Photo celebrates unsung NASA software engineer Margaret Hamilton



You forgot one other important detail.

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I believe one of my college math professors, also a woman, was on the moon landing programming team. Such a shame that more of this isn’t heralded, especially since “programming” was considered akin to stenography at the time, many of the more talented women from that era are likely miscategorized as “support personnel” rather than being given credit for their significant contributions.

Aside; I watched The Imitation Game the other day and was seriously disappointed by the way that Joan Clarke was portrayed. Overall it was a very interesting story, but not a terribly good movie.


Not to be confused with the actor.


Was this the code “braided” into Rope Core Memory?

I really want a chunk of that stuff. It just sounds so freaking weird/awesome.

in the interview she puts “rope mother” alongside “systems guru”. searching turned up little. tell me more! :smile:

I don’t know a whole lot about it myself. Just that it was a way to physically program code with wires. Which I find just amazing. We think of computer code as sort of ethereal - “It’s IN the computer.” Sure we have disks, but they may as well be magic. We can’t ever see it or hold it. We can print it out, but then the computer can’t understand it.

The rope core with the way it was made programmed the 1s and 0s. So it is like ROM memory the computer could read. But at the same time its a physical “thing”. Like if you carved code into rock or printed it out and the computer could still read it.

IIRC they approached places like linen companies, where people were used to working with fine threads all the time, and had women basically weaving code. Harkens back to the day we would weave stories into blankets as well.

I assume you read this -


Found a probably related reference:

“Indeed the IL began assigning a person responsible for the program for a particular flight, for managing it through the entire process from coding through manufacture and test. In typical IL style, they called this person the ‘rope mother’ (though it was usually a man).”

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Thank you so much, this is so fascinating. It’s like my computer history went from punch cards to magnetic tape, skipping this entirely.
This is totally a DIY computer tinkerer dream, I’m so putting down the Arduino for a while and start weaving some code!

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Nasa actually released all their source code, but here are some links I found:

Source code for Apollo and Gemini programs -

In case you’re interested, there’s also an emulator available for the guidance computers in those programs. I haven’t played with it myself, but it looks like there’s a fair bit of documentation for it.

[edit] Oops, that site is also what the page you linked to eventually links on to. Never mind. :slight_smile:

I can’t remember the actual code number, but if you watch the Apollo 11 landing, there is quite a pucker moment. They call out and error code, which basically meant the computer was down and they would have to land manually. They acted like it was no big thing.

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With a microscope, we can see the structures that hold the information fairly well. With a school-grade optical microscope we have to be happy with older chips, but e.g. the instruction decoder matrix of any processor looks fairly telltale; long parallel lines of the instruction word, with perpendicular shorter wires that are connected only to some of the long lines and lead to the tangle of processing structures right next to this “dislocated crystal”. (Then there are caches and other memory structures that are much more regular.)

Similar to punching holes to cards or to tape. Or to manually burning fuses in a PROM, in my case a stepper motor encoder made from a 74188 chip and a 74193 bidirectional counter.

Things are pretty physical even today. We just keep forgetting that because all those amazing microstructures are hidden in opaque epoxy cubes, so within reach but at the same time so out of sight.

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Not to take anything away from her achievement, but she didn’t “write that code by hand”. Those are “listings of the software developed by the team she was in charge of, the LM and CM on-board flight software team.”

Old school, represent! Have you ever tried programming a sequence using hydraulics or pneumatics? This used to be commonly done (and may still be; it’s been years since I did it) in heavy manufacturing.


I recall watching a programme about rope core memory … but I’m damned if I can remember where. It could have been Hanks’ (excellent) From the Earth to the Moon series. Hmm. Maybe youtube.

Edit: oh, ok, [rope core memory nasa] at youtube returns a whole bunch of videos.

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Margaret Hamilton mentions her current work on USL “Universal Systems Language”. A taste of USL:

Systems are asynchronous, distributed, and event-driven in nature, and this should be reflected inherently in the language used to define them and the tools used to build them. This implies that a system’s definition should characterize natural behavior in terms of real-time execution semantics, and designers should no longer need to explicitly define schedules of when events are to occur. Instead, events should occur when objects interact with other objects so that by defining such interactions the schedule of events is inherently defined.

It should be noted that most of the team she led at NASA was men. As she says: “In the case of the Apollo project my colleagues (mostly male) and I were friends and we worked side by side to solve challenging problems and meet critical deadlines. We concentrated on our work more than whether one was male or female.” While those who contributed to such great efforts all deserve recognition, Margaret Hamilton is getting her second 15 minutes of fame precisely because she is a woman; nearly all the Apollo-era engineers and others contributing to the design and building of the spacecraft and other technical efforts were men, many of whom should also be remembered for their work.

Hamilton may give the wrong impression when she states “We still do other things out of ignorance today, such as continuing to pay women lower salaries than men.” While it is <a href=">true that overall there is a 6.6% gap in pay between college graduates even after correcting for just about every imaginable factor (“graduates’ occupation, economic sector, hours worked, employment status (having multiple jobs as opposed to one full-time job), months unemployed since graduation, grade point average, undergraduate major, kind of institution attended, age, geographical region, and marital status”), this is specifically not true for engineering, math, computer and physical science professions. There is an apparent gap when comparing graduates with these majors, but it is due to a greater proportion of women than men choosing to pursue other careers after majoring in these subjects. Comparing those actually working in these fields shows no gender pay gap. (On the US national level, not just college graduates, correcting for nothing, the hourly pay gap is 14%. However the spending gap between men and women goes strongly the other way, with women spending more than men, but the exact proportion is unknown. Some indications of the gender imbalance of control of spending can be seen for instance in the consumer market in the prevalence of female-targeted ads and the proportion of space devoted to men’s vs. women’s clothing in stores, and in the business market in the overwhelming prevalence of women in HR - over 85% - a group which virtually determines who gets what jobs at what wages.)

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cool, thanks! i was too hung up on finding “rope mother”, and only found what @Nonentity also found. i am so re-coding all future programs into conductive fiber blankies.

hmmm… stories in blankets… how about a game with leds or elwire as a display and the memory in the blanket itself… :smiley:

it really might not be much of a stretch:

  1. she wasn’t just a manager, she was an engineer.
  2. on some teams, the lead – which she was — often writes a lot of core code themselves.
  3. most of the programs were doubtless written on paper (ie. the by hand part) before they were punched, or woven(!)
  4. how much code can fit in 78kb!?
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Quite a lot. At least used to, in the Dark Ages of Handcrafted Machine Code, long time before Objects ruled the sources with their bloated hand.

Today you can still see glowing shards of these forgotten gems on the demoscene, in the form of e.g. “4K intros”, graphical eye-candies limited to 4096 bytes of binary code.

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