Student of group 961-21 Babadjanov Jamshid English lesson Self studies

Student of group 961-21 Babadjanov Jamshid English lesson Self studies
Topic-3
Types of storage devices
The computer needs a place to store data and program files when they are not in use. The purpose of storing is to hold data even when the computer is turned off. So storage device is used in the computers to store data Storage devices is used for storing, extracting data files and objects. Storage devices can store information temporarily and permanently. We can use storage devices internally or externally. We store data on storage devices in binary form. Many types of storage devices can be seen and each of them has benefits.
Usage of storage devices

The storage devices are mainly used for storing data. There are different types of storage devices and they have different types of advantages. They are different in size, shape. The Primary memory as RAM, ROM, and Cache is used for storing data in CPU. The secondary internal storage as Hard disk is used for saving frequently using digital data as well as the secondary external storage, offline storage, some flash memory storage online cloud storage is used for carrying data for transferring. The tertiary storage is served as a mass storage device. Tertiary storage such as Magnetic tape, Optical disc is typically used for data that is rarely accessed and this is useful for extremely large databases, accessed without human intervention.
Types of storage
There are four types of storage

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  Primary storage
  
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  Secondary storage
  
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  Tertiary storage
  
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  Offline storage
  

Primary storage
Primary storage is also called main memory. Main memory is directly or indirectly connected to the central processing unit via the memory bus. The CPU constantly reads instructions stored on it and executes them as needed. In primary storage, we can read and write data quickly. We can identify different types of primary storage.

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  RAM — RAM is called Random access memory. Because any of the data in random access memory can be accessed just as fast as any of other data. RAM stores data till the computer is working. When the computer is turn switched off, data is erased. RAM is volatile because when there is a power failure data stored data is lost.
  

There are two types of RAM

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  DRAM ( Dynamic Random Access Memory)
  
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  SRAM (Static Random Access Memory)
  

o Dynamic Random Access Memory
DRAM is continually refreshed to maintain the data. The refreshing is performed by memory placed on a refresh circuit, it rewrites the data several hundred times per second. DRAM is cheap and small. All DRAMs are made up of memory cells consisting of one capacitor and one transistor
o Static Random Access Memory
SRAM does not need to be refreshed regularly. SRAM chips use a matrix of six transistors and no capacitors. SRAM uses more chips than DRAM for the same account of storage space. The cost of manufacturing SRAM is higher.

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  ROM — ROM means Read-Only Memory. ROM is used as the computer begins to boot up. Small programs like firmware are often stored in ROM chips on hardware devices. ROM memory cannot be easily or quickly overwritten or modified. So ROM is non — volatile. ROM is hold data when power is turned off.
  
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  Cache — Cache memory is small in size and volatile memory. It provides high-speed data access to a processor and Cache stores frequently used computer programs, applications and data. Cache makes data retrieval easy and efficient. The cache acts as butter between RAM and the CPU. Most computers today come with L3 cache and L2 cache, and older computers included an only L1 cache.