Apollo-Era Coincident Current Core Memory Plane, 5 x 5, which presents itself as a fascinating example of early random access memory (RAM), similar to the type used in the Apollo Guidance Computer (AGC). A magnified view of the memory plane reveals the wires threading the doughnut-shaped ceramic magnetic cores. Arrangement of the wiring through the cores allows the computer to address any one of the cores in the memory plane (representing a single bit as 0 or 1). In fine condition.