Hello, thanks for clicking, reading and being there.
Recently visited the ''Rechenwerk Halle'' with a mate to see some computers from the German Democratic Republic.
Link to the museum:
I was mostly interested in their magnetic core memory after reading a book about the Apollo Guidance Computer and also wirewrapped computers courtesy to Apple 1 Revision 0 prototypes.
To my surprise, they had both, a lot of it. And more.
First one shows a magnetic core memory card. The concept behind it is pretty neat.
Imagine two very fine wires called ''set'' and ''sense'' and an energized ferrite core. If strong current flows through the ''set'' wire, a small voltage is induced in the ''sense'' wire, thanks to the core changing its polarity. Such a small voltage could be read as a ''1''.
If the ''sense'' wire goes around the core, instead of going through it, no voltage would be induced in the wire upon a polarity change and it could be read as a ''0''.
So a single ''sense'' wire can store a binary word based on wether or not it's going through a row of ferrite cores.
The picture shows a ROM card. The resolution is sadly too low to see the wires going through the cores, so trust me on this one.
You can see the cores more clearly in the next picture.
Obsolete way of prototyping circuit boards. Both ends of 30 AWG wire get stripped and wrapped around a pin header.
Circuits in the 60's and 70's running at 1 MHz with TTL IC's didn't mind the crosstalk induced by the wires and tall pin headers, can still be used today on rare occassions.
Just typing 9.109e-31 into Python and receiving the electron mass in perfect scientific notation is a real luxury once you see how floating point extension units used to look like.
I might find more decent pictures on my phone later. Until then, thanks for reading.
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