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
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.
Abbreviations
RAM - Random-Access Memory
ROM - Read-only Memory
PROM - Programmable Read-Only Memory
EPROM - Erasable Programmable Read Only Memory
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