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- Опубліковано 6 жов 2024
- Dave tests to see if the chips in a 1960's Apollo LVDC Saturn V Launch Vehicle Digital Computer still work.
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My dad worked for IBM on various space projects including Apollo. I myself have worked on military aircraft electronics. Solder has lead in it. Lead = weight. Weight costs fuel to move. So weight is bad. Apollo frequently used welded connections and wire wrap connections. ie., no solder.
Iron core memory is not susceptible to cosmic rays. Unlike modern semiconductor memory.
I thought people might be interested.
Thanks for this insight. I was wondering about the strange construction of these boards. I guess the miniscule weight of solder would add up considering how many of these you'd need to make a functioning computer.
+mike94560 While solder is heavy, you don't need much of it on a circuit board.
The reasons for not using solder are probably
1 - vibration. Everything is heavily vibration tested for space missions. A solder joint can crack, they're not meant for heavy mechanical strain.
2 - reliability. Solder joints can grow tin "whiskers", which reach out and cause short circuits. With the many thousands of connections in a computer, that's flying to space, and absolutely must not fail, solder's not quite reliable enough.
The clips mentioned would survive vibration much better. Welding them would also make a stronger joint.
Magnetic core RAM has a few advantages, yes it's immune to cosmic rays, and it retains it's contents without power. It's also the only thing that was available. Semiconductor memory didn't arrive until the 1970s, and was very low capacity for most of that.
The weight / fuel problem is worse than that. You don't just need more fuel to lift weight, you need more fuel to lift the extra fuel. Every bit of weight you can save can make a big difference, either in the distance you can travel, or the size of the rocket. In the later Apollos they managed to bring a self-assembly electric car to the Moon. They weren't allowed to drive it further than they could walk back from, just in case.
I seen tin whiskers growing in certain types of transistors but not on/from solder. I service equipment which is 70+ years old and have not seen this. Zinc hair growth and Cadmium dust, I've seen a fair amount of that.
Here is NASA's report on tin whisker growth within transistors.
nepp.nasa.gov/whisker/anecdote/af114-transistor/2005-Brusse-tin-whiskers-AF114-transistors.pdf
I believe the reason the avoided soldered joints was the high level of vibration experienced during launch which could cause the joints to crack.
You must be an engineer by training...it is still amazing that these held together for nearly 50 years, however I am sure that trying to recreate all of this for a modern mission would involve using OTS shelf parts including modern computer technology.
Apollo Diodes, high current, high voltage, and Bob's your uncle Dave! Great Work!
Nice! The follow up!
Bob is indeed my uncle. My dad's brother.
All this fancy equipment that shows up just like random. watching Steve is always like looking into the secret lair of Santa Claus...
(must be, since it's down under...)
EEVblog Helping others... I had to google a little about uncle Bob: (wikipedia) ...And Bob's your uncle is an expression of unknown origin, commonly used in Britain and Commonwealth nations. Typically, someone says it to conclude a set of simple instructions, similar to the French expression "et voilà!". (English is not my native language)
Paco Montañés I prefer to say *_"BINGO"_*
Your shirt just made me think of doing something hilarious. I have a small surgery coming up to remove a tumor in my back. I'm going to get a washable marker and write "Warranty VOID If Opened" near the spot they will be making the incision. I hope the surgeon gets the joke.
PLEASE record that! That's got viral video written all over it - pun intended.
Hahahaha I'll try.
Dave, I think the clip mounts are for vibration and possible board flexing during flight. Having a clip mount would provide a greater resistance to mechanical failure of the board and solder joints.
Yep, almost certainly.
Totally, greater contact surface. The more the better and when you're stuck in the mm scale, you become creative, as such we have wrap-around grippers.
You find the concept in all sorts of applications not just electronics.
InXLsisDeo Certainly. Tho, not in the case of the failed equipment, rather on the existing "clones".
Since the LVDC was located in the S-IVB the ones used on the moon missions would not have ended up on the bottom of the ocean but instead would have either ended up in a heliocentric orbit or crashed on the moon.
The answer I was given to packing more in when I worked on some "micro 16" computers which were old in the late 70's (ferrite core memory etc) was "tyranny of numbers" IE the more dies you pack in the more likely it is one die will not work. Rework was not really an option and the tech for testing bare dies did not really exist. So basically it was a yield issue.
I'm going to an abandoned US military MISTRAM base this week. I'm sure I will find plenty of goodies from the 60's. May have to bring my geiger counter to make sure the place is not radioactive. I'll be making a video.
