Apollo Guidance Computer Part 28: real DSKY display works again after 50 years

For the first time in about 50 years, we relight a real Apollo DSKY screen! And we can finally see the mythical glow in person. Much to our collective surprise, the screen is stupendously good - it could pass for a modern high resolution phone screen.
We thank our sponsor Samtec for fabricating the NASA-spec connector pins, and of course Marcel for lending us just not one, but two of his precious displays.
Chapters:
00:00 Intro, Apollo DSKY relight short
01:27 What's an Apollo DSKY?
02:51 Block I and Block II DSKY
07:18 DSKY Reproductions
10:19 We get our hands on two real DSKY displays
12:30 Rewiring the DSKY
14:07 Latching relay drivers
16:39 First light with the early DSKY prototype
17:16 Checking out the NASA relay logic
22:40 Samtec pins and wire wrapping
23:57 SUCCESS! Functional flight spare DSKY!
25:55 Debugging the driver circuit
29:44 We've been hosed by CCA wires!
31:32 FIXED! Beauty shots of the working DSKY display
DSKY Relight short video: • Real Apollo DSKY scree...
Carl's blog:
rescue1130.blogspot.com/searc...
Applied Science videos on EL displays
- Electroluminescent displays: • Electroluminescent pai...
- DSKY display recreation: • Build an electrolumine...
Apollo Guidance Computer Restoration playlist: • Apollo Guidance Comput...
Many thanks to Samtec, who re-manufactured the NASA-spec contacts: www.samtec.com
Our sponsor for PCBs: www.pcbway.com
Support the team on Patreon: / curiousmarc
Buy shirts on Teespring: teespring.com/stores/curiousm...
Learn more on the companion site: www.curiousmarc.com
Contact info: kzbin.infoa...

[@teddymills1]

50 years later and still a cooler display than anything else today.

[@moneydriveshuman]

Verry True

[@jean-pierresteenberg]

still a cooler display than anything else today 🤓☝

[@Emma__Smith]

Click click... click click click click...click.. Music to my ears. It's such a satisfying sound!

[@russellhltn1396]

Now I want a DSKY alarm clock.

[@rtlgrmpf]

@@russellhltn1396 And instead of an alarm sound you just power on the Soyuz clock.^^ clickityclickyclick zzZZZ clickclickclick zzzZZZ cliTACKTACKTACKTACK

[@stopthephilosophicalzombie9017]

Isn't it a lovely noise? I wonder if the astronauts were able to hear that noise as well or if it was so buried they couldn't hear it.

[@Emma__Smith]

@@stopthephilosophicalzombie9017 these are the real questions!

[@stopthephilosophicalzombie9017]

@@Emma__Smith What do you think? I suspect the relays were so far behind the panels they couldn't hear them.

[@bobpospick1649]

CCA wire ... just yesterday we spent a few minutes cursing at the jumper wire in the lab that refused to take solder ... no matter how much flux was added! Now I know. Thanks!

[@wonderbars36]

The fact that it used in mains cables (D-cable specifically) is baffling to me. So dangerous. I've seen it go "ohmic" like that.

[@FrozenHaxor]

We call it Crappy Chinese Aluminum...

[@BobWiersema]

Where do you buy that junk. Where I live it's been illegal to sell or use aluminum wire since the 60's.

[@FrozenHaxor]

@@BobWiersema Proper aluminum wires are still used for running power into buildings (AsXSn), it is massive in size though and requires proper termination to avoid corrosion, especially when joining with a dissimilar metal like copper, but it's cost effective.

[@wonderbars36]

@@BobWiersema Well, I don't use it when I find it, but it's sort of acquired by accident when they come with certain appliances I've purchased that use D-cables to get to the wall (US). Laptop-style power adaptors most prominently is where I've seen it. Breadboard wires? That's pretty sad.

