secondary storage devices of computers

-

  • secondary storage devices of computers :

In order to store all information permanently, the computer Secondary Memory devices are used. These secondary storage devices are used to store large files and data and then can be reloaded into the main memory, for processing. Once the files are saved into the computer, You can retrieve it, as and when required by the user. The Secondary storage devices has a large storage capacity and is cheaper than Primary storage. The Magnetic memories are used for secondary storage and thus, they are semiconductor devices.

The Magnetic memories are divided into two categories.

i) Carriable memories
Examples: Floppy disk, Compact disk, Magnetic disk

ii) Non–carriable memories .
Example: Hard disk

The popular secondary storage devices are 

  1. magnetic disk,
  2. magnetic tape
  3. CD ROM.


 1)   MAGNETIC DISK:

The Magnetic disks are made up of synthetic plastic material. The disk plotter is coated on both sides with magnetic material and both the surfaces can be used for storage. The magnetic disk provides direct access of data.


  • The magnetic disks are divided into two types.
         i) Floppy disk
         ii) Hard disk

 i)  FLOPPY DISK: -

1. The floppy disk is flexible, low cost storage device. It is a circular thin plastic disk coated with magnetic material on the both sides.

2. It is divided into tracks and sectors magnetically. When reading and writing is performed, the spindle holds the disk and rotates very fast.

3. It is used to record and take the information from one computer to any other computer easily.

4. It we don’t need the information stored in a floppy, we can delete the unwanted information and store some other information in its place. The limitation of floppy is that we can store only limited amount at data depending on the size of the Floppy. The floppy disks are available in two sizes.

i) 5  1/4 (Five one by four)  inches (1.2 MB)
ii) 3 1/2( Three one by two) inches (1.44 MB)

ii)   HARD DISK:-

1. The hard disk contains a group of thin magnetic plates coated on both sides with magnetic material.

2. These disks are fixed to a spindle one below other

3. The spindle is fixed to a metal to rotates the disk very fast (60 rotations per second)

4. It has a group of magnetic heads mounted on an arm. The main arm can move the head radically         over the disk.

5. Each magnetic plate is logically divided into tracks. The track is a circular path to the disk. The set of concentrate tracks on all surfaces of the disks is called a cylinder.

6. The track is further divided into sectors. The data is stored sector to sector.

7. To axis the data from the disk, the specified cylinder number, surface numbers and sector number is read.

8. After giving the command to access the specified data, the time for the disk to access is called access time.

9. Access time is the sum of seek time and latency time. The seek time is the time taken for the head to reach the specific cylinder. The latency time is the taken to reach the specific sector on the cylinder.

10. The storage capacity of Hard disk is 80GB to 500 G.B and even more.
2)   MAGNETIC TAPES: -

1. Magnetic tape is a storage device. It used as back up storage.

2. The advantage of magnetic tape is its low cost and large storage capacity.

3. Its main disadvantage is that, it can store and execute the information sequentially. So the access time is very high.

4. The magnetic tape is made up of magnetic material. The standard type is ½ inch wide and has 9 tracks. It is created with iron oxide and has 9 tracks. It is created with iron oxide magnetic material.

5. The newer ½ inch wide type contains 19 tracks and coated with chromium dioxide.

6. The data is stored as records and group of records are called as a block. While storing, a gap is left between the blocks. It is called inter-record gap block.

7. A set of blocks form a file. The tape contains file identification marks to recognize the beginning and ending of file.
3)  COMPACT DISK( CD): -

1. Compact disk is the most existing development that has taken place in secondary storage in recent years.

2. It is the latest technology with high capacity storage disk that work with laser.

3. It is the optical fibre disk having shine metal coating with 5¼ inches diameter.

4. The information is stored by creating pits on the surface of the disk with the laser beam while reading a disk, the head send pits and converts them into digital data.

5. If there is a pit it is one otherwise zero.

6. We can store different types of data such as audio, video, text files, animation, pictures and graphics on the disk.


Comments

Post a Comment

Popular posts from this blog

What is OSI model ? Explain the Layers of OSI model with diagram .

-
Image
What is OSI model ? Explain the Layers of OSI model with diagram . What is OSI model? The OSI model (Open System Interconnection) model defines a computer networking framework to implement protocols in seven layers. A protocol in the networking terms is a kind of negotiation and rule in between two networking entities. Layers of OSI model: Physical layer The Physical layer is also called as the Layer 1. Here are the basic functionalities of the Physical layer: ·        Responsible for electrical signals, light signal, radio signals etc. ·        Hardware layer of the OSI layer ·        Devices like repeater, hub, cables, ethernet work on this layer ·        Protocols like RS232, ATM, FDDI, Ethernet work on this layer Data Link layer The data link layer is also called as the Layer 2 of the OSI model. Here are the basic functionalities of the data link layer: ·        Responsible for encoding and decoding of the electrical signals into bits. ·
Read more

BUS AND MEMORY TRANSFERS

-
Image
BUS AND MEMORY TRANSFERS          A typical digital computer has many registers, and paths must be provided to transfer in formation form one register to another. The number of wires will be excessive if separate lines are used between each register and all other registers in the system. A more efficient scheme for transferring information between registers in a multiple-register configuration is a common bus system. A bus structure consists of a set of common lines, one for each bit of a register, through which binary information is transferred one at a time. Control signals determine which register is selected by the onus during each particular register transfer.           One way of constructing a common bus system is with multiplexers. The multiplexers select the source register whose binary information is then placed on the bus. The construction of a bus system for four registers is shown is Fig . Each register has four bits, numbered 0 through 3. The bus consists
Read more

General Science(Biology) Bit

-
General Science(Biology) Bit Questions 1.       Who invented Pencillin ? Alexander Fleming 2.       A Sphygmomanometre is used to measure ? Blood Pressure 3.       Total Number of Chambers in Human Heart ? Four 4.       Photo Electric Effect Invented by ? Albert Einstein 5.       What are leucocytes ? White blood cells 6.       Who is called as Father of Evolution ? Charles Darwin 7.       What is the full form of ICBN ? International Code for Botanical Nomenclature 8.       The Light reaction happens in which membrane ? Thylakoid 9.       The Chain of Amino Acid is also known as ? Polypeptide 10. Influenza infects which system in human body ? Respiratory system 11. ______ measure s how far a wave rises and falls ? Amplitude 12. Buyoyant force can be calculated using ______ Principle ? Archimedis principle 13. Which animal is closest to humans ? Chimp 14. How many lungs are there in Human body ? Two 15. The study Poll
Read more