3 years later, have you made this video?
@@JerryDodge Just checked, the miitary base videos are there (no MISTRAM in the titles). I found 2 videos on his channel about this - the 1st shows the base (power station) and the 2nd shows the parts he got:
* Old/Abandoned U.S. Military Base Power Station(mid 50's), Feb-2014: ua-cam.com/video/Bmm7i6YD2I8/v-deo.html
* Trip To Old Military Base & Dump For Salvaging Parts, Dec-2013: ua-cam.com/video/L5uNekLFeK0/v-deo.html
And while on the subject of military bases, a 3rd video added later:
* Tour Abandoned US Military Base School, Nov-2015: ua-cam.com/video/TifcwEHU8zM/v-deo.html
This is one of the coolest videos you've done Dave.
The covering on the bottom is fiberglass/epoxy resin.
No asbestos?
One reason to modularize the chips on the board was for quality control. It's a lot easier to clip a new chip for an inverter than the desolder/resolder the silver contacts again.
I'm pretty sure the pinkish fill is most likely some kind of high-heat ceramic for dissipating extra heat in those tiny little high-power transistors.
It looks like the PCB pads and traces are the same layout in every chip position. Maybe the intention was that you built up your circuit from a standard board and a standard menu of chips by placing the chips in different positions. Then built your computer from multiple boards all assembled in the same way from the same limited number of parts. That may account for low density of components - any more and the chips weren't reusable in other circuit positions. It also meant that if you made a design error on any one board you could replace it with a redesigned board with different chip pattern to correct the error. In which case it's brilliant.
I seem to remember that the chips are not connected on the board itself; the connector on the bottom is used to connect the chips together in different ways, so the board can be used for different purposes. So they could use identical boards in different connectors for different things - probably made it easier to carry spares too, since the same board could be used in multiple slots in the ship!
Mike's electric stuff might be interested, he has done out-of-this-world stuff before!
So glad you finally made this video. Been hoping for it ever since the teardown !
Great technology! And none of those launch vehicles ever failed.
Great T-shirt! Thanks for this history video blog, really a piece of collection. Cheers Dave!
it's cool to see an all-silver board from a launch vehicle. Silver has a lower resistance over distance than copper, but corrodes quite easily in comparison. It was used on launch vehicles because it's lower resistance was much more important and a bit of corrosion wasn't really that much of an issue.
Good stuff Dave. I haven't fooled too much with DTL hardware. It's amazing when you look at what they accomplished with low density stuff back then! Especially given the power, weight, temperature, and physical space limitations they had to work with.
Going to see the Saturn V in person was just amazing. I knew they were big but you just can't get the scale of it unless you're there in person. What it must have been like to see one of these beasts go up. Nice video!
Didn't Fran determine that the resistors were all on the bottom surface? That might explain why you couldn't probe any resistors via the top-surface metalization. I suspect it is the mounting clips that connect the two surfaces. That would mean that the resistors have to be probed from the bottom.
The clips take care of that. Probably dicky contacts. Like I couldn't contact the transistor either.
i like that new audio recording setup on that block of sound absorbing foam!
It would be nice to see this chip reused in a modern circuitboard. Just for fun. Or to make a statement: We are standing on the shoulders of giants :-)
+DasIllu I thought that too! I'd love to get my hands on a few of the chips, mount them in a project in a little window to show-off, sticker that says "1964 Inside" :)
You can still buy DTL chips if you know where to look.
I find it fascinating to see that both SMD technology and multilayer PCBs were around already back in those days.
Jeri Ellsworth or Shahriar Shahramian from the Signal Path Blog would be my top candidates for the next round of probing.
I wonder if any of the designers are still alive and might be watching ? Loved the video Dave, being old enough to remember the moon landings I'm knocked out that these components still work. What an era !
Pass it to "Applied Science". I bet he will recognise some materials its made of.
Please Do! It would be great to see what metals and type of potting compound were used. Maybe he could even use his SEM on one of the dice!
Dave: Awesome! I don't know much about DTL... perhaps this would be an interesting topic for a Fundamentals Friday episode? Cheers mate!
I wonder if some of that stuff on the bottom is asbestos
You were commenting about how they could've done a bit more in cramming in more components on the chips (Apparently there are thin-film resistors on the backsides of some of the chips) well it was early days and had to be very robust to stand up to the rigors of a launch. Anyway the design for the LVDC was frozen in 1964 so the technology for the board you examined is literally 50 years old.