[@vibrolax]

You need to sample that relay click sound for incorporation into the microcontroller based replica DSKY's

[@williammanganaro9070]

Great idea !!!

[@joyange1]

Great. just what we need. Another fake shutter sound for a digital camera. Another fake turn signal sound that plays out your car's speakers. Another fake telephone bell ringing sound that plays from your cellphone. When will this madness ever end.

[@Damien.D]

Simply use a real relay that sound similar and pulse it when necessary....

[@batman-cw2hd]

they should hav jus used lcd touchscreens then ther wouldnt hav been no clicking and all.

[@vibrolax]

@@batman-cw2hd Well the first LCD screen wasn't produced until 1982, 20 years after the electronics for Apollo were designed. And the brightness and contrast of the early LCD's were quite poor.

[@TubeTimeUS]

literally the week after we filmed this, i was at work and ran into issues that turned out to be caused by CCA jumper wires. awful stuff.

[@MRichK]

Is it just for fraud? What is the point of CCA over just Aluminum wires if the copper is so thin it make not difference? The degradation would seem to make it unusable over time.

[@acmefixer1]

The copper coating is to prevent the aluminum from oxidizing when the air hits it. Aluminum wire is a fire hazard when you use it in house wiring. If I find any of it, I make sure it's never used, it gets recycled.

[@compu85]

I always wondered why some of my jumper wires just didn't work... I've started beeping them out before I use them.

[@johndododoe1411]

An older version of CCA was approved for house wiring decades ago. It had thicker copper cladding, but didn't succeed commercially.

[@TheEmeraldMenOfficial]

@@MRichK Aluminum oxide (Al2O3) is downright explosive in certain conditions, and if memory serves it is often used as the fuel for SRBs as the results of its combustion are comparatively nontoxic. An example of this is the Ariane 5’s boosters.

[@badguy1481]

I worked on the Apollo Guidance Computer software and hardware. Before that I worked on Electronic telephone exchanges. The mech charts you showed brought back old memories. Before there were sophisticated enough computers for control of equipment, we had hard wired NOR and OR gate technology to perform logical operations. Computer memories were not sophisticated enough to handle most applications (in the mid-1960's). The Apollo computer was truly unique in that it had a simple (by today's standards) core memory (called "ropes"). Those "ropes" controlled a central processor that gave instructions to the guidance and navigation system on both the Command Module and the Lunar Lander without the need for "hard wired" NOR and OR gate decision making.

[@MLX1401]

Haha, the relay modules do indeed make the display sound like a telephone exchange :)

[@thromboid]

Awesome! You're in good company - weren't Shannon and Flowers both working with telephone switching systems before basically inventing modern computers?

[@owensmith7530]

@@thromboid If you mean Tommy Flowers inventor of Colossus, yes he was a GPO engineer I believe at Dollis Hill.

[@TheBreadlord]

The first Turing complete stored-programme computer was the Manchester baby though, which used vacuum tubes instead of relay logic. Colossus was kind of a dead end as far as early computer development went.

[@owensmith7530]

@@TheBreadlord But we're now into the issue of defining what constitutes a computer. Manchester uses "stored program Turning complete" because it makes them first. The US omits the "stored programme" part so it can claim EDVAC was first. Cambridge uses "stored programme general purpose computer service" ie one with input and output because that makes EDSAC first (baby had no means of output other than reading the dots on the CRTs of the Williams Tubes). And so it goes on. They were all steps on the road.

[@z06rcr]

Great ending..not just the relays clicking.. but listen closely and you can hear the high frequency tone of the EL display change in volume as more digits light up..Very nice.

[@CuriousMarc]

Indeed, it does that. Fine ear you have!

[@_..---]

"lots and lots of relays" and yet still an understatement, cool video man

[@emgre]

This is the most satisfying display I have ever seen. The colour, the brightness, the clicking sound, the "animation" to get all the segments properly lit. A marvelous piece of engineering!

