Re-Creating The Apollo DSKY’s Display

Apollo astronauts used the DSKY (Display-Keyboard) to interact with the flight computer with a series of 2-digit codes punched into a numeric keypad. Above the keyboard was a high voltage electroluminescent (EL) display whose segments were driven by electromechanical relays; old-ass technology not seen in operation in decades.

[Fran Blanche] is working to re-create the DSKY’s display, and is raising funds to make her first prototype. She was actually able to go dismantle a real DSKY at the Smithsonian, and this drove her desire to re-create the DSKY’s unusual display.

As [Fran] points out in her video, cinematic re-creations typically involve LED displays and CGI rather than the authentic EL 7-segs. Who would want that when you could have the original?

The DSKY is one of the most recognizable and historically relevant parts of the Apollo Command Module and it’s also quite rare. There are only a handful of  them around and of course none of them work. [Fran]’s display could help museums, collectors — and yes, moviemakers — re-create DSKYs with greater authenticity.

[Fran] is a good friend of Hackaday. If you missed her Hack Chat on antiquated technology last Friday you can check out the transcript here.

56 thoughts on “Re-Creating The Apollo DSKY’s Display

    1. Yes, that would be an interesting story. I assume it starts with figuring out how the Smithsonian would benefit from the project. Bonus points for getting a grant to pay for the work.

    2. I suppose it starts with knowing your stuff. Fran’s got quite a reputation in this field. The original designers are probably all gone by now so chances are she’s the only one in the world who could pull off this particular job.

      1. Not at all the same hardware. I think that part was made up to try to link the calculator industry to something more glamorous. The video specifically claims that the Apollo Guidance Computer used MOS circuits (as do most electronic calculators). This is not true – the AGC used bipolar transistors throughout, with relays to drive the displays, and magnetic core RAM and ROM. Not a MOS transistor in the lot. The AGC was more closely related to an early ’70s minicomputer than to a calculator in its technology.

        Also, while the AGC DSKY display had a blueish-green display like the vacuum fluorescent displays used in many desk calculators, the technology for these was very different from the DSKY’s electroluminescent displays, which are the part Fran is trying to reconstruct.

        1. The closest thing to this kind of display in calculators would be Panaplex manufactured by Sperry / Burroughs roughly in the same era.

          But it’s not likely any gas/vacuum calculator display technologies were used in Apollo as the computer and display would need to work reliably under a wide range of temperatures, pressures, and exposure to radiation.
          EL would be a good choice as it’s nearly solid state and was fairly well developed by the 1960’s.

  1. I have an ongoing project to build an instrument panel for Kerbal Space Program, and a lot of my game controls and digital readouts (Apoapsis, Periapsis, Altimeter, Eccentricity, Inclination, etc) will be displayed on a device that’s heavily inspired by the DSKY. I’m not even trying for accuracy or anything like that… Mine’s not even gonna be a replica at all… I’m fine with LEDs and not matching dimensions, cause I’m only taking my inspiration from he DSKY, not trying to reproduce it…

    What Fran is doing though… This is ART! This is a masterpiece, and I am awed entirely by the entire project! I wish her the best!

    1. She’s bitten off a big job here. I used to have a clock that was a demo board for Sperry neon digital displays. They were very visible orange, but didn’t catch on. You can still see them occasionally. They looked very similar to the DSKY display, but that’s EL.

      Good luck to her. It’s a journey down a rabbit hole, that’s for sure.

      1. Yeah. it’s one thing to build something original that’s inspired or influenced by something. It’s a whole different story when trying to reproduce an accurate replica. I’ve actually got a rather impressive collection of vintage calculators and computers. Several use the old Burroughs Panaplex displays. Those were pretty cool. 7 segment neon flat plane multi digit displays. Only required 180 volts, give or take! :P

        LEDs and LCDs really did change everything.

        I kinda feel some of her challenge. One of the things I’m trying to make on my Kerbal Space Program instrument panel is a “tape meter” to display the radar altimeter. Just trying to find a screen printing shop that’ll take a small one off order like that is kind of a hassle. Any place is gonna want to run a bulk lot to make it cost effective and just assumes you are expecting less=cheaper. Of course, that’s not true, and I know it… If only I could convince them that I know it.

