ANATOMYMEMORY / 001

Least recently used.

A small cache has a simple rule: keep what you use.
When it fills up, let the oldest access go.

LRU / 04
MOST RECENT
  1. A
  2. B
  3. C
  4. D
LEAST RECENT
REQUEST
Cartridge to watchFour resident cache slotsFetch dock / eviction trayEvery access renews recency. A hit reuses a resident entry; a miss brings one in from the left dock. When all four slots are occupied, the entry used least recently leaves through the right tray. Punched holes identify A–E.
STARTS WARM

A, B, C and D are already cached. Try C for a hit, then E for a miss.

HITS
0
MISSES
0
EVICTIONS
0

One access is enough. A new access makes a key most recent, even if another key was used many times before.

In software. A hash table finds the entry; a doubly linked list moves it to the recent end. The moving cartridges illustrate that change in order.