Verbs, Nouns, and the Apollo Guidance Computer



a lot of you guys have asked about the whole verb now the thing on the Apollo guidance computer well that's what we're talking about today in brief on vintage space the comparison is often made that a modern cellphone has more computing power than the Apollo guidance computer well yes that's true but your iPhone can't get you to the moon it doesn't exactly have that software and really the beauty of the Apollo guidance computer is in how tightly packed and specifically organized that software really was when we think of a computer or even a smartphone we think of interfaces that are familiar to us like a screen and a word processor and a keyboard and even just a basic calculator well the Apollo guidance computer had none of those things it was designed to run a very small set of specifically designed program needed to run a mission to the moon things like checking the guidance platform alignment and firing the engines everything on an Apollo mission was done through the computer and it took about ten thousand five hundred keystrokes to get one mission to the moon and back but because the guidance computer didn't have those interfaces that we're used to like keyboards and word processors and all those things the inputs had to be a little bit different this is the interface of the Apollo guidance computer the display and keyboard commonly referred to as the disk II now you can see that it does have a screen it does have keys but it's not a typical screen like we're used to using on our home computers there aren't alphabetical keys and the screen doesn't list information in words in fact this keyboard is anything but common to us so how exactly did the astronauts use the disky well it actually offered a very simplistic interface for crews starting with the warning lights kampf activity lit up when the computer was turning a program off link activity was lit when there was data being received from the ground temp lit up when the temperature of the platform was out of Tolerance no a TT lit up when the inertial subsystem could not provide an attitude reference in block lit up when the middle gimbal angle was greater than 78 degrees signifying that the spacecraft was close to hitting that deadly gimbal lock scenario standby lit up in the computer system was on standby program lit up when the computer was waiting for additional information to be entered by the crew to complete a program here l lit up when the computer needed control of the dis key to complete a program restart was lit up when the computer was in the restart program operator error was lit when the computer detected an error on the keyboard and tracker lit up with one of the optical coupling units failed the lunar module dis key had three additional warnings one to signify a problem with the autopilot and two more to signify problems with the altitude and velocity of the lunar module spacecraft in addition to these 10 warning keys we have other keys verba noun + – numbers and handful of command keys so there's no obvious way to write in a command like run a guidance platform alignment program so how exactly did the astronauts actually interface with the computer using the disk II well this is where nouns and verbs come in but to understand this we actually kind of need to leave the spacecraft for a second and go down to maybe the streets of New York City so imagine you're in New York City you are a tourist and you don't really speak any English you've got about five words in your arsenal none of them include excuse me but which way to a lovely restaurant in this find neighbourhood of the city so you find a policeman knowing that this is the kind of person who might be able to direct you towards what it is you're looking for so you go up to the policeman and you use one of your words to tell him what it is you want to do that word is eat and that is a verb but there's a lot of food in New York City to choose from so you have to define what it is you want to eat and so you use one of your other words Pizza which is a noun so do you see where we're going with this just like you're awkward a broken English conversation with the New York City policeman all data going through the Apollo guidance computer used verbs and nouns the verb is defined as the action being taken and the noun is defined as the data set being acted on there's actually a really simple computer-based version of this that we all use but don't really think about because it's not expressed as a noun and a verb printing a document if you select print that is the verb the file name is the noun which is basically the data set or in this case document that that verb is acting on so the astronauts inputted all their data using nouns and verbs into the Apollo guidance computer there were 100 sets of noun verb pairs all defining a specific thing that the Apollo guidance computer would do on a mission so let's look at an example let's say you enter verb 37 that tells the computer that you are about to make a change to the program then you hit 3-1 and that tells the computer to run noun 31 which is a targeted rendezvous program and there are a host of others the crew could request maneuver angles with verb 50 now and 18 the crew could monitor changes while a maneuver was in progress with verb 6 now and 18 or even request velocity change required for the next maneuver using verb 6 now and 84 once the noun and verb pairing was entered into the computer the relevant information was displayed on the disk II and of course as you can expect when doing something big like going to the moon there were different kinds of programs so different kinds of nouns and verbs regular verbs verbs 0 to 37 were used to display monitor or update data meaning they needed a noun they needed something to be acting on whereas extended verbs were verbs 49 through 99 and they didn't need a noun to execute a program they told the computer to perform a simple operation of course there is so much more to the Apollo guidance computer than this super quick look at nouns and verbs and so I would urge you all to check out Frank O'Brien's book the Apollo guidance computer which as I've said before and I always remind Frank is said with love and ingest it is more than you ever need to know about how the Apollo guidance computer worked so do you guys have other questions about the Apollo guidance computer I'm not saying I can answer them off the top of my head but I can read and then figure it out for you let me know if any of this makes sense or if none of this makes sense or if you have other things you would just love to figure out about how the Apollo guidance computer worked leave all of those and of course any other comments and things you would like to see covered in future episodes down in the comment section be sure to follow me on Twitter and on Instagram for new vintage space ish content every day of the week and things are going to be changing just a little bit on this channel but I'm still doing it classic vintage space education episodes every Monday or Tuesday depending on upload schedule so if you don't want to miss any of those be sure to subscribe just so you never miss a video

