Apollo Core Rope Memory (Apollo Guidance Computer Part 30)

Core Rope Memory, which contained the programs that landed man on the Moon in the 1960s, is insanely complicated. But that won't stop Mike from making a custom reader for it, so he can recover Apollo Guidance Computer programs lost to history.
Mike Stewart's Core Rope Visualizer: apolloguidance.computer/rope/
Apollo Guidance Computer Restoration Playlist: • Apollo Guidance Comput...
Core Memory Videos:
• Core Memory Explained ...
• Playing with Soviet Er...
• IBM 9020 Core Memory M...
Look Mum No Computer Core Rope Drum Machine: • DRUM MACHINE USING NAS...
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00:00 Intro: Apollo Guidance Computer restoration
02:21 What is core rope memory?
05:16 Previous core rope recoveries with our AGC
06:44 Our AGC is sold at auction
07:36 Mike's core rope reader prototype
11:09 Last minute core rope "hack" for Apollo 11
14:04 Software recovered so far
14:48 Trying the reader for the first time and error
17:56 Core rope explanation: data encoding
20:13 Transformer rope is not core rope
21:24 Core rope explanation: reading using bistable cores
26:09 Core rope explanation: molybdenum permalloy cores
28:22 Experimental demo of moly cores
31:49 Core rope explanation: addressing with inhibits
33:59 Apollo core rope simulator, inhibit wires
35:56 Set and reset wires
37:45 Parity wires and the design error
45:02 Mike fixes the reader and tries again
47:38 Success! Congrats Mike!

[@user-sd3ik9rt6d]

You just never know when you need a rope core memory reader.

[@cpt_nordbart]

I have this mosquito encased amber... Let the Dinosaurs walk again.

[@chrishartley1210]

I remember 2 of 3 people where I worked wiring and repairing memory cores like these about 40 years ago. Obviously they must have had a method of reading the cores. I don't remember what machines they were for, the rest of us were programming PCs and minicomputers.

[@RBLevin]

A portable one, no less ...

[@PsRohrbaugh]

A usb memory reader that can read the oldest memory out there

[@VenturiLife]

Needed one just the other day.

[@ZaphodHarkonnen]

Huge props to the auction house and the previous owner for letting you read the memory modules. Sure it was only a minor risk but they didn’t have to say yes. ❤

[@CuriousMarc]

And the CHM and the MIT museum. We need more museums like these!

[@fredknox2781]

True, but in the case of the auction house, it was also free publicity.

[@menotyou8369]

@@fredknox2781 And if something unforeseen happened, damaged merchandise.

[@CuriousMarc]

Where did you see them publicizing it? I don’t think they ever talked about it.

[@fredknox2781]

I supposed that your video came out before the auction. Perhaps that is incorrect. I think many Apollo fans watch your channel, so if they had advance notice of the auction, that would have been publicity for the auction. The auction might have attracted bidders that otherwise would not have known of it. Still, nice of them to let you to readout the memories.

[@readams]

I'm hoping Lenovo adds a core rope slot to the next Thinkpad

[@Thisandthat8908]

Apple is on the search for the next proprietary hardware they can make some money on, after that whole EU USB-C debacle....

[@bigbaddms]

@@Thisandthat8908 how about a proprietary screen that you can only view using the new Apple $5000 VR glasses ?

[@BokBarber]

It was very disappointing when they took out the core rope ultrabay slot after the T420.

[@M1keLucien]

I think the framework 16 laptops Expansion module bay could fit maybe 50kb of core rope memory 😄

[@sail4life]

LOL, the emperor's new screen ;-) @@bigbaddms

[@agluebottle]

The seamstresses who wove the rope core memory by hand were incredible. Total unsung heroes of the Apollo Program.

