MIT Science Reporter—"Computer for Apollo" (1965)

these test engineer's are checking out a sophisticated collection of telescope gyroscopes and electronics for project Apollo this guidance and navigation system will be mounted in an Apollo spacecraft to aid our three astronauts on their voyage to the moon and return the miniaturized computer at the very heart of this system is our story today on science reporter hello I'm John Fitch MIT science reporter today we're at the MIT instrumentation laboratory which has been given design responsibility for this guidance and navigation system which will direct our Apollo spacecraft on the way to the moon in fact at one time direction of the Rising Sun or perhaps winding riverbed with all that man needed his Restless search for a new land centuries later the quadrant of the magnetic compass guided his way even across the open sea even after familiar landmark had long since disappeared today we speak of traversing a million miles of empty space where there is no North or South no rising or Setting Sun not even any up or down it's an extremely complicated task requiring many many measurements and millions of calculations as you can see from this Apollo flight plan there are several critical maneuvers that have to be performed after the Apollo spacecraft reaches its Earth orbit it must be injected into a trans lunar trajectory at just the right place in time and faith someone has compared it to shooting at a moving target from a revolving platform which is mounted on a train which is going around occur then at the halfway point long about here the program force must be examined for errors and possibly a mid-course correction Bay there are many other similar maneuvers and to learn about the guidance and navigation system which will make this possible we talked with mr. Elden hall deputy associate director of the instrumentation lab guidance and navigation system consists of two major elements controls a computer and the computer display and control the inertial measurement unit shown up here but normally bounce back consists of Gerald's and accelerometers that measure the angles and velocity of the craft miss fashion the spacecraft rotates the inertial measurement unit holds the reference so that angles can be measured the sextant is an instrument very similar to that used by the sailors to navigate on the surface of the earth now what kind of a problem might you have to solve most basic problem is determined the possession at any point in time and that can be illustrated in these charts the section shown here represents the spacecraft and to determine the position an angle must be measured between a point on the earth and a star and you can see that as you move away from the earth this angle would now down thus giving the distance between the earth and the spacecraft the astronaut first positions a spacecraft so that a point on the earth a landmark is visible through the Sexton then he positions the sextant angle so that the star is superimposed upon this landmark what kind of a landmark maybe see this one is San Francisco Bay as you can see here however the Great Lakes or Cuba Cape Cod the tip of Florida any of these points make suitable landmarks and then through some system of mirrors you actually superimpose the star on that's right the the mirrors inside the section will bring the star within the field of view so that he can superimpose it on the landmark how is this angle actually measured it's done automatically by the computer the astronaut must first identify to the computer the star in the landmark planning to use then as he's positioning the spacecraft and the sexton the computer is measuring the angles between the two when the astronaut is satisfied that the star is superimposed upon the landmark he pushes the mark button telling the computer to record these angles and the time of the measurement from that information the computer can compute the position spacecraft space well now that you know the position what can you do about it if it isn't right a computer and position the spacecraft turn on the motors and starett and truck motors off will you be coasting on a new and corrected path that's right to see the Apollo guidance and navigation system in operation we visited the systems test laboratory and talked with mr. Ramon Alonso assistant director of the instrumentation laboratory one of the interesting aspects of the guidance system is the way in which the astronaut controls the guidance equipment through the computer and he does so by means of the display and keyboard which is a subsystem there are two instances of the displaying keyboard one is with the rest of the navigation equipment in the lower equipment Bay and the other is near the couches where the astronauts can operate the computer without leaving their couches the system of codes used is reasonably simple consists of a numeric verb in an American now these are little sentences made of numbers then essentially a straight a bit the an example of it might be a verb 16 which is continuous display in decimal in a noun which is time quick these work I'm now told the computer what I want but I'm not I have not yet told it to go ahead and do what I want when I press enter the computer proceeds to display time and it does so giving you times from launch perhaps in hours and hundreds of hours 98.5 six hours from launch it also gives me a fine view of the lower part of the time in seconds and hundreds of seconds that is useful occasionally I just think it's around launch time at the interstate yeah the computer will continue to display that information until told otherwise and it's told otherwise by another verb in this case the verb is terminate 34 it's now forgotten that command another example of the use of the computer might be to position the object now that is something that can be done manually and usually would be but it affords us a good view as to how the computer is operated the optics are not pointing in a certain direction and I want to change that direction to another target and I will invoke a verb which is point 41 and a noun which is optics 9:55 point the telescope point the telescope when I press enter the computer then proceeds to request the angle to which I wish the optics pointed well the numbers have changed another flashing that's right the flashing indicates that action is requested off the operator and the verb in nouns have changed to tell the operator what it is that it's expected of verb 21 is load load the first component first thing in now 57 and used to be 55 is the angle 55 was the telescope and 57 is the angle which the telescope makes this case the angle I want is 180 degrees and I enter that and now it asks for the second angle 22 second angle is plus 325 now when I press ENTER the camera which will come close to the eyepiece will see the telescope slew and point to another target as you can see the crosshairs were lined up on the edge of the right most of the two targets and the computer is now driving the optics telescope with relation to the spacecraft and it's aligning it on the right was the whisper of thing there you can see the crosshairs right in the middle of the target suppose now that we had done the optical sighting by hand rather than by the computer in that we wanted to inform the computer that we are on target this is part of the procedure that is done when star sights that are made as Gerald Hall mentioned previously that is done by means of a mark puppy just located in the lower equipment Bay when the telescope is on target the astronaut presses the mark button and the computer changes the display to display that's the verb mark information number 56 and what it displays are the two angles that the telescope is making and the time at which that measurement was notice