Magnetic-core memory

Magnetic-core memory was an early form of computer memory that played a crucial role in the development of digital computing systems. It was widely used from the mid-1950s until the mid-1970s and is considered a significant technological advancement in the history of computing hardware. Magnetic-core memory utilized tiny magnetic rings, the cores, through which wires were threaded to write and read information. This article delves into the principles, history, and eventual obsolescence of magnetic-core memory.

Principles of Operation

Magnetic-core memory stores bits of information in each magnetic core. The cores are magnetized in one of two possible orientations, representing binary values of 0 or 1. Information is written to the cores by sending currents through the wires threaded through them. The direction of the current determines the orientation of the magnetic field and thus the bit stored. Reading the information involves sending a current through a select wire to detect the orientation of the core's magnetic field. This operation was destructive; reading the data erased it, requiring a rewrite after each read operation.

History

The concept of magnetic-core memory was developed in the late 1940s and early 1950s by several groups working independently. Notable contributions came from An Wang, who patented the pulse transfer controlling device, and Jay Forrester at the Massachusetts Institute of Technology, who is credited with significant developments in the design and application of magnetic-core memory in computing systems.

Magnetic-core memory became the dominant form of memory in computers from the mid-1950s, providing a reliable and relatively fast means of storing and accessing data. Its use peaked in the 1960s and began to decline in the 1970s with the advent of semiconductor memory, which offered higher densities and speeds.

Advantages and Disadvantages

The primary advantage of magnetic-core memory was its reliability compared to earlier forms of memory. It was non-volatile, meaning it retained information without power, and was resistant to shock, vibration, and radiation. These characteristics made it particularly suitable for military and space applications.

However, magnetic-core memory was relatively expensive and had limitations in speed and memory density compared to later semiconductor memories. The physical size of the cores and the complexity of the wiring also limited the maximum memory capacity.

Obsolescence

The development of semiconductor memory, starting with silicon-based integrated circuits in the late 1960s, led to the gradual obsolescence of magnetic-core memory. Semiconductor memory was cheaper, faster, and could store more information in a smaller space. By the mid-1970s, most new computers used semiconductor memory, and production of magnetic-core memory ceased.

Legacy

Despite its obsolescence, magnetic-core memory played a pivotal role in the history of computing. It was a key technology that enabled the development of early digital computers and laid the groundwork for the advances in memory technology that followed. Its principles of operation and the challenges it presented also contributed to the understanding and development of modern computing systems.

See Also

• Computer memory
• History of computing hardware
• Jay Forrester
• An Wang
• Semiconductor memory