Memory
Hierarchy
Memory is
categorized into volatile and nonvolatile memories, with the former requiring
constant power ON of the system to maintain data storage.Furthermore,
a typical computer system provides a hierarchy of different times of memories
for data storage.
Memory
hierarchy can exploit in 2 approach:
Approach 1
:Expose
Registers, Main Memory, Disk each available as explicit
storage alternatives
Approach 2
:Hide
Machine automatic assigns
locations, depending on runtime usage patterns of single
kind of memory, single address space.
Now to
exploit the memory hierarchy, there are two technique that depend on CPU speed.
The CPU speed is dominated by the memory performance. They are caching and
virtual memory. Caching make slow main memory appear faster and virtual memory
make small main memory appear bigger.
CACHE Memory
Cache memory
is random access memory (RAM) that a computer microprocessor can access faster
than it can access regular RAM.Cache is a small
high-speed memory. Stores data from some frequently used addresses of main
memory.Cache memory
also is The level of the memory hierarchy closest to the CPU.
CACHE
Analogy
You are
writing notes in a notepad in llibrary.
-In your
work, youneed take a reference book to table.
-Sit down
and write.
-Suddenly
stop writing and take a book on the table to reference.
-You are
not return the book to the shelve immediately,
you just put on the table.
-Then you
need another book to refer, go take another book for your work.
-Soon, your
table have a few books that you need to refer.
-Now you can
do your work smoothly without get the reference book from the shelve.
-You see,
the table where you use is the cache for the library.
Cache Example
Here is the
example of cache.
Now, we
need:
-8-blocks(1
word per block)
-direct
mapped
-initial
state
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