Computer Science I / Cache and the Memory Hierarchy
Practice question · Put in order

Order these storage layers from fastest to slowest.

Hints
  1. The ordering by speed is also the ordering by size, but reversed.
  2. Among the cache levels, the lower the number the closer it sits to the CPU.
Show the answer
  1. Registers
  2. L1 cache
  3. L3 cache
  4. Main memory (RAM)
  5. Disk or SSD
Why

Speed falls and capacity rises as you go down: registers hold bytes, caches hold kilobytes to megabytes, RAM gigabytes, disk terabytes. L1 is nearer the CPU and faster than L3. The hierarchy exists precisely because no single technology is both fast and huge.

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