Specifications

Computer Architecture and Maintenance (G-Scheme-2014)
Cache Memory
Q.Write Short on Cache Memory
Ans. cachememory is a high-speed memory buffer that temporarily stores data the
processor needs, allowing the processor to retrieve that data faster than if it came from
main memory. But there is one additional feature of a cache over a simple buffer, and
that is intelligence.
A buffer holds random data, usually on a first-in, first-out basis or a first-in, last-
out basis. A cache, on the other hand, holds the data the processor is most likely to
need in advance of it actually being needed. This enables the processor to continue
working at either full speed or close to it without having to wait for the data to be
retrieved from slower main memory. Cache memory is usually made up of static RAM
(SRAM) memory integrated into the processor die, although older systems with cache
also used chips installed on the motherboard.
Cache (pronounced cash) memory is extremely fast memory that is built into a
computer’s central processing unit (CPU), or located next to it on a separate chip. The
CPU uses cache memory to store instructions that are repeatedly required to run
programs, improving overall system speed. The advantage of cache memory is that the
CPU does not have to use the motherboard’s system bus for data transfer. Whenever
data must be passed through the system bus, the data transfer speed slows to the
motherboard’s capability. The CPU can process data much faster by avoiding the
bottleneck created by the system bus.
As it happens, once most programs are open and running, they use very few
resources. When these resources are kept in cache, programs can operate more quickly
and efficiently. All else being equal, cache is so effective in system performance that a
computer running a fast CPU with little cache can have lower benchmarks than a
system running a somewhat slower CPU with more cache. Cache built into the CPU
itself is referred to as Level 1 (L1) cache. Cache that resides on a separate chip next to
the CPU is called Level 2 (L2) cache. Some CPUs have both L1 and L2 cache built-in
and designate the separate cache chip as Level 3 (L3) cache.
Cache that is built into the CPU is faster than separate cache, running at the
speed of the microprocessor itself. However, separate cache is still roughly twice as fast
as Random Access Memory (RAM). Cache is more expensive than RAM, but it is well
worth getting a CPU and motherboard with built-in cache in order to maximize system
performance.
Prepared By – Prof. Manoj.kavedia (9860174297 – 9324258878 ) (www.kavediasir.yolasite.com)
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