        Ugh… My alternative is trying to hand stamp the number on the tape using stamps and a jig… So much no…

        1. richfiles: why silkscreen? Are you also trying to replicate an old instrument?

          I’ve done some low-volume silkscreen myself, and it’s not that difficult. There is a photosensitive emulsion available (I got it from an art supply store, made by Hunt/Speedball, but that was many years ago), so you can print your artwork on transparency and expose the emulsion from that. While it’s a multi-step process, all of the steps are pretty simple. Getting the exposure dialed in is tricky, but that’s just trial and error. Of course, if there are multiple colors this makes things more tricky.

          Since you’re considering using rubber stamps for the numbers, another option here is a technical pen and lettering templates. Most art supply stores carry these, and with just a little practice you can get much better looking scales with these. Some fiber-tip fine-point pens can also be used for this. This is quicker and simpler then silkscreen.

          What kind of mechanism are you using to move the tape?

          1. The materials I’m using are actually salvaged from old test equipment, so it’s a one shot… I only have two tape loops. The plan is to print on the back side of the tape, so i can get the scale I need.

            This is the unit I’ll be using.

            The original test equipment had a window on the end to view a single number. I wanted to loosely mimic the style of tape meter used by NASA, so I machined the long opening. And yeah, I know… It’s pretty rough. I’ll likely widen it a bit toward the left, and refinish that lower and right edge. All I have is a mini mill, so it’s not exactly the highest quality tool, and it was only the second thing I’ve machined since… well, for about a decade. The other thing was plastic.

            The tape is a continuous loop.

            Due to the fact that I don’t want to crease it, I need to print this in 2-3 passes. I’d use a spacer between the tape to keep it from pressing flat. the scale would be printed in two halves. There is a feature I’d like to print between the top and bottom of the scale, in the dead space. Due to the way using a spacer would work out, it’d require a third pass at printing.

            I only have two of these tape loops, so I don’t get too many shots at getting it right. It’s kinda why I’d prefer to find a professional to do it.

          2. Sounds like fun. I agree that silkscreen would be the best bet, especially if you’re doing white numbers on black background. If it was black on white, I’d still consider technical pen.

  2. While I appreciate the purity of reproducing the DSKY display using the electroluminescent technology of the day, and the minute detail to which Fran has documented the details of the display, I fear that the results will be limited by that very technology.

    I maintained a military system (AN/GPA-122) that used 7-segment EL displays similar to the DSKY’s in the mid-1970s, and even though these were used exclusively in darkened rooms and were dimmed accordingly, after a few months of continuous use, the most often used segments would be so dim as to be unreadable. Since these displayed transponder codes from aircraft, some of the digits often had the same numbers displayed (such as 1200 or 2100), so the segments that made up these numbers dimmed much faster than the remaining segments, which remained at nearly their original brightness.

    I suppose this wasn’t a major issue for NASA, since the DSKYs only had to work for a week or two, and I assume the displays were only on when the computers were in actual use. I don’t know what Fran’s plans are for her reproduction once it is completed, but if _I_ were building such a thing, it would spend a lot of time illuminated.

    I guess the best advice would be to treat these like CRTs: just don’t leave the same display on for extended periods.

      1. Ostracus: No idea. But I DO know that another similar technology, OLED, has similar limitations. OLEDs don’t actually emit light from the junction like conventional LEDs; they rely on phosphors just like EL devices do.

      1. Prove your credentials or retreat back into mom’s basement. It’s you vs. a well know entity in the community and all you are at this point is a load of figurative hot air.

  3. While I do not have a problem with [Fran Blanche] and have enjoyed some of her projects that have been on this site, I do have to agree that there are some questions bothering me about this project and HAD’s apparent promotion of it.
    This is old and well documented dead tech. Google searches gave me several sources with lists of compounds used and some info on the process used to do it and several reasons why it never became a mainstream product (2000 hour usable life and $$$$). Still if Fran wants to do it Kudos to her, it’s a cool hobby project.
    However using “go fund me” as a funding source raises a huge red flag whenever I see it and I find it hard to believe that HAD didnt put some sort of disclaimer on there about it warning people to at least do their own due diligence into the funding type and project viability.

