Really retro: working with core memory: 64 bits of it. 
A review of the kit at IEEE Spectrum shows you need to know how to delicately weave the core memory, just like in the good old days.
Core64 unites authentic Core Memory and LEDs in a unique and interactive way. Core memory is a magnetic memory technology from the 60’s and 70’s. It was used in the Apollo Guidance Computers and several other down-to-earth applications. It is made of tiny rings of ferrite material which can be magnetized in one of two polarities: clockwise or counter-clockwise. The polarization is assigned a binary “0” or “1” status and the polarity can be written and read back into a computer. This fundamental trait makes Core Memory usable as RAM or ROM. An additional benefit is persistent polarity - cores do not require power to maintain the polarity. It is similar to more recent forms of magnetic memory like floppy discs and hard drives. In the Core64 kit, the core memory is visible as the array of wires suspended over the top of multicolor LEDs. The stylus has a magnet in the tip which enables interaction with the LEDs by way of the core memory. In practice, you can think of it as a magnetic touch screen.
The Core64 kit includes many more features with a lot of room for interactive learning and creative expansion. A wide range of experimentation is unlocked with this kit - you can think of it as a Dev Kit for Core Memory!