Apollo 11 Guidance Computer source code • Hacker News Board

Re: Apollo 11 Guidance Computer source code

#81

Post by nameless912 » Thu, Jul 07, 2016, 5:37 PM UTC

datenwolf wrote: post #65

mbrumlow wrote: post #34

Earlier quoted context omitted.

I could be wrong. But I think part of why they did it this way was so they could edit things on the fly if a emergency dictated so. Having to ship a compiler (would have likely been an entire separate computer) would have not been feasible. With things done this way and documented this why they could (fairly sure did) have the pages printed out on paper and such. And if say there was some bug or new routine that need…

> I could be wrong. But I think part of why they did it this way was so they could edit things on the fly The AGC code was stored in ROM. Notably a specific kind of ROM called "rope memory".

Hey, uh, Apollo 10 and n ? This is Houston. Could you pull out the ROM banks and flip a couple of bits for us? we made a mistake or two. All you need are some wire cutters and a very steady hand.

Re: Apollo 11 Guidance Computer source code

#82

Post by artellectual » Thu, Jul 07, 2016, 5:39 PM UTC

Wow this is surreal. I can't believe I'm seeing this. It's historical, thank you for sharing.

Re: Apollo 11 Guidance Computer source code

#83

Post by jsingleton » Thu, Jul 07, 2016, 5:41 PM UTC

js2 wrote: post #21

Watch the landing: https://www.youtube.com/watch?v=k_OD2V6fMLQ During the landing, you'll here mention of 1201 and 1202 alarms. Here's what that's about: http://www.hq.nasa.gov/office/pao/History/alsj/a11/a11.1201-... Here's 1201 being called: https://github.com/chrislgarry/Apollo-11/blob/dc4ea6735c4646... And 1202: https://github.com/chrislgarry/Apollo-11/blob/dc4ea6735c4646...

The high quality originals were taped over by NASA.

https://www.theguardian.com/science/2009/jul/16/moon-landing...

Re: Apollo 11 Guidance Computer source code

#84

Post by elcapitan » Thu, Jul 07, 2016, 5:49 PM UTC

This is amazing and contains so many gems.

I think this one is my favorite module: https://github.com/chrislgarry/Apollo-11/blob/master/THE_LUN...

		CAF	CODE500		# ASTRONAUT:	PLEASE CRANK THE
		TC	BANKCALL	#		SILLY THING AROUND
		CADR	GOPERF1
		TCF	GOTOP00H	# TERMINATE
		TCF	P63SPOT3	# PROCEED	SEE IF HE'S LYING

        	TC	BANKCALL	# ENTER		INITIALIZE LANDING RADAR
		CADR	SETPOS1

		TC	POSTJUMP	# OFF TO SEE THE WIZARD ...
		CADR	BURNBABY

Re: Apollo 11 Guidance Computer source code

#85

Post by ceocoder » Thu, Jul 07, 2016, 5:58 PM UTC

ceocoder wrote: post #31

sjtgraham wrote: post #6

BURN_BABY_BURN--MASTER_IGNITION_ROUTINE.s - https://github.com/chrislgarry/Apollo-11/blob/dc4ea6735c4646...

I really wish we can do an AMA with these two, > # THE MASTER IGNITION ROUTINE WAS CONCEIVED AND EXECUTED, AND (NOTA BENE) IS MAINTAINED BY ADLER AND EYLES. I had to look this up, NOTA BENE is latin for, observe carefully or take special notice

I found Don Eyles' website[1],

> At MET 102:39:31 the best possible confidence builder occurred — throttle down, right on time. "Ah! Throttle down... better than the simulator" commented Aldrin, "Throttle down on time!" exclaimed Armstrong, their excitement palpable. In the official transcript of communications between spacecraft and ground during the powered descent, these are the only exclamation points[11].

goosebumps.

[1] http://www.doneyles.com/LM/Tales.html

Re: Apollo 11 Guidance Computer source code

#86

Post by arc0re » Thu, Jul 07, 2016, 6:08 PM UTC

akshatpradhan wrote: post #39

If this were to be rewritten in a high level language, I wonder what would it look like?

Probably procedural C or C++ with some inline assembly bits

Re: Apollo 11 Guidance Computer source code

#87

Post by brendangregg » Thu, Jul 07, 2016, 6:14 PM UTC

It's amazing that this is all online now, and easy to browse. Lots of source here too http://www.ibiblio.org/apollo/links.html

FWIW, I did performance analysis of the guidance computer and the 1202 and 1201 alarms at the start of my ACM Applicative 2016 keynote: https://youtu.be/eO94l0aGLCA?t=4m38s

Re: Apollo 11 Guidance Computer source code

#88

Post by Animats » Thu, Jul 07, 2016, 6:20 PM UTC

There's a simulator, if you want to run it.[1] But it's just a simulator for the computer; there's no spacecraft attached.

There's a mod for Kerbal Space Program which gives it real solar system planets and dimensions. (KSP's world is way undersized so things happen faster.)[2]

There's another mod for Kerbal Space Program to give it real dynamics.[3] (KSP doesn't really do dynamics right; the spacecraft is under the gravitational influence of only one body at a time. This is why there's that sudden trajectory change upon Mun capture.)

Someone should hook all that together and do a moon landing in simulation.

[1] http://svtsim.com/moonjs/agc.html [2] https://www.reddit.com/r/KerbalSpaceProgram/comments/1piaqi/... [3] http://forum.kerbalspaceprogram.com/index.php?/topic/62205-w...

Re: Apollo 11 Guidance Computer source code

#89

Post by thevibesman » Thu, Jul 07, 2016, 6:22 PM UTC

ianbertolacci wrote: post #32

Have they considered rewriting it in rust?

hehe

(A friend of mine, who when in search of a new go-to-programming language instead of Python, was more interested in Swift vs Rust because of this attitude).

Re: Apollo 11 Guidance Computer source code

#90

Post by kps » Thu, Jul 07, 2016, 6:30 PM UTC

nameless912 wrote: post #80

alehander42 wrote: post #20

people could've really used a higher-level language compiling to optimized AGC(apollo computer) assembly. Is there any reason why they didn't develop one? It seems it would've helped tremendously with the productivity and verification (and a lot of the explanations and equations would be readable as code, not as an non-executed comment)

Long story short, in circa 1969 higher-level languages were mostly the purview of academics. No one had a computer powerful enough to run a language compiler/runtime, and programmers were real men(tm) and wrote assembly by hand because that was all they knew how to do. That's not to say that there weren't any advantages to using a higher level language, but in the case of something like the apollo computer, they coul…

There were programming languages in widespread commercial use (e.g. Fortran and COBOL) and many others for niche applications or associated with particular manufacturers.