29 thoughts on “Verbs, Nouns, and the Apollo Guidance Computer

  1. The noun/verb thing reminds me of microsoft powershell commands

    No, i dont like microwoft. I <3 Linux

  2. If you are in US, even if you have a good vocabulary don't go to the US Police… The only verb they know is "shoot" and only noun they know is "ass".

  3. I wrote my first basic program in 1969… teletype/paper tape using 110 baud phone hook up to MIT HP1000… I retired two years ago…. rope memory as read only to store the programs….

  4. The RAM (if you want to call it that) was something called “core memory” it had to be hand-woven. And, because of the space limitations in the CM and the LEM, it had to be folded. Core memory for mainframes was never folded because, here on Earth, we have space. (Pun not intended.)

    How many of those memory modules broke, crossed wires and otherwise had to be discarded because of the need to squeeze the RAM into a smaller space?

    ROM was “rope memory,” again, also folded and compressed. How many of those needed to be thrown out because of broken wires?

    How many man-hours (they used mostly women, though) were needed to make this circuitry for the AGCs? Apollo 8 did not have a LEM. Did Apollo 9 and 10 have a full complement of AGCs?

  5. Good explanation. One additional note I'd make (probably the most important part) is that when stating that the AGC didn't have keyboards/mice/touchscreens/etc, it's because they hadn't been invented yet; and the designers, knowing that they were dealing with pilots, not programmers, tried to come up with something they'd all be familiar with in order to interface to the computer: the concept of nouns/verbs from English. I really liked the comparison to Word, where you have an action to perform (print), and a piece of data or target to act on (doc).

  6. so.. basically.. todays phones are MUCH MUCH more capable and have better graphics, interfaces, software, hardware, etc etc..
    ….and THAT is how apollo went to the moon and back? lol great arguement…
    go back to bar-tending…

  7. dear vintage space: Did the astronauts movements inside the CM or Lunar lander affect the trajectory enough for the auto pilot to have to correct for their movements. On the trek to and around the moon and back to the earth did the autopilot put a "spiral" on the CM like a football for a more 'stable' journey?

  8. Hello, very nice chanel. I like what you do, just subscribed 🙂
    And yes, just one little comment about the video. You indicate V37N31E in your video (4:30). But in fact it is V37E31E. For a program change, you have to use the Enter key and not the Noun key.
    Very good video anyway !!
    Cheers 🙂

  9. This is a question from below (a year ago) that went unanswered and I find it interesting. No idea if you still monitor these older videos but here goes … "Absolutely this was very interesting. BUT WAIT! You didn't explain what that tool is used for that they placed vertically on the screen at 4:55. I'm intrigued by it, can you offer any further info in this regards?" This was originally asked by user

    Martin Ottaway.

  10. Great video! My interest in computers began when I saw the DSKY diagram. It was mysterious and I didn't get it. This is a fine primer, Thanks.

  11. Thank you so much for explaining this. I'm a machinist using G code on CNC machines, and when you actually showed the code as you were saying the actions it all made perfect sense. It was like a light went on in my head and dots started suddenly connecting.

    I really appreciate you doing these tech heavy segments!

  12. https://www.youtube.com/watch?v=2KSahAoOLdU Video where guys are restoring an Apollo Guidance Computer.

  13. So what you're saying is that computers were a lot more stable before Bill Gates started dicking around with basic?

  14. Verb : Fly
    Noun : Moon
    Why didn't all the engineers of the NASA think about that ? They chose the difficult way where an easy way out is possible xD
    (Here is the evidence im the smartest :P)

  15. You got some things wrong the warning light PROG (program) lit up when there was a program running. Verb 37 meant to run a program.

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