What is Cache Memory?

R. Kayne

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.

The CPU uses cache memory to improve the overall speed of a computer system.
The CPU uses cache memory to improve the overall speed of a computer system.

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.

RAM card.
RAM card.

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.

Disk caching applies the same principle to the hard disk that memory caching applies to the CPU. Frequently accessed hard disk data is stored in a separate segment of RAM in order to avoid having to retrieve it from the hard disk over and over. In this case, RAM is faster than the platter technology used in conventional hard disks. This situation will change, however, as hybrid hard disks become ubiquitous. These disks have built-in flash memory caches. Eventually, hard drives will be 100% flash drives, eliminating the need for RAM disk caching, as flash memory is faster than RAM.

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Discussion Comments

anon270921

Where is cache memory located with respect to a Central Processing Unit and main memory?

anon212393

That was a precise and excellent explanation of cache.

- vinod

anon165723

very helpful and precise. hope you will explain all parts of the computer like this one.

anon165441

this cache memory is built right into the processor.

anon163253

then what is the difference between SRAM and DRAM?

Adaickalavan Palamneeyappan

Clear information. Good!

anon149373

this is very nice and clear information. thanks for you who has written this.

anon132765

it is primary or secondary?

anon131839

which one these is on chip memory?

a.main memory

b.cache

anon130079

what is the main role of cache memory and where is it?

anon128820

I love wise geek. Thanks for the info on cache. I wasn't even pronouncing it right.

anon126520

Thanks for sharing your knowledge.

anon111795

can you help me with some details about cache? and some information?

anon107959

thanks, just what i needed - short, clean and simple explanation.

anon106955

Excellent and precise piece of information. Thanks.

cool.

anon105772

I can say only thanks. i got what i needed.

anon105530

I just want to ask: what are the various types of i/o buses and what are their functions?

anon96783

I want to know where's the cache memory is located? Is it in RAM?

anon90222

Very nice concept. Simple and short. Thanks.

anon89129

should a cache ever be cleared?

anon87760

Really crisp and clear definition. Was searching Web and was getting idea which was not penetrating my dumb head. It is really awesome. Thanks for it. Satya

anon86901

flash memory is not faster than RAM. Get your facts straight.

anon79018

very helpful and precise. hope you will explain all parts of the computer like this one. thanks

anon78804

What's the general size allocated for cache memory?

anon72439

it's simply awesome.

anon70727

Super, dude. Very short and clear.

anon70689

short and sweet. Thanks.

anon68923

what is the performance of the system when it has more cache?

anon68521

Thanks for the info, short but to the point and clear.

anon65757

what is your prediction when hdd will be 100 percent flash? What are your predictions on when common cpu's will reach 1gb/10gb/100gb of L1?

anon58594

Well informed. good job Pro

anon57899

Thanks a lot. This post is extremely superb. The explanation is really really cool.

anon55307

Please help me. MY L2 cache's value is 0 when it is read by my TuneUp Utilities... but by reading it with CPU-Z it has its values.

anon54404

how can you rank speed from primary memory and secondary memory?

anon54390

thank you for giving the good answer,

but i just wanted to how many levels are there in a cache.

anon52025

Simply superb!

anon47752

Thank you, this article was very helpful. I'm doing A Level IT, and I found it extremely useful!

anon43965

"if i clean my cache will this fix my youtube? the sound works but the picture freezes." ROFL

anon43232

Marvelous article. Just continue to write this type of articles. Thanks.

anon43120

if i clean my cache will this fix my youtube? the sound works but the picture freezes.

anon42487

Great effort. Any computer user could understand it. hats off.

anon39147

The way of explanation is excellent.

anon37529

does intel 8086 has a cache memory???? answer me please?? thanks.

anon37366

It was excellent article. i want to ask about the difference between the role of Ram and cache in mother board

lsujatha

cache memory is made of?

From which processor cache started? What is the speed and width?

anon35242

Fantastic answer. It explains it so well!

anon31732

It would be better to have 2MB cache and 1GB RAM as Cache is generally a lot faster (2-3 times) than RAM.

anon31727

Basic Factors to consider before buying a new computer are:

1. What will it be used for? This will determine whether or not you need a powerful processor, extra RAM or overall performance capabilities.

2. Reliability. Will all the components work correctly and efficiently?

3. Will it require space for future improvements? If in the future you wish to upgrade your pc, you will need to have extra space such as extra PCI slots and drive bays.

4. Spacial Awareness. How much room have you got to put your PC? Do you need a small, more compact PC or can you manage with a big pc that takes up a lot of space?

anon21965

What are the basic factors that I should consider before I buy a new computer?

anon17823

does cache memory prevent the processor from being idle? if yes then how?

glassbarrel

I have a similar question....is it better to go with 1mb L2 cache and 1gb ram or 2mb cache and 1gb ram?

anon8020

hi i just wanted to ask if there is a big difference in performance between a 1mb & 2mb cache and any way in which i would feel the difference when im using the laptop? thnx a lot

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