A FAIR DEBATE

[Bob B.]

Very few hoaxers are actually stupid. The vast majority are simply willfully ignorant.

Although I certainly understand the distinction between stupidity and ignorance, I can't help but believe that willful ignorance is in many ways a sign stupidity.  I find it difficult to understand how a truly intelligent person could care so little that he/she doesn't what to learn.

[bobdude11]

"Core rope" is entirely different from multithreading. Multithreading is a common software technique for executing more than one task (logically) at once. If you have multiple CPU cores, then you actually can execute those tasks at the same time. Threading is usually distinguished from multitasking (an older concept) in that each task has its own address space, while threads usually run in a common address space. Both methods are very widely used.

"Core rope" is a long-obsolete hardware technology used in the Apollo Guidance Computer as a read-only memory holding all the computer's programs. It was called "rope" because that's what it physically resembled. It consisted of wires threaded through a series of small transformer cores, forming a "rope" that was folded up and mounted on circuit boards in the computer.

Awesome! I did not know that is what Core Rope meant and my ignorance showed when I likened it to Multi-Tasking (I knew the definition of that one - just did not know how to compare anything I know to Core Rope).

Thank you for the lesson - I will file this one away with my other Apollo knowledge (some from books and manuals, much from here).
--bobdude11

[bobdude11]

I think it would depend on the person. The humans who lived 1,000 or 10,000 or even 100,000 years ago were essentially identical to us living today, and were just as smart. One should still be able to understand modern technology if they are willing to learn.

But, as is evidenced in most science texts and historical items, persons in those eras were ignorant of was actually happening. I believe it is safe to say, though, that should you explain modern technology to the likes of DaVinci, Van Heuk, or similar minds, they would be able to comprehend much of what is known and use the information to understand the rest. This goes directly to your statement about hoaxsters being unwilling to learn even when faced with overwhelmng evidence.

[nomuse]

A couple thoughts, building on each other.

It is easier to explain a cell phone to someone from the modern industrialized world then it would be to, say, Shakespeare (a fairly witty and well-read person of his time) because many of the basic ideas are common and embedded in that later cultural context; electricity, batteries, radio, etc.

In a way, it is like the problem of believing three unlikely things before breakfast; for the modern one has to accept just a few unknowns, such as cellular distribution networks and the generally-unseen grid of cell towers.  Poor Will has to accept your explanation on electric current and all the way up to (if he asks), plastics.



But...and here is where it gets interesting...the average modern doesn't actually understand the cell phone any better than Will would after your explanation.  What they have, in fact, is not an understanding of  electricity, but an acceptance of it, and some experience with it in a variety of contexts.  So when you flip the cell phone face-out and say "This is an OLED screen; it's a display technology derived from LEDs" the modern will grasp the concept of "display technology" and "LED" but they don't actually have any idea how they work.

c.f. Clarke, for most people, you could be saying "The goddess Luminatica makes the images.  She's the same goddess that makes computer monitors work, and is sister to the goddess that runs stoplights and hazard flashers."  Because you are only providing a limited but consistent framework.  And, really, very few of us are ever going to need to brew our own organic dyes, grow crystals, draft up micro-fabrication templates, and otherwise understand at that level of detail how a display works.  Even for us geeks it is a matter of how much voltage to apply to which lines.



But then we have an even more interesting jump.  I'm too tired this morning to put it in terms of common technologies (worked two back-to-back 12-hour shifts with a nasty stomach virus that wouldn't let me eat), so I'm going to reach for an attempted example from the sport of bouldering.  So apologies to all.

Anyhow, the idea is that some technology is refinement, but other technology is on entirely new principles.  You can grok clockwork very well, and you can model increasingly complex devices are being merely very tight clockwork, but eventually you will run into something that can only be understood by grasping the concept of the electromagnet.  Or the shape-memory alloy.  Or whatever comes along next.  Sometimes these leaps have the appearance of a new thing because they have built so far...I like to think of making the leap from "a lightbulb" to "millions of lightbulbs crammed into a small flat plane so that images could be produced."  Or think of Marconi interacting with a cell phone -- his first thoughts are not going to include the concept of a cellular network.

Err, I guess I don't need the bouldering example anyhow.  Here it is though; boulderers always watch each other climb, and they learn a lot from that.  But it is generally accepted as a truism that you can only grasp what a climber a few grades above you is doing.  If there are four grades between you, the typical experience is to go "here's a weight shift, there's a nice little hook, I see the crimp she's using there, and....how the heck did she make that cross!"  Some of the moves are simply incomprehensible -- they might as well be magic.

