Memory and storage systems-3

Question 1

Magnetic Disks

Answer 1

• It is a flat disk that is covered with magnetic coating for holding
  information.
• It is used to store digital information in the form of small and
  magnetised needles.
• These needles help in encoding a single bit of information by
  getting polarized in one direction represented by 1, and opposite
  direction represented by 0.
• Magnetic disk can store a large amount of data and is less
  expensive as compared to RAM.
• it takes more time to read the information from a specified
  location, its data access rate is slow compared to the main
  memory.
• It allows the random access of data and provides the facility of
  erasing and re-recording the data as many times as required.

Question 2

tracks

Answer 2

The data is stored in a magnetic disk in the
form of tiny dots on the tracks, which are
known as spots

Question 3

sectors

Answer 3

The broken-up units of tracks are known as
sectors

Question 4

There are two popular types of magnetic
disks:

Answer 4

– Hard disks
– Floppy disks

Question 5

Addressing and Geometry

Answer 5

• Externally, hard drives expose a large number of
  sectors (blocks)
  – Typically size is 512 or 4096 bytes
• Drive geometry– Sectors arranged into tracks
  – A cylinder is a particular track on multiple platters
  – Tracks arranged in concentric circles on platters
  – A disk may have multiple, double-sided platters
• Drive motor spins the platters at a constant rate

Question 6

Storage Evaluation Criteria

Answer 6

• Access mode
• Access time
• Storage capacity
• Storage type
• Cost

Question 7

Access mode

Answer 7

– Access mode is used for accessing some specific data
from the memory.
– The different access modes include random access mode,
sequential access mode and direct access mode.

Question 8

Access time

Answer 8

– Access time refers to the time taken by the processor in
completing the requests made by the user for performing
the read and write operations.
– The access time depends on the type of storage device
used and the access mode of the data.
– The access time of primary memory is faster than that of
the secondary memory

Question 9

Storage capacity

Answer 9

– Storage capacity is defined as the size of the memory available for
storing the data in the system.
– The storage capacity of the secondary memory devices is more than
the primary memory devices.

Question 10

Storage type

Answer 10

– It refers to the type of memory used to store the data.
– The storage type includes the temporary and permanent memory.
– The temporary memory is also known as the volatile memory, which
is able to store the data only when the power or computer system is
switched on.
– The permanent memory is also known as the non-volatile memory,
which is able to store the data, even when the power or computer
system is turned off.

Question 11

Cost

Answer 11

It refers to the cost of the storage device used in
the computer system for holding the data.