History of Computers - Magnetic Core Memory

Page created by Lacey Rybarczyk

Magnetic core memory is an early form of RAM (random access memory). It uses cores, small magnetic ceramic rings, which are threaded by wires. It stores information via the polarity of the magnetic field they contain.^[1]

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Overview

Magnetic core memory was an early version of RAM (random access memory). It was invented to replace vacuum tubes and mercury delay lines. The earliest invention that sparked the idea of magnetic core memory was created by the Shanghai-born American physicists, An Wang and Way - Dong Woo. They created a pulse transferring device in 1949. An Wang and Way - Dong Woo worked at Harvard University's Computation Laboratory at the time yet did not pursue their project much further because Harvard had no interest in promoting inventions created in their labs. ^[3] An Wang did go onto to patent his invention somewhere else, it was the write-after-read cycle. Later invented at MIT in the late 1940's by Jay Forrester's group, the head of the Whirlwind computer project, was the coincident-current system. After seeing an add for a magnetic material, Jay Forrester came up with the idea of storing data in a magnetic field instead of electrical charges. His new magnetic storage technology replaced Whirlwind's electrical vacuum tubes and was the industry's standard for memory for the next 20 years ^[4]. Both of these inventions helped lead to the creation of magnetic core memory in 1951. Magnetic core memory consists of a large number of small ferromagnetic ceramic (ferrite) rings and ores held in a grid structure with wires, which are woven through the holes in the cores' middle. ^[5] The earliest version of magnetic core memory contained four wires, X,Y, Sense and Inhibit, yet they have advanced since then and now are created much larger. The wires that pass through the cores and hold the grid together create magnetic fields. In order to change the location of memory a magnetic filed greater than its intensity can cause the field to change polarity. In order to pick the new memory location, one of the X and Y line are driven with half of the current required to cause this change. ^[6] By causing the current to drive through the wires in a certain direction, the result is an induced field that forces the selected core's magnet to flux in one direction or the other circulating. 0 and 1 are the directions in which the current can be caused to flux.

Significance

In the 1950's the Magnetic Core Memory was created. It was one of the essential parts to creating some of the first personal computer. Without Magnetic Core Memory the computers would not have been able to retain any information. Although many computers memory is now constructed of silicon chips Magnetic Core Memory helped find a crucial component for personal computers. It also used the system of 0 and 1's that helped define which direction to send the memory. Ultimately magnetic core memory sparked ideas for today's method of storing memory and helped memory technology advance to what it is today.