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OT: Build Your Own Apollo 11 Landing Computer

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  • OT: Build Your Own Apollo 11 Landing Computer

    I'm in awe of the level of spacegeekery.
    Remember the computer on the Apollo 11 Eagle lander that kept reporting "1201" and "1202" alarms as Neil Armstrong and Buzz Aldrin approached landing on the Moon? Well, now you can have one of your very own. Software engineer John Pultorak worked 4 years to build a replica of the Apollo Guidance Computer (AGC), just so he could have one. And then he wrote a complete manual and put it online so that anyone else with similar aspirations wouldn't have to go through the same painstaking research as he did. The manual is available free, but Pultorak says he spent about $3,000 for the hardware.

    The 1,000 page documentation includes detailed descriptions and all schematics of the computer. You can find them all posted on Galaxiki, downloadable in pdf. format (the files are large).
    Now all he needs is a LM to put it in!

  • #2
    I would rather have a replica makeshift air scrubber from Apolo 13.

    Steve

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    • #3
      4 k of ram and 32 k of rom. I have wristwatches that are much more powerful. The real question is WHY? It would be an almost trivial exercise to build an emulator in software.
      Free software for calculating bolt circles and similar: Click Here

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      • #4
        Actually 4k words of RAM and 32k words of ROM.

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        • #5
          Originally posted by Evan
          I have wristwatches that are much more powerful. The real question is WHY?
          Because we all have things each of us find interesting or are fascinated by. I am sure you have built many things to which most most folks would also ask why....

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          • #6
            Why? it is obvious!!!

            Go to the Smithsonian. Go to the Cape. Go to Houston. That same computer is missing in EVERYONe of the displays of the LM.

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            • #7
              I remember the LEM knocking the apollo capsule about a half a mile while attempting to dock. Almost a real disaster. I had a suggestion back then that got me a application for employment.

              Then, I remember buying a scientific calculator a few years later with more smarts than the landing computer.

              Why have we stopped exploring and taking challenges? We should be living on the moon as a jumping spot for other worlds.
              Excuse me, I farted.

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              • #8
                If you are of about my vintage, you may remember very well early minicomputers built using TTL and core memory. Tho he did not use core memory, this guy designed and built an all TTL throwback computer. Did the software for it as well. Pretty impressive in my book.

                http://www.homebrewcpu.com/

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                • #9
                  My internet dead. 200 bytes a minute
                  Free software for calculating bolt circles and similar: Click Here

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                  • #10
                    Originally posted by Bruce Griffing
                    Tho he did not use core memory, this guy designed and built an all TTL throwback computer. Did the software for it as well. Pretty impressive in my book.
                    Agreed -- the Apollo Guidance Computer was a bit-slice design built entirely with bubble-gum logic. This is a very impressive reconstruction.

                    This guy's build was done on perfboard with an insane amount of wire-wrap -- I didn't read through his individual design documents, but I'd be surprised if NASA/MIT didn't use a PCB board, if nothing else, for weight.
                    "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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                    • #11
                      Originally posted by David E Cofer
                      Why have we stopped exploring and taking challenges? We should be living on the moon as a jumping spot for other worlds.
                      http://www.nasa.gov/mission_pages/co...ain/index.html

                      We're on our way

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                      • #12
                        Speaking of the primitive (by today's standards) computers and early orbital and space missions...

                        Way back one of my first out of college jobs was in numerical analysis with an aerospace company. I shared a cubicle with an odd guy. He came to work in the morning, didn't say much, no small talk other than once in awhile ranting about how athletes and movie stars were grossly overpaid. I never knew what he did, he was always hunched over his desk writing something. Never took breaks with the group. No programming that I knew of. I thought he was retarded or had some strange disability and was kept on as a charity case.

                        I started asking around the old timers what was with this guy. Turns out he had done programing on one of the orbital missions that had a major bug in the software. He was rushed to Houston to correct the bug to save the mission.

                        The guy came out of this as a hero. To me, that was weird. It was like everyone forgot he was the one who wrote the software with the bug. I came to find that was the nature of the company's system. Make a mistake and fix it, you were rewarded. Make a mistake and don't fix, that wasn't so bad either. Kind of an old boy's network where you didn't want to punish errors because the next one might be your own.

                        Apparently this guy was riding on the coat tails of his save of the mission.

                        I didn't stay with the company long enough to find out what eventually happened to him, but I imagine as time went on and new management came in his hero status much diminished.

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                        • #13
                          Robert-
                          You did not check the link in my message - it was a different computer, but more impressive in my book.

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                          • #14
                            Originally posted by isaac338
                            But the budget will still only accommodate a 4K word guidance computer
                            Chris
                            Merkel, Tx
                            http://raceabilene.com/kelly/hotrod

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                            • #15
                              Originally posted by Bruce Griffing
                              You did not check the link in my message - it was a different computer, but more impressive in my book.
                              Bruce, I looked at his project, and it's definitely an impressive feat to build your own microprocessor out of 74-series TTL's and port LCC and Minix to it, but it's a weird architecture: he built a 1-byte opcode, so the machine is heavily microcode based, it's got a 16-bit virtual address mapped into a 22-bit physical address space, ...?? He started with a pure accumulator-based architecture (no registers), then realized that porting C was going to be a bitch, then added a couple of registers after the fact...

                              But most importantly, why on earth did he build it out of 30 year old logic components, when he's not faithfully reconstructing a historical design, like the Apollo AGC computer? In other words, why didn't he use an FPGA? If you look at the "Homebrew CPU" web ring, there are dozens of home-built CPU's constructed with 74-series logic, but they were from the 70's and 80's. Most guys these days are building their own microprocessor on an FGPA...

                              In any event, to me, the forensic re-construction of the Apollo computer was more impressive -- reminds me a lot of Rich building a model of the Monitor engine from partial images and vague descriptions in historical accounts...

                              But all are very impressive projects!
                              Last edited by lazlo; 07-15-2009, 04:00 PM.
                              "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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