Core memory

Core memory, also known as magnetic-core memory, is an early form of computer memory that played a crucial role in the development of digital computing systems from the mid-1950s until the mid-1970s. It was widely used in computers of that era due to its reliability and relatively high speed compared to other storage methods at the time. Core memory uses tiny magnetic rings, the cores, through which wires are threaded to write and read information. Each core represents a single bit of data, which is stored by magnetizing the core in one of two possible directions.

History

The concept of core memory was developed in the late 1940s and early 1950s. The invention is credited to several individuals, including An Wang, Way-Dong Woo, Jay Forrester at the MIT, and Frederick Viehe. The technology was a significant improvement over earlier forms of memory storage, such as delay line memory and Williams tubes, because it was non-volatile and retained data without power.

Operation

Core memory works by passing currents through wires threaded through the magnetic cores to change their magnetization direction, representing either a 0 or a 1. Reading the data stored in a core involves sending a current through the cores and detecting the direction of the resulting magnetic field. A notable characteristic of core memory is that reading data is a destructive process, meaning the original data is lost during the read operation and must be written back if it is to be preserved.

Advantages and Disadvantages

One of the main advantages of core memory was its non-volatility; it retained information without power, which was a significant benefit over other types of memory at the time. Additionally, it was relatively fast and durable. However, core memory was also expensive to produce, and its manufacturing process was labor-intensive. The advent of semiconductor memory in the 1970s, which was cheaper, faster, and required less power, led to the decline of core memory.

Legacy

Despite being replaced by more modern forms of memory, core memory played a pivotal role in the history of computing. It was used in many early computers, including the IBM 704, PDP-1, and the Apollo Guidance Computer used in the NASA Apollo missions. The principles of core memory operation have influenced the development of later memory technologies.

See Also

• Computer memory
• Magnetic storage
• Semiconductor memory
• History of computing hardware