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Build Your Own Apollo Guidance Computer

Posted by michael on from the some-assembly-required dept.

PingXao writes "Well, if you can't exactly give the Moon you can give the gift of a computer to get you there. Almost a year ago this Slashdot story about the Apollo 11 Guidance Computer referenced a pretty cool Dr. Dobbs Journal article from their History of Computing series. Now there's this guy who built one in his basement! It took him 4 years, $2,980 in cash, 2,500 hours of labor and 15,000 hand-wrapped wire connections with 3,500 feet of wire to build. It might be next Christmas before you could build one of your own to give as a gift, but he promises you can build your own for less and it will be better than his. The perfect gift for the space geek who has everything. This guy is my hero."

16 of 218 comments (clear)

  1. Kinda makes you wonder, by DoraLives · · Score: 3, Insightful

    with those old boxes, how in hell did they ever make it to the moon and back alive.

    --
    Is it fascism yet?
    1. Re:Kinda makes you wonder, by Detritus · · Score: 4, Insightful

      They had IBM 360s and other big iron on the ground to do the heavy-duty calculations. If you have a choice between doing something on the ground and doing it on board the spacecraft, it's almost always better to do it on the ground.

      --
      Mea navis aericumbens anguillis abundat
    2. Re:Kinda makes you wonder, by UniverseIsADoughnut · · Score: 4, Insightful

      well, you could do it without computers, would just be even harder, plus astronauts would have one sucky time flying the craft by hand to the moon. But it could be done, there is always a way without a computer.

      The other thing is they took a very simple approach to thing, to do it today would be even harder because we would over complex thing thing with uber redundancy and sensors for everything and so forth. Thus why we could get to the moon, or russians get space stations, but the space shuttle and space station suck.

      Not that getting more computers involved is bad, it just makes it easier for things to crap out and not know why. Mechanical stuff is easy to figure out why it's not working, electrical not so much, and code and semiconductors very hard.

      I too look at how we did it, am are amazed it all worked. But then, look at a Model T or a Steam Locomotive, today it seams amazing people would trust those thing cross country or that they would be very durable, but they did it just fine.

      I'm pretty sure my powermac has failed on my more then my atari 800 ever did.

    3. Re:Kinda makes you wonder, by Glonoinha · · Score: 4, Insightful

      Heh.
      Most of us wear watches with more horsepower than a single System 360 of the time.
      I would imagine that every computation performed at all of NASA from T minus 10 until splashdown could grind through my desktop in less time than it took me to reply to this message.

      The difference wasn't in the hardware.
      It was in the people, their abilities, and in the working relationship those people had with each other.
      It was in the management of those people, putting success and excellence above all else.
      It was in the work - putting men on the moon wasn't just a job, it was an adventure and it was a dream.

      --
      Glonoinha the MebiByte Slayer
    4. Re:Kinda makes you wonder, by bigberk · · Score: 3, Insightful
      The difference wasn't in the hardware. It was in the people... it was an adventure and it was a dream.
      I agree with you. Look at the incredible computation abilities we now have, it really boggles the mind. We have made leaps forward in speed, miniaturization, and power usage. Materials science has also brought us an entirely new set of possibilities since then. Now, if we had a real goal -- like to start human exploration of space in earnest (longer missions, more frequent), I think we could really do some amazing things.

      Personally I think we're being really stupid by not funding more space exploration. Yes, I know people on earth are starving. But both you and I know that it's not the starving Ethiopians competing with NASA or ESA for funding...
    5. Re:Kinda makes you wonder, by GuruBuckaroo · · Score: 3, Insightful

      There's a Heinlein quote that I'm trying to think of, that goes something along these lines:

      There are three stages to the development of any technical project. In stage one, the device is simple, does only what it needs to, and works most of the time. In stage two, the device is vastly overcomplicated, overpowered, does far more than it needs, and works occasionally. In stage three, the "improvements" are thrown out, the device is again simple, does only what it needs to, and works all the time.

      I've been waiting for Stage Three for a long time now. My money is on Burt Rutan.

      --
      Poor means hoping the toothache goes away.
    6. Re:Kinda makes you wonder, by UniverseIsADoughnut · · Score: 4, Insightful

      well, they are unstable for the purpose of getting better performance, not to make the concept of planes to fly work. You can build a plane without a computer, and could achieve the same basic concepts, but it wouldn't do it as well.

