No matter how smart you are, you wouldn't know anything if you couldn't remember. Thoughts and ideas would go in one neuron and out another, forever lost in the entropy of the universe. You know things because you can call back thoughts and ideas, to work on them again or just talk about them. A computer, too, needs some way of retaining its thoughts. Like you, it needs both short-term memory for holding ideas while it works on them and long-term memory to store all the facts and old ideas that, by chance, it might need another day.

The short-term memory of computers is often called simply memory. The long-term memory is often termed mass storage and involves several technologies. Hard disk drives hold the ideas you put into the computer, ...

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