    1. You need a news source to tell you to do due diligence?

      [fran] is well known around here. She shipped that one piece of the DSKY around to let other experts decipher the chips, if I remember correctly. I think she has even judges some of the HAD contests. The folks behind Hack-A-Day, and probably many readers, know her. The lack of a disclaimer like “we are just reporting on this and don’t know the people involved” is because they do know the person. Hence, none of that sort of disclaimer.

      And if you need a “this is crowd funding, risks are involved” warning, may the gods watch over your soul. Every kickstarter I’ve pledged to has gotten me the item I wanted, save the ones that have not yet crossed the delivery date. And this isn’t a “send money and get a prize” project; any money you donate to [fran] for this just goes to [fran]. There is no promised reward. So if you want to help this scientific art project, donate; if you don’t, don’t; pretty simple really.

        1. You may think your being clever, but you come across as mean spirited troll.

          Fran is so highly regarded, that the Smithsonian invited her to there storage facility (can’t remember where but it is at a USAF base) which is NOT OPEN TO THE PUBLIC. They have a non-flown DSKY in storage there. It is not in working condition. She disassembled it with the aid of one of their staff and was able to take measurements and identify components. In fact this device is not well documented, as much of the records have been lost. She shot a video which is on here channel. If she succeeds it will be of great use to museums and historians. She is documenting the whole thing and some of the problems, for instance obtaining the right sort of glass, have been quite daunting. This is not a vanity project, but a piece of valid historical research.

      1. Quin, about disclaimers, HAD has done numerous articles on funding types explaining how they work what the risks are and what to look for when choosing to back a project through different sites. This is the first time that I can recall them promoting a project on go fund me and it would have been nice if they had at the least said that virtual hugs were the rewards for donating, though they could do more and with as many scams as have been discovered on go fund me they probably should have.

        Fran on one of the youtube pages thanks Brian Benchoff along with several other people for all the help with the project, at this point I personally don’t care if it was technical advice, personal funding, or promotion but Fran made a connection between her project and HAD staff so that connection should probably have been disclosed in some form. As you also stated she does play a large role here at HAD having more of her projects reported on than any other single person that I can recall and I enjoyed reading about them but to me that means any links between Fran and HAD should be out in the open when they begin promoting her go fund me page.

        What is the endgame of this project? You stated it was a “scientific art project” and that was the feeling I got at first also but after looking at the project at bit harder I got more of a “this is the R&D phase of a small niche company”. can it be both, sure but a bit more clarity and consistency by Fran or HAD staff in their writings would have made it more likely for me to contribute.

        These are of course just my personal feelings but you asked why I felt the need for disclaimers so I answered, I do wish the best of luck to Fran in her endeavors and hope to see more about this in the future.

        1. Far from an “art project” this is an attempt to restore a lost and undocumented peice of technology, while *also* providing public access to it at a facility.

          Your bizarre skepticism is clearly disengenuous as every aspect of this project and Fran’s involvement is very clear. The Fund raising is not questionable either, as it is *also* very clear that this is goign to support her work.

      2. I don’t see this as a scientific art project, but as an art/history project. Since EL numeric displays are close to extinct now, what Fran is doing is preserving the look and feel of 1960s technology. And while this article focuses on the EL display, Fran also comments that the key switches on the DSKY are the best buttons she’s felt anywhere, anytime. Others are content to preserve a very limited notion of the original look and feel, using cheap tactile switches and LEDs. Only Fran appears to care about the whole package.

        For those complaining about this being just funding for somebody’s hobby, well, don’t donate. Everybody who DOES donate understands that they’re not going to get a DSKY out of the deal, so what’s your point? What Fran contributes to the world is similar to what any museum contributes. Her work has value.

  4. Might I suggest getting off your high horse? The lack of oxygen is turning you into a bit of a self-righteous prick. And pissing that much vinegar has GOT to sting…


    A professional Mechanical Engineer (Ba.Sc.)

  5. The left side mini panel of buttons needs to be recessed a bit (maybe 0.040″) to be identical to the original. Note the shadow around that little panel, on the originals photo.

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