Dave, the LVDC was in the Instrument Unit (IU) which was a three-foot high ring structure mounted in between the top of the S-IVB stage and the conical adapter module which connected the Apollo-CSM to the Saturn-V rocket (The LEM was inside the adaptor). Of the various S-IVB's launched into the ones form Apollo-7, Apollo-9, Skylab, Sklabs-2 through 4 and Apollo-18 all re-entered the Earth's atmosphere and were destroyed. The S-IVB's for Apollos 8, 10, 11, 12 all were sent into solar-orbit while the S-IVB's for Apollos 13, 14, 15 ,16 and 17 were intentionally smashed into the Moon to creative a seismic-signal for the seismometers left on the Moon. So aside from the those S-IVB's in solar-orbit the only surviving LVDCs are mounted on the two remaining Saturn-Vs on display in the US.
I suspect the reason for not having one big chip was due to cost and also many smallers chips can be replaced so they could in theory change the circuit design without refabbing the entire chip (just a thought).
FAAAANTASTIC I love this stuff !
I clearly remember watching the Gemini and early Apollo missions when I was a kid and was in complete awe over the technology especially the Saturn V rockets, I would love to be able to take a closer look at this module but couldn't do anything practical with it, I'd just drool all over it !
Don't forget that these things were largely hand made, there were no automated processes to put them together at that time so the tools were the limiting factors. Also they wanted to be able to locate and identify individual faulty components in order to track reliability and continue with the R&D as everything was in it's infancy and nobody had very much experience at that time !
This Chips are Soldered in this Clips. You can hear breaking the solder Points during the Slideout of the Chip.
Jeri would surely love playing with that, and do an awesome job. You should ask her.
I agree however, I don't see much of Jerri on any of her channels any more. I would think she has become far to busy with her latest project. If you know of a new place she is posting I would be grateful if you would pass it along.
It was 1984 and I was with my business partner and fellow space hardware collector Bill. We had just traveled to Birmingham Alabama, where he had a collection of NASA equipment from the Marshal Space Flight Center.
He had been buying military and NASA space hardware and storing the proceeds of many government sales in warehouses all over the country. The hardware in this particular storage unit was about to be sold to a local scrap dealer and all we had was a half ton Chevy Van. Not nearly enough capacity to rescue all of the material stored there.
While Bill discussed the particulars with the scrap buyer, I did my best to rescue as many circuit boards as possible from two extremely corroded Saturn V Instrument Unit Launch Vehicle Digital Computers. Being constructed from a Lithium Magnesium alloy the entire frame was mechanically distorted and totally crusty. Undeterred, I wiggled, jiggled and pried each board after a generous dowsing with WD-40. I saved about 60% of the circuit boards.
Fast forward to the new millennium. eBay was growing into a significant marketplace of online auctions. I decided to sell some of the IBM Computer circuit boards on their site. These artifacts ended up being purchased by people from the U.S., U.K., Europe and Australia.
Each unit is actually two separate fiberglass boards with a central Magnesium heat sink and support. Some of those boards had been corroded to the point that the two boards were physically pushed apart.
A friend recommended Glacial Acetic Acid as a chemical that should dissolve the Magnesium without damaging the electronics. I tried it on a few examples. It turned out that it was not an ideal solution. Pun intended.
It left a discolored and slightly corroded surface just like the example seen on the video. I have wondered if there is a connection?
Is it possible the layer on the back is made of Asbestos?
+Falney I was thinking the same thing. I just look at old white stuff and automatically think 'sbestos
+MiniM00se I was also thinking the same thing. This was back before they knew it was dangerous right? But then wouldn't it have been destroyed? Not released to the public.
+TechMantra That depends on how stringent laws are. For instance you can still buy radium clocks from antique dealers in the US despite ya'no radiation.
I would be $1000 that it is asbestos. it would be the logical choice for the purpose and it looks like it too.
Maybe the chips were so simple to meet very high military spec of the day. Also a Saturn V probably put them through a 8.0 earthquake or so for 5 min or so. Awesome.
Those boards were laid out like that because that’s what the military did, they worked to create discrete functional logic modules to cobble together into circuits for easy modification if necessary, that way you have a small set of standard parts to swap out easily with known specification, no board swapping or soldering required. Useful when you’re in space and have a logic unit fail on a very important board, you can always just slide on another module by hand with no power or heat required.
