In order to perform real time calculations on aircraft in flight, a form of memory more reliable than electrostatic memory
from memory tubes was required. On May 11, 1951 Jay W. Forrester
applied for the basic patent on three-dimensional magnetic-core memory
. US Patent 2,736,880 entitled Multicoordinate Digital Information Storage Device
was granted to Forrester on February 28, 1956. Forrester's invention, the coincident-current system, enabled a small number of wires to control a large number of cores enabling 3D memory arrays of several million bits. The first use of core was in the Whirlwind computer. Magnetic core memory greatly increased the reliability of memory technology and remained the predominant form of random-access computer memory
from about 1955 to 1975, after which it was replaced by solid-state memory.