that these angles are very close to the ones that were commanded originally in our earlier efforts this information is part of what is necessary for the computer to then estimate the present position and velocity of the spacecraft to estimate what the velocity correction is that ought to be form and then to execute that velocity correction to learn more about the remarkable little computer at the heart of the guidance and navigation system we talked with mr. Albert Hopkins assistant director of the instrumentation laboratory this computer is similar to its ground-based big brothers that are dominating our lives so much today and that it's fundamentally a high speed adding machine with the additional features of having a memory into which it can write results and from which it can take data very much as an accountant as his ledger and it also it has a self-contained list of instructions analogous to an accountant training so that this said this tells the computer what to do in sequence if we look over here I can show you more about how the computer operates the adding machine of this computer is a high-speed arithmetic unit which carries out the fundamental arithmetic processes all of the complex operations that we've seen today can be broken down into long lists of arithmetic the arithmetic unit receives its data from a memory divided into two sections and it puts its results back into the erasable portion of that memory this is the portion which is similar to the accountants ledger the fixed memory is unique to the space age it is a memory which cannot be written into by the arithmetic unit and it contains information which must blast the entire mission it's here for safety this contagion of stars and things who wouldn't want to forget that's right this contains a list of instructions which are fed one at a time the sequence generator which generates all of the controls necessary to operate the entire computer input data which comes from the angle measuring devices that we saw earlier the keyboard comes in through input conditioning circuits and is available in the erasable memory the arithmetic unit can operate upon this input data and compute results designed to be output these results are placed in a particular portion of the erasable memory where they are sent through output conditioning circuits out to other instruments which need this data such as for instance the displays or perhaps a rocket motor when you say this computer is very much like land-based computers and yet I think of them as occupying all Bay's of equipment you've got all this squeezed into a little box how did you do that miniaturizing a computer like this requires a judicious choice among many quantities its first necessary to minimize the number of circuits which you use it's necessary to minimize the size of the components which you used and it's necessary to package them as tightly as possible now this must not be carried too far if it's carried too far it can endanger the reliability of the computer so that a compromise must be sought now what kinds of circuits are involved in the memory and also in the power supplies and then the input/output of the computer conventional components are used with the exception of the fixed memory piece of which we see here this fixed memory is actually composed of magnetic cores with wires woven in and out sewn in with a pattern where the information here is in the pattern of the sewing see the remainder of the computer the arithmetic unit the sequence generator the so-called connective tissue the logic section so-called of the computer is made up of a single type of unit this is a micro circuit gate 4300 of these are used in the computer to make up this entire segment these are packaged together tightly they fit in a fairly small space and are interconnected in separate modules in one side of the computer the Apollo computers are manufactured by the Raytheon Company in Waltham Massachusetts the computer itself consists of two trays one containing logic modules the other memory modules to learn how these modules are put together we talked with mr. Jack Poundstone raytheon's Apollo engineering manager in this room John we run all of the electrical components through a screening and vernian process you know there are over 30,000 parts that go together to make this machine every part is put through an electrical test and then a series of environmental stresses as an example this girl is placing the micro logic units into a fixture that will be used in this centrifuge here the fixture is fun at a very high speed and twenty thousand G's of force is placed on each component that's a lot more than it will ever experience yes that's true but we put more forces on more stresses than we really expect to ensure the high reliability this is really sort of a torture chamber that's right in addition we run all the parts through a leak test make sure there's no leaks in the can the part is put into a high pressure helium tank and if there is a leak the helium will be forced into the king then we put it in a vacuum chamber and evacuate and test for the amount of helium coming out see in the final phase of the screening and burning process the girl puts the parts as she's doing here into a test socket then those parts are placed on this burning rack here they will be operated for almost a week at a over over voltage stress condition actually our operating yes we're operating the parts now any failure any significant failures of any our tests is cause for rejection of the entire lot of 5,000 parts after we've insured do we have good components then we want to make a module now the little cans here are placed in these holes and a complement holder then we take a matrix which is a complex wiring pattern it's placed on the back and the wires are full / and welded to the leads of the Myka logic unit itself I'd like to show you now how we make the matrix here we see an operator who is placing a piece of mylar insulator that has adhesive on both sides and this insulator has previously had a pattern of holes punched onto it now this is placed on this longitudinal wire winder as the piece advance strips of nickel ribbon are laid down in longitudinal direction on the mylar next its taken to the vertical wire wire here the operator is placing it on the machine and as the drum rotates wires are laid down on the opposite side of the mylar in a vertical direction the wires are will be laying down right over the areas where the holes have been punched some running one way and one side and others running the other way on the others that's right darling now the next operation is to perform the welding this is done on a automatic welding machine this machine we are advancing the matrix underneath these weld heads and whenever the a hole appears under a weld head the weld is commanded to drop and perform a weld and this makes a feed-through connection from one side of the insulator to the other and the final operation this girl uses a cutting tool to remove the excess pieces of wire to give us the final configuration of our precise wiring pattern this matrix then is the wiring that sort of connects one little micro electronic circuit to another that's right John this wiring diagram shows you how the matrix can be used to interconnect the micro logic elements see here a wire will run from this can down here where it's welded through to the other side run down break out to another and up here to another now after that operation the operator can now take the matrix fold it and cement it to complement holders then the little micro logic elements themselves will be placed in the hole and we're ready to bend the wires down and make a well after completing that operation the entire assembly is then put into this metal header now this header contains it provides