[@cuteswan]

As a little kid I thought our electroluminescent night lights were the neatest things with their eerie glow, like the older unit's bluish color. Now, despite making me think of moonlight on a summer night, they don't hold a candle to the beautiful intricacies of how this whole system operates. Thanks for the thorough video.

[@TobyAsE120]

"The dude next to him is TubeTime" I literally cried out in excitement!

[@andymouse]

Bloody CCA Dupont wires, if a pound for every wire problem I have chased I could buy the entire space program !...cheers.

[@sircompo]

I can't imagine how devastating dropping that display must have been. Also, love that cat clock at 30:00!

[@CuriousMarc]

This sure was annoying. But this was nothing compared to the joy of being able to demonstrate the working AGC to its creator, Eldon Hall, in person! (and I love the cat clock too!)

[@paulstubbs7678]

@@CuriousMarc I had to rewind to check out the cat

[@jkeelsnc]

It’s amazing to see how sophisticated this technology was for the time. Incredible. Still impressive engineering today.

[@1959Berre]

I was 10 years old when Armstrong and Grissom landed on the Moon. It is barely believable how sofisticated and how robust the AGC was, over 50 years ago. The dedication of those engineers and technicians was amazing.

[@littleloner1159]

My dad (in Germany) and his friend built their own cardboards rocket and almost jumped out of a height wise third story balcony to fly to the moon haha They thankfully got caught just in time but it's amazing to me how impactful these moon landings were at the time Wish I could've been there its hard for me to imagine how it must've been

[@RCRadioShow]

Armstrong and Aldrin. Sadly Gus Grissom perished along with Ed White and Roger Chaffee in Apollo 1 fire in 1967.

[@tim_bbq1008]

The more I know, the more I know I don't know. Thanks Marc

[@greendryerlint]

That display is beautiful and more legible than most anything manufactured since then.

[@siberx4]

Your comment about the blue-green colour playing tricks on the cameras and your eyes is interesting. I've recently bought some deep red LED flashlights (for astronomy; the redder it is, the less it ruins your night vision when stumbling around in the dark) at 660nm, much redder than the usual 620-630nm red you'd get in a "standard" red LED. What's most interesting is that while the 660nm LED lights do seem pretty blood red when you turn one on, what you notice even more is how decidedly *orange* a regular red LED looks immediately after viewing the very deep red 660nm ones. It's like your eyes suddenly notice "oh! things really _can_ be that red!" and your brain suddenly shifts all other colours slightly up the spectrum to compensate. The effect goes away after a little while, but very fascinating to see.

[@marklimbrick]

That relay clicking sound is the kind of thing set designers on movies never think of. The contacts would have a limited number of cycles, but enough to get on the moon and back safely. The thing about just doing an audio sample is it depends on which segments are on or off at any one time, they are all slightly different contact/release times!

[@CuriousMarc]

Relays are much more reliable than you’d think. They got perfected for many many years for telephone exchanges that demanded very high reliability.

[@stopthephilosophicalzombie9017]

15:28 "Mechanical memory"(memory capacity of one bit). That's one of the more interesting ways to refer to an on/off switch I've heard lately. Spoken like a true computer scientist.

[@MRCNC1967]

When push came to shove, the humble relay helped put man on the moon.

[@acmefixer1]

The humble *latching* relay! These save a lot of power since the coils do not have to be constantly energized. So a whole bunch of relays could be powered form a 9V transistor radio battery.

[@LacasseEric]

I thought that the DSKY they used on the set of "Apollo 13" looked great. Until I saw the real deal in this video. This looks way better! And the sound too!

[@programorprogrammed]

What a legend Ben is!

[@graemedavidson499]

The quality of engineering, ingenuity and even the fit and finish of the AGC systems is astonishing.

[@povertyspec9651]

Especially considering that they were under immense time pressure.

