Cache memory
Fast, small memory storing frequently accessed data reducing main memory access latency. Caches exploit locality of reference enabling near-main-memory speed at processor speed.
Formula
Hit rate = cache hits / total memory accesses × 100%
Real World
When you scroll through your Instagram feed, recently viewed images are kept in your phone's cache so swiping back loads them instantly rather than re-downloading from Meta's servers.
Exam Focus
Distinguish L1, L2, and L3 by size, speed, and location — examiners expect all three levels described with comparative detail.
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