the structure for the assembly and it has a row of male pins here and the leads from the matrix will be welded to the pins so that one logic stick can be connected to another one that's right let's take a look at how the operators do this operation in detail this operator is loading the little micro logic elements into the complement holder note that she takes each one and dips it a little adhesive before she puts it into the holder I see so it's really faster than plate that's right done now she's ready to weld the wires to the leads coming out of the can you don't solder them here actually welded welded she takes her little pair of tweezers and properly aligns a wire to the pin of the can when the alignment is right she then makes the well now that little flash you saw there was when the weld was actually made after that matrix welding is completed she's ready to place the assembly into the header it actually does fit in there yeah he very gently forces it in and she's ready now to weld the matrix wires onto the pins of the header upon completion of that operation we now have an electrically completed module a test man will now take this module and run an electrical test he plugs the module into a special test socket and then this special piece of equipment will electrically energize all of the circuits to ensure that they are properly working the information for the test is stored on a piece of paper tape after this testing then this logic stick is ready for the computer no there's one more stage John and that's the potting of the module what do you mean about plumbing the potting is this plastic coating that provides a covering for the wiring and the components now the module is ready to be plugged into the logic tray assembly number 38 and there all these other modules - that might be a little different that's right what about the memory modules the memory modules of the computer are made using a basic component which is a doughnut-shaped magnetic core now this core would be placed into a component holder like so now after the compound holder has been completely loaded with cores were then ready to do the wiring in order to perform the wiring operation we store about 20 feet of wire in this needle now the operator will take core holder and pass the needle through the core around to the other side and then weave it back through now let's watch how the girls do this operation and a little more detail now here we have a pair of girls who are wiring the address wiring of the Koro module now they pass the wire back and forth stored in the needle and put it through the core in a particular wiring pattern each time the wire goes through they must very carefully wrap the wire around one of those little nylon pins as you can see what that does is pull the wire away from the center of the core to allow room to pass the needle through again now these address wires go to every single core that's right now when the wire is completely weaved into the rope it must be terminated on a little Sutter terminal now the girl strips the insulation from the wire and very carefully wraps it around the pin then they use a magnifying glass to inspect their work now the fence wiring information or the wiring that contains the program of the fixed memory is performed by using this machine the Machine indexes to a particular location of a core and then the girl passes the needle through the aperture and allows provides the wire to go through the right core she doesn't have to think about which Cora goes through next no the Machine does that Porter now note each time the wire passes through that little aperture jogs down and pulls the wire around one of the nylon pins when she passes a needle through she will trip the switch with the needle which causes a tape reader to advance there's the tape reader and that in turn causes the Koro plane to move its position now after all the wiring is completed these nylon pins that we use to temporarily hold the wire can now be removed next we must press the wires very gently down into place so we'll be able to fold up the whole assembly now this operator is holding the core planes into a sandwich type construction and laying them into the header of the module now we're ready for electrical tests we must ensure that every wire in every component are properly located the operator puts it this piece of special test equipment and a program stored on paper tape is then used to exercise the month this is certainly a complicated looking maze of wiring here it certainly is gone that module contains 512 fours over a half a mile of wire and it performs the function of storing over 65,000 individual pieces of information I mean you put that potting compound all over this - yes in the final form here's the module parties and it's all ready to be plugged into the memory tray assembly I mean how do you connect one module to the next one of these trays well that's done on the backside of the tray let me show you oh I see here you see a fairly complex wiring pattern we're able to interconnect from module to module by running wires on this pin say that pin right now this pattern is so complex that we've used a computer program to determine the exact layout of each wire that is we may run a wire from here to here by going down this way and over here yeah right that well that's to avoid a density problem where the wires could build up if we laid them all in the same Channel but I should think that'd make it rather hard for somebody who was trying to wire from one pin another to remember all that's true in fact the wiring is so complex that a human being just can't do it so we use a machine to do all of this plan this is the automatic wire wrap machine the operator has placed the tray in the machine and is starting the wiring operation now this machine has two wire wrapped tools the can be incremented to the proper location on the tray when it's found the right pins the wire is stretched out and formed in the right pattern then the insulation is stripped from the ends of the wires and finally the two tools drop down and wrapped two pins simultaneously now in order to corners and things yes you can and in order to run the wire in a different direction sometimes the tray is rotated it can be positioned in four different locations now the information to command those wire wrap tools is contained on these IBM cards each card has the information for a single wire how is the wire actually fastened to the pin is it soldered or welded no this is this is what's known as a wire wrap connection the soft copper wire is very tightly wrapped around the pin and you might see that the pin is a spare cornered pin and in this fashion the wire digs into the sharp corners of the pin and provides a good electrical connection now we're entering the computer system test Barry had gone after the trades have been potted modules assemble to the trays we bring the machine into this area and finally we must perform a complete electrical check out of the computer now this piece of equipment is the computer tester this provides a means to enter data into the team and monitor all of the various outlets here we have a piece of equipment that provides the power and interconnects the computer the tubes playing keyboard now what kind of tests would you perform on it well actually we've written a very special fix memory so as an example we can have the machine tested all the possible displays to be created let me show you as I enter that you see that the displays go from online to old age and so forth down the line now it's just the last time that the computer is tested before it actually is blown No thank you very much today we visited the instrumentation laboratory at MIT and the Raytheon Company in Waltham Massachusetts I'm John Fitch MIT science reporter you

