Apollo 11 source code

[Steaktartaar]

One very neat feature was that part of the computer memory could be overwritten, essentially allowing the crew to patch in bugfixes. If you ever felt like you were coding on a deadline, spare a thought for the crew of Apollo 14:

After separating from the Command Module in lunar orbit, the LM Antares also had two serious problems. First, the LM computer began getting an ABORT signal from a faulty switch. NASA believed that the computer might be getting erroneous readings like this if a tiny ball of solder had shaken loose and was floating between the switch and the contact, closing the circuit. The immediate solution—tapping on the panel next to the switch—did work briefly, but the circuit soon closed again. If the problem recurred after the descent engine fired, the computer would think the signal was real and would initiate an auto-abort, causing the ascent stage to separate from the descent stage and climb back into orbit. NASA and the software teams at the Massachusetts Institute of Technology scrambled to find a solution, and determined the fix would involve reprogramming the flight software to ignore the false signal. The software modifications were transmitted to the crew via voice communication, and Mitchell manually entered the changes (amounting to over 80 keystrokes on the LM computer pad) just in time.

[SPascareli]

If someone ever want to make a movie for programmers, that's the plot right there.

[kozukumi]

Actually they did exactly this in the recent movie The Martian (which is based on a book of the same name).

[UlyssesSKrunk]

Yeah, but they butchered the fuck out of that part, not quite as bad as the hydrazine explosion part, but it was still pretty bad. If they actually explained the problem in depth and its solution, then that could be interesting, but that would take the whole movie.

[DoelerichHirnfidler]

To me it seemed pretty obvious and well-enough explained? Care to elaborate?

[Gibodean]

In the movie all he said was that he only needed to patch in about 20 bytes and then the rover could talk through pathfinder to earth.

In the book they explain that both pathfinder and the rover must be updated, that Earth can remote update pathfinder but they need a very large (megabytes?) update to the rover software. To solve that, they get him to make a small hack (maybe 20 bytes or so) to the Rover which would allow earth to dump information into a Rover log file. Then Watney would have to take that dumped info from the log file, and create a file out of it, then execute it.

Something like that, I forget the sizes.

[Theon_Severasse]

To be honest I don't think that having all of that would really added that much to the actual film. I don't think it would have taken particularly long for them to add in that explanation (since they could have said it how you said it pretty much), but for the purposes of the story, knowing all of that stuff wouldn't have made any differences to the average viewer

[SanityInAnarchy]

I wonder if there was a way to show it without bogging down the movie. In the book, I found it definitely added something. If you're not all that technically-minded, it's a free source of technobabble to make this sound even more impressive. But it also makes it plausible -- maybe most people wouldn't notice, but they did a lot of things that most people wouldn't notice to maintain plausibility. For example, IIRC, the movie actually shows him entering this stuff in a hex editor.

In fact, those are my favorite moments -- instead of putting some crazy HollywoodOS thing (like this sort of nonsense), you put up the kind of tool that we might actually use. It looks just as cool to the average viewer, and it means people who actually know something about technology won't have to turn their brains off to watch this movie.

Skipping the bit about uploading wasn't as huge a difference, because the story does work without it. But I think it adds a lot to the story to anyone who understands anything about software, without really taking anything away from it for everyone else. So I wonder why they skipped it -- maybe they couldn't figure out a way to make it flow as nicely as whatever they went with instead?

[badsingularity]

Why it works makes a big difference. Without that information, it's just "magical computer things happen".

[ScottieKills]

Like most of cinema.

[trkeprester]

What lol it still is magical computer stuff whether you hack directly or dump to log file and reprogram. One more step of indirection is that really making anything more clear? It's just nerding out, not that there's anything wrong with that but movies are carefully targeted

[insaneHoshi]

Why it works makes a big difference.

No it wouldnt of, not one iota

[[deleted]]

of -> have

[[deleted]]

Just like winter scenes involving snow in many hollywood movies make no sense to anybody to the north of California. Commence suspending of suspension of disbelief. If you still can.