[@petesapwell]

I’m a tech, I repair old arcade machine game boards & thought I was quite smart, Mike makes me feel like a complete idiot :) and that makes me happy, brilliant work you guys. I’m going to have to re listen/watch the explanation of how this crazy stuff works! Happy Days

[@Jimmeh_B]

I learned to program in CPM when I was 8-10 years old thanks to my father handing me a book and letting me at his Sanyo MBC1000. (Not that I've done any serious programming since I was 17) I had bumped into Octal a few times but never understood why anyone would want to use it. Now I understand! I too am going to have to watch this a few times to get my head around it's complexity.

[@NotProFishing]

My cousins husband is a pinball nerd and he showed me the guts of one of the earliest electromechanical games and it terrified me. How the hell do you begin to troubleshoot anything. Hundreds of relays I thought the old printing presses I worked on were complex.

[@jeffreyyoung4104]

The technology for that old 'computer' is quite easy once you are used to it, and having worked on it for a couple of years allowed me to start working on video arcade games and pinball machines of the early 80s, once I moved from computers to digital video games! I made more money servicing the machines on the road, than I did the book keeping computers of the day! And you are smarter than you think if you can troubleshoot and repair the digital boards on the video games!

[@petesapwell]

@@giusdbg That helps, the data is in the wiring not the cores..Brill Ta!!

[@petesapwell]

@@NotProFishing Electromechanical pinballs are amazing :)

[@RicoD5]

It’s already 4 years since you started the Apollo series. They spread such valuable knowledge and preserve the great Apollo history. Thanks to you all for making my day just a little better. Again and again.

[@techhead-bedhead]

honestly i think NASA was a complete failure and the main reason we only went to the moon , the whole agency was a government propaganda machine and they achieved so little with NASA that it is not surprising at all that people think the moon landings were fake personally i think they were real but purely done to boost the us presidents poll numbers at the time of launch , the total achievements of nasa over the last 60 years are honestly laughable

[@henrivanbemmel]

Mike is just amazing. Honestly, for his work recovering this important American history, I think he should be nominated for a Congressional Space Medal of Honour. What he has done with exceptionally limited resources is just remarkable!!! Damned well done!

[@MarcusHCrawford]

Yes! Agree. Preserving Apollo history. Give them a medal.

[@Pwnulolumad]

Presidential medal of freedom more likely since the Medal of Honor is for military gallantry

[@henrivanbemmel]

@@Pwnulolumad I believe the Space Medal of Honour is more open than the CMH.

[@rainerkaskinen3056]

I cant imagine how smart Mike and Marc are, it’s beyond belief! Guru level 1337!!!

[@jasontiscione1741]

They're smart but they'll never get past AI resume screeners with this stuff.

[@rainerkaskinen3056]

I’m not sure what you mean, but thank’s for the feedback anyhow👍🏻

[@jasontiscione1741]

If an AI sees "magnetic core memory" on your resume it will decide your experience is out of date. Make sure to call it "NASA technology" instead.@@rainerkaskinen3056

[@TechValleyJeff]

​@@jasontiscione1741 Resume scanners are limited in their ability to determine the best software engineers because they rely solely on the information provided in a resume. While resumes can provide valuable insights into an individual's skills and experience, they often fail to capture the full extent of a software engineer's abilities. Technical proficiency and problem-solving skills, which are crucial for success in this field, cannot be accurately assessed through a resume alone. Hiring the best software engineers requires a comprehensive evaluation process that goes beyond resume scanning. Personal interaction, such as phone interviews, allows for a deeper understanding of a candidate's capabilities, communication skills, and cultural fit within the company. These factors are essential for building a cohesive and high-performing team of software engineers. Another limitation of resume scanners is their inability to assess a candidate's potential for growth and adaptability. Software engineering is a rapidly evolving field, and the ability to learn and adapt to new technologies is crucial for long-term success. A resume may not accurately reflect a candidate's willingness and ability to continuously learn and stay updated with the latest industry trends. Additionally, resume scanners cannot evaluate the intangible qualities that make a software engineer exceptional. These qualities include creativity, problem-solving mindset, and the ability to work collaboratively in a team. These attributes are often best assessed through personal interviews, where candidates can showcase their problem-solving abilities and demonstrate their approach to real-world scenarios. Ultimately, relying solely on resume scanners to determine the best software engineers is a flawed approach. To truly identify top talent in this field, a holistic evaluation process that includes personal interaction, technical assessments, and an understanding of the candidate's potential for growth is necessary. By recognizing the limitations of resume scanners and adopting a more comprehensive approach, companies can ensure they are hiring the best software engineers for their teams.

