What is cache memory?

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What is cache memory?

We explain the different categories of cache memory, and how it differs from RAM

What is memory? When talking about PC hardware, memory can sometimes get confusing. There are multiple different types of memory, often with separate sub-categories within them. For example, the memory that your computer uses to store files and documents on is not the same as the memory allocation that it uses to complete tasks.

This means that the CPU can access the data on it more quickly, which means that the CPU can operate faster. A larger cache will also improve processor speed, as it can store more instructions at once.

There are three different categories of cache memory, graded in levels: L1, L2 and L3. L1 cache is generally built into the processor chip and is the smallest in size, ranging from 8KB to 64KB. However, it is also the fastest type of memory for the CPU to read. Multi-core CPUs will generally have a separate L1 cache for each core.

L2 and L3 caches are larger than L1, but take longer to access. L2 cache is occasionally part of the CPU, but often a separate chip between the CPU and the RAM.

Graphics processing chips often have separate cache memory to the CPU, which ensures that the GPU can still speedily complete complex rendering operations without relying on the relatively high-latency system RAM.

Cache memory generally tends to operate in a number of different configurations: direct mapping, fully associative mapping and set associative mapping.

Direct mapping features blocks of memory mapped to specific locations within the cache, while fully associative mapping lets any cache location be used to map a block, rather than requiring the location to be pre-set. Set associative mapping acts as a halfway-house between the two, in that every block is mapped to a smaller subset of locations within the cache.

This article originally appeared at itpro.co.uk

Copyright © ITPro, Dennis Publishing
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