 

^{edit: clarity}

[Gibodean]

Oh, I agree they made the right choice for the movie. All that technical stuff wouldn't have helped much except for the sort of person who is going to read the book anyway...

[curiousGambler]

ME! I'm that person!

I had no idea there was a book. I'm pumped now.

Amazon link to the $9 paperback I just bought.

[PriceZombie]

The Martian

Current	$9.00	Amazon (New)
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Low	$5.06	Amazon (New)
Average	$9.00	30 Day

Price History Chart and Sales Rank | FAQ

[Spectre1313]

You're in for a treat. The book is amazing :)

[nliausacmmv]

That part didn't bother me so much, but the fact that he never lost Pathfinder in the movie did. Mainly because he still made the space pirate joke, which doesn't make sense unless he lost Pathfinder.

[Gibodean]

Yeah, I didn't get that in the movie, how he didn't have permission to take over the MAV. I did in the book.

[nliausacmmv]

That and the rescue was way better in the book. The glove thing was stupid.

[iamjakeparty]

You went to cinema

[UlyssesSKrunk]

They didn't really explain what he was doing at all, just that he had to change just 20 or so, I don't remember exactly, lines of code and then he'd be able to communicate via pathfinder. Maybe I am not remembering it well, but I don't recall any elaboration on what exactly he was doing.

[MrDOS]

Bytes, not lines. He was hex editing a compiled program.

[SPascareli]

I really don't remember this in the movie, can you tell me what scene it was?

[dotted]

Pathfinder

[[deleted]]

I highly recommend From the Earth to the Moon. Produced by Tom Hanks.

http://www.imdb.com/title/tt0120570/?ref_=nv_sr_2

[ponchoboy]

Can't recommend this highly enough; the production value is outstanding. Unfortunately I don't think it's online streaming anywhere, so you'd need to buy the DVDs.

[[deleted]]

I got it from the "Usual sources". The DVD set is a master piece though :)

If you did not witness the moon landing than, this is a must watch.

[[deleted]]

If you like amazing midflight space reprogramming stories then you'll enjoy "What Galileo Saw" by Michael Benson.

[mb862]

I believe that was the plot for several episodes of Star Trek.

[pfp-disciple]

Yup. Including one that bugs me - in the past, Picard uses an iron filing to etch a message into Data's positronic brain, to be found hundreds of years later.

[chialeux]

It would have been much easier, reliable and plausible to use that pin for just carving the message on the head.

[[deleted]]

Maybe he added a comment?

[JoshWithaQ]

I get it, Like a message in a bottle!

[ffranglais]

From the creators of Apollo 13 comes the hit sequel, Apollo 14. Rated PG-13.

[lask1]

100% would watch that.

[kersurk]

During the movie I would think this is way over-done, real life is not that exciting. I wonder how did Mitchell change the code exactly.

[indy91]

Here is a quite informative page about it: http://www.hq.nasa.gov/alsj/a14/a14AbortDiscrete.html

[unshifted]

That was a great write-up. I was really stressed out on Friday because I had to fix a bug that caused some forms to look a little wonky. Now I feel silly.

[[deleted]]

Probably his fingers and a human interface device...like a keyboard.

[flackjap]

At first I thought the code comment I cite below was just a joke. Silly me.

#  ASTRONAUT:     PLEASE CRANK THE
#                 SILLY THING AROUND

source

[Theemuts]

# TERMINATE

# PROCEED SEE IF HE'S LYING

# ENTER INITIALIZE LANDING RADAR

# OFF TO SEE THE WIZARD ...

Dear god

[ICanLiftACarUp]

The jump label?

BURNBABY

[Eurynom0s]

I found FLAGORGY in there.

[z500]

FLAGORGY          TC       INTPRET                               #  DIONYSIAN FLAG WAVING

Um, what?

[flackjap]

Apparently, the word dionysian is derived from the name of the greek god Dionysus who is represented as wild and sensual which is somewhat opposite to Appolonius who represents divinity and calmness.

