Thread: How did creators of early computers know what materials they needed?

I want to know this for my 6th Grade research project about computers, can anyone lend me a hand please?

Many early computers used devices that already existed -- mechanical relays and vacuum tubes, which were already in widespread use in telephone switching systems, radios, etc. And later, similarly, transistors.

But there were things that I think were invented specifically for computers; "core memory," for example.