[@_________________404]

It's experience rather than "smart". Since there isn't much learning material or people who would teach about this they had to do all the research on their own. The average tech university student would probably be able to learn this if there was available material. You don't have to be some kind of "genius" to learn this.

[@Trenchbroom]

My brain hurts, which means I'm watching CuriousMarc.

[@TomKappeln]

Same here ! lol

[@I967]

This video makes all the vintage HP equipment repair videos look nice and easy. Thanks for the exhaustive explanation of all the magnetic magic, Marc.

[@CuriousMarc]

My thoughts exactly. After this one I’m going to relax repairing an HP instrument that has only 10 faults in it. It will be a walk in the park ;-)

[@dodaexploda]

I'm the opposite. This is one of the videos I understand. But this probably due to my lack of electrical engineering knowledge.

[@pa1wbu]

@@CuriousMarc Like a HP5342A with a broken sampler, which requires you first design and build a wire bonder 😵‍💫

[@chuckvanderbildt]

Mike is a treasure.

[@calfeggs]

This guy has done some serious programming, the rope reader itself is impressive, but the software supporting it is absolutely mind-blowing.

[@elioboezio7107]

Whenever I start getting ideas that I might actually be comparatively intelligent, I watch this channel and it brings me back down to Earth with a bump - and my knuckles go back to dragging on the ground! These guys are seriously smart: rocket scientists, even!

[@Tezzzaaa]

Yeah me too. After these I usually go find a flat earth video to feel like a flippin genius again! 😁

[@philkarn1761]

The key to understanding "core" rope memory is that the cores don't store anything themselves. They're actually a clever memory address decoding mechanism. I worked out that if the dual 3-input NOR gate chips used elsewhere in the AGC had been used in address decoders, it would have required many more than in the actual computer.

[@mahtin]

“We will explain what they do in painful detail later” - love it! This is why we tune in for every video! Thank you Mark, Mike, Ken, etc.

[@User720-ik6mv]

Mike is Scary Brilliant, plus his Passion , you can see it in his eyes. One in a Million Genius 💯

[@cyndi5hunt]

6:00 “Well, it was lost no more.” This type of thing is what I like to hear. Great job

[@sloth0jr]

The more I see what Mike gets up to, the more impressed I am.

[@Richard500]

When I first joined IBM I was offered a job operating a tool to "weld" the ends of the wires fed through the memory array frames. I declined the job and took a job in the warehouse instead. Ferrite core memory arrays were assembled in the UK and sent to Portugal to have a single gold wire fed through the centre of the array, They were then shipped back to us in the UK to assemble in the mainframes in production. This was 1969.

[@user-yr7m2]

This is just simply mindblowing. You are really actually working on abandoned humankind history. I find it intresting that core memory can keep its state after all the vibrations and space and 60's and all. Amazing!

[@EricLikness]

Mike (and everyone else in this band of merry pranksters) is unstoppable, relentless even. And we are all the better for it. 👍

[@fridgeffs5662]

Im one of the original creators of the memory modules. We were so happy to find out about your work. Thank you for keeping this great part of history alive!

[@jeremiefaucher-goulet3365]

Mike just built the coolest smart media card reader

[@kargaroc386]

"dumb media"

[@78Ratje]

In genuine awe of the knowledge, passion and skill of Mike just now.