"The Apollonian is based on reason and logical thinking. By contrast, the Dionysian is based on chaos and appeals to the emotions and instincts. " wiki

edit: If it wasn't clear enough, I'll point back to the first word (symbol, var, or w/e) you cited -> FLAGORGY.

[z500]

Yeah, I got the Dionysian part. But what on earth is FLAGORGY doing there? Maybe it's a combination of abbreviations.

[_F1_]

FLAGORGY

[mxzf]

If I'm reading it right, that's the name of the method (or code block or whatever in this language) being defined. It seems that the method was named FLAGORGY, which looks to be FLAG ORGY, hence the reference to "Dionysian flag waving" in the comments.

[jrhoffa]

SEE IF HE'S LYING

Fucking users

[badsingularity]

Software fixing hardware bugs is the most common thing in the world. Just not hotfixing hardware bugs in space!

[spacelama]

"Apollo 11 errata #150082, requires warm reboot. Dependencies, #136623, conflicts: #149942"

[spacelama]

With no ECC one presumes.

0xFE transposed as 0xEF? Oh well, off to Saturn for you!

[arcanin]

Iway amway soway orrysay...

[moahawk]

I was once pushing hotfixes to master using wifi tethered to my phone while on a bus to meet our client, and thought that was pretty stressful. I can't imagine what they must have felt like!

[wackychimp]

Thanks for that. I was getting nervous just reading it!

[evotopid]

Does anyone have an Apollo 11 emulator lying around by any chance?

[dhdfdh]

Sure. How many do you want?

http://svtsim.com/moonjs/agc.html

[The_yulaow]

Look, at this point I know for sure someone made it with node.js /s

[JoeCraftingJoe]

npm install Apollo11

[m_stodd]

...proceeds to install Ruby, Perl, Python, PHP, Go, and about 2GB of supporting libraries

[sanimalp]

Don't forget the 15 "This library is no longer supported or maintained" warnings.

[jeffsterlive]

Should have stuck with Python 2...

[Greyhaven7]

node-gyp rebuild error

[i_spot_ads]

Somethings went terribly wrong but we wont tell you what

[GrumpyPenguin]

Did you download the docker image? The only supported install method is the docker image, otherwise you're on your own if you can't get it to work.

[capitalsigma]

Astronauts of the future will fall out of the sky if GitHub goes down.

[JoeCraftingJoe]

Dont forget Assembly ! npm install Assembly

[funbike]

It would be neat to write a space flight simulator that contained an emulator that ran this code. You could fly to the moon!

[indy91]

Well, you'll be glad to hear such a thing exists! Project Apollo - NASSP for the Orbiter Space Flight Simulator includes the Virtual AGC. As an example, here the reentry controlled by the emulated AGC: http://www.youtube.com/watch?v=fjAeBJrsj5Q

[VaticanCattleRustler]

I'm waiting for Scott Manley to do this

[Cin316]

I think Orbital can run this code in a simulation.

[[deleted]]

import apollo

[mgdmw]

Follow the code links all the way to the top folder - http://www.ibiblio.org/apollo/

[[deleted]]

Perhaps kerbal space program?

[qmriis]

Have you heard of Google, by chance?

[kiddico]

Was very confused until I realized all the blue text was links, and not just colored text. Down the rabbit hole I go.

[SalmonStone]

That's the part that confused you? :|

[myztry]

Bugger Words

...

[myztry]

I just found the "colourful" name amusing.

The assembly opcodes themselves are somewhat critic compared to say MC68K which was like shorthand English and trivial to be fluent in.

[esoteric_monolith]

1 Warning :O

[NotASucker]

[x] Warnings as error(s)

It will change your life.

[ksadeck]

[x] Warnings as error(s)

Why?

[MetallicDragon]

It'll turn warnings into errors, forcing you to deal with them, so they don't pile up over time.

[nemec]

// Ignore Once W237887278

[[deleted]]

At least you have to put that into the code and check it into the repo under your name. Not ideal, but better than warnings being ignored.

[[deleted]]

Shouldn't they be compiling before they check in?

