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

Carl's blog:

Applied Science videos on EL displays

[teddymills]

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

[vibrolax]

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

[greendryerlint]

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

[Bob_Burton]

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

[richardredcastle]

Love the clicking! A PCB full of them and 7 segment displays flashing in sync. What a way to make Covid lockdowns fun.

[VKCSJ]

Fascinating stuff...thanks for doing the video!

[chriholt]

Those relay clicks are so satisfying!

[VegasCyclingFreak]

Very impressive display for the time with the technology available

[AndySpicer]

What do you mean that Carl is moving!?!? That’s a bummer. I hope he’s going to find a way to stay involved with the channel. Either way, thank you Carl for all of the knowledge and entertainment you’ve so generously given us. Safe travels.

[eugenioarpayoglou]

How did they get any sleep with that damn DSKY clicking away the whole flight to the Moon?

[petevenuti]

I wonder how Fran labs version would have looked up next to Ben's and the original. Anyone else do an El replica from scratch?

[bobpospick]

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!

[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.

[Emma__Smith]

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

[badguy]

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.

[_..---]

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

[zrcr]

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.

[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!

[sircompo]

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

[warrentb]

Carl is moving to Florida? Did I hear that right? I hope he'll still show up on videos occasionally!