Apollo Guidance Computer Part 24: the restored AGC does Moon landings in front of its creators

this is the 1966 Apollo guidance computer the computer that flew in the Apollo spacecraft and guided the lamb to a moon landing if you follow the restoration saga you know that we got ours working just in time for the 50th anniversary of the moon landing so in the nick of time we are going on the torn East Coast to participate to some Apollo celebration events we decided that the first person to see the demo would be no other than Eldon Hall the father of DHEC Eldon famously pushed the visionary decision to use the recently invented and completely unproven integrated circuit to build the AGC we talked with mr. Elden hall deputy associate director of the instrumentation lab guidance and navigation system consists of two major elements controlled a computer and a computer is playing control Eldon is now 96 years old and lives in Florida he has kept several important historical artifacts about EGC most famously he gave Mike the schematics we were missing to restore it but he also has some very early block to prototype modules in a format I had never seen before and most importantly he has one Corrib module that he is going to let us read after the demo unfortunately I could not attend the event set up at Eldon's condo I am told he was quite happy to see his old computer again Mike flew a landing and that worked perfectly with the real AGC as we had expected we ended the day by reading Aldens co-op module this rope should contain part of Sundance which was flown on Apollo 9 and of which we have absolutely no record 3:02 in gross before duck dude this is the first time we have ever seen any code from Sundance whatsoever okay but we only have one sixth of the code yes as skin just pointed out this is only one of six modules but as you'll see later we were able to archive two more Sundance modules later in the trip yeah we can next stop on the tour was at the cradle of aviation museum in Long Island New York they have lots of cool Apple or related hardware there there's a model of the AG seat back there partial Tommy it looks like that Columbus downscaled so there's not room for ya so you can see that's a G see here is missing its connector pins that's how you can call its fake they had a fool em simulator on display including this very awesome console that controlled the whole thing and this is scans favorite panel the malfunction insertion unit used to insert Hardware Falls to spice up the simulations [Music] our setup now even included the Lego LEM rigged up with little LED that light up when the thruster is fired by the agency and of course many AGC landings were flown throughout the day for visitors of the museum but our biggest event was to happen right at the birthplace of EA GC in Cambridge Massachusetts the MIT Museum was organizing a special lunar day for the anniversary of the moon landing anywhere one of the featured attractions it's a dinosaur no it's a robot made by some clever MIT people but besides all that they had some really interesting Apollo hardware the inertial measurement unit boy do I want one a gyro I already have one and this is the control panel for the alignment optics or the guidance system the telescope and the sextant with all the AGC words and nouns on it the very listing of luminary 99 we used recompile the original Apollo 11 landing software which are flying in the demo a disc II recently donated by Don Isles and yes even an AGC or half of one d'etre beef to be exact and I even got to wheel down and install a moon rock brought back by Apollo 16 which was the star of the exhibit besides us that is from the white color I suspect this is an ortho site a primordial Rock that established that the moon was formed to a part of the earth after a very large impact which is one of the major scientific discoveries from the Apollo exploration I'm Debbie Douglas I'm the curator of Science and Technology and the director of collections at the MIT Museum I'm the lucky person that gets to Stewart a million and a half objects but one of the most precious and certainly this week most interesting objects that we have in our collection is the Apollo guidance computer Debbie graciously agreed to let us take a closer look at their agc of great interest to us this agc also has a full set of rope modules that we will try to read to recover the original software once again a program that had been lost to history the other half is on display at Draper laboratory right now wait was born yeah well yes other this machine was born in a different building altogether but where you are sitting right now actually was also part of the instrumentation laboratory and the instrumentation lab did a lot of the gyroscope testing in this particular building that we're we as part of the inertial measurement unit and when we fit the unit and we can finally see the Rope module we hope to recover this is sunday OE the command module system test program which only takes three modules so what does he have for OB I'd use a jumper yeah give me the fixed jumper so that's this one yep so should be a complete yeah so these four are a complete set and we don't have sin dial anywhere right this would be the first time we yep this is the same series deserve this might be our sister agc from the part number on the alarm module it looks like this might be - Oh eight one maybe which would be the agency they've won under vacuum testing in the command module in Houston versus ours Madrid I'm so this might be the command module part of it might be Mike thinks this is the sister AGC two hours used during the man rating of the command module and LM in Houston ours was in the LEM and this one was in the command module Mike thinks he can tell for sure if he manages to find the serial number hiding somewhere on the chassis what's the riddle Mike oh you're going to figure it out we can narrow it down a lot I don't know if we can positively identify it but if we wired assembly number for tray be here mm-hmm it has over 31 at the end that'll get us down to as far as I can tell one of two ADCs either serial number eight which was actually originally in LT 8h where we originally destined for LT eight cars replaced it later on oh really but since that has command model ropes in it it's much more likely to be our sister AGC you know the one that was in the command module is under way during the women