I wonder if any documentation exists to describe the Apollo computer logic designs. For example, what was the data width? 8 bits? How much memory was available? Did it have a floating point processor? It would be fascinating to emulate it as a virtual machine!
swillswill I think I've heard of an emulator in browser JS, so if you'd like to play with it and do find it back, please report back. I think there is a great chance of the data being public today: NASA shares and publishes lots of scientific research (which they should do for tax dollars, and I cannot overstate the respect for making it available internationally), and I wouldn't be surprised if they also released their engineering after it had faded from a military secret to a historical artifact.
They may have limited what they put in a package for redundancy. If a part would fail and half the system was on that part, there goes half your system. Multiple small ones would limit the chances of an underlying mistake and if there was one, they could have something to detect that and switch to a replacement
I think the chips were soldered to the clips, and when you pushed the chip out it just broke the solder joint. Some of the clips bent pretty far before yielding. It seems unlikely that they would choose to assemble a bunch of clips to the board and then slide the chips in. The chips in the center would have to slide through three neighboring sets of clips before reaching its destination. Rework would be very difficult.
The actual complete computer was housed inside a blue or sometimes black container comprising as many as thirty or more of these boards. There is a surplus store in Winter Park Florida just outside of Orlando called Skycraft who sold tons of this stuff throughout the 50 plus years they have been around. I have Shuttle heat shield tiles, an Apollo capsule drogue parachute, small control panels from various capsules. I even bought a Norden Bombsite from a B-29 in 1983 for 25 bucks. Today there are still slews of this stuff around, but getting harder and harder to find. My prized find was a gimbal controller from a Mercury capsule that over the years I was able to have 6 of the seven original Mercury Astronauts sign. Unfortunately, Virgil Grissom died when I as five, and will never get him to sign it.
The low density integration was very likely because of radiation interference. It was easier and cheaper than other hardening methods.
Canthus13 LOL. Those device densities were "state of the art" at that time. "Stone Age" of electronics. They aren't even "integrated circuits." They were among the earliest TRANSISTORS and DIODES miniaturized and pre wired in modules.
They probably didn't pack the chips more densely due to heat disapprobation issues. The thing as a whole already had to be liquid cooled so heat was quite definitely an issue with the LVDC
i think the low density design is to ensure the longevity of the chips, the radiation in space would destroy them too early if the die is "too" densely packaged.
You keep saying this is 'state of the art' Dave. I do not think that they wanted 'art' to be involved in the Apollo missions; they wanted RELIABILITY! That means old, tested, and well characterised. Great vid - thanks for showing, Dave.
Fantastic stuff. To add some info, I don't think any of the LVDCs from Apollo ended up in the ocean. They were mounted on the S-IVB upper stages and all of them went into space. Some were crashed on the Moon. Quite a few ended up in solar orbit - and I'll bet they still work. Perhaps on a return visit by Apollo 12's S-IVB to Earth's vicinity, someone will meet up with it and bring back the LVDC. It came close in 2003.
The more complex the IC is, the more likely it'll get rejected for defect at manufacturing I assume... Perhaps that would be why they made them so simple considering the high defect rates of the era?
Are you sure they already made a complex multi layer circuit board back in the days? The fibre-looking thing on the back looked like it would contain the conductor paths ...
for the rant at around 11:20 : why do we have single transistors in TO220 or voltage regulators which use 4 pins of a dip8 package? the answer is: they are making moulds and stuff for the chips, so they prefer to use them for every chip instead of having 3-4 different packages and having to manufacture and research expensive moulds for each of them.
Good point, however these Apollo chips could have been a small scale type of thing anyway so perhaps they really could have gone for more components/chip.
So the SMU can be used like a Huntron tracker huh?
Very interesting vid on the "state of the art" Apollo electronics. NICE!
It should not be too difficult to reverse-engineer the design and functionality of this entire board. We know that each IC seems to contain transistors and/or diodes, and that many ICs probably forms logic gates. We also have documentation for two of the ICs. So:
1. Remove sample ICs of unknown types, and put them in an X-Ray machine. This will show the internal structure of the chip. Metal connections, silicon chips and so on.
2. Draw a diagram of the internal connections and silicon chips.
3. Perform measurements to identify the silicon chips.
4. Work out the function of the IC.
5. After all types of ICs are reverse-engineered, put the entire board in the X-Ray machine.
6. This will show all the internal copper layers of the board.
7. Trace each and every signal line in the board from the X-Ray images.
8. Based on the tracing and identified functionality of each IC, it is now possible to draw a complete circuit diagram of the board.
