Thanks! Here are the two past submissions with comments:

Apollo 11 Guidance Computer source code for the command and lunar modules - https://news.ycombinator.com/item?id=22367416 - Feb 2020 (30 comments)

Apollo 11 Guidance Computer source code - https://news.ycombinator.com/item?id=12048945 - July 2016 (145 comments)

The LM landing algorithm was also based on a polynomial, with "time-to-go" as the variable. Problems would occur if that variable went negative.

Given the constant launch delays how could they justify hard coding a 15 day window like this?

And I'm scared to hardcode some negligible config value that will never change

This remains to be my go-to example for how YouTube can be a remarkably effective and valuable platform for the kind of enthusiast whose interests have exceeded the bounds of typical documentaries and media produced for the general public.

It’s sadly getting more difficult to surface these kinds of examples, as we’re seeing a lot of lowest common denominators and slop-py channels run by people who only want to be YouTube content mills, rather than people who have expertise to share and who learned to leverage YouTube as a means to those ends.

and Master Ken and co...

The DSKY was the main input system for the AGC, and commands were inputted using the verb/noun system. Verb says what you want to do, and Noun says what you want to do that verb to.

For example, "Verb 35 Enter" lights every single segment and light on the DSKY, to make sure they're all working. "Verb 16 Noun 17 Enter" displays the IMU measurements, "Verb 16 Noun 36 Enter" displays the current time and "Verb 16 Noun 43 Enter" displays the current GPS lat/long. Verb 16 indicates to display something as decimal, and the noun indicates what to display.

Other commands could be used to input data, or set what program the AGC was running, for example if you wanted to change the current running program to 67, that would be "Verb 37 Enter 67 Enter"

The funniest thing is that DSKY was, IIRC, a "temporary solution" that became the norm, and despite all the platitudes today it was apparently hated by astronauts.

Or you use the virtualagc project linked in the readme to do the same thing without wasting a bunch of money on tokens.

I have been collecting Autonetics artifacts off ebay for decades. What I find interesting about this time period is that Autonetics made 3 different efforts for digital inertial guidance. The first version used vacuum tubes and was never commpleted. The second version used the new discrete components developed by Sprague Electric. This version went into production. Autonetics then set about exploring the lithographic process to shrink the discrete component version into an IC based system. Autonetics essentially built the same computer using 3 different circuit construction methods. Here are some pictures of pieces of all 3 systems. The IC's are from about 1967.

One of the 2 nerds in the photo is Richard Stallman next to the Autonetics D-17B. An early inertial guidance system distributed to universities to study as real time computers after decommissioning.

There are also the hard disks(which the D-17B used as a clock) and gyroscopes that served as inputs.

https://www.icloud.com/sharedalbum/#B1iG4TcsmGWIVSf

> knowing that Apollo 11 is coded purely in assembly

Of course. According to Wikipedia, it was introduced in 1966, so it's development must have been started earlier. Also according to Wikipedia higher-level languages like Fortran and Cobol were introduced in 1957/58. They were a cutting-edge technology of the era.

So programmers of the day would have been comfortable with assembly, and the inefficiency and novelty of higher-level languages would have probably been a bad fit for the application.

> Not sure if it has any compiler.

What you're looking for is an assembler.

The assembler you're looking for, is called YUL. [0]

You can find much of that code here [1], but unless you have a Honeywell, it isn't much help. yaYUL is a modern remake, and can assemble most of the Apollo code.

[0] https://www.ibiblio.org/apollo/Documents/agcis_13_yul.pdf

[1] https://klabs.org/history/software/yul/

Part of the AGC ROMs implemented a virtual machine for things like matrix multiplication. So, a higher level of abstraction was available but it was still very much coded in its own assembly language.

With our current RAM prices we may soon need to lose lowercase again.

Not the same goals, risks, monetary budget, time budget.

If your goal was to absolutely prevent any errors and you would go great lengths to do it, you would.

Just look at any safety critical systems: medical, transportation. There has been some incidents, but some systems do work really well that are developed today.