[@LauwersFreddy]

If they needed that much hardware to light up the display, one can see why the spacex crew dragon is so roomy. Amazing times we live in. Thank you for making these videos!

[@rtchrg440]

Absolutely outstanding Marc - really cool seeing a genuine DSKY come back to life!

[@youbecha64]

It just keeps getting more and more complex and innovative as you dig down into the tiniest parts!

[@chrisd5610]

Wonderful! That SO needs to be recreated in the same form/look as a clock or weatherstation, replete with sampled but switchable/variable clicking noises and then mass-produced and marketed appropriately as the ‘’Apollo clock’. I’d buy one 😆👍

[@leandrolaporta2196]

Man, the clicking of the relays is absolutely gorgeous, I love that thing, the quality is amazing specially for 1960's tech OMG!

[@ClausB252]

In 2005 I wrote a LabView VI to model the relay logic in the 5 bit to 7 segment decoder, based on the circuit shown in the Apollo 12 Mission Report Fig. 14-1. FYI the 5 bit codes are in the AGC source code in a LUT named RELTAB in T4RUPT PROGRAM and are used in PINBALL GAME BUTTONS AND LIGHTS.

[@rbmwiv]

Looking at all those same color wires makes me thankful for color coded wiring.

[@rpavlik1]

That is amazing to see. Way brighter and crisper than I would have expected.

[@gregkrekelberg4632]

Marc, you have some of the most eclectic stuff in your lab: An OS/2 box on the table and then a Marlburo box under the table. Congratulations to Carl and the crew, what a cool piece of history!

[@pixlot]

those relay sounds are sooooooo calm and relaxing 34:30 Im making a mp3 loop to help me sleep.... precious

[@fink94]

14:41 that lamp is AWESOME!!!

[@beck3k]

That logisim schematic easily put a smile on my face!

[@MikeKobb]

30:55 - one of my computer hardware classes I ended up doing poorly on a lab assignment because *one* gate on a 74LS-series quad gate chip was bad. It absolutely never occurred to me that that was possible. Finally a TA helped debug it. I learned a great lesson from that. Fortunately, I’m old enough that crappy Chinese CCA wire wasn’t a thing yet, or that probably would have bit us as well!

[@grubboy3514]

Loved the ASMR whisper at the end Marc 🤣🤣🤣

[@lexihaley2887]

This

[@retrofitter]

I know, what a nice touch. The sound has dynamic range like classical music

[@shaanee]

I love the relay sound .... its amazing that it holds up today.

[@moneydriveshuman]

Big shoutout to the Real legend "Eldon Hall" such a brilliant and genius animal on this planet Earth. We can't even imagine this kind of display at that time. The technology was much much much much ahead of his time. Big shoutout to those relay modules too 😅😅😅 it's so dammnnn difficult for relay to maintain it's state when it's so much vibration out there in those space capsule or lander whatever... But see the brilliant minds made it to success.

[@666Blaine]

I seem to recall that human eyes are more sensitive to green than the other colors. So all else being equal a green display would seem brighter, even if it technically wasn't. I wonder if NASA went full-nerd and did a study to find out which wavelength of green was the easiest to see and then tried to use it. Or maybe it was just the paint they had at the time...

[@acmefixer1]

That color is "stop light green" because those who are color blind need a little blue with the green to tell it from the red.

[@nobytes2]

Knowing Nasa engineers I highly doubt this was just a random color picked

[@madmax2069]

I always loved the glow of EL (also used in night lights, and Newton message pad and other stuff).

[@ArtemKashkanovLive]

incredible perfect device! I love EL displays - My next video would be about powering up the whole collection of my 7-segment, 8-segment, 19-segment and etc. EL displays. Unfortunately, all my small relays has 150V test voltage and couldn't be used here, so I selected triac optocouplers.

[@Sir_Uncle_Ned]

Those relay clicks are truly amazing. I'd imagine they would raise some concern aboard a spacecraft which is why they were insulated, but down here they're very zen.