[@VladAndreis]

I know it's been said before but the way those core rope memory modules were made is a true work of art. The Apollo program was cutting-edge engineering and art intertwining in a beautiful symbiotic way. I get goosebumps every time I see a non-potted module.

[@giovannifontanetto9604]

We should call this Archeoeletronics, and this man is one the top experts on one of the most important spacecraft ever made.

[@robertfallows1054]

Unbelievable that such a complex task as going to the moon depended on this technology. I have a board with core memory datacraft dc 38 that I hung onto from the 60s. Just kind of blows my mind when I look at it. Kudos to all those engineers!!

[@Gozne]

Its so unbelievable that I dont believe it. Like most intelligent people.

[@TheNefastor]

As a computer scientist who does work in aeronautics, it will relieve the future historians among you to know that me (and all my colleagues) now keep extensive archives and documentation of our code which is, obviously, under version control so that you may even rebuild specific versions in the future. Though I admit, this kind of archaeology sounds like a lot of fun evenings.

[@st.charlesstreet9876]

This is absolutely amazing how your research brought back so much important history. My appreciation for all the hard work!

[@pmcKANE]

This whole series is immeasurably valuable.

[@dadbear5316]

I wish I had the level of ingenuity that the engineers who made Apollo possible had, I am but a humble engineer standing on the shoulders of giants

[@AlamriHussam]

Core rope memory t-shirt needed .. amazing episode as always looking forward to many recoveries of historic softwares

[@pipsqueak2009]

Congratulations Mike, and thanks for capturing on the excellent video Marc. This is such wonderful work. Inspiring.

[@jjones503]

Your videos are absolutely astounding. The work your team is doing is so historically valuable.

[@sweetpeaz61]

The world needs more Mikes in it..seriously top of his game. Thank you Marc and crew for your chanel and the amazing history you are all not only saving but explaining and bringing to a wide audience.

[@CookRacingUK]

Love your dedication and passion for this project guys. Historians in generations to come will be very grateful.

[@dingolovethrob]

Mike & Marc, I am in absolute awe of your dedication and skill level. Well done Mike on a superb design. Simply fantastic.

[@islandhopperstuart]

In awe of the skill, knowledge and dedication applied by Mike.

[@vmiguel1988]

It’s just mind blowing Mikes dedication into a so complex project like this! ❤

[@OmegaTI]

This gives one a whole new level of respect for everyone involved in this phase of the Apollo missions. Mind blown.

[@MVVblog]

Your explanation makes the Core Rope Memory seem like a very simple device, so much so that I was able to understand how it works. You have done something incredibly fascinating!

[@niceshotapps1233]

the circuit for performing correct sequence to read it and to do something useful with the read content were probably way nastier than the physical idea of this memory itself

[@chadwickalexanderjr1758]

Incredible. Thank you for taking on this monumental project and sharing it with the world.

[@scoobtoober2975]

We saw the apollo displays at the DC museum and pointed out the guidance systems to my kids and had to explain the memory size vs a phone. Incredible tech back then. Exciting.

[@Shady-Socks73]

The hours of craftsmanship that went into these old analogue systems. Full respect

[@carldaniel6510]

Great video! The elevator music explanation of how Core Rope works was brilliant. The design error in the core rope was interesting to hear about, and you set it up perfectly - as soon as you mentioned their optimization to save energy I thought whoops! Half-inhibited cores. Amazing that the original designers missed that given how careful they were about everything they did. Congrats to Mike for getting a working core rope reader up and running!

[@CBJamo]

Always a joy when one of these is released, keep up the good work!

[@russsommer]

This series is just some of the best content on youtube. Always been fascinated by the Apollo programme, I'm getting to see stuff I never thought I would ever see, Thank you for sharing, 😍

[@octane613]

God i love your content. The knowledge of you and your crew, the things you work on, the energy you have, and the way you pace the videos. Your stuff is incredible man, and youre the only one on YT working on this stuff.

[@voodoolilium]

I'd love to know what the engineers who worked on the Apollo program think of Mike's core rope reader!

