Question

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(d) Storage, also called secondary storage, auxiliary storage, holds items such as data, instructions, and information for future use. Explain the following storage devices. [9 marks] Tape Hard Disk Floppy disk (iii)

Answer 1

(i) Tape - In tape type storage device we have a reel on which data is written. And this reel is folded in circular form. Now whenever we need to access them we have to access the data sequenctially by traversing through each data in between our destination. So therefore due to this reason average access time of tape is very large. Still these are used to make archives. Because cost of tapes is cheap. Strength of tape is based on data it can hold per inch. So if the tape can hold 8 bytes per inch then we call storage density as 8 BPI . While Tape width is somewhat fixed to 0.5 inches.

Storage capacity of tape drives are very large . You can go over terabytes of data to store in tape. The main purose of using tape is for archiving because data on tape last for very long and tapes are cheap. However tape can not be used for storing items which need fast access because tapes are slow.

(ii) Hard Disk - In computers nowdays this is the most important component for storing data permanently. See in computers we have RAM and secondery storage. And for this secondery storage we use hard disk. So structure of hard disk is just like CD drive. Now when you open a hard disk you see a pointer on tap of a circular disk. Now this circular disk is used to store the data and pointer which is also called rw head is used to access and modify the data on disk. Now these disks are divided into some structure so that accessing the data on it can be easier and fast.

Sector Read Write Head Track

Storage capacity of hard disk is from 100 GB to in terabytes. As you can see read write head can move linearly and disk rotates. Hard disks are used present day. And they are now replacing by Solid state drives.

(iii) Floppy Disk - This type of storage was used in very early stage of computers. Storage capacity of floppy disk was 720 KB in1986. There are 3 sizes of floppy disk 3.5 inch , 5.25 inch and 8 inch. Floppy disks are also magnetic disks . Average access time of floppy disks are very high and also their storage capacity is very less thats why floppy disks are in no use today.