PRIMARY STORAGE AND UNIT OF STORAGE

Storage Unit-Storage unit of a computer system provides space for storing data and instruction, intermediate results, and results for output.

     Memory receives instruction and data from the input devices and stores them till they are needed by other parts of computer.

  Once the instructions are executed, the results transferred  to a permanent location which are then stored in a storage device.

There are two types of storage:-

Primary storage: - Primary storage of a computer system, also known as main memory, stores pieces of program instructions and data, intermediate results of processing, and recently produced results of those job(s) on which the computer system is currently working. Primary storage is volatile, and it loses the information it as soon as the computer system switches off or resets.

Secondary storage: - Secondary storage of a computer system, also known as auxiliary storage, takes care of the limitations of primary storage. It can retain information even when the computer system switches off or resets. A computer system uses secondary storage to store program instructions, data and information of those jobs on which the computer system is currently not working but needs to hold them for processing later.

Primary Memory can be classified into two groups:

RAM( Random Access Memory) : It holds the information temporarily, during the ongoing operation of a computer. When a computer is under operation, the data or instructions come into its memory for instant access. During the course of the execution of instructions, some intermediate results may be produced which are stored in the RAM.

RAM is a volatile memory. 

RAM chips are made of Metal Oxide Semiconductor(MOS).

RAM is available in  different capacities. Like: 2GB, 4GB, 8GB, 16GB, etc.

There are different types of RAM Like: SRAM, DRAM, SDRAM, EDRAM etc.

ROM( Read Only Memory) : It stores a set of predefined instructions for the internal operations of a computer. It is also referred as ‘Non-volatile memory’ or ‘firmware’.

    Once the user switches ‘ON’ the computer, the computer automatically does a series of sequential task known as POST (Power On Self Test) before the user starts its operation. The instructions for such predefined set of tasks are stored in the ROM. Such information on this memory can only be read. There are different types of ROM Like: PROM, EPROM, EEPROM, Flash Rom.

BIOS is stored in ROM and it operates when the computer is switched ‘ON’. It contains set of essential softwares that test the setup of hardware devices during startup. It helps to start the operating system and supports the transfer of data among the hardware devices.

CACHE MEMORY: Beside RAM and ROM, there are some other primary memories like Cache or Buffer memory. Cache Memory is a part of CPU and used when there is swapping of information between the primary memory and the ALU.

Unit of Storage:

A computer understandz its own language. All the data and information that are fed into a computer are converted into its own( machine) language.Its language consists of two digits i.e. 0 and 1 which are called ‘Binary Digits’.

Each digit 0 or 1 is known as ‘Bit’.

Agroup of four bits is called a ‘Nibble’.

A group of eight bits is called a ‘Byte’.

Storage of data is measured in multiples of bytes.

Different units of storage of data are:

8 bits = 1 byte

1024 bytes = 1 kilobyte (KB)

1024 kilobytes = 1 Megabyte (MB)

1024 Megabytes = 1 Gigabyte (GB)

1024 Gigabytes = 1 Terabyte (TB)

1024 Terabytes = 1 petabyte (PB)

1024 Petabytes = 1 Exabyte (EB)

1024 Exabytes = 1 Zetabyte (ZB)

1024 Zetabytes = 1 Yottabyte (YB)

1024 Yottabytes = 1 Brontobyte (BB)

1024 Brontobytes = 1 Geopbyte