Re: "Colo[u]rs"

Larry McVoy (lm@bitmover.com)
Sun, 9 Dec 2001 23:51:26 -0800

On Sun, Dec 09, 2001 at 11:21:23PM -0800, David Lang wrote:
> Larry, I thought that direct mapped caches had full mapping from any cache
> address to any physical address while the N-way mapped caches were more
> limited. modern caches are N-way instead of direct mapped becouse it's
> much more expensive (transistor count wise) for the direct mapped
> approach.

That's not correct unless they changed terminology without asking my
permission :-) A direct mapped cache is the same as a 1-way set
associative cache. It means each cache line has one and only one
place it can be in the cache. It also means there is only one set
of tag comparitors, which makes it cheaper and easier to build.

> If I'm mistaken about my termonology (very possible :-) what is the term
> for what I am refering to as direct mapped?

Fully associative cache, I believe.

-- 

---
Larry McVoy            	 lm at bitmover.com           http://www.bitmover.com/lm 
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