CODEWITHSUNDEEP
cpu
user855
user855

Reputation: 19948

Why are CPU caches faster than RAM?

Can the same technology/idea that is used to make caches fast not be used to make RAM fast too?

Or is there a fundamental tradeoff to be made here between speed of access vs. size of the store.

Upvotes: 0

Views: 1092

Answers (2)

flyingturtles
flyingturtles

Reputation: 903

The Distance: CPU is much more tightly packed than a RAM and therefore electric signals need to travel a lot longer.

How they work:

  1. RAM uses a small capacitor that’s connected to the transistor which stores a tiny charge. This charge will not stay long and it needs to be constantly refreshed to maintain its state which makes it slower.

  2. CPU Cache on the other hand uses a flip-flop gate which retains its state without refreshing. It’s more expensive to develop but it’s much faster.

Upvotes: 1

Carl Norum
Carl Norum

Reputation: 225162

Cost. Cache is SRAM and main memory is DRAM. Different technologies, different use cases. You couldn't afford a computer that used SRAM for (a reasonable amount of) main memory.

Upvotes: 3

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