Storage and speed

New idea

Why does your laptop need two memories?

A typical laptop has 16 GB of RAM and a 512 GB SSD. The SSD is 32 times bigger, and it remembers everything when the power goes off. So why not keep everything on the SSD and skip RAM?

Because of waiting. RAM hands the CPU a byte in about 100 nanoseconds (billionths of a second). An SSD takes about 100 microseconds (millionths of a second). That's roughly 1,000 times longer.

That's why the last lessons had apps copied from storage into RAM before the CPU runs them. The CPU fetches billions of instructions a second, and it can't wait that long for each one.