The Computer That Got Us to the Moon - The Apollo Guidance Computer
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- čas přidán 14. 05. 2024
- #TheApolloGuidanceComputer was built to navigate and guide the #Apollo astronauts to the moon. The #AGC and the inertial measurement unit (IMU) told astronauts where they were. The IMU contained gyroscopes and accelerometers. The IMU was calibrated using an onboard telescope and sextant. The AGC also controlled the engines and reaction control thrusters. The astronauts talked to the computer using verb and noun commands on DSKY (display and keyboard). The computer itself was make of core memory. The fixed memory was woven core rope memory. This is where the programs, constants, star charts, and landmark charts were woven and saved for each flight. The logic unit was make of integrated circuits (dual NOR gates). The computer could only run one job at a time. The executive determined what jobs to prioritize and run. The computer could restart programs, put them to sleep, and had very basic error checking. It was designed by MIT's Instrumentation Lab and built by Raytheon. There was one for the command service module and one for the lunar excursion module. New versions were built for every flight.
Many of the images and video came from this site. It is a great site to explore. Thanks for releasing this for the Apollo 50th Anniversary .
wehackthemoon.com
Mindell, David A. Digital Apollo: Human and Machine in Spaceflight. MIT Press, 2008.
O’Brien, Frank. The Apollo Guidance Computer: Architecture and Operation. Springer, 2010.
Hall, Eldon C. Journey to the Moon: The History of the Apollo Guidance Computer. AIAA, 19996.
Eyles, Don. Sunburst and Luminary: An Apollo Memoir. Fort Point Press, 2017.
Unman, Bernd. AN/FSQ-7: the computer that shaped the Cold War. 2014
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history.nasa.gov/SP-4219/Cont...
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I can tell this video was an incredible amount of work to produce. Great job!
Any video requires work.
Great to hear that from you!
The big moon HOAX
And an incredible lie also
Its a wonder it even worked. I dont know who the AGC Software Programmers were, but they are the unsung heroes of Apollo 11. Making the first computers and knowing even one realtime bug would be a disaster.
This very intelligent lady did amazing research for this video. As an engineer I am very impressed.
Yes but don't forget that lady who wrote program for AGC back in 60s using assembly
This video has the best explanation of ferrite core memory I have seen, which is strange since that isn’t even the main subject of the video. Thanks for a great video.
AGC remains a remarkable step in computing.
I believe MIT was awarded the contract because one of their initial work on the gimbals and gyroscopes allowed them to demonstrate being able to fly a plane without any visual reference. Great video!
Draper specialized in guidance control systems
Wow! This is a fantastic presentation. Good Work!
Wow the magnetic core memory section blew my mind
Fabulous video. I read a lot about Apollo and you taught me a very great deal. Brava!
From a mechanical engineer: that was great. Thank you.
Thanks
Probably one of the most interesting engineering videos I have ever seen
An outstanding explanation of the workings of core memory. Brilliant!
Very nice explanation. I have watched a lot of videos on the AGC and this one does a very good job of describing all the key elements.
hoax
What a time to be alive!
Your succinct explanations and the choice of footage makes this the best explanation of the AGC out there, anywhere. I've tried several times to find out how the core rope memory works, and your explanation is the only one that has made sense. Thanks!!
Wow, that means a lot. Thanks so much. I’m looking forward to checking out your channel.
Thanks for the bibliography! Every American should be familiar with the DSKY. Heck, I want one in my car!
This lady is amazing! She can say all of this without edits or mistakes?!? Impressive.
Most of the video is B-roll, so there's plenty of places to make edits to the voiceover. The key is not making those edits detectable :)
You're videos are great, I hope you keep making them.
This was absolutely fascinating! ... didn't understand 99% of it but, it was still really really good.
If I'm going to the moon I want her as Flight Director. 👍
She will get me back to earth. 🙏
Very nice job creating this video! Fascinating sections on memory and circuits for the AGC. Thanks for doing this! ~ Mark
Your videos are awesome, SciJoy : )
Thanks! Sorry I missed you at VidCon this year.
Pretty good summary, with accurate details, deep insight in many fields while remaining very accessible.
Thanks you.
You got a new sub, and you deserve way more!
My 2nd grade Report Card from 1972 is a punch card :)
And I thought syntax in DOS-Land was bad. LOL
This is amazing, love this video
Flashback to my old (67-70) EE classes! Also, had the privilege of working summer jobs @ Grumman plant on L.I. to support preliminary LEM testing! Fun days, and an interesting set of technologies!
this is the Quality I was looking for, it was a veryyy great informative video +sub +like :)
nice - love hearing about early computers and the AGC
What are some other great early computers?
