The Space Shuttle could hold a flying laboratory called Spacelab in its cargo bay.
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Interesting coincidence: On Thursday in datamuseum.dk I started scanning documents relating to programming for SpaceLab computers.
I hope to have them online next weekend.
@bsdphk Those documents should be very interesting. Do the documents describe programming the Spacelab computers in assembly, HAL/S, or something else?
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The Space Shuttle could hold a flying laboratory called Spacelab in its cargo bay. Three French-made computers ran Spacelab. I opened up a Spacelab computer and found that instead of a microprocessor, it is built from a multitude of simple chips. Let's take a closer look at the computer...
@kenshirriff Honestly, even with the bodge wires, this looks really clean for what it was and what it was meant to do.
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The Space Shuttle could hold a flying laboratory called Spacelab in its cargo bay. Three French-made computers ran Spacelab. I opened up a Spacelab computer and found that instead of a microprocessor, it is built from a multitude of simple chips. Let's take a closer look at the computer...
@kenshirriff Thank You for sharing!
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The boards need a lot of chips because a chip didn't do much back then. Even the ALU chips had just 170 transistors. Multiplexers (mux) select which inputs to add, registers hold temporary values, and logic gates (NAND, inverters) tie things together.
@kenshirriff NAND-GATE not -flash-memory. Younger people might only know the last one.
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The Space Shuttle could hold a flying laboratory called Spacelab in its cargo bay. Three French-made computers ran Spacelab. I opened up a Spacelab computer and found that instead of a microprocessor, it is built from a multitude of simple chips. Let's take a closer look at the computer...
@kenshirriff Fun fact: That's me in front of the Spacelab exhibit on Airbus' Bremen site back in 2012. We won an exclusive guided tour by a German Astronaut instructor (whose name I forgot)
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@kenshirriff Fun fact: That's me in front of the Spacelab exhibit on Airbus' Bremen site back in 2012. We won an exclusive guided tour by a German Astronaut instructor (whose name I forgot)
@kenshirriff here we are in ESA's backup operation center watching live video and audio from an ISS spacewalk
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R relay@relay.publicsquare.global shared this topic
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For more on the Spacelab computer, see my latest article: https://www.righto.com/2026/05/reverse-engineering-spacelab-computer.html
@kenshirriff amazing article, thanks. I found in particular very interesting your views about the failure of the Plan calcul.
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@LukefromDC @kenshirriff You’d expect space tech to be fancy, but I think it takes ages to certify tech for such applications, so it is actually quite old?
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The boards need a lot of chips because a chip didn't do much back then. Even the ALU chips had just 170 transistors. Multiplexers (mux) select which inputs to add, registers hold temporary values, and logic gates (NAND, inverters) tie things together.
@kenshirriff TTL? Or...?
I tried blowing up and sharpening that image but I still can't make out the numbers on those chips, alas. I still suspect TTL.
Edited to add that I blew up a different set of your pics with better results, and what threw me is that these are 77 series chips rather than 74 series, but I'm guessing that's because it's special MILspec for those; the 7714 is clearly equivalent to 7414, and none of those are post-LS technology.
Yep--TTL. -
@kenshirriff I recall an electrical engineering professor back in the late 1970s who said the way to invent the better mousetrap was to figure out how to put one megabit of memory on a single chip.
His version of the Holy Grail.@kenshirriff After graduation I had a job where I did some testing on a particular IBM machine that had 4K RAM modules, each about the size of a small toaster with tiny ferrite cores and orthogonal wires inside. That made the Holy Grail seem unattainable.
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@bsdphk Those documents should be very interesting. Do the documents describe programming the Spacelab computers in assembly, HAL/S, or something else?
I think it is high-level block-diagrams mostly, but I didn't bring the files home, so you'll have to wait until thursday
One of them was a ~20mm thick description of the overall SpaceLab concept.
There's also a binder which may be ass'y manual.
As far as I can tell from contemporary news reporting, KampSax & CR were responsible for software for ground checkout, "an interpreter" and a "data reduction system.
Train your Danish on: https://danmarkshistorien.ing.dk/titles/ingarkiv/7678/publications/9400/pages/16
(Bottom 3rd col.)
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The Space Shuttle could hold a flying laboratory called Spacelab in its cargo bay. Three French-made computers ran Spacelab. I opened up a Spacelab computer and found that instead of a microprocessor, it is built from a multitude of simple chips. Let's take a closer look at the computer...
@kenshirriff If you ever heard the term "electronics porn" that's IT ! I am actually drooling over such pictures of that HW 🥰 🥰
"This is how computers should be made" "able to stand a launch in Space" no fancy smancy LEDs on ram modules or fans with coloured spinning blades of funkopops things close to the CPU and the GPU with a logo shown like if it'd be "Armani" 
THIS in the pic is "the HW that makes me dream" 
I dream one day to actually build something like this ! -
Around 1991, the Spacelabe computers were upgraded, replacing the French Mitra 125 MS computers with more powerful IBM-made AP-101SL computers. The new computers still used simple ICs, but the "flat-pack" ICs were packed more densely. They also used semiconductor memory instead of magnetic core.
@kenshirriff I suppose if you make them a lot smaller, they suffer more from radiation.
But now there are laptops on the #ISS. -
The Space Shuttle could hold a flying laboratory called Spacelab in its cargo bay. Three French-made computers ran Spacelab. I opened up a Spacelab computer and found that instead of a microprocessor, it is built from a multitude of simple chips. Let's take a closer look at the computer...
@kenshirriff So cool! Thanks for sharing
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The boards need a lot of chips because a chip didn't do much back then. Even the ALU chips had just 170 transistors. Multiplexers (mux) select which inputs to add, registers hold temporary values, and logic gates (NAND, inverters) tie things together.
@kenshirriff I've been studying these old ALU chips, as a way to teach myself about computer hardware design. 170 transistors is an amazing feat of engineering.
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The Space Shuttle could hold a flying laboratory called Spacelab in its cargo bay. Three French-made computers ran Spacelab. I opened up a Spacelab computer and found that instead of a microprocessor, it is built from a multitude of simple chips. Let's take a closer look at the computer...
@kenshirriff Compagnie d'informatique militaire spatiale et aéronautique - didn't know about this one (whence it came, what it became)
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The Space Shuttle could hold a flying laboratory called Spacelab in its cargo bay. Three French-made computers ran Spacelab. I opened up a Spacelab computer and found that instead of a microprocessor, it is built from a multitude of simple chips. Let's take a closer look at the computer...
哇，能亲眼看到Spacelab计算机的内部结构真是难得。用那么多简单芯片而不是微处理器来构建整台电脑，那个时代的设计思路还挺特别的。
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@LukefromDC @sandorspruit @kenshirriff Wrong : you can do an Apollo13 fixup if you have the guts to do so
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@kenshirriff I recall an electrical engineering professor back in the late 1970s who said the way to invent the better mousetrap was to figure out how to put one megabit of memory on a single chip.
His version of the Holy Grail.@bouriquet @kenshirriff Im old enough to remember the days when memory may be carried by a delay line. More fun then to data process.
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For more on the Spacelab computer, see my latest article: https://www.righto.com/2026/05/reverse-engineering-spacelab-computer.html
@kenshirriff Finally got to the end of the footnotes. GE only acquired Alstom's energy business, not the rail infrastructure business the company is now best known for, and despite taking that enormous write-off in 2018, the power turbine business that GE acquired is now a big part of the reason GE Vernova, post-breakup, is trading for $1000 a share and nearly 90% of the market cap of GE Aerospace (the old GE) after being spun off on a 1-for-4 basis.