Channel: From the Vault of MIT

Views: 233,122

Rating: 4.8952703 out of 5

Keywords: Computer Science (Industry), Apollo Program (Space Program), MIT, Massachusetts Institute Of Technology (College/University), 1965, Science Reporter, Science Reporter TV Series

Id: ndvmFlg1WmE

Length: 29min 21sec (1761 seconds)

Published: Wed Jan 20 2016

Reddit Comments

[u/Ski7les420]

The hand woven memory still amazes me. 50 years later and the hardware is still being studied and analyzed. Incredible.

[u/neetoday]

The Apollo Guidance Computer used integrated circuits, but each IC was only a three-input NOR gate. The post above is a video describing its assembly.

This paper describes a bit in text:

https://www.ibiblio.org/apollo/hrst/archive/1716.pdf

"The logic element utilized in the Apollo Guidance ' Computer is the three input NOR Gate as shown in Fig. 1. At the time that the decision was made to use integrated circuits, the NOR Gate, as shown, was the only device available in large quantities. The simplicity of the circuit allowed several manu- facturers to produce interchangeable devices so that reasonable competition was assured. Because of recent process development in integrated circuits, the NOR Gate has been able to remain competitive on ths basis of speed, power and noise immunity. This circuit is used at 3V and 15mw, but is rated at 8V and 1OOmw. Unpowered temperature rating is 150°C. The basic simplicity of the three input gate aids an effective screening process. All transistors and resistors can be tested to insure product uniformity. The simplicity of the circuit also aids in the quick detection and diagnosing of insidious failures without extensive probing as required with more complicated circuits. One additional integrated circuit used in the Apollo Guidance Computer is the memory sense amplifier. As seen in Fig. 2, the circuit is considerably more complex than the NOR Gate. The experience with this more complicated circuit has been comparable with the logic gate. However, since it is a low usage item there is available less information of historic interest, that is, reliability information such as failure rates and modes of failures. The balance of this report relates to history of the logic gate."

[u/trojan2748]

I'm glad these old videos are archived somewhere. I wonder how much we've lost.

[u/KevinAndEarth]

65 thousand pieces of information!

64kb of read only memory.

Wow

[u/bubblesort33]

Them "girls" are doing a good job!

[u/nilaykmrsr]

If anyone’s interested in taking an intricate look at the restoration of one of the AGC (Apollo Guidance Computer) you take a look at this YouTube channel. A bunch of energetic hardcore engineers trying to bring back this classic piece of hardware.

[u/slash196]

The dude referring to a grown-ass woman that looks like she could have grandchildren as a "girl" was jarring.

[u/Conmanx360]

If anyone is interested, the source code is posted on GitHub. It's interesting to poke around in.

[u/printflour]

around what year would this have been filmed?