[@DadofScience]

Legendary work, Mike. Thanks Marc and Co for this most excellent content.

[@LOOKMUMNOCOMPUTER]

Amazing Marc! And thanks ever so much for the shoutout! Really need to do a mk2 of that machine. If only there were more hours in the day!😂

[@Controllerhead]

Man i'd love to hear some interstellar MIDIs pumped through that pipe organ of yours for these epic space videos... You guys are both amazing!

[@Tech-dr9xf]

Love the way old technology most of us never have heard of is presented and explained so detailed that we actually can understand why it was used and how it worked.

[@cpm1003]

Fascinating! I had no clue how the core rope memories worked, but now I do. You guys are just awesome!

[@guyh3403]

Wow. The things Mike can do are so incredibly amazing.

[@onedeadpixel12]

Was always curious how core rope memory worked but always struggled to wrap my head around it. Your explanation and visualization was fantastic.

[@chriscody2852]

You tickle my brain in a way that no one else has. I'm absolutely in love with all these amazing explanations and the wizardry that Mike brings to every project. Thank you for sharing with us.

[@murrij]

Thank you so much for your work on this! I could watch you all working on this for days. So inspiring.

[@FrancSchiphorst]

Just amazing how much knowledge went into just these modules and how many disciplines were involved figuring out the core ring materials and all the wires doing their bit. And then decades later more skills in hard and software to read back these modules. Awesome!

[@timnixon2889]

for several years I worked on 'core' memory assemblies for the old IBM Federal Systems Division (now part of lockheed/martin) They used much smaller versions in Space Shuttle and most avionics computers (A6/7 F111 etc). They were the only nonvolatile memory at that time. The shuttle Challenger computers surived the disaster and the memory contents were still intact

[@jimmyschmidt14]

I worked on 'core' memory assemblies

[@Thuja814]

@@jimmyschmidt14I worked on ‘core’ memory assemblies

[@almosthuman4457]

Thank you to the whole team for doing this work to preserve and archive all of this. The world needs more people who are devoted to acquiring and preserving information and less people devoted to war and destruction. Much respect to all of you.

[@legnumracermitsufan7626]

Mike ist simply doing things he Loves, its great that people like him can have the chance to do so.

[@andyrobinson6052]

Your videos and explanations are awesome. In reality I understand about 5% of this but listening to and watching your videos makes me feel like I understand at least double that, maybe even 11 or 12%! Keep them coming, love it.

[@alpcns]

You people are utterly brilliant, this is absolutely stunning work of the highest caliber. In fact IMHO you all deserve a medal (not to mention generous funding!) for preserving and restoring such important history and artifacts. It also shows the incredible engineering of the fantastic Apollo program and the magic of that era. What a breath of fresh air this is, in the insane world of today. You guys make my day, week, and month - with each fascinating episode. Thank you all!

[@ShaunakDe]

Thanks for making these and for saving such an important part of our history. ❤

[@gerryjamesedwards1227]

I've just finished rewatching the whole saga so far, and then this comes out! Perfect timing!

[@jimmyschmidt14]

The more I see what Mike gets up to, the more impressed I am.

[@MrCydoo]

Mike is really a very great engineer ! So happy to see the future secure by a young man ^^

[@user-hy1nn3cn8s]

If I see there is a new CuriousMarc video, I know I am in for a treat! One should recognize how valuable these videos are, marcs explanations of long obsolete technology are easy to follow, and one can feel his passion for the old computers. Then there is Mike, a brilliant engineer, whith a seemingly never ending output of great ideas to make the old apollo systems working and preserving them for the rest of us. Thanks so much guys!

[@admirerofclassicalelectron2858]

I'm so impressed by Mike's genial work and your great explanation of core rope memory, made a difficult system easy to understand. Thank you for one of the best episodes of the AGC series.