[@Bob_Burton]

That relay logic is beautiful. I would have been very proud to have been the person who worked that out

[@GingerNingerGames]

This thing is beautiful, sight, sound, function, form. It's got it all.

[@RobertWood042]

Well now I want and EL display clock. That looks amazing

[@smakfu1375]

Wow... that relay clicking in time to the DSKY screen, I could watch that for hours.

[@kevito666]

Watching the videos of yours is like living a fantasy out vicariously, keep it up. I learn so much from your hard work!

[@nonono285]

That really is a beautiful display, there's something about it's quality and color even through video. Fantastic.

[@Gazdatronik]

EL displays are so beautiful. The ones in the 1966 Dodge Charger were equally crisp and wonderful upload.wikimedia.org/wikipedia/commons/b/b8/66ChargerDash2.jpg

[@stephendavies923]

Marc. To put it simply, loved it!

[@drivewayhero]

Holy moly... this is fascinating and mind boggling to someone that struggles operating windows 10.. and thinking how this was done decades ago... wow

[@compwiz101]

I still find myself impressed by how utterly *sharp* that display is

[@michaelcarey]

There is something magical about electroluminescent illumination. My late 80s Realistic radio scanner had EL backlighting for the LCD display. That soft blue/green glow was fantastic. I also recall that the first few GPS navigators released by JRC (Japan Radio Company) in the early 90s used EL backlighting as did some models of rudder angle indicators make by Tokimek (TKC) I spent almost 30 years in the marine electronics industry 🙂

[@jimmyzhao2673]

These DSKY modules are a work of art. Those relays made such a satisfying clicking sound.

[@VincentParisien]

That's so cool to watch, I never get enough of your content!

[@c.j.1089]

That is amazing stuff. The relay box with the EL display is so satisfying.

[@hernancoronel]

At 27:00 OS/2 Warp in the background! I worked at IBM when it was launched back in 1994 supporting it. Thanks for the video Marc!

[@stevejohnson1685]

Thanks for your work on OS/2 Warp! When it came out in 1994, IBM also provided dial-up internet access to subscribers. That inspired me to start an ISP in chronically underserved southwest Michigan. I figured if everyone I knew was willing to switch from Windows 3.1 to OS/2 Warp just to get internet access, there must be a market. I was right :-) The company, now absorbed at least twice, still exists 27 years later.

[@murda2999]

You guys are amazing! This is satisfying on so many levels. The color, the sound and the mad skills to put it all together.

[@chriholt]

Those relay clicks are so satisfying!

[@VK3CSJ]

Fascinating stuff...thanks for doing the video!

[@joe08867]

Great job guys, very satisfying to watch and listen to. Thank you

[@nrdesign1991]

You have amazing friends to geek out with. Congratulations at getting the project working!

[@djohnsto2]

Amazing! It's extremely visible and clear with the room lights on, and not too bright with the lights off. And yeah CCA speaker wire - When you strip it and twist it, the fibers fall apart in your hands and little fragments go everywhere. The thought of that carrying mains voltage is terrifying.

[@camhyde9701]

It's great being able to see the grain of the luminescent compound.. like medium ISO film but better... gorgeous display

[@keithglaysher9201]

Amazing work as usual Marc.

[@simonstrandgaard5503]

Impressive display quality. And the clicking sounds are wonderful. Great job. Love you all.

[@alpcns]

Superb. Absolutely brilliant. Fantastic work!

[@bdhaliwal24]

Astounding job! Marvels of ingenuity like this are truly inspiring.

[@eierreiter]

It's amazing how Marc supply well edited videos in such a high rate. Chapeau! Thank you very much for entertain my brain.

[@binarydinosaurs]

Amazing, something I never thought I'd see when I was growing up. Absolutely love the relay noise too.

