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Saturday 3 September 2016

CACHE MEMORY

Cache memory is random access memory (RAM).Which is a computer microprocessor can access more quickly than it can access regular RAM. As the microprocessor processes data, it looks first in the cache memory and if it finds the data there (from a previous reading of data), it does not have to do the more time-consuming reading of data from larger memory. 
Cache memory is sometimes described in levels of closeness and accessibility to the microprocessor. An L1 cache is on the same chip as the microprocessor. (For example, the PowerPC 601 processor has a 32 kilobyte level-1 cache built into its chip.) L2 is usually a separate static RAM (SRAM) chip. The main RAM is usually a dynamic RAM (DRAM) chip. 

In addition to cache memory, one can think of RAM itself as a cache of memory for hard disk storage since all of RAM's contents come from the hard disk initially when you turn your computer on and load the operating system (you are loading it into RAM) and later as you start new applications and access new data. RAM can also contain a special area called a disk cache that contains the data most recently read in from the hard disk

TYPES OF CACHE

1.Memory cache

2.Disk cache

The two main types of cache are: memory cache and disk cache. Memory cache is a portion on memory of high-speed static RAM (SRAM) and is effective because most programs access the same data or instructions over and over. By keeping as much of this information as possible in SRAM, the computer avoids accessing the slower DRAM.
Like memory caching, disk caching is used to access commonly accessed data. However, instead of using high-speed SRAM, a disk cache uses conventional main memory. The most recently accessed data from the disk is stored in a memory buffer. When a program needs to access data from the disk, it first checks the disk cache to see if the data is there. 

Another type of cache is known as "Internet browser cache" also known as "Temporary Internet Files". Internet cache is used to help improve how fast data is opened while browsing the Internet. In most cases, each time a web page is opened, it is sent to your browser's temporary cache on your hard disk drive. If that page is accessed again and has not been modified, the browser will open the page from your cache instead of downloading the page again. This saves users a lot of time, especially if that user is using a modem, and can also help save the web page owner on bandwidth. 

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