In computing , memory refers to the computer hardware integrated circuits that store information for immediate use in a computer ; it is synonymous with the term " primary storage ". Computer memory operates at a high speed, for example random-access memory (RAM), as a distinction from storage that provides slow-to-access information but offers higher capacities. If needed, contents of the computer memory can be transferred to secondary storage , through a memory management technique called " virtual memory ". An archaic synonym for memory is store . [1]

Most semiconductor memory is organized into memory cells or bistable flip-flops , each storing one bit (0 or 1). Flash memory organization includes both one bit per memory cell and multiple bits per cell (called MLC, Multiple Level Cell). The memory cells are grouped into words of fixed word length , for example 1, 2, 4, 8, 16, 32, 64 or 128 bit. Each word can be accessed by a binary address of N bit, making it possible to store 2 raised by N words in the memory. This implies that processor registers normally are not considered as memory, since they only store one word and do not include an addressing mechanism.

In the early 1940s, memory technology often permitted a capacity of a few bytes. The first electronic programmable digital computer , the ENIAC , using thousands of octal-base radio vacuum tubes , could perform simple calculations involving 20 numbers of ten decimal digits which were held in the vacuum tube accumulators .