Meet Margaret Hamilton, the badass '60s programmer who saved the moon landing

Posted by $ nickursis 8 years, 11 months ago to Technology
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Something for the old folks (like me) I remember seeing roped memory. I thought this was an intresting insight into just how the Appollo moon lander got it's programming, remember when landing on the moon, Neil Armstrong had to drive himself because the computer was too slow and locked up.
SOURCE URL: http://www.vox.com/2015/5/30/8689481/margaret-hamilton-apollo-software


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  • Posted by khalling 8 years, 11 months ago
    great article! Her smile is infectious! I really enjoyed that. "Roped memory" is an excellent reminder to those (including software engineers) that software is a way of "wiring" the hardware.
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    • Posted by ewv 8 years, 11 months ago
      Software does not "wire" a computer, it is used to control it. The "wiring" does not change while a program is running. There have been many ways to represent binary states in computers; the Apollo guidance computer (which had less power than the one on your desk, lap, or hand!) used integrated transistor circuits with a combination of transformer coiled ("roped") and magnetic core memory. The essence of software is that it is a means to logically control the states of a machine regardless of how those states are represented in hardware. That includes the original punch card programming for mechanical gears and levers in Babbage's original computer design in the 19th century.

      But Hamilton's smile was typical of the sense of intellectual accomplishment in logically programming computers in a new field. (It's good thing she was short, if she were taller they wouldn't have had time to write more code for a higher pile!)
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      • Posted by $ 8 years, 11 months ago
        My understanding is the roped memory acted as a ROM (Read Only memory) since by making it physical instead of any of the (then new) DRAM that was available to DARPA, they could avoid any possibility of corruption. There was a lot of questions then in regards to cosmic ray damage to electronics. A lot of the boot systems used for mainframes had it just like todays BIOs. I had a similar boot system on 2 UYK-7s on a Trident SSBN back in the 80s and early 90s.
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      • Posted by khalling 8 years, 11 months ago
        we have argued this before and I think we have different understandings of what switches do. I'm not going to hijack the post for that discussion. I do agree with Hamilton's smile reflecting a sense of life I so appreciate.
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        • Posted by $ 8 years, 11 months ago
          I'm ok with that, the technology side is just a side conversation on the main. I liked the article because it showed just how someone who is producing, is doing it in the background, yet it was a vital piece of the whole. And she didn't really get the recognition some others did. There are probably a lot f stories similar to this with Apollo.
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        • Posted by ewv 8 years, 11 months ago
          What switches do is an elementary fact. The claim that software "rewires" circuits is a misunderstanding. The essence of the role of software is that it is used to control the hardware for a specific purpose.

          The sense of life illustrated in Hamilton's photos is what has kept so many people up for long hours and overnight so many times again and again building software for ever increasing intellectual challenges -- while the likes of nihilists like Obama were hanging out on drugs, then project their own mentality with the "you didn't build that" nonsense as they seek power over those who _do_ "build that". Computers and electronics in general could make such enormous progress over several decades because the bureaucrats didn't understand it or realize it would, by their premises, be worth controlling. There have been ominous signs that that freedom is now being undermined. You don't find Hamilton's smile under the fist of a Cuffy Meigs.
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          • Posted by dbhalling 8 years, 11 months ago
            No it is not a misunderstand it is a fact. A switch changes the direction that current flows. That means that when a switch changes it changes the wiring. The current flows to a light if the wiring (switch) is set one way and not the other. That is rewiring PERIOD. And that is all that software does
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            • Posted by ewv 8 years, 10 months ago
              Switches restrict the paths of current flow. They do not change the wiring, which remains in place and connected to the poles of switches. Yelling with capitalized spelled out punctuation doesn't change that.

              Software does not physically do anything, let along throw switches or change wiring. Software consists of sequences of instructions read into a computer and interpreted to sequentially change states at the clock rate and in accordance with the possibilities in the instruction set built into the hardware. Computers are not made of millions of physical switches, let alone switches thrown by software, let alone circuits rewired by software. A "switching circuit" refers to changing binary states, not to physical switches and not to "rewiring". Physical switches used for that have not been the basis of "switching circuits" since before World War II when relays were used. There are many ways to represent binary states; the commonly used transistors do so by voltages exceeding a threshold on a continuous characteristic curve, not by acting as literal physical switches.
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              • Posted by dbhalling 8 years, 10 months ago
                what a bunch on nonsense. Of course they change the wiring. They change the current flow.
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                • Posted by ewv 8 years, 10 months ago
                  Current flows _within_ the wiring. Changing the patterns of current flow within a physical circuit does not change "wiring". When you turn on a light switch you are not "rewiring" your house. Software does not "rewire" the circuits in a computer and my summary of its relation to the hardware is not nonsense. Those who are interested in how computers work and how software and hardware work together can read about it for themselves.
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              • Posted by CircuitGuy 8 years, 10 months ago
                Is sequential VHDL (i.e. VHDL inside a Process) code used to change wiring?
                Is sequential VHDL software, or do you call it firmware because it configures an FPGA rather than being feteched-decoded-executed by a state machine?
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  • Posted by $ Thoritsu 8 years, 11 months ago
    Now that is a hot woman! Sigh.

    Love the "Core" memory note. That stuff was so cool. Non-volatile from the start! Back when 16 bits was the size of a roll of lifesavers.