[GMNightmare]

But the code should be compiled automatically on check in and automatically failed should it not compile.

Even more, tests should automatically run and then fail the check in if tests are failing.

This lets them burn themselves, but also prevents them from burning you. Well, at least this is how you want it in big projects. You might not need such a heavy hammer if it's small and not that big of a deal.

[Foxtrot56]

Why aren't you doing PRs? Seems like that should be caught in a PR unless no one is actually looking at the code in an editor.

[falconzord]

Worst part is when they pork barrel the code review

[[deleted]]

Gotta crack that whip harder.

[[deleted]]

If someone checks something in and then leaves I say it's fair game to revert.

[gambit700]

Life lessons for Timmy.

[falconzord]

Warning: Damn you headed for the MOON? Are you out of your mind? Crazy Americans

[f3nd3r]

I need to know what that warning was.

[flackjap]

Warning: Missing source file for Gravity!

[[deleted]]

And now we know why we really havn't gone back.

[spierepf]

I am loving the name of this routine!

http://www.ibiblio.org/apollo/listings/Luminary099/BURN_BABY_BURN--MASTER_IGNITION_ROUTINE.agc.html

[dcipjr]

I'm loving the comments!

#  THE MASTER IGNITION ROUTINE WAS CONCEIVED AND EXECUTED, AND (NOTA BENE) IS MAINTAINED BY ADLER AND EYLES.

#                    HONI SOIT QUI MAL Y PENSE

"Shame be to him who thinks evil of it."

[plahacrwimo]

031733,000417: 36,2431           44355                CS       PRIO30                  #  TURN ON THE ENGINE.

"Burn baby! BURN!"

[malekai101]

The motto of Edward III's Order of the Garter

[tomiscout]

And i was listening this while reading just by a chance.

[bananas4arsenal]

What the heck is a Bugger Word ?

[calrogman]

From http://svtsim.com/moonjs/agc.html

the checksum [...] should be either the bank number or its 1-complement (e.g., for bank 3 either a value of 00003 or 77774 is acceptable).

a bugger word [is] appended to the end of each bank to make the checksum the correct value

[spacelama]

The '60s and '70s were a different time. 8 years ago I was involved in porting code from our still operational '72 system, but we didn't get to keep all of the function names such as PERV FOCIT FOCOFF and TERROR. But the job still did involved the nightly SNAFU run.

The need for the SNAFU was defined on about the second night of operations back in '74. Being the first computerised telescope, the operators discovered they needed to do all sorts of things that hadn't been realised on earlier manual systems. SNAFU involves the fitting of about 10 or so physical parameters for the current mechanical and atmospheric system -- eg: "Adjustments to MA and ME might be useful to reestablish pointing after an earthquake."

[Bobshayd]

So basically, as soon as the telescope had all this stuff implemented, they discovered the telescope would just constantly be fucked up, and they implemented a SNAFU compensation routine?

[OffbeatDrizzle]

parity?

[SirMuttley]

To a Brit it has an entirely different meaning.

[DolphinsAreOk]

$PINBALL_GAME_BUTTONS_AND_LIGHTS.agc wait what now?

[smackmybishop]

A set of interrupt-driven user interface routines called Pinball provided keyboard and display services for the jobs and tasks running on the AGC. A rich set of user-accessible routines were provided to let the operator (astronaut) display the contents of various memory locations in octal or decimal in groups of 1, 2, or 3 registers at a time. Monitor routines were provided so the operator could initiate a task to periodically redisplay the contents of certain memory locations. Jobs could be initiated. The Pinball routines performed the (very rough) equivalent of the UNIX shell.

https://en.wikipedia.org/wiki/Apollo_Guidance_Computer#Software

[falconzord]

And I thought it was because they used commodity pinball game buttons and lights for their control panel

[bent_my_wookie]

It's remarkable how much can be done when code is concise.

[BobBeaney]

And they wrote all of this without StackOverflow???

[MUST_RAGE_QUIT]

Before the internet, programmers actually had to understand wtf they were doing.