[bobdude11]

Good thoughts nomuse - I hadn't really considered that, yes, I have a basic understanding of how cell phones work, but some of the more intricate parts require much more study to get past the "magic" of how they function.

[Tedward]

Often wondered about this comment about magic.
[...]
PS, just google Shannon information theory. Pass me a couple of tin cans and some string... (actually, some of it rings a bell).

So don't dismiss the accomplishment too quickly.

Ah, did not mean it come across as such. More joke on a level for me was the string and tins. But reading what you post with interest. I am a serial abuser of equipment rather than the designer, as always I increase my knowledge on here.

[Kiwi]

Two questions:
1. Was it truly called "Core Rope Technology" (I hope I am not misremembering the term I heard)?
2. Is this similar to multi-threading (or perhaps multi-tasking) or does it just allow the system to pull in the appropriate program at the correct time? (assuming I am not merely confused by the Hollywood aspect of 'From the Earth to the Moon' - Episode was 'We have cleared the tower' - it was during the interview of the computer technician that I remember him mentioning Core Rope Technology or something along those lines)

Additionally, are the schematics and source code listing available to the general public? I am trying to find everything I can about Apollo (and some WW2 aircraft) for light reading in my off hours.

Bobdude11:  If you're interested in the construction of the Apollo Guidance Computer, you'd probably find the Spacecraft Films 2-DVD set Mission to the Moon worth watching.
http://02e5a89.netsolstores.com/missiontothemoon.aspx
It has nine TV documentaries in black-and-white of about 28-29 minutes each, made by MIT for Nasa in about the mid-1960s, plus one shorter colour documentary about Apollo 4.

They are quaint and amusing by today's standards, but full of information.  Some of the interviewees are stiff as a board and probably terrified of the TV camera, and they glance off-camera to get a reminder of what they should be saying - perhaps words or hints written in chalk on a blackboard and traced by a finger of one of the film crew.

One documentary has Tom Kelly giving a tour of Lunar Module construction at Grumman.  Another is "Computer for Apollo", which I found it so fascinating I did a 7-page transcript of the soundtrack.  If anyone who's interested sends me a PM with an email address I can send a copy.

Besides the construction, we are also shown how the DSKY was operated and how the AGC was linked to the navigation instruments.

Some excerpts:

0:00:47   Fitch:  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 and back.
0:01:04   Fitch:  At one time, the direction of the rising sun or perhaps a winding riverbed was all that man needed in his restless search for new land.  Centuries later the quadrant and the magnetic compass guided his way, even across the open sea, even after familiar landmarks had long since disappeared.
0:01:23   Fitch:  But today we speak of traversing a million miles of empty space, where there is no north nor south, no rising nor setting sun, not even any up or down.  It's an extremely complicated path requiring many, many measurements and millions of calculations.
0:01:41   Fitch:  As you can see from this Apollo flight plan, there are several critical manoeuvres that have to be performed.  After the Apollo spacecraft reaches its earth orbit, it must be injected into a translunar trajectory at just the right place in time and space.
0:01:58   Fitch:  Someone has compared it to shooting at a moving target from a revolving platform, which is mounted on a train, which is going around a curve.
0:02:08   Fitch:  Then at the half-way point, along about here, the programmed course must be examined for errors and possibly a mid-course correction made.  There are many other similar manoeuvres, and to learn about the guidance and navigation system which will make this possible, we talk with Mr Eldon Hall, Deputy Associate Director of the Instrumentation Lab.
0:02:30   Eldon Hall:  The guidance and navigation system consists of two measurement elements, controls, the computer, and the computer display and control.  The inertial measurement unit, shown up here but normally down at the back, consists of gyros and accelerometers.  It measures the angles and velocity of the spacecraft in this fashion.
0:02:56   Hall:  The spacecraft rotates and the inertial measurement unit holds the reference, so the 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.
0:03:10   Fitch:  Now what kind of a problem might you have to solve on the way to the moon?
0:03:14   Hall:  The most basic problem is to determine the position at any point in time, and that can be illustrated in these charts.  The sextant 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 narrow down, thus giving the distance between the earth and the spacecraft.
0:03:48   Hall:  The astronaut first positions the spacecraft so that a point on the earth, a landmark, is visible through the sextant.  Then he positions the sextant angle so that the star is superimposed upon this landmark.
0:04:05   Fitch:  Now what kind of a landmark might this be?
0:04:07   Hall:  This one is San Francisco Bay, as you can see here.  However, the Great Lakes, or Cuba, or Cape Cod, the tip of Florida — any of these points make suitable landmarks.
0:04:20   Fitch:  Then through some system of mirrors you actually superimpose the star on that feature.
0:04:24   Hall:  That's right.  The mirrors inside the sextant will bring the star within the field of view so that we can superimpose it on the landmark.
0:04:33   Fitch:  Now how is this angle actually measured?
0:04:36   Hall:  It's done automatically by the computer.  The astronaut must first identify to the computer the star and the landmark he is planning to use.  Then, as he's positioning the spacecraft and the sextant, the computer is measuring the angle between the two.
0:04:54   Hall:  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 of the spacecraft in space.

