Memory hierarchy
Levels of memory with different speeds and capacities: registers (fastest, smallest), caches, main memory, and secondary storage (slowest, largest). Memory hierarchy balances speed and cost. Locality principles enable effective caching.
Real World
Apple's M3 chip places 36 MB of unified L2 cache close to the CPU cores, so frequently used app data loads in nanoseconds rather than waiting milliseconds for the SSD — this is why apps feel instant on modern MacBooks.
Exam Focus
Draw the hierarchy as a labelled triangle showing speed increasing upward and capacity increasing downward — include specific example sizes.
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