Apollo 11 Guidance Computer source code

[drhay53]

I thought some of you software folks might find this interesting:

https://github.com/chrislgarry/Apollo-11

 

[Snark]

Moving to Science & Spaceflight.

[sumghai]

This is my favorite issue on their tracker:

https://github.com/chrislgarry/Apollo-11/issues/3

Spoiler

This describes the wiring short that caused the infamous oxygen tank explosion during the Apollo 13 mission

 

[drhay53]

4 minutes ago, sumghai said:

This is my favorite issue on their tracker:

https://github.com/chrislgarry/Apollo-11/issues/3

  Reveal hidden contents

This describes the wiring short that caused the infamous oxygen tank explosion during the Apollo 13 mission

 

The comments are awesome, thanks for that

[Ultimate Steve]

2 hours ago, drhay53 said:

The comments are awesome, thanks for that

"This software has reached end of life and is no longer receiving security updates. NASA strongly recommends that you migrate to a supported version. Unfortunately no such version exists at this time."

 

 

[Gargamel]

Quote

Did you try SCE to AUX?

Even better.

 

 

Edited September 28, 2018 by Gargamel

[YNM]

Hang on... I thought they were "hard-coded", as in the coding was done by physical means of weaving the numerous wires ?

 

What language is it ? Pure machine language binary ?

[drhay53]

1 minute ago, YNM said:

Hang on... I thought they were "hard-coded", as in the coding was done by physical means of weaving the numerous wires ?

 

What language is it ? Pure machine language binary ?

"This source code has been transcribed or otherwise adapted from digitized images of a hardcopy from the MIT Museum. The digitization was performed by Paul Fjeld, and arranged for by Deborah Douglas of the Museum. Many thanks to both."

 

Also: https://www.ibiblio.org/apollo/assembly_language_manual.html

[YNM]

13 minutes ago, drhay53 said:

assembly language

Ah, I see.

Didn't know that ! I genuinely thought they had to physically code it by weaving the many many wires, which sounds really odd, but now it's a bit more sensible.

[satnet]

Actually they did weave it physically in the ROM. They just wrote it in assembly first, then wove the resulting binary program into the memory. Curious Droid has a pretty good video on the subject:

 

[wumpus]

On 9/28/2018 at 7:59 PM, YNM said:

Hang on... I thought they were "hard-coded", as in the coding was done by physical means of weaving the numerous wires ?

What language is it ? Pure machine language binary ?

I doubt it.  When you hear of ROM (from before the 1990s), it typically meant transistors or diodes mean a one, no component means a zero.  The only thing is, unless they were using actual chips (doubtful, memory was "rope memory"), you could produce small/lighter memory using magnetic core (each bit is just a magnetic ring, not a diode).  They might not like this as it wasn't quite as reliable as true "hard coding", but since it could be re-rigged if something else failed (and was strongly reliable on its own), I'd expect that the program was stored on (re-writable) rope memory.

Now that I think about it, it wouldn't be *that* hard to imagine replacing "rope memory" with specific ROMS that only included a magnetic ring on the one and was missing it on the zero.  I really wouldn't expect it to be any cheaper, but they might try it (save what, a few grams?  Worth it in the lander, probably worth it in the command module as well).

[YNM]

49 minutes ago, wumpus said:

Now that I think about it, it wouldn't be *that* hard to imagine replacing "rope memory" with specific ROMS that only included a magnetic ring on the one and was missing it on the zero. 

You nailed it on the head, apparently.

Core rope memory (read-only) :

Magnetic-core memory (random access) :

Edited September 30, 2018 by YNM

[Nuke]

On 9/28/2018 at 1:13 PM, sumghai said:

This is my favorite issue on their tracker:

https://github.com/chrislgarry/Apollo-11/issues/3

  Hide contents

This describes the wiring short that caused the infamous oxygen tank explosion during the Apollo 13 mission

 

i want my hour back!

[DerekL1963]

18 hours ago, wumpus said:

I'd expect that the program was stored on (re-writable) rope memory.

The program was stored read-only (not re-writeable) rope memory - https://en.wikipedia.org/wiki/Core_rope_memory.

[wumpus]

4 hours ago, DerekL1963 said:

The program was stored read-only (not re-writeable) rope memory - https://en.wikipedia.org/wiki/Core_rope_memory.

The wiki doesn't compare mass.  I suspect it isn't much (but *anything* is significant on Apollo command modules and moreso the lander).  It is entirely possible the board it is connected to makes up most of the mass difference (board mass should scale with cubic meter, but is probably less than the mass of the rope).

As far as I can tell, rope is a packaging technology that traded mass for repairability.  It just happened that the only use of rope involved replacing magnetic cores with transformers (for ones only), making it ROM.

[DerekL1963]

14 hours ago, wumpus said:

As far as I can tell, rope is a packaging technology that traded mass for repairability.

Rope memory isn't repairable - once it's woven, it's done.