*****

0:13:51   Fitch:  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.
0:14:04   Fitch:  To learn how these modules are put together, we talk with Mr Jack Poundstone, Raytheon's Apollo engineering manager.
0:14:12   Poundstone:  In this room, John, we run all of the electrical components through a screening and burning process.  You know there are over 30,000 parts that go together to make this machine.
0:14:23   Poundstone:  Every part is put through an electrical test and then a series of environmental stresses.  Now, as an example, this girl is placing the micrologic units into a fixture that will be used in this centrifuge.
0:14:37   Poundstone:  Here the fixture is spun at a very high speed and 20,000 g's of force is placed on each component.
0:14:43   Fitch:  That's a lot more than it will ever experience, isn't it?
0:14:45   Poundstone:  Yes, that's true, but we put more forces on, more stresses than we really expect, to ensure the high reliability.
0:14:51   Fitch:  So this is really sort of a torture chamber.
0:14:53   Poundstone:  That's right.  In addition, we run all the parts through a leak test, to make sure there is 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 can.

*****

0:18:48   Poundstone:  This operator is loading the little micrologic elements into the component holder.  Note that she takes each one and dips it in a little adhesive before she puts it into the holder.
0:19:00   Fitch:  I see.  So it's really fastened in place.
0:19:02   Poundstone:  That's right, John.  Now she's ready to weld the wires to the leads coming out of the can.
0:19:08   Fitch:  You don't solder them, you actually weld these wires?
0:19:10   Poundstone:  They are welded.  Now she takes her little pair of tweezers and properly aligns the wire to the pin of the can.  When the alignment is right, she then makes the weld.  Now that little flash you saw there was when the weld was actually made.
0:19:26   Poundstone:  After that matrix welding is completed, she's ready to place the assembly into the header.
0:19:33   Fitch:  It actually does fit in that little space.
0:19:35   Poundstone:  Yes, she very gently forces it in, and she's ready now to weld the matrix wires on to the pins of the header.  On completion of that operation we now have an electrically completed module.
0:19:49   Poundstone:  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 energise all of the circuits to ensure that they are properly working.  The information for the test is stored on a piece of paper tape.
0:20:02   Chapter 5.
0:20:10   Fitch:  After this testing, then, this logic stick is ready for the computer.
0:20:14   Poundstone:  No, there's one more stage, John, and that's the potting of the module.
0:20:17   Fitch:  What do you mean by potting?
0:20:19   Poundstone:  Well, the potting is this plastic coating that provides a covering for the wiring in the component.  Now the module is ready to be plugged into the logic tray assembly.
0:20:28   Fitch:  That's number 38 and there are all these other modules too.  They might be a little different.
0:20:32   Poundstone:  That's right.
0:20:33   Fitch:  What about the memory module?
0:20:35   Poundstone:  Well, the memory modules of the computer are made using a basic component which is a doughnut-shaped magnetic core.  Now this core is placed into a component holder like so.  Now after the component holder has been completely loaded with cores, we're then ready to do the wiring.
0:20:55   Poundstone:  In order to perform the wiring operation, we store about 20 feet of wire in this needle.  See how that wire comes out of there?
0:21:02   Fitch:  Uh-huh.
0:21:03   Poundstone:  Now the operator will take the core-holder and pass the needle through the core, around to the other side, and then weave it back through, in different positions.  Now let's watch how the girls do this operation in a little more detail.
0:21:20   Poundstone:  Now here we have a pair of girls who are wiring the address wiring of the core module.  Now they pass the wire back and forth, stored in the needle, and put it through the cores in a particular wiring pattern.  Now each time a 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 centre of the core to allow room to pass the needle through again.
0:21:49   Fitch:  I see.  Now these address wires go to every single core?
0:21:54   Poundstone:  That's right.  Now when the wire is completely weaved into the rope, it must be terminated on a little spudder 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.
0:22:12   Poundstone:  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 the core, and then the girl passes the needle through the aperture and provides the wire to go through the right core.
0:22:34   Fitch:  She doesn’t have to think about which core goes through next.