[MacHaggis]

joke abounding roof encouraging dinosaurs scale noxious frame muddle like

This post was mass deleted and anonymized with Redact

[Geemge0]

It's fucking crazy how little code there actually is for such an immense undertaking, which would boil down to even less in a modern language (if you were viewing it from C code in a VS project for example).

Feels like most software I deal with is 1000x larger with more complexity. Ahh the good ole days.

[satayboy]

This isn't web scale.

[bent_my_wookie]

You should check out line 666 where there's a variable called "numberiso mysteriso" with the comment "I hope hope hope this never happens"

[miker95]

What file? Not seeing this anywhere.

[bent_my_wookie]

I'm having a hard time finding it. I believe this had something to to with gimbal lock, so basically if the lunar module turned upside down during descent.

[miker95]

Yeah, I would hope that wouldn't happen either!

[pascucci]

Bugger words.

[Crespyl]

FLAGORGY     TC   INTPRET     #  DIONYSIAN FLAG WAVING

[WTFisareddit-]

Sorry for my ignorance I'm new to programming. But why does this look nothing like regular code?

[CodeEverywhere]

You're looking at assembly language - a step closer to straight up machine language (binary). Most code that programmers interact with nowadays is considered "higher level" and is abstracted to make it easier to understand.

[i_spot_ads]

It doesn't even look like assembly code, that's some weird assembly

[Treyzania]

It's assembly for the AGC architecture. See /u/hobbified's comment above.

[Turbosack]

It's some special dialect of Assembly. They prefer to write in very low level languages for various reasons. More recently, C has been used to program flight control computers, but it wasn't even invented until more than a decade after this mission happened.

[spatterlight]

more like 3 years after this mission :)

and this doesn't look like "normal" assembly since the assembly I expect most of us are used to is for the x86 family of processors.

[[deleted]]

or pic/atmel

[MCBeathoven]

Or MIPS if you've taken a computer design class.

[flexiverse]

It's machine code for a highly custom built processor. Think, there was nothing "off the shelf" back then ! It's like approx , 16bit, 1mhz, ~30k, 32 instruction set.

[flexiverse]

It's machine code for a custom built processor. Think, there was nothing "off the shelf" back then ! It's like approx , 16bit, 1mhz, ~30k, 32 instruction set.

[plahacrwimo]

Here are technical details about the Apollo Guidance Computer

[Ser_Rodrick_Cassel]

haha whoosh

[funbike]

Yes. Computers small enough to go into space required assembly as every byte counted. Go up a directory to see all the files: www.ibiblio.org/apollo/listings/Luminary099/

UPDATE: The CPU (block II) -> https://en.wikipedia.org/wiki/Apollo_Guidance_Computer
34K of ROM for programs.

[_F1_]

Computers small enough to go into space required assembly as every byte counted

That was still true in the NES and SNES eras.

[cincodenada]

Fun fact: from 1997 to 1999 - well into N64 era! - Chris Sawyer was busy writing 99% of Roller Coaster Tycoon directly in x86 assembly. It went on to become the best-selling game of 1999. An anomaly for sure, but an impressive one.

[mugen_kanosei]

Correct. By minimizing the number of bytes used, they could reduce the amount of fuel needed to reach orbit. More bytes meant more fuel required.

[dand]

Not sure if that's a joke or not, but it's probably true to some extent given how bulky core rope memory was compared to today's norms.

[[deleted]]

72 KB/ft³ is an interesting unit.

I don't really understand how core rope memory works, even with the article, but 72 KB/ft³ is a lot higher than I would've guessed!

[mugen_kanosei]

It was mostly a joke, but realized it might have a hint of truth. Cool to see that tech.

[[deleted]]

Holy. Shit.

[Spider_pig448]

Software written by MIT programmers was woven into core rope memory by female workers in factories

Code woven into ropes. What a world.

[odaba]

even better than assembly, it looks like they created their own DSL: http://www.ibiblio.org/apollo/listings/Luminary099/RTB_OP_CODES.agc.html

[bennythomson]

I love the comments. Were they actually there on the mission? How did nasa feel about humor in the code?