But the function of the entire board may not be very interesting. Given the logic density, the entire board may be nothing more than a multiplexor or a comparator.
Given how critical these systems are, I'd guess the semiconductors are packed in this way so each component is then discretely testable. May not be the most compact design... but I'd think it would make compliance testing for each package easier. :)
answering what you were talking about at around 11 min in.
The individual modular design accroding to some of my older family members who worked with some of the folks who were designing this. it comes down to redesigning on the fly.
Basickly from what i gathered the design functionality when compared to modern equivalent is a PLGA or PGA if you think of the PCB being a logic block and the chips being veralog programming.
Wonder if Mike have any ideas on stuff to do with that.
Thumbs up go you and Fran!
Interesting stuff Dave. Don't know if it's been mentioned but the LVDC was part of the Instrument Unit (IU) which was on the third stage of the Saturn V (the SIVb). On manned missions this was used for trans-lunar-insertion (TLI). Post TLI, the SIVb would fly past the moon into heliocentric orbit. So these things are still in space; I wonder whether they still work as well! One would expect they're in better condition physically as they've been in a vacuum so won't have corroded. My guess is the 1960s semiconductors would have quite a high resilience to the radiation too, but someone can probably correct me on that. [For completeness; A couple did drop into the ocean after the earlier test flights, and some later ones impacted the moon. I feel these may be in somewhat worse condition.]
I put this on Fran Blanche's video as a comment, but a thought, if most of the circuitry between each chip is layered internal to the board itself, then it might not be too far off to suggest that the chips themselves might be the same in construction.
+suzi noone, At the least one layer of circuitry on the top and a second layer of circuitry on the bottom.
10:04 Possible because this design of pcb allows fast improvement and changes only by changing or swaping ICs. Larger scale of integration is not priority. Actualy, this whole board is one IC.
My father worked on similar chips for the Apollo program. He said that film on the back is asbestos based...
It should be possible to restore one of those computers,but the connections will need cleaning.
I would want to incorporate this working chip into a fun project to show it off, like a Saturn 5 model.
None of that 7nm technology, this is genuine 7mm chiplet technology. Some of the best chiplet design ever.
I like how he is excited about something I don't understand
Are you sure that thing on the back is not asbestos! I hope not.
Hmm, yes, I hope not too! Asbestos basically has to be ground up to be dangerous though.
Looks like asbestos heat protection, seen it in navy equipment before.
That was my first thought when I saw it too.
Looks like it to me with my untrained eyes. I was worried about it when he was messing with it.
Abedallah Soliman I think so.
Who are you going to pass this onto like Fran wanted?
1st row on chip label could mean YYBBBWW, where YY = year, BBB=batch (or something similar), WW = week.
I'd love to remove one of those IC's and incorporate it into one of my projects as just a diode or similar - as a homage to the history!
Jeri would be a hot candidate as the next recipient but considering her work with castAR at the moment means that she's already working 8 days a week and wouldn't have time for any serious tinkering...
My vote for next recipient is mikeselectricstuff since he's both very skilled and has excellent talent for both coming up with projects/reverse engineering and presenting them!
On a side-note, many people laugh at NASA soldering instructions with its 20+ step procedure on how to solder a single wire to a connection... This piece of electronics shows why it still "works" after 50+ years and why the Voyager space probes will continue to work for many years to come!
The fiberglass looking bit on the bottom side actually looks like one of the PCB layers delaminating. In the close up it looks as if that would have gone under the metalized pads. No idea what the white coating over it is though.
As for the chips, high level integration just wasn't really a thing back then. Most logic was effectively a "tube replacement". Basic functions, that were then combined on a larger scale. This elemental block approach also allowed for more rapid development.
It was about a decade after IC chips came out...so my thinking is that the shrinking of these chips from the late 60"s may have not been possible until the technology improved.
you do some good work nice one sir BOGAN !
You have to remember what kinds of stresses the computer was under. They had to get it right the first time with no error correcting ICs. Also, American hands are generally too big for this delicate work. We didn't have machines to pick and place back then.
Would have been interesting to see the reverse bias breakdown voltage.
The pink stuff on the top of the chip looks like thermal gap filler. When you have 1 amp and 5 volts drop, your chip will be warming up at 5 watts. The stuff on the back of the board looks a lot like Hysol Epoxy which is likely to prevent the back of the board from shorting out against anything metal under the board.
this guy is awesome I have no Idea what this guy is talking about but I still find this really interesting
It looks like it has been to the moon and beyond and then back ;-)
Strange thing is that it would not be difficult to make it less heavy, so why did they not do that.