    Necessity was the mother of invention = good code. Today, code is a monstrous pile of resource hungry lines, analogous to the young people today. Anybody else remember the DOS editor, TED, a tiny editor ~8K total, with all the Word Perfect controls...cntl+k+b...cntl+k+k...cntl+k+c...
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  • Posted by $ MichaelAarethun 8 years, 11 months ago
    Back then they were stlll dealing with two spaces for the year to save space. almost thirty years later I got my first computer in CPM a Kaypro with 64 K of RAM. We've come a long way...
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  • Posted by saucerdesigner 8 years, 11 months ago
    Great article. In 1980 I worked as a designer/drafter at C. S. Draper Labs in Cambridge, MA on the inertial navigation platform for the Navy's Trident Missile program. I'd never heard of Margaret Hamilton before now.
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  • Posted by Herb7734 8 years, 11 months ago
    When my son worked at NASA he told me about this legendary software engineer, Margret Hamilton. What? The woman who played the witch in the "Wizard of Oz?" He gave me his famous eye-roll and said, "Dad, you're showing your age, and playing dumb." Personally, I counted that as an achievement.
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  • Posted by jimslag 8 years, 11 months ago
    The pre-wired part of the computer was actually the ROM as brought up by ewv. A lot of instructions to the computer were in the ROM and the "software accessed the necessary parts of ROM as needed in the program. All that had to be hand wired in manufacture and was engineered by the program. I started with computers that were mainframes and had tape drives or early hard disks that were tucked into a special air conditioned, computer room and took up numerous cabinets. Most of those computers had less computing power than the average cell phone and it doesn't even have to be a smart phone. My wrist watch has more memory and a faster processor than those computers.
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    • Posted by ewv 8 years, 11 months ago
      The integrated circuits were also "pre-wired" (though the miniaturized conducting paths are not literally "wires" at all). The ROM transformer coils were hand wound and connected; the integrated circuit boards were manufactured by Fairchild. The built in instruction set is what the software sequentially uses to control the states in the machine. Whether using huge computers in rooms filled with cabinets and 80 MB disk drives the size of a large washing machine or what we have today, it is all an amazing achievement of the human mind implementing an engineered integration of conceptual, logical thought and action in material reality.

      An excellent explanation of the role of mathematical and logical abstract systems underlying the operation of a computer, as well as the physics of transistors used in them to represent the binary states, is our favorite modern physicist Richard Feynman's Lectures on Computation http://www.amazon.com/Feynman-Lectures-C... It goes well beyond the elementary description of computers as "cpu + memory + io" etc, yet is very well presented and understandable.
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  • Posted by $ allosaur 8 years, 11 months ago
    I recall being in a high state of suspense while watching (the in real time simulation of) the moon landing on TV way back in 1969.
    Simulated was the moon's ground coming up beneath an animated flame.
    I do appreciate someone finally telling me about Margaret Hamilton 45 years later.
    Thanks, nickursis.
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    • Posted by $ 8 years, 11 months ago
      You are very welcome, I just stumbled across it. I remember living in Sweden at the time and they overlaid Walter with a Swedish woman's voice translating. The result was a bit bizarre.
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  • Posted by strugatsky 8 years, 11 months ago
    What I most appreciate about the article, is that it written about an interesting person, an interesting time and gives a reader something to think and learn from. Only incidentally it happens to be about a "woman." It is refreshing to acknowledge an achievement of a person, as opposed to today's sickening push to create achievements for groups of the month.
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  • Posted by Temlakos 8 years, 11 months ago
    I remember Astronaut Armstrong saying he had to steer clear of the original LZ, which was a football-field-sized crater strewn with automobile-sized boulders.
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    • Posted by $ WilliamShipley 8 years, 11 months ago
      At the time, everything seemed so routine -- if landing on the Moon can be considered routine. Only afterward have we found out that the 1201 and 1202 alarms which were quickly overridden were potentially mission ending computer errors.

      I had also been under the impression that the 60 seconds and 30 seconds were not the time to landing but the time to a fuel level abort.
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      • Posted by ewv 8 years, 11 months ago
        What seems routine and is taken for granted throughout the engineering that modern civilization relies on is filled with constant problem solving. Solving problems, one after another, _is_ the routine in engineering and science.

        Earlier in the engineering development of modern American civilization there was a saying about engineering: "The difficult takes a week, the impossible takes a little longer." We don't see that positive attitude nearly enough now as viro nihilists and 7th century religious fanatics morally denounce "development" and "industry" and are pandered to by civilized people who ought to know better.
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    • Posted by CircuitGuy 8 years, 11 months ago
      I heard that. I heard they struggled to find a landing zone with a flat enough grade because if the grade were too steep they would not be able to take off again. They had something like 60 seconds of reserve fuel that was supposed to be for emergencies, but they used some of it b/c paraphrasing Buzz Aldrin, you don't have the right stuff if you come all this way and abort the landing to maintain a reserve.

      While all this was going on, they had two false alarms.

      I hadn't heard of Ms. Hamilton or how she wrote a custom RTOS of sorts that helped save the landing. Very cool.
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      • Posted by Temlakos 8 years, 11 months ago
        This also explains why CapCom said back to them, "Roger, Twank--uh, Tranquillity. We copy you on the ground. You've got a bunch of guys about to turn blue. We're breathing again. Thanks a lot."
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  • Posted by johnpe1 8 years, 11 months ago
    I spent 11 years, one night, trying to code the y12
    nuclear weapons components factory production
    system. . we were using knowledgeware code-
    writing software. . we only achieved part of the goal,
    buying Comets for scheduling the work. . I worked
    with one of the Margaret Hamiltons enough that
    I proposed marriage. . she married someone else,
    and is living happily ever after!!! -- j
    .
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