Victor GijsbersJan 3, 2023
Looking for people who know something about early computing, especially in the Netherlands. Please boost and help me solve the mystery of this custom made plate that used to belong to my grandfather Bram Jan Loopstra, one of the pioneers of Dutch computing. What do the pictures mean? #computing #history (EDIT: Wow, thanks for the overwhelming response! You may have to check the post on my instance to see all the MANY helpful reactions.)
Show threadVictor GijsbersJan 3, 2023
The binary is obviously a date, 8-3-1956. That's the year that my grandfather and his collaborators finished the ARMAC computer. So my first hypothesis is that it's a commemorative plate for that. If so, the pictures may have something to do with this computer.
Show threadVictor GijsbersJan 3, 2023
The words at the bottom are the motto of early modern Dutch scientist Simon Stevin. It means something like: "It's a miracle, but not a miracle", indicating the power of science to explain the seemingly miraculous.
Show threadpenguin42Jan 3, 2023
@victorgijsbers The diagram on the left to me looks like a valve; possibly a pentode: https://commons.wikimedia.org/wiki/File:Pentode_symbol_labeled.svg
The thing at the top I'm guessing is a core memory?
The thing to the right looks to me like a diagram of hysteresis ( https://en.wikipedia.org/wiki/Hysteresis ) - which hmm I'd guess would be related to the magnetic cores??? But hmm the lines with the black blobs; it could be a baudot representation https://en.wikipedia.org/wiki/Baudot_code
File:Pentode symbol labeled.svg - Wikimedia Commons

Show threadBarry Schwartz 🫖Jan 3, 2023
@penguin42 @victorgijsbers Oh, yes, that’s certainly a pentode. (The surrounding circle would just mean it was in a tube by itself.) And that’s definitely hysteresis, which is symbolic of (any kind of) memory.
Show threadBarry Schwartz 🫖Jan 3, 2023
@penguin42 @victorgijsbers (I’m a little curious why a pentode instead of a triode, but I have very little knowledge of tubes/valves and certainly not of their use in digital circuitry.)
Show threadpenguin42
@chemoelectric @victorgijsbers Yeh same here; I wonder if you end up with something like a 3 input AND gate?
Jan 3, 2023 at 4:09pmWeb
Show threadBarry Schwartz 🫖Jan 3, 2023

@penguin42 @victorgijsbers Could be. Let’s see ...
‘Tube computers primarily used triodes and pentodes as switching and amplifying elements. At least one specially designed gating tube had two control grids with similar characteristics, which allowed it to directly implement a two-input AND gate.’
https://en.wikipedia.org/wiki/Vacuum-tube_computer

So, good catch!

Vacuum-tube computer - Wikipedia

Show threadBarry Schwartz 🫖Jan 3, 2023
@penguin42 @victorgijsbers One might think it would have a special symbol, though, since it’s not a pentode in the usual sense.
Show threadMysteriousBenjiJan 3, 2023
@chemoelectric Wikipedia says that the pentode (as featured on the plate) was used heavily in some of the very early British computers; perhaps the Dutch did likewise?