Non-volatile random-access memory: Difference between revisions

Revision as of 04:20, 27 November 2023

Revision as of 16:26, 12 January 2024

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==Early NVRAMs==

Early computers used core and drum[[Disk_storage|Disk memoryStorage]] systems which were non-volatile as a byproduct of their construction. The most common form of memory through the 1960s was [[magnetic-core memory]], which stored data in the polarity of small magnets. Since the magnets held their state even with the power removed, core memory was also non-volatile. Other memory types required constant power to retain data, such as [[vacuum tube]] or solid-state [[Flip-flop (electronics)|flip-flop]]s, [[Williams tube]]s, and semiconductor memory (static or dynamic RAM).

Advances in [[semiconductor fabrication]] in the 1970s led to a new generation of [[Solid state (electronics)|solid state]] memories that magnetic-core memory could not match on cost or density. Today dynamic RAM forms the vast majority of a typical computer's [[main memory]]. Many systems require at least some non-volatile memory. Desktop computers require permanent storage of the instructions required to load the operating system. Embedded systems, such as an engine control computer for a car, must retain their instructions when power is removed. Many systems used a combination of RAM and some form of ROM for these roles.