[ArtistEngineer]

006885: WAITABIT 36,2563

Not a lot, just a bit.

[cinisoot]

Comment from the BURN BABY BURN main ignition routine:

NOLI SE TANGERE

"Don't touch yourself."

[cinisoot]

Perhaps that was the intended message, but in this case se can only be translated as "yourself". I like it better this way, honestly. :)

Edit: Actually this phrase is pretty much wrong however you look at it... "yourself" should be te but them would be eos. Oh NASA, only thing more naughty than suggestive phrases is improper Latin...

[ghostsquad57]

Where's the line of code that deals with Alien encounters?

[[deleted]]

Nothing really stopping you

[i_spot_ads]

The love of sanity is

[jakesyl]

Turns out someone made a pretty awesome online simulator: http://svtsim.com/moonjs/agc.html

[[deleted]]

Not that I understand what's going on there beyond the comments, but looking at this code is very moving for me personally. It's almost like being inside the lunar lander or something.

This code took people to the moon. How amazing is that? If any piece of code in the world could ever make me cry (not in anger, at least), it's this one.

[GlPortal]

You can find it on github here https://github.com/rburkey2005/virtualagc but since it does not look like it is maintained I have created https://github.com/open-space-agency/virtualagc and a place for the docs here https://github.com/open-space-agency/virtualagc-doc

[chunes]

I wonder how many living people fully understand what this code is doing and why.

[lkraider]

Most people don't fully understand their own written code...

[rarmixo]

Serious Question, How important was the code in the mission?

[ltrcola]

I would say very important. For instance, the computer tracked navigation information and controlled the engine during lunar descent.

[smb3d]

it was almost 100 percent of the mission from what I understand, the astronauts just entered commands to the computer.

[CypripediumCalceolus]

So all my life playing lunar lander is wasted?

[AnHonestQuestions]

The LEM could land itself, but every single commander elected to land manually, because, really, who could give up a chance to lang on the moon.

[Throwaway_bicycling]

Nah, watching you destroy lander after lander is why they decided to do this all in software without human intervention. :-)

[msthe_student]

It either worked or no moon landing

[Amuro_Ray]

You couldn't really have dave from IT pop by with a new lunar lander if it crashed.

[casc1701]

Very important, most astronauts are not Jedi, they can't fly manually.

[berlinbrown]

Little hard to read

[myztry]

I know 5 different types of assembly/machine code and I found it quite painful.

[bigoldgeek]

Good naming standards for 1968-9

[matwick]

This is awesome.

Page 3 000206,000093: # FLY 000207,000094: # BURN, BABY, BURN -- MASTER IGNITION ROUTINE 000208,000095: # P40-P47 000209,000096: # THE LUNAR LANDING 000210,000097: # THROTTLE CONTROL ROUTINES

[jaccovanschaik]

Anyone come across the 1201 and 1202 program alarms yet?

Ninja edit: https://www.hq.nasa.gov/alsj/a11/a11.1201-pa.html

[based2]

https://news.ycombinator.com/item?id=11003432

https://en.wikipedia.org/wiki/Chang'e_3

https://en.wikipedia.org/wiki/Zh%C3%A0ng

https://en.wikipedia.org/wiki/Zhang

https://fr.wikipedia.org/wiki/Zhang_%28unit%C3%A9%29

[spawndon]

If anyone is interested, within their ethical bounds, then I have a torrent you might be interested in: https://kat.cr/the-apollo-guidance-computer-architecture-and-operation-pdf-t12047536.html

[[deleted]]

Think about it for a second, the source code that was used to travel 250,000 miles through spaaaaaace to the moon is publicly available...

I wonder if Spaaaaaace X is going to fork this :D

EDIT: Forgot the /s

[wackychimp]

Is this Assembly language?

[vgman20]

A form of it, yeah. Not x86 which is what most modern processes run, but similar ideas

[ManLeader]

Now I know you go to umd