rating with this and you think the number is hidden behind the memory module yeah it's right I can see the first half of it but the - number is right behind the screw of the erasable memory module and go 200 300 6-3 - that's 4 1 1 and this is our HTC yeah this picture is from our ADC and it still has a - a 1-1 here okay so that oh 3 1 we've printed somewhere else the exclusive NASA drawings have tables that match a particular AGC with the serial number of its parts using this as a decoding table Mike hopes to find the true identity of this agency he's looking for telltale - oh 31 number hey everyone alright so this is a dumb very expected yeah I believe looking at the configuration drawings that this would narrow it down to one of three computers with ours being one of those three okay really close serial number eight being another one but serial number eight was originally used in guidance system 602 or a lunar module this has a sundial command module groups in it which is what the command modules would have had during the vacuum testing so I think this is it's it's very likely that this AGC it's the one that went with our AGC Sevierville m and this should be the command module yep they would have been in the vacuum chambers at the same time in Houston well don't you know look how do you know about them and I meant you my dear Watson yes that's that's really interesting after Mike's brilliant identification of the AGC we proceeded to remove the rope modules in order to read them in our own AGC yep I see it's one two three four get it make sure they get the right module on the right slide rule for them I'm ready in boom-boom blue and still doing it there you go look at what we got sanity checks data data looks good so we might as well try to run the program straight from the ropes in our AGC as at the door fifty years ago during the man rating test right so we just got the software the ropes running on our computer and it's working on the real thick disc II and it's passed seven tests it asked us everything one one yes yeah so we have a perfectly healthy computer and perfectly healthy Kyle can you get us through this certain so before the demonstration we start with the Apollo guidance computer we have this connected up through mics test monitor to its control station to make sure everything's going well and then to the simulation and this other large connector is taking all of the the signals that would normally go throughout the spacecraft and routing them to this big panel where we can interface them to the display keyboard front as my dis key which will be displaying the output and the interactions with the mission and then here we have a lego lunar module LEDs on and it's going to light LEDs alight as the agency commands different thruster movements and the engine Bell will light up as the same tension doesn't yeah so now when President Kennedy committed the country to project Apollo it was a commitment to take people to the moon land on the surface and bring them back safely and frankly at the time the commitment was made it was really on the edge of impossible since or to talk a bit about what makes the Apollo guidance computer such a revolutionary system so they made the big time integrated circuits now we do gated circuits had just been invented four years earlier and they you know bet the whole Apollo project on them it only had the equivalent of four kilobytes of RAM and 72 kilobytes of Rome storage and so you know with has very limited memory somehow they made it to the moon so we're going to start at what's called powered descent initiation or PDI once we get down to about 10,000 feet the computer is going to switching to program 64 and pitch forwards of the astronauts can see the landing site and then once we get down low there's two technically three but practically two options for landing I programmed 65 which is a completely automatic control by the ADC and programmed 66 which is like a semi manual which is what I'm going to be flying and what they flew on Apollo 11 our pilot today is my skirt besides knowing every gate in EGC is also an accomplished LEM pilot and you will see actually we have the outputs the fire the thrusters have put wired to this NASA approved LEGO version of the LEM we couldn't find a real one and it has no lights on it so every time the AGC pushes us no actually to thrust Treadwell's it will glow red this is quite close reenactment of Apollo 11 we are using the same computer the same software but once again the lamp is a simulation but it responds to the command of of the CCDF own computer so the computer here flies the whole thing so first step here which would have done this and much earlier in the real mission is to turn on our computer so the first thing I'm going to do here is start program 6337 enter 63 turkey and now we are waiting for ignition - 7.5 seconds which is when the ollege burn with the reaction control and the tanks start so Neil I'm so cold engine armed vehicle village that polish and I'm flashing $4.99 across the proceeds to confirm ignition Pro 10% yeah and there's tanker central so that's a momentous time right we are leaving orbit and now our trajectories intersecting with the moon surface so if we don't control it we crash that watch how is movement on the sick response to the firing and he's going to command a constant role so it's going to move all the way to the right but it's called only going to light distress there for a little bit because the computer understands it just wants to roll at concentrate so it just needs to keep the movement they won't do anything until brings it back to the center and we'll kick it in the other direction so it's fly-by-wire right it's a computer in between you and the thrusters we go and we see a trusters so watch the ball on the right Mike is going to get it to 90 degrees [Music] so notice no ID begin to thrusters to revisit [Music] they go Wow down so all day long time exclamation point so they were once again very worried whether EGC was patrolling the sing as yeah tons of other communication problems and data problems anywhere they very reassured by that one so there's t 64 and now we are pitching for me and I can see my landing site yeah and it looks like we're flying fine so right now my Linh sites right about here if 49 50 I'm gonna push work a couple times three times in a forward program Laura what I got program are it's a little dude Houston