0:22:37   Poundstone:  No, the machine does that for her.  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 the 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 core plane to move its position.
0:23:03   Poundstone:  Now after all the wiring is completed, these nylon pins that were used to temporarily hold the wire, can now be removed.  Next we must press the wires very gently down into place, so we will be able to fold up the whole assembly.
0:23:18   Poundstone:  Now this operator is folding the core plane into a sandwich-type construction and laying them into the header of the module.  Now we are ready for a electrical test.  We must ensure that every wire in every component are properly located.
0:23:35   Poundstone:  The operator puts the module into this piece of special test equipment, and a program stored on paper tape is then used to exercise the module.
0:23:45   Fitch:  This is certainly a complicated-looking maze of wiring in here.
0:23:49   Poundstone:  It certainly is, John.  That module contains 512 cores and over a half a mile of wiring.  And it performs the function of storing over 65,000 individual pieces of information.
0:24:03   Fitch:  Tell me, you put that potting compound all over this too?
0:24:06   Poundstone:  Yes.  Now in the final form here's the module potted and it's all ready to be plugged into the memory tray assembly.
0:24:15   Fitch:  Tell me, how do you connect one module to the next one in these trays?
0:24:19   Poundstone:  Well that's done on the back side of the tray.  Let me show you.
0:24:25   Fitch:  Oh, I see.
0:24:27   Poundstone:  Now here you see a fairly complex wiring pattern.  We’re able to interconnect from module to module by running wires from this pin to, say, that pin.  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 to there.
0:24:51   Fitch:  Why is that?
0:24:53   Poundstone:  Well, that's to avoid a density problem where the wires could build up if we laid them all in the same channel.
0:24:58   Fitch:  Oh, I see.  But I should think that'd make it rather hard for somebody is trying to wire from one pin to another to remember all that.
0:25:02   Chapter 6.
0:25:04   Poundstone:  Well 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 wiring.
0:25:14   Poundstone:  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-wrap tools that 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 wire, and finally the two tools drop down and wrap two pins simultaneously.
0:25:45   Fitch:  Can you go around corners and things?
0:25:46   Poundstone:  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.
0:26:12   Fitch:  How is the wire actually fastened to the pin?  Is it soldered or welded?
0:26:16   Poundstone:  No, this is what is 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 square-cornered pin, and in this fashion the wire digs in to the sharp corners of the pin and provides a good electrical connection.
0:26:35   Poundstone:  Now we're entering the computer system test area, John.  After the trays have been potted and the modules assembled to the trays, we bring the machine into this area and run through exhaustive temperature tests and vibration tests.

[ineluki]

I can't help but believe that willful ignorance is in many ways a sign stupidity.  I find it difficult to understand how a truly intelligent person could care so little that he/she doesn't what to learn.

It's probably what you meant anyway, but I think the stupid part isn't mere wilful ignorance, but ignorance about the subject one tries to discuss.

[JayUtah]

Awesome! I did not know that is what Core Rope meant and my ignorance showed when I likened it to Multi-Tasking (I knew the definition of that one - just did not know how to compare anything I know to Core Rope).

Thank you for the lesson - I will file this one away with my other Apollo knowledge (some from books and manuals, much from here).
--bobdude11

Core rope and erasable core work similarly.  We wire up erasable core in a grid on a substrate because it's easier to see where the wires are supposed to go.  The grids implement the address mechanism, plus the set-reset mechanism.  The little cores magnetize in a certain way if they are "addressed" and a set-reset wire has certain electrical conditions.  That causes a signal on a sense wire.

Rope works the same way, except that the set-reset mechanism is absent and the cores are permanently magnetized.  The sense wire either passes through each core or it doesn't.  Because of this more permanent setup, the entire assembly can be essentially wadded up without loss of functionality, and thereby stored in a more convenient form factor.

The operating system in the AGC actually used a pretty sophisticated job management strategy.  It had real-time processing capability as well as pre-emptive multitasking and interrupt-driven processing.

