.”

DEC was a very young company focused on selling its “Digital Laboratory Module” line of system building blocks to engineers, who more often than not used them to build test rigs for computers. Business was booming, and when Olsen laid out his vision to engineer Ben Gurley in 1959, the company had the resources to move quickly.

In just three and a half months Gurley and his team brought the Programmed Data Processor-1 to market, building it largely from DEC’s existing modules. The machine was smaller and cheaper than the mainframes of the day, and so it appealed to smaller companies and academia. In fact, the prototype was donated to MIT, where some of the more famous applications for it were developed. The video below shows the PDP-1 that the Computer Science Museum has lovingly restored running some of those, including Spacewar!, an surprisingly sophisticated game from which later classics like Asteroids clearly drew inspiration.

The bottom line is that the PDP-1 was really the first computer that encouraged users to sit down and play. While IBM machines did the boring but necessary work of business behind closed doors and tended by squads of servants, DEC’s machines found their way into labs and odd corners of institutions where curious folk sat in front of their terminals, fingers poised over keyboards while a simple but powerful phrase was uttered: “I wonder what happens if…” The DEC machines were the first computers that allowed the question, which is really at the heart of the hacker culture, to be answered in real time.

So if you happen to be in Mountain View some day, pay a visit to the PDP-1, the machine that started everything by making it okay to play.

[Featured image source: The Dot Eaters. Thumbnail source: Joi Ito via Wikimedia Commons]

32 thoughts on “The PDP-1: The Machine that Started Hacker Culture

  1. I went to the Computer History Museum quite a few years ago. Part of my fun was seeing all the computers that we used to have at home because the micro age was born and grew during my early adult years. When I went to the museum was not that large but well worth it. One of my favorite was one of the first servers of Google, basically PC boards on a rack separated by plastic something I would have done to get the proof of concept out the door.

  2. i have been to bletchley, this looks absolutely awesome as well, it amazes me how creative a lot of the problem solving is in old computers, bedstead paper memory was absolutely brilliant.

  3. Check the opening times before going to the Computer History Museum!
    Once I was there on a Tuesday: closed :-(
    Fortunately I was able to redo it a couple of years later. It is awesome!

    1. One day I was visiting the Computer Museum in Boston and helped debug a problem with that PDP-1. A bit in the paper tape read register was stuck and was hanging the data bus. A quick module swap (4 bits per module) got it back to running Spacewar…
      I still have that module around here somewhere.

  4. Another recommendation for visiting the CHM. Well worth the trip if you’re in the area. Plan on spending at least 3 hrs.

    When I was at UMass/Amherst, in the 70s, we had pieces of a PDP-1 there. I remember the display and the NCR typewriter, and a lot of module parts and frames. Perhaps a few card cages. I don’t think it was ever operational, maybe a prototype or pieces they didn’t want any more. We also had a 2 ft section of some sort of missile. It was interesting, seeing how they packed the electronics into the round form. Never got the backstory on either of them.

    CSB: One of my classmates sent away for an Intel 8008 student eval kit, and proceeded to build an 8008 system on three (maybe four) large prototyping boards (the white strips into which you plug DIPs and wires). The thing took up most of the bench, and at the end of it, he had a video display and a Pong program. He ended up getting a job at Intel when he graduated.

  5. HaD said: “The PDP-1: The Machine that Started Hacker Culture … at the root of it all is the Digital Equipment Corporation’s PDP-1. That’s a tall claim for a machine that was introduced in 1959 and only sold 53 units, compared to contemporary offerings from IBM that sold tens of thousands of units.”

    Yeah-OK. But to claim the PDP-1 is “…at the root of it all…” is a bit of a stretch IMHO HaD…

    I say the IBM 1130 (c.1965+) “Started it All” for “Hackers” due to the numbers sold, longevity, a removable/replaceable disk cartridge, and decent documentation that allowed users to break-out GPIO (with care mind-you).

    https://en.wikipedia.org/wiki/IBM_1130

    The 1130 had boards that were user serviceable if something went bad, and the software was fairly friendly when it came to writing device drivers in assembler accessible via a high-level language (almost always FORTRAN). Then there was the freedom introduced by the removable disks (cartridges).

    I actually built robust general-purpose PHY GPIO interfaces for devices that connected to an older IBM 1130 when I was working trying to pay for my EE degree (yeah, I’m old – but still Dangerous). It didn’t take long before I understood why I was dealing with an 1130 vs. something like a PDP-11.

    The 1130 lived long after it should have, for good reasons. I remember dealing with old IBM 1130 machines even after the likes of the PDP-11 appeared. The primary reasons old 1130s lived were (1) the 1130’s hardware was well documented and user-serviceable (IBM-intentional or not), (2) 20mA current-loop TTY (later RS-232) interfaces/drivers were eventually hacked into existence for the 1130 (no more card-punch stations or huge page-printers), and (3) you could always trust that an older 1130 would just WORK without draconian license and maintenance “contracts” that DEC aggressively enforced through intentional obscurity (arguably, we call it DRM these days). IBM did this too, but by then it was too late, the 1130 just worked, and there was no need for IBM involvement any more. Plus later on, due to numbers sold you could always find replacement parts for the 1130 from donor machines.

    So be careful when you make a sweeping claim that a particular machine “Started Hacker Culture”. There’s a LOT more to backing that statement up, not just how old the machine was.

