Note
The 1960 RCA 16x16 Ferrite Core Memory is a fascinating piece of computing history.
Magnetic-Core Memory:
Magnetic-core memory, often called core memory, was a dominant form of random-access computer memory from the mid-1950s to the mid-1970s. It used toroidal ferrite cores to store information.
How It Works:
Each core represented one bit (either 0 or 1). Wires passed through the cores, creating an X-Y array. When an electrical current exceeded a threshold, a core became magnetized (clockwise or counterclockwise). Writing involved selecting an X and Y wire to half power, writing the desired value to the core. Reading was done via a separate sense wire that detected induced voltage changes during field transitions.
Reliability and Non-Volatility:
Core memory was non-volatile, retaining data even when powered off. Read-only core rope memory was used in critical systems like the Apollo Guidance Computer during NASA’s Moon landings.
Density and Cost:
By the late 1960s, core memory reached a density of about 32 kilobits per cubic foot. Costs declined significantly, from about $1 per bit to about 1 cent per bit.
It was a crucial component in early computers and contributed to the evolution of memory technology.
