Off-topic but looking at that old network card picture reminded me of a very vague memory of more than one card with a component that looked like a capacitor, except it looked cracked.
Is my mind playing tricks? Were they faulty units or was there meant to be a crack?
That looks like a capacitor with a built-in spark gap. I've seen them in CRT circuitry. They're probably using it in the network card so if there's a huge over-voltage (e.g. lightning somewhere), it will jump across the spark gap, limiting damage.
I still have a load of them gathering dust somewhere. However a system with ISA on it is a bit rare now and I'm not sure I can be bothered to compile a modern kernel small enough to boot on one. Besides, it will probably need cross compiling on something with some grunt that has heard of the G unit prefix.
Is my mind playing tricks? Were they faulty units or was there meant to be a crack?
This picture could be the same thing:
https://www.vogonswiki.com/images/3/37/Viglen_Ethergen_PnP_2...