[@gfr2023]

Your videos are allways of high value !!! Keep posting

[@AndyH2O]

This is great. Lovely. And particularly fine clicking, I could listen to that all night.

[@pjineurope3941]

It's amazing that these Apollo videos keep coming. Each video lighting a different angle on the matter. I'm very much intrigued, indeed. Greetings from Belgium :)

[@metatechnologist]

You're right, that Apollo green is fantastic. Good video.

[@tamberp]

There is something so satisfying about listening to relay logic chittering and clicking away!

[@FlyingAce1016]

Adam Savage would go nuts to see this!

[@profwaggstaff]

Wow. That was really fun to watch. I didn’t realize they used relays. Thanks.

[@BorisZech]

Super! I loved the EL display on my 1980s tape deck.

[@lutzweb]

your job and expertise is amazing, as a computer scientist and system engineer this is oustanding to see and understand what they did to land man on the moon and you to recover this from blueprint

[@Xboerefijn1]

Thanks for the huge amount of documentation you collected, published and to some extend explain here. In my quest to build a replica of the AGC(and if time and money permit the whole cockpit) this is for me the most valuable place to find info. Hope you'll have some more of this lined up^^

[@michaelmiller641]

Absolutely amazing ! Thank you!

[@mariodistefano2973]

Oh, Mark! that's a really nice video. The display appears SUPERB! also BEN did a fantastic job, replicating from the bottom up, this astonishing display tech!. Congratulations to you all!!!. BTW, the relay clicking is sooooo relaxing, that I'm thinking to make a clock with them!!!!

[@Ticklestein]

1:21 - hearing that sentence in that accent, thats like a ray of warm sunshine straight on the heart strings.

[@MrMilarepa108]

phew glad someone checked that the moon thing was not a hoax. And there I was thinking "ha how could they fly to the moon with five relays hooked up to their seven segment display" but I'm glad you cleared that up. Faith in humanity restored.

[@arielwollinger]

Wow, fantastic work there!

[@biz0r07]

oh man that clicking...I wish I could have a display like that...so beautiful, so crisp...and I love the sounds

[@williammanganaro9070]

Very enjoyable video ! Another fine production. Lucky you had a great resource for those displays and replay modules. ;-)

[@rocketmentor]

It's so nice to have sparkys that can bridge the 1060's with the 2020's, I consider myself a mechanical type who can and has hot fired antique rocket engines including the Bell X-1 engine that broke Mach one in 1947, thank you - Ken

[@72polara]

This video shows how important private collections are. Museums will not let people play with their artifacts, while a private collector who desires to learn more will let experts do their their thing and bring rare devices back to life. Same idea holds true with rare firearms, old cars, or anything vintage. I do my part, I let people shoot my rare firearms and drive my old cars. You cannot know history without living history. If you see me in a parking lot and start a conversation, most likey you can drive my Fluid Drive DeSoto.

[@donmoore7785]

That is a truly awesome display for the time period. The holy grail, finally unveiled.

[@marcelh85]

Great as always.... just mind bogeling

[@dmorgan1307]

amazing. you guys have patience like no other

[@watchguy7986]

Amazing…. So freaking cool wish I could see in person.

[@TEK-Vectors]

Fabulous!! incredible video - thanks for reliving the 1969 lunar landing computer interface! Wow!

[@BM-jy6cb]

It's a good job I wasn't one of the astronauts - I'd have been so entranced by those clicking relays combined with the individual segments turning on and off, I'd have likely crashed the ship. ASMR indeed!

[@nicolemellott1983]

that relay click sound, has a very calming effect on me love it love the work you put in to bringing her back to life if i could afford one would dearly love to have a rep of the Apollo DSKY thank you for sharing

[@richards7909]

What a lovely sound.

[@gloverelaxis]

the constrast is just so incredible. what a beautiful piece of technology

[@Mach7RadioIntercepts]

Watching this, I have a new appreciation for the flight management conputer / control display units of modern aircraft.