[@NinerFourWhiskey]

Thanks for the deep explanation of core-rope memory and how it functions. I've read of it and about it since I was a kid growing up in the 70's, but I'd never seen a detailed explanation of how it actually functioned, anywhere until this video. I watched it twice to make sure I understood it!

[@OhHeyTrevorFlowers]

That's an amazing bit of work and a wonderful explanation of core rope. Thank you.

[@davida1hiwaaynet]

Fascinating technology! It is amazing that you guys are able to build a tool to read this old memory. So fascinating to watch this.

[@krisztiannemeth6148]

Incredible work with a perfect, easy to follow explanation. Thanks for both of you!

[@adrianobueno6984]

I have been struggling for years trying to understand how exactly core rope memory works. Amazing explanation and demonstration. Thank you so much!!!

[@aussiedazvk4djh889]

Congrats to Mike and another great video Marc. 👍

[@davidcoates4852]

I think I just about followed that. A friend's dad who was a professor showed me a ferrite core memory grid when I was about 13 years old, I am 55 now. I love the history of electronics and this video is just as historically important as the programs being recovered from the rope core memory's. Thanks and keep it up.

[@elext9q]

Most of this goes wayyyyy over my head but still fascinating to watch!

[@david25876]

The genius of this tech is its simplicity and the result is incredible reliability.

[@dmacpher]

Dang - that caddy setup is slick!

[@400_billion_suns]

This channel is fantastic. Thanks for all the work you guys do.

[@rogeratygc7895]

Insanely ingenious! What a brilliant video; I don't know whether to be more impressed with the inventors of rope memory or Mike for figuring it out and creating the reader. I'm old enough to remember the earliest days of space exploration, and to have used a computer with core memory in my first job, but I always assumed rope memory was simpler.

[@jackbauer5830]

Me: This is relevant to my interests, thanks, youtube algorithm! Also me: Part 30?! 🤯

[@petegreenwood2793]

Thanks so much for taking the time to make such great videos - easily my favourite KZbin tech channel!

[@markfrombriz]

I can't even conceive the level genius of the engineers that dreamed this all up and made it work!!

[@adeeponion9152]

Agile minds at play. Thanks for taking me along!

[@DoctorNemmo]

Thanks for preserving this important achievement!

[@alasdairmunro1953]

Massive well done to Mike, for coming up with the reader.

[@DFX2KX]

that visualizer is a work of art.

[@AsbestosMuffins]

here I am looking for a usb floppy drive, you've gone and made yourself a USB core rope drive

[@Oxim1nus]

This should have millions of views, EPIC

[@BudoReflex]

Absolutely amazing. The module reader is spectacular.

[@niyokochan]

Way to go Mike!! Thanks for sharing this with us Mark. 😊

[@christopherjackson2157]

Mike never fails to impress. Kudos

[@Padoinky]

Y’all are just crazies - but it’s amazing that y’all are able to identify, find and then recover and record these artifacts - 👏

[@wgmskiing]

This is such a fantastic explanation of a technology I did not even know existed. Thank you Mike and Marc for sharing this tool and the wonderful elevator music explanation.

[@paulkocyla1343]

That´s some massive trickery involved there, fascinating! You guys are excellent.

[@brocktechnology]

I've been wondering about this for years. I'll stop by and watch this again every year or so to see if I've gotten smart enough to understand it.

[@makowskid8]

Very fascinating, i find it inspiring seeing younger generations keeping the ball rolling, so to speak!

[@campbellmorrison8540]

Wow Mike is definitely needed in lots of places, what a guy

[@KpxUrz5745]

Amazing video. I enjoyed seeing this actual demonstration of core memory. My dad was an early rocket scientist and he spoke with awe about how blocks of core memory were quite laboriously hand-wired through countless dense blocks of tiny core rings. He worked at White Sands, New Mexico and later on the ICBM missile base at Kwajalein, Marshall Islands (South Pacific). This really clarified for me how this early technology worked.

[@classicaudioadventures]

Wow. Incredible work by Mike!