Core memory is the simplest kind of main memory you could build from really basic components (no chips!), and easy enough to understand well.
I always wanted to understand computers to their core (no pun intended), and to build one myself from the ground up. The following kit seems to make it quite fun to do that for working memory (RAM), while being physically large scale enough to allow for inspecting and measuring what is going on.
In the picture above, the core memory itself is just the wire net on the left with the small rings (that look like beads/dots). Enjoyably simple.
The chips on the board are there to easily write and read the hand-built memory and to provide an interface to an Arduino (or other microcontroller).
The kit comes with all the necessary components, including the PCB, magnetic cores, wires, etc., while requiring some soldering to assemble it. Head over to Jussi’s blog to read the complete documentation for the shield and how to get one.