      Also, planes like the Stealth Bomber are said to not be able to fly without a computer for reasons like you mentioned, especially landing it. But really it's a issue of it makes it practical, not needed. The Northrop flying wing worked in the late 40s and it obviously had no computers. The B2 is based off that planes design (actually has the exact same wing span), the computers just made it more feasible and overall better.

      In the case of going to the moon, it could be done without a computer, rockets went up without computers, plus people make a great computer. The computers for apollo did pretty straightforward stuff, and were mainly there so the astronauts didn't have to keep doing stuff non-stop. They could still sight stars and calculate there path and manual fire rockets to adjust (like they did in Apollo 13),

      The thing is we have all gotten so used to doing stuff with a calculator that we forget you can do it without. When was the last time you did a square root by hand (or even remember how). I think this is the kind of thing that causes people to wonder how things like the pyramids were made, people just can't think of how to do things without modern tools, cause thats all they know. To the Egyptians building them probably wasn't that hard to figure out.

    7. Re:Kinda makes you wonder, by R2.0 · · Score: 2, Insightful

      "There is really precious little to be learned from travel outside our own atmosphere with the technology currently available that cannot be learned more conclusively and safely here on Earth. When one combines this fact with the enormous cost of getting all but the most insignificant payloads into orbit, there is a very persuasive argument for forgetting about our space travel dreams, at least for the present."

      Which completely misses the point - it's not the learning, it's the doing that matters.

      --
      "As God is my witness, I thought turkeys could fly." A. Carlson
    8. Re:Kinda makes you wonder, by westlake · · Score: 2, Insightful
      The Model T compared to a modern car SUCKS

      The Model T entered the market when there were no hard surfaced roads or trained auto mechanics outside the cities, no high octane gasolines, no gas stations, no certainty that fuel or lubricants would be as advertised.
      Under those conditions, a simple, tough, forgiving, automobile with a 20hp engine that can cruise comfortably at 35-40, and gets 20-30 mpg doesn't look half-bad.

    9. Re:Kinda makes you wonder, by jfengel · · Score: 2, Insightful

      Or a networking stack, or threads, or security, or a clipboard, or plug&play, or localization, or...

  2. Already /.ed.... by kerbe6 · · Score: 1, Insightful

    So here's a mirror!!

  3. FPGA by saned · · Score: 4, Insightful

    Not to undermine his job, which I think is a major accomplishment, not only by building it but by reimplementing the whole logic from diagrams. But looking at the logic, it seems it could fit easily in a Spartan 3 FPGA. So yes, it could be done cheaper and faster, but not with the degree of detail this guy put on.

    Kudos to him

    --
    signal_connect(0, "test_top.dut.my_sig", "clk");
    1. Re:FPGA by murderlegendre · · Score: 2, Insightful

      But looking at the logic, it seems it could fit easily in a Spartan 3 FPGA.

      Pretty amazing, isn't it; how far we have come in so little time.. And the fact that this guy took the time to properly execute the project, and document it as he went along, really allows one to gain a sense of scale when it comes to computing devices. This thing has about as much computing power as an Atari-2600 and it takes a truck to move it. And just about ten years later, we were playing pong in the living room.

      And it took people to space, and back again safely. The AGC I mean, not the Atari.

      --
      There's a Starman, waiting in the sky / He'd like to come and meet us, but he hasn't got the time.
  4. No disrespect, but... by fmaxwell · · Score: 3, Insightful

    I have the utmost respect for the initiative, intelligence, and generosity of the man who built this computer. That said, he didn't build a replica of an Apollo Guidance Computer (AGC). He did not use the same parts, constructing it with higher integration 74LS parts that gave about a 10-to-1 IC package reduction. The original AGC prototype used core memory and his uses static RAM and EPROM. There are countless other differences.

    Again, he is deserving of high praise, but he did not replicate the original AGC I prototype. He created a working model which was very true to the original at the block diagram level.

  5. Comment removed by account_deleted · · Score: 1, Insightful

    Comment removed based on user account deletion

  6. Re:Oh? by Detritus · · Score: 2, Insightful
    Your best bet is to take a course in computer architecture or pick up a textbook on the subject, esp. one that has a good survey of older computers that introduced significant architectural advances.

    The IBM 360/91 was an important high-performance member of the IBM 360 family. The CDC 6600 was also an innovative system from the same era.

    The Space Shuttle uses the IBM AP-101. See Computers in Spaceflight: The NASA Experience.

    --
    Mea navis aericumbens anguillis abundat