4th Class Computers Computer Memories Secondary Memory Devices

Secondary Memory Devices

Category : 4th Class

*      Secondary Memory Devices  

 

All computers store and retrieve data. Since primary memory has a limited storage capacity and is not permanent, secondary storage devices are used to store large amount of data permanently. Secondary memory devices are external devices and stores data for the future. Secondary memory devices include magnetic disks like hard drives and floppy disks, optical disks such as CDs and CD-ROM and magnetic tapes, which were the first forms of secondary memory. Secondary memory (or secondary storage) is the slowest and cheapest form of memory. It cannot be processed directly by the CPU. It must first be copied into primary memory (also known as RAM). Secondary storage (or external memory) differs from primary storage because they are not directly accessible by the CPU. The computer usually uses its input/ output channels to access secondary storage and then transfers the desired data using an Intermediate area in primary storage.

 

 

 

 

 

 

 

 

 

 

Secondary storage does not lose the data even when the power goes off?it is non-volatile. (See Figure 4,2.6) In modern computers, hard disk drives are usually used as secondary storage. The time taken to access a given byte of information stored on a hard disk is typically a few thousandths of a second or milliseconds. By contrast, the time taken to access a given byte of information stored in random access memory is measured in billionths of a second or nanoseconds. Some other examples of secondary storage technologies are: flash memory (e.g. USB flash drives or keys), paper tape, punched cards, standalone RAM disks and Iomega Zip drives. (See Figure 4.2.7)

 

 

      
*         COMPUTER MEMORIES          

 

 

Question.jpg    

 

 Fill in the blanks:

1. Secondary memory devices are ___ devices and stores data for the __ .

2. Secondary memory is not directly accessible by the ______ .

3. Secondary memory is the _________   and cheapest form of memory.

(A) Internal, Present, Modem, Fastest

(B) External, Future, CPU, Slowest

(C) External, Present, Modem, medium

(D) Internal, Future, CPU, Slowest

(E) External, Present, Hard disk, Slowest  

 

Answer: (b)

Explanation

Correct Option:

(B) Options given in (B) are correct.

Incorrect Options:

(A) Options given in (A) are incorrect. Therefore, option (A) is incorrect.

(C) Options given in (C) are incorrect. Therefore, option (C) is incorrect.

(D) Options given in (D) are incorrect. Therefore, option (D) is incorrect.

(E) Options given in (E) are incorrect. Therefore, option (E) is incorrect.  

 

 

 Given below are the statements about secondary memory. Select the correct statement.

1. Flash memory, paper tape and punched cards are the examples of secondary memory.

2. Secondary storage devices are used to store small amount of data permanently.

3. Secondary storage also loses the data when the power goes off and it is called volatile memory.

(A) 1 and 2                                                         

(B) 1 and 3

(C) Only 1                                                           

(D) All of these

(E) None of these  

 

Answer: (C)

Explanation

Correct Option:

(C) Only statement 1 is correct.

Incorrect Options:

(A) Statement 1 is correct but statement 2 is incorrect. Therefore, option (A) is incorrect.

(B) Statement 1 is correct but statement 3 is incorrect. Therefore, option (B) is incorrect.

(D) All the given statements are not correct. Therefore, option (D) is incorrect.

(E) All the given statements are not incorrect. Therefore, option (E) is incorrect.      

 

 

You Know.jpg   

  • The main memory or the internal memory or the primary memory is also known as IAS (Immediate Access Store).    

 

Important.jpg   

  • Volatile memory: is computer memory that requires power to maintain the stored information.
  • Non - volatile memory: is computer memory that can retain the stored information even when not powered.    

 

Summary.jpg   

 

  • Computer memory refers to devices that are used to store data or programs (sequences of instructions) on a temporary or permanent basis for use in an electronic digital computer.
  • Resources on Net: http://www.wikipedia.org  

 

*               Abbreviations

RAM                      -              Random-Access Memory

ROM                      -              Read-only Memory

PROM                   -              Programmable Read-Only Memory

EPROM                 -              Erasable Programmable Read Only Memory

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