Tech Support > Computers & Technology > Learning as I go along...
Learning as I go along...
Posted by ChrisCoaster on April 7th, 2008


Just a casual question to help clarify my understanding of RAM/memory:

On my Vista machine(Yes - the most hated OS since M.E.!) when I go
into the performance tab of Task manager I see memory reported in
three components:

Total: 2940(MB)
Cached: 2279
Free: 33

I can pretty much figure out that 658mB RAM are actually in use(Total
minus sum of Cached + Free), and "Free" is a no-brainer, but what does
"cached" mean exactly?

None of the defintions on line are in the type of English most people
would understand, so I would appreciate your help here.

-ChrisCoaster

Posted by Jeff Strickland on April 7th, 2008


Try positng this one on the Vista news group ...

microsoft.public.windows.vista.general

Having said that, I should know the answer to your question but I don't.





"ChrisCoaster" <ckozicki@snet.net> wrote in message
news:a3dd86ef-06a1-4f1f-b775-71ad2527432b@a9g2000prl.googlegroups.com...

Posted by jameshanley39@yahoo.co.uk on April 7th, 2008


On 7 Apr, 19:58, ChrisCoaster <ckozi...@snet.net> wrote:
the idea is that when you have one memory to store all your stuff, and
a smaller faster memory(cache memory / a cache), to store the stuff
that is most frequently accessed. (obviously so you can access it
from the faster memory instead of RAM, which is slower.. and obviously
since you cannot put everything in cache, you have to choose what to
put in there, and for efficiency, it makes mose sense to put in what
is most frequently accessed).

cache memory is Random Access, and Memory, and it is writable (which
makes it more like RAM than ROM!). But the technology it uses is
better, and the it is being used for is different
one reason why this is done is price. The faster memory is very
expensive. So you cannot just use the memory technology of the cache
memory, for the RAM, and abolish the cache.

.

I suppose a similar thing is with Hard drive and RAM. One doesn`t
call RAM "cache", but relative to the hard drive, I suppose it is.
Things are loaded into RAM and then accessed quickly.. (the CPU can
access things in RAM, not the hard drive. Perhaps it was designed that
way because accessing from the hard drive would be slow).
And there is an analogy there with capacity too. Hard drive is like
160GB, RAM is 512MB.
(though of course the issue with RAM is data goes when the computer is
turned off)

If people could have cache memory in quantities of RAM, then I suppose
they would use that memory for their RAM. And abolish the extra "cache
memory".

I remember in 1995, RAM may have been 16MB(I cannot remember the RAM
quantities, 8 or 16 or 32).. But the latest cool advertised thing was
"pipline burst cache".. So a P120(pentium 120Mhz) had perhaps 16MB
RAM, and also, 256KB pipeline burst cache.

I have heard the term CPU cache... That may be the same thing..
CPU communicates with RAM.
Any cache memory is in between. Like a faster, smaller RAM.

I am not big on CPU architecture, but that is the idea.

Posted by Baron on April 7th, 2008


Jeff Strickland wrote:

Assuming that you have 3Gb ram then 2.279 Gb of it is in use storing
stuff the CPU might need next. Programs, data etc.

--
Best Regards:
Baron.


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