@@SciJoy I've been getting into the details of first and second generation computers recently. ENIAC, EDSAC, CSIRAC etc. mostly around how they are constructed, how memory access is done, programs are stored and all that. Ben Eater over at czcams.com/users/eaterbc has a great series on making a computer from scratch on a breadboard. Was watching that at the same time as watching the AGC restoration video over at Curious Marc's channel czcams.com/users/mverdiel as well as this breakdown of how the AGC works czcams.com/video/xx7Lfh5SKUQ/video.htmll. I find it fascinating when people do something about doing so much with so little and there's something tactile about knowing how it all works at the hardware level.
Wow, very very good production.
You did good
Such a good video! I wish more people would see this.
Incredibly succinct and informative video
Excellent video. Lots of good information here.
Wow, great job. With just my rudimentary algebra math, I was able to understand your explanation.
Excellent !!!
Hoping you're doing okay. This was an excellent video.
Super explanation.
so, when people say, "it's not rocket science," i will have a new appreciation for the seriousness of that claim. wow.
🏆Excellent!!💎Big like!!🏆
The restart is described as being done that way: There were regular points of the program, called "way points", in which all the current data was saved in memory; when a restart had to be done, the computer was going back to the closest waypoint, reloading the data which had been saved at this waypoint, and restarting from this waypoint.
But, as the address of the next instruction to be executed was stored in the program counter, and the data was still present in memory, it would have been simpler and more efficient to restart from the current address with the current data.
Moreover, proceeding this way was meaning that memory had to be reserved to save the data, which was making less usable memory, and also it was taking time to save data at the waypoint, much time, time that the AGC could not afford to lose.
One of the best videos I have seen about the engineering behind AGC. Great explaination 😀
Fantastic video! Kudos!
The IMU was not directly giving angles and speeds to the AGC, but pulses that the AGC had to count to update them.
If the AGC was stopping working, it was losing the pulses, which means that the variations of angles and speeds were lost meanwhile.
The AGC had special instructions (they call them "unprogrammed instructions"), PINC and MINC, to count (and decount) hardware pulses.
And in the meanwhile everybody has a supercomputer, compared to the Apollocomputer, in the pocket.
WOW!
Solar System Positioning System, said as an acronym, is SSPS. Coincidence? 🤔
It might be necessary to slow down playback speed in order to capture everything said...failing that, you could just watch it again. XD
Correction, the backup AGS WAS used twice, once on Apollo 11 due to a gimball lock, and during Apollo 13 to save energy over the AGC.
After watching all of this, all I can say is thank you aliens!
that lunar landing would have to be one of the greatest human achievement's, considering the technology they had at there disposal at the time, they had to invent every piece bit by bit as they went along and they pulled it off miraculously ???
Yeah, that was an exceptional piece on engineering.
Some of this seems quite dumbed down, at least from my current vantage point, but other parts have much deeper diving.
BTW one thing about the LM I only recently realized: The descent and ascent stages have totally different engines, but both can be throttled, both use hypergolic propellants pushed by pressurized helium, and both are controlled from the same point, in the cabin where the astronauts ride.
I have two degrees in Computer Science and I don’t think it is “dumbed down.” I think it is remarkable for a short video on a complex subject.
14:33; center of mass (not gravity).
The whole comprises the parts.
Well Joy, did you really need to over simplify such a complex subject? 😂 Just jokes, this video was amazing. Thank you.
Wonderful video & great job!! But your opening statement is a bit false; this computer was built to fly the rocket as well be robust enough to handle the vibration of launch & control the spacecraft, amongst other things. You explain this later so it's weird you open w/that.
The Saturn V rocket had an entirely different computer.
Are you aware that the Phalanx CIWS uses a version of the same computer
I don't know why this always bugs me so much, but when people talk about going to the moon and saying that the craft needs to leave the Earth's orbit, they are mistaken. At no point on any lunar mission did any craft leave the orbit of Earth. Think about it. The MOON is in Earth orbit. You don't LEAVE Earth orbit to go to the moon; you're just put on a highly elliptical orbit until you make another burn to orbit the moon. You're still orbiting the Earth though. You and your orbit around the moon are collectively in orbit around the Earth. You never leave Earth's orbit.
@@colinsouthern This is incorrect. The TLI burn from Earth that sent them to the moon put them on a trajectory known as "free return" - - meaning if they did nothing else, they would circle around the backside of the moon and be slung around and return to Earth. At some point on the way to the moon, once various systems checks were performed, they altered this trajectory that would allow them to be captured by the moon. At no point in time where they ANYWHERE NEAR a trajectory that would escape the Earth's gravitational influence.