[cjameshuff]

Rope works the same way, except that the set-reset mechanism is absent and the cores are permanently magnetized.  The sense wire either passes through each core or it doesn't.  Because of this more permanent setup, the entire assembly can be essentially wadded up without loss of functionality, and thereby stored in a more convenient form factor.

Slight correction...the cores aren't permanently magnetized at all, they operate as simple transformer cores coupling address wires to sense wires. It was a lot denser than rewritable core memory, as adding another word of memory only involved threading another wire through the same set of cores (and then, only for the ones representing a set bit)...you only needed more cores when there was physically no more room for more wires.

The operating system in the AGC actually used a pretty sophisticated job management strategy.  It had real-time processing capability as well as pre-emptive multitasking and interrupt-driven processing.

Including the capability to drop low-priority tasks in order to continue running critical real-time tasks, as was inadvertently demonstrated in the Apollo 11 landing.

It's rather ridiculous that there's people claiming the AGC was somehow inadequate, when there's enough information available for people to count the machine instructions and see exactly why the 6400 cycle steals/second from a minor hardware design error (an independent, non-phase-locked clock) in the radar plus the 1668 DELTAH display task were too much for the computer to handle, and what the machine did to continue operating despite this...

[Count Zero]

The Apollo Guidance Computer: Architecture and Operation is a terrific book on the subject.  As the title says, it goes into detail about the how the computer was built and also goes through each step of the mission program-by-program.  I learned a lot from reading this.

[ka9q]

Some of the interviewees are stiff as a board and probably terrified of the TV camera, and they glance off-camera to get a reminder of what they should be saying - perhaps words or hints written in chalk on a blackboard and traced by a finger of one of the film crew.

Don't you know the real reason? A CIA hit man kept a gun pointed at the interviewee's first-born child off-camera during the entire interview to discourage any beans-spilling about the whole Apollo project, including the AGC, being a massive hoax. That's why they had to put in all those hidden incoherences that are only now being discovered!

[ka9q]

Slight correction...the cores aren't permanently magnetized at all, they operate as simple transformer cores coupling address wires to sense wires.

Actually the transformer cores coupled a "set/reset line" to the sense wires, which as you say were wired through or around the core depending on the bit to be stored at that location. The set/reset line threaded through all the cores.

Each address wire was threaded through or around the cores in such a way that when an address was supplied to the wires, every core but one had at least one energized address line. (There were two lines for each address bit, one driven by the bit and the other by its inverse. Only one of each pair went through any given core.) The lines carried enough current to magnetically saturate the core, inhibiting it from coupling a subsequent pulse from the set/reset line to the sense line. This allowed a single sense wire to thread through the bits of many locations while having only the desired location respond.

A design optimization had an extra pair of address lines threaded through the cores and driven by the parity of the address such that each deselected core actually had at least two activated address lines. This allowed the current in each address line to be halved.

I wouldn't know any of this if I hadn't read up on Apollo core rope memory while debunking Hunchbacked's ridiculous assertions on the topic. Never let it be said that much can't be learned from Apollo denial. You just don't learn it from the deniers themselves.

[cjameshuff]

Each address wire was threaded through or around the cores in such a way that when an address was supplied to the wires, every core but one had at least one energized address line. (There were two lines for each address bit, one driven by the bit and the other by its inverse. Only one of each pair went through any given core.) The lines carried enough current to magnetically saturate the core, inhibiting it from coupling a subsequent pulse from the set/reset line to the sense line. This allowed a single sense wire to thread through the bits of many locations while having only the desired location respond.

So, a sort of saturable reactor/mag amp setup. That is clever...the descriptions I found weren't very detailed, and left the impression that each word had its own address line with an external multiplexer. Doing this, the multiplexing is all done in the cores themselves...each address bit saturates half the cores (a different subset each, overlapping with the others), excluding them from being read and leaving one "live" core in the end, with sense lines for each bit either going through or around each core depending on the value stored. Removing the external multiplexer and replacing a wire for each word with a wire for each address bit would greatly simplify things from what's required for ordinary core memory, and considerably reduce the number of components prone to failure.

[gillianren]

Don't you know the real reason? A CIA hit man kept a gun pointed at the interviewee's first-born child off-camera during the entire interview to discourage any beans-spilling about the whole Apollo project, including the AGC, being a massive hoax.

That's how I figure reputable actors end up in disreputable movies, too.  We refer to them around here as "grandmother in a basement" movies--someone's got the person's grandmother at gunpoint in a basement somewhere unless whoever-it-is agrees to make a terrible movie.