    1. You are a bit wrong. First computer that helped create hacker culture was TX-0 at MIT Lincoln Laboratory. First future hackers started experimenting with it in 1950s. Then they’ve got access to PDP-1 and used their experience with “tixo” to create awesome software for it. Without PDP-1 and its interactive mode of operation development of hacker community would stall for years perhaps. Unix was later created on DEC PDP-7, not on IBM machine. Its first port was for PDP-11/20, not IBM machine. TX-0 and PDP-1 are the beginning of computer hackers, not IBM machines. And without success of PDP-1 other DEC computers might not have been created…

      1. @Moryc

        Nice reference to the TX-0 (c.1955/6), and let’s not forget the TX-2 (c.1958, the TX-1 was skipped). The TX-0 & TX-2 were progenitors leading to the DEC saga. (Yet another thing left out in the HaD O.P.)

        https://en.wikipedia.org/wiki/TX-0

        https://en.wikipedia.org/wiki/TX-2

        But when you say “You are a bit wrong.”, I disagree. The 1130 was a little later in date, but the take-up was much larger and as stated in my post resulted in many (if not most, especially later in-time) users hanging on to the 1130 because it was so “Hackable”. Read the paragraph in my post after “The 1130 lived long after it should have, for good reasons.”

        Bonus: Does anyone remember where the ASM place-holder directive *-* came from? AFAIK – from IBM, especially in the once-ubiquitous shared 1130 code examples among users. So maybe the 1130 was the machine that started Open Source Software movement? It’s arguable, but good for the next retro-computing click-bait blog-post title!

      2. Gees… you guys… all of you have bursted my bubble. I thought I was a dinosaur and one of the true “first” historic programmers when I started with the PDP-11 in about 1974. Now I learn there was a generation of REAL programmers that had already retired by the the time I started!

        I built my first S-100 system in between dropping off data “job” cards overnight for a IBM mainframe in about 1975 and thought I was cutting edge. I feel so young again :)

    1. Nah, Zuse or Babbage have a much better claim, unless the model train people had some really really really impressive stuff. Relay logic’s been around as long as relays.

  6. I had done a similar display for the PiDP-8 running Spacewar, which plays in a fairly similar way to the original, on hackaday.io. I was hoping that someone else would pick it up and refine the code, but I don’t think that anyone else with a PiDP-8 has tried it. The code made the screen too ‘flashy” to run with a star background, and at least some of this had to do with the nature of multitasking on an ESP8266 (the rest of it, my iffy coding skills). I may pick this up again once again when my ESP32 shows up.

  7. I’VE BEEN THERE! :D sorry from England and I went there last year when work sent me to Facebook HQ in September 2016 and saw the demo of this machine as well as having a go on space wars! was AWESOME! cannot recommend a visit there enough. and the good old boys who did the PDP demo were the ones who wrote the original programs (music synth, space wars and others programs) in the 60s as well as were the ones who helped restore it. they have some fantastic tales to tell (which i wont spoil for you :D)

  8. I’ve been to the CHM twice. During the first visit I was able to see more machines. Then they remodeled and made a path and it feels like you see fewer machines. But they had other new stuff to see. The highlight for me though was seeing the Babbage Difference Engine (serial number 2) do sums. It was amazing! It’s not there anymore (it’s back at its owner’s home).

  9. Thanx for posting this info about the PDP-1. I had never seen one before. I watched the video with Lyle Bickley, and it was really interesting to me, since my very first experience with a computer that I could actually touch, was with a PDP-11/45. The PDP-11 still had toggle switches and lights. The machine was at a research foundation at Univ. of Waterloo in the 1970’s, and it had just been setup, and had no disk-drive connected yet, and I recall using the front panel to toggle in a 4 line machine language program in octal, to send a ctrl-g to the console, and then branch back to beginning. I remember being so pleased when I toggled in the octal start address, and then toggled “Run/Stop”, and the console went: “beeeeeeee…” until I toggled “Run/Stop” again. It was magical. I was just messing around, waiting for a friend to finish his work, so we could go out and drink beer, if I remember correctly. I wasn’t even in computer-science, but messing about with that PDP-11 was a real education. I had only used cards+listings, or 3270 terminals on IBM mainframes before that, and the mainframe was sealed in a big room where only “systems” people could go. To mess around with (“hack”, we would say now) a real computer, and make it do something interactively, under one’s direct control, was very liberating in a way that is hard to explain to people nowadays, since that is everyone’s experience now.
    And I am really impressed by seeing Spacewar, and learning that it was only 4K of assembler code! And that radar screen with the light-pen and the persistant phosphor is just magical.. and the “Snowflake” program proves it. And all this in 1959! I didn’t realize DEC was making machines that far back. And it ran DDT! Thanx again for posting the video, and bravo to everyone who worked on restoration of the PDP-1. The whole configuration looks like it could be on the bridge of a 1959 Orion nuclear-powered spaceship (which, in actual fact, I suppose it could have been…)

  10. That takes me back. I learned BASIC programming on a PDP-8i computer, surprisingly similar to this PDP-1, back in the early 1970s. My high school was one of only four in the country in 1971 that had its own computer. Most other schools had to tie into some nearby university computer by acoustic-coupler at 175 baud to do their programming. We had three ASR-33 teletypes with paper tape punches and readers for input/output and would change the compiler or interpreter by punching in an octal “fat-finger routine” in the control console, which would then load a large fan-fold tape like the one in this video. I got so good at BASIC my teacher asked me to tutor the language to some honors 9th graders who were bused in from a neighboring Jr High school to use the computer. That became my first computer job. However, the machine didn’t like power surges and broke down at least once a week. I got to know the DEC field engineer very well as I watched him troubleshoot the thing down to component level where he’d often solder in a new transistor or DTL chip rather than replace the module it came from. I didn’t know it then but I would soon make my own career as a field engineer for Honeywell Information Systems, and about 15 years later found myself overseas working on military Honeywell H716s. Those were very similar machines having 4K core memories,16-bit words and 10-platter/16-megabyte disk drives. Bringing up the fans and watching the blinking lights after a long repair was music to my ears!

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