As for the ISS, the whole "centripetal force" explanation is a gross overcomplication. It doesn't matter how strong the gravitational field you are in is. If you are in free fall, you will be/feel weightless. Many people conflate this with the absence of gravity - which it most definitely is not.
The notion that you leave Earth's orbit simply because you are experiencing weightlessness is erroneous logic. You can ride a free-fall type roller coaster right here on the surface of the Earth and experience literally the same state as a spacecraft in space. It's the same weightlessness, and it is not caused by any alterations in the gravitational field, but rather the result of being in free fall WITHIN that gravitational field - - which was the case for the vast majority of the trip to and from the moon. They are simply coasting. A free fall ride here on Earth just lasts a fraction of a second as opposed to the days Apollo astronauts experience en route to and from the moon / and in orbit.
@colinsouthern no. They far surpassed escape velocity. They aren't even orbiting the sun. They have reached escape velocity of the entire solar system.
Challenge me all you want. I know what I'm talking about.
@@colinsouthern No.
STEP ONE : Launch
STEP TWO : Get into Earth orbit
STEP THREE : Translunar Injection - - AKA, send them to the moon. THIS trajectory was a free return.
STEP FOUR : Midcourse (between Earth and moon - AFTER systems checks, etc.) taken off of a free return to a trajectory that would allow them to get into lunar orbit
STEP FIVE : Get into lunar orbit.
For example - the Apollo 13 explosion occurred during a point in the mission that they had already performed the maneuver that would take them OFF the free-return trajectory and on one that would allow them to perform a lunar insertion burn once arriving. They actually had to perform another burn to put the BACK onto a free-return trajectory and return.
I feel like none of this is going to make sense to you.
@@colinsouthern I'm not stating an opinion.
it is all a hoax
"Geminee" 😂
Concerning the famous alarm 1202 (which caused much trouble in the control room, and which happened after Buzz Aldrin changed the radar switch from LGC to SLEW, because of an "erroneous" indication of the checklist), in a comment of the anomalies section of the mission report of Apollo 11, entitled "Computer Alarms During Descent, at page 16-13 you find this:(excerpt of the comment):
"Any difference in phase or amplitude between the two 800-hertz voltages will cause the coupling data unit to recognize a change in shaft or trunnion position, and the coupling data unit will slew (digitally). The "slewing" of the data unit results in the undesirable and continuous transmission of pulses representing incremental angular changes to the computer. The maximum rate for the pulses is 6.4 kpps, and they are processed as counter interrupts. Each pulse received by the computer requires one memory cycle time (11.7 microsecond) to process. If a maximum of 12.8 kpps are received (two radar coupling data units), 15 percent of the computer time will be spent in processing the radar interrupts. The computer normally operates at approximately 90 percent of capacity during peak activity of powered descent.) When the capacity of the computer is exceeded, some repetitively scheduled routines will not be completed prior the start of the next computation cycle. The computer then generates a software restart and displays an Executive overflow alarm."
End of quote.
Now tell me:
1) Why would the engineers have provided a radar mode which was causing a problem that they perfectly knew that it would happen (and which was not happening when the radar mode commutator was on the LGC position)?
2) Why would engineers have made the processor count itself the radar pulses when, in all other systems, including the one of the Saturn rocket, these pulses are counted by electronic counters instead and never, NEVER, by the processor itself; for, if these unwanted parasite pulses had been counted by electronic counters, the processor would just have read the count of pulses on the electronic counters (like all other systems do, and the AGC had an instruction allowing it to do it), and could have seen that the count of pulses was too high; it would not have had to restart, it would just have issued an alarm that the radar mode was on the wrong position.
❤️🇮🇳
And no, there was no program to make the lunar module automatically land, the final program, P67, was entirely manual (the previous program P66, was semi automatic, which means that it was the AGC which was controlling the main engine, while the astronaut was controlling the RCS).
And, while it was up to the astronauts to shut off the engine when they were seeing the contact light (activated by the contact of the lunar probes with the lunar ground), it could also have been automatically made by the AGC, for the LGC could also automatically shut off the main engine.
It would have been much safer if the landing had been entirely automatically made, including shutting off the engine upon detection of the lunar probes.
Armstrong shut off the descent engine as the lunar module was already resting on the lunar ground.
In Apollo 15, the engine's nozzle touched the lunar ground because of the way it landed, and it would have been catastrophic if the engine would still have been firing at touchdown, but Scott shut if off before the touchdown; if Scott had been as slow as Armstrong to shut off the engine, it would have ended in a catastrophy.
If the landing was automatically made, this scenario would be sure not to happen!