I think the weight was a big issue for them.
just because there were a lot of these boards in the capsule I think.
I'll make a speculation on why they didn't pack more into each package. By each "chip" only performing one function you give yourself more flexibility. Each chip is the same package but the input to output function would be whatever chip you socketed in. So if you found yourself needing another inverter function you could just swap the chip out with the one you were using and not have to mess with any wiring. Standard IO for interoperability.
That's my guess anyways. Cool video. Would love to find some old tech to figure out. Cheers
I wanted to shout "X-Ray next!" but apparently it's already been done and you can find it on Fran's channel.
I think you're probably right about why they didn't pack more functionality into each package. The components were probably chosen very early in design and vigorously tested to meet a high standard of reliability. Upgrading to better components late in the project was likely a no-go.
You see the same thing in modern space engineering. The cameras in the Curiosity rover are 2 Mega Pixel sensors with 8 GB of flash memory. They were way behind state-of-the art tech when the mission launched in 2011, but the sensors have been thoroughly tested and vetted by NASA long before the mission was ready to launch, so they kept it.
From the Wikipedia article:
"Malin also developed a pair of MastCams with zoom lenses, but these were not included in the rover because of the time required to test the new hardware and the looming November 2011 launch date. However, the improved zoom version was selected to be incorporated on the upcoming Mars 2020 mission as Mastcam-Z."
So a mast cam that was lagging state-of-the art by a wide margin in 2011 might fly again in 2020. That's risk aversion!
Most engineers working on this way back are no longer with us.
I offered to Fran to image that board in a live X-Ray machine designed for the task and I'll make you the same offer, Dave.
actually spacex dove to and or recovered (i forget) one of the saturn 5 stages for help designing their heavy rocket
Great video Davo!
I have some cards that look very similar to that made by UNIVAC Sperry. Mine were in some envelops dated 1976.
This reminds me of a curiosity i have since a while.
As tin decays at a not so low temperature, what kind of effect does this have on solded connections especially when it comes to getting close to 0 K.
Most likely a board like this wouldn't encounter low temperatures like that, but knowledge about this is available.
Hey Dave. I run a smaller channel called Frozen Electronics, would love to do some more work on it, reverse engineer the other chip's pinouts.
I think those are early leaded chip carriers.. and you are meant to desolder everything not break the chip out sideways from its leads...
A product of a jobs program, not a space program. Except for the programming of the brains of the masses.
cool vid, but would have liked to see it do some calculations so we could see what it actually did (suppose to do)
Fran is great.
That's one small step for subscribers. One, giant leap for EEVblog kind.
Fran is awesome!
all the pads, vias and traces have the same format, so... maybe they did not integrated this more because this is just a "very expensive breadboard" built to accommodate many circuits depending on where in the board you drop the chips
do you have any ultrasonic cleaning? might help with getting inside some of that gunk
I've been thinking about a "foot mouse" or a device that could be voice activated or by clenching your teeth.
Also - did it never occur to you that this resembles the testing of the antenna motor unit (AE something) in 2001?
One of the original pioneers in integrated circuits was General Micro-electronics which together with Victor produced the Model 3900 calculator (October 1965) which had many problems:
The Victor 3900 - History's Forgotten Miracle
oldcalculatormuseum.com/d-victor3900.html
Actually the 1400 Model 322 was delivered in April of 1964.
oldcalculatormuseum.com/vic14-322.html
oldcalculatormuseum.com/v3900ic.jpg
just interested in where it went next?
Why didn't they "pack more in?" Because NASA doesn't send lives into harms way with bleeding edge technology. The robot arm was still running on DOS back in the day because their vetting processing (which takes years) was able to make the transition of Windows or other platforms. Very cautious! And their safety record reflects how well this works most of the time.
As I posted on Fran's blog these transistors are most probably Germanium not sure about the diodes. That was the semiconductor of choice for IBM mainframes of the day. Since the board was built by IBM this is likely what they are made of. So when you make your readings take that in to account. As to why they didn't put more on a single chip remember these things were started in the early 1960s, and took a lot from the Atlas and Titan I guidance systems. Though this was "cutting edge" for civilian this was quasi civilian and military so IBM probably used known products so some of these chips may have had origins in the late 1950s.
It is not irrelevant. Imagine sending a probe out to deep space. We now know the board will still be working half a century later, and probably will still be working after centuries in space.
I wouldn't mind seeing a modern version.