give us a really go to 1202 and you're going at 12:02 so kind of kind of not this is a catastrophic failure the computer just restarted in front of your eyes they would be this there's a harder loss function in the radar and it overwhelms the computer giving it false data but in their infinite wisdom the people at MIT the people at MIT has programmed the computer so it was checkpointing so you could restart and continue where it left off and that we saved the mission and I'm still waiting for that feature on Windows and press my gradient descent switches so I have gone into current 66 and now have some like manual control over the flight so call on the ground would be attitude hold we better stay quiet now so there he may let me see that Neil Armstrong has got manual he was going to land in a field of boulders he doesn't want that so he has taken over and is moving really fast so the imagine he know he's in a tackle and gene Kranz says from now on you only announced fuel and they stay quite not to distract him and now it's relax relying on the skill of the pellets the pilot is not easy so he's an ace pilot one minute that's what the fuel he has to go to land my watch we do rely to the top picking out a test two and a half now 14 feet okay so now we've made it on the moon thanks to the incredible pilots and the incredible HDC and know of arson escalation we cannot do an EPA if we look outside the window and there's no Starbucks so it's a very inauspicious place so we decide to simulate an abort instead and go back home so so I'm going to press the afford stage button and uh uh so if they design this to be as safe as possible at any point during the landing I can press support stage and regardless of my switch positions if you look at my buttons over here I have two engine stop button pushed in I don't have any engines armed it doesn't care if I press that abort button it's gonna get me out of here and back into work right so from now on the AGC is gonna be in charge and will get us back into orbit and then my colleagues will rescue us so we're going to end the demonstration here and know these and gentlemen our ace pilots [Applause] incredible [Music] you get at the reading on the 1202 program alarm back on earth few were more nervous than a young computer programmer who had written the code for the lunar landing we were landing on the moon the first time it's not surprising there were problems my name is Donna Isles I wrote a good part of the computer code for the on-board computer that was active during the lunar landing phase of the apollo mission Dinsmore who worked on for days the other powered flight phases it's Sharon Albert who helped with the landing and some other things you brought I have a couple of modules they don't know for sure what program they relate to each of these is about 12 kilobytes and this weighs about a kilogram and you have the ability to read them and find out exactly what's on them yeah hopefully we'll be able to tell you tomorrow I think they're both Sundance one is 302 one is 306 I think and then and then you got the third Sundance module from Alden earlier this week yes so we would have like with one revision one of the modules did a slightly different revision from the other two Michael Blair Smyly but mucosa I wanted to be able to congratulate you in person I'm doing this euro a time care Thank You following you and on our last day we attended the Radian of the Draper labs people that work on a pole they had this great caricature of dr. aper the inventor of inertial navigation and even his car driven by his son there was of course great photo taking of all the veterans and even a recreation of a famous picture of the five programmers that did the famous hack on Apollo 14 that basically saved the mission and it's nice to see them alive and kicking and in particular to hear the stories it was hard to record in the noise but I caught a few it sounds like it might be [Applause] [Music] so is there is a coast somewhere with the lamp back to that somewhere in why why Tomoko kids what drove your choice because we had lined the my company's samtech because they were made by a machine shop on the west side of Chicago this guy had walked in and walked into the paragraph there's a watch The Forgotten staff in Chicago and children these and we'll you said ground race electron now they block - that was really hoping it really doesn't smell and I believe is what surface-mount suffer he has a real problem I needed a second car have had five Mary blares oh yeah we where my power ground or three six we were so impressed by that that you had five alegre hedges they had not existed what are the guys okay I heard about some Paul Church Virginia who's been making thick courts for the Minamata take a look and so that was to have a very slated to 100 it consulting for a company that was having a mother board computer board I have to be careful I had a logical they might well I took a look at that about so you have the dong eyes book signed by Donna eyes those with my elven Hall block signed by Eldon can you sure they're the cover

Channel: CuriousMarc

Views: 114,997

Keywords: CuriousMarc, Moon Landing, AGC, 50th Anniversary, Apollo Guidance Computer, Vintage Computer, Restoration, Repair, 1202 error, Draper Labs, MIT Museum, Eldon Hall, Don Eyles, Core Rope, Demonstration, Cradle of Aviation Museum

Id: 9iavKBdPo4U

Length: 28min 39sec (1719 seconds)

Published: Sat Jul 27 2019

Reddit Comments

[u/[deleted]]

I live on long island. IF your ever in the NYC area the cradle of aviation museum is a must. They show it but I don't think they said what it was but they have the next lunar lander that was going to go to the moon when the program was cancelled. You can even find ex Grumman employees working the museum. One of the project managers of the lunar lander program at Grumman does taxes for aarp here on long island. My grandfather worked on the lander as well but he has Parkinson's now.

[u/Triabolical_]

The whole CuriousMarc series is worthwhile to watch if you like that kind of thing.

[u/[deleted]]

If memory serves me correctly this is the first real fly by wire computer as well as the first with integrated circuits. At one point in time NASA was purchasing 70%+ of all integrated circuits produced to get this thing working. They essentially created the market. NASA is the reason why we had the PC revolution and why we have smartphones.