A computer so good it was the peak of computer technology in 1972. Too bad it’s been destroyed. Nothing weird here
That's a blatant lie. There are videos on YT showing a restorted unit operating.
Hard fail for the hoax nut crowd. Maybe you should just keep your ignorant claims to yourself.
It hasn’t been destroyed. See the AGC restoration here on CZcams
That is not true. The Apollo Guidance Computer formed the basis of the fly-by-wire system installed into an F-8 Crusader to demonstrate the practicality of computer driven FBW, for example.
I wouldn’t say it was the peak of computer technology. That has no real meaning. The AGC was optimized for its purpose, and contained innovations needed to help it meet its requirements, but other computers with different purposes also contained technological innovations. There is no peak.
Are Ashtronauts cremated astronauts ?
The technique of the way points was completely absurd; it takes time to save data at regular points, it contributes to overload the computer, and it also contributes to reduce the available memory, and it is completely useless; the program could resume from the point it had been interrupted, with the current data, after having released the memory resources it had become short of.
Have you watched the AGC restoration videos ? I agree with what you found about P63. The claim is made they are running P63 though it is hard to tell when they are running their own code ? I am not sure if they are controlling their DSKY with the AGC or their FPGA ?
The little phone in my pocket has more computing power than they had back then, so wky is it were unable to return to the moon???
Because computers are only a small part of getting to the moon. 100 m tall rockets remain hugely expensive.
It's astonishing how some seems to think that we're going to space on the back of microprocessors.
It may surprise you, but to go to space, one needs *a rocket* not a computer.
Mercury/Gemini/Apollo required about 400,000 people and an unlimited budget to implement.
Kiss my gimbal lock
Great presentation! NASA has been saying for YEARS (now 2023) that they lost ALL the information on how they got to the moon. NASA says it will take YEARS to figure out how we got our astronauts to the moon and back safely traveling 25,000 miles each way thru the Van Allen Radiation Belt. Maybe you can talk with NASA to help them?!
_NASA has been saying for YEARS (now 2023) that they lost ALL the information on how they got to the moon._
As a matter of fact, NASA said no such thing. Whoever told you that lied to you.
_NASA says it will take YEARS to figure out how we got our astronauts to the moon and back safely traveling 25,000 miles each way thru the Van Allen Radiation Belt._
Again, NASA said no such thing.
Utter nonsense. Everything is in the archives and on the web. Oh and James Van Allen said that the trip would be fine. Speed and belts.
Don Pettit from NASA said - we used to have the technology to go to the moon but we destroyed that technology and it's a painful process to build it back again.
@@benrussell1946
You need to see the full interview and exactly what he meant. Every blueprint is on the web and real Saturn V’s are sectioned and on public display. Several individuals have restored an AGC all serialised here on CZcams
It only took the astronauts a few minutes to travel through those belts, and that radiation does not pass through a metal.
The slow scan tapes were only erased on the first moon landing.
Hahaha… FICTION.
no way in 1969 technology is enough to got you to the moon.
Tell us exactly what was missing. Be precise.
Thanks.
OK so They cant do it now GTFOOH
NOBODY went to the M00n.
They did six times. Installed EASEP, ALSEP, and LRRR. Left behind a lot of garbage too..
that is true... all 12 astronauts that walked on the moon were alive....
hoax forever
@@physicalivan
Prove it!
@@physicalivan please hold your breath... for as long as it takes...
You go to Moon only in your dream. Thats it
But NASA astronauts did go there.
those puppets didnt go anywhere and we all know it...@@ThomasKundera
@@ekiskaliburnirvana9047 : You are just misinformed, I'm afraid.
But why do you think they never went to the Moon?
@@ThomasKundera no way in 1969 technology is enough to got you to the moon.
@@unsalbulent / Tell us exactly what was missing. Be precise.
Thanks.
excellent video for a hoax
Which "hoax"?
Oh another tinfoil LEM believer in my recommendations 😢
What is the to "believe" in the LM?
@@ThomasKundera believal comes when you propagate the 'fact' and destroy evidence in the same time
@@za_ozero : _"when you propagate the 'fact' and destroy evidence"_
Which "evidence"' have been "destroyed" by whom?
with transmission delays,how could real time data be any use??they would have hit the ground hard with those delays.another naza fairy tale and cheap effects.if you don't look,you can't see.maddog.off grid.West cork
during most of the mission, there was lots of time to correct errors. The time-critical parts of the mission were done by the AGC on board the LM, so there was no delay.
Juste for your information: in English, "Space" is spelled with an "s", not "z" (not "Zpace"), so it's naSa, with an s, not a z.
Dead channel
How can she say all that? so few cuts!
She's reading a teleprompter
I think there must be cuts.
WOW!