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RAM

RAM definition - computer

(Random Access Memory) A type of memory that provides direct access to any byte on the chip. This "byte addressing" means that the contents of any byte can be read or written without regard to the bytes before or after it. In addition, read and write speeds are symmetrical. It takes no longer to write a byte than it does to read one. In contrast, writing to non-RAM memories such as flash takes considerably longer than reading (see flash memory).

The most common RAM chip is the dynamic RAM (DRAM) used as a computer's main memory. Any chip that has RAM in its name implies byte addressing and symmetric read and write speeds. See future memory chips, memory types, memory module, dynamic RAM and static RAM. To learn more about how memory works, see computer and memory.

Some Old Fashioned RAM

Not exactly random access, and hardly a chip, this magnetic drum unit was the memory in the IBM 650 computer, introduced in 1954. It held two thousand 10-digit words. That much memory today would fit inside the period at the end of this sentence. See also core storage and early memories. (Image courtesy of the Hagley Museum and Library.)

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