1.Explain Backing up of data.

Backing up refers to the copying of files and data to a different medium like disk,tape,flash drive etc.in case of a problem with the main storage device.Backing up files and data on a regular basis is seen as good computing practice.

2.Mention any three Important reasons for depending Back up data.

    There are Various reasons for depend back up datas.some of the more common reasons are as follows:-

    (a)Data could be lost due to failure of the original storage device. This could be due to hardware failure,accidental over written files etc.

    (b)Hackers could be responsible for the corruption or even loss of data.The very act of hacking in to files could cause problems such as corruption or data loss.

    (c)Backup are also made in case the file need to be used else where the original files are then protected against possible corruption or loss.

3.What are the two main methods of accessing  data? Briefly describes it,with example?

Two main methods of accessing data are:-

     a)Serial Access    b) Direct Access

a)Serial Access:- In this system,to access data it is necessary to start at the beginning and then access each piece of data in turn until the required information is found.It is primarily used on magnetic tape system and is a very slow form of access.

When a magnetic tape needs updating an additional tape is required so that the old information can be merged with the New data to produce the updated tape.

example:-Magnetic Tape

b)Direct Access:-In this system is used with magnetic disks and with optical media.The computer uses a key field to calculate where data has been stored.It is then able to access the data directly from the calculated position.Direct access is much faster than with serial access.

example:-CD

4.What are the three types of Backing Storage Media? Explain each? One example of each?

Three types of Backing Storage Media are:-

a)Magnetic     b)Optical   c)Solid State

a)Magnetic:- In magnetic type,magnetic tape is used.A magnetic tape is a very thin strip of plastic which is coated in a magnetic layer.They are read and written to by a read/ write head.The data is stored in magnetic areas.This type is a good example of serial access.

example:-magnetic tapes

b)Optical Storage media:-In optical storage media all use optical read/write methods.A laser beam is used to write and read from the optical media.

example:-DVD

c)Solid state:-In solid state technology are similar to magnetic and optical media in that data is still stored as 1s and 0s.Solid state system control the movement of electrons with in a microchip.The 1s and 0s are stored in millions of miniature transistors with in the microchip.if the transistor conducts a current,this is equivalent to a '1',otherwise it is a '0'.

example:-pen drives

5.What do you mean by fixed hard disk?

Fixed harddisk drives are available on all computer and are the main method used for data storage.On a PC this is usually a fixed harddisk with read/write heads allowing data to be written to or read from the disk surface.the disk surface is coated in a magnetic film which allows data to be stored by altering the magnetic properties to represent binary 1s or 0s.Fixed harddisk drive to allow them to quickly retrieve and save data.

6.What are the main uses of fixed harddisk drives?

Some main uses of fixed hard disk drives are as follows:-

(a)Fixed hard drives are used to store the Operating System and working data.

(b)They are used for storing applications software that needs fast retrieval and storage of data.

(c)real-time system like robots,control of a plant and online system like booking airline tickets,used fixed hard drives

(d)They are used in file servers for computer networks.

7.Write any two merits and demerits of fixed hard disk.

Merits of fixed hard disk are as follows:-

a)They have a very fast data transfer rate and fast access time to data.

b)They have very large memory capacities.

Demerits of fixed hard disk are as follows:-

a)They can be fairly easily damaged

b)They lack portability unless a portable hard disk drive is used.

8.Explain portable hard disk drives.

Portable hard disk work drives work n much the same way as fixed hard disk drives but are usually connected to the computer via a universal serial bus port and can be disconnected and used on different computer.The disks are generally capable of storing more data than the equivalent optical disk like CD,DVD etc.

9.Mention any two uses of portable hard disk drives?

a)portable hard disk can be used as back-up systems to prevent loss of data.

b)they can be used to transfer data,files and software between computer.

10.What are the main advantages and disadvantages of portable hard disk drives?

Advantages:-

a)The data access time and data transfer rate is very fast

b)They have large memory capacities.

c)They can be used as a method of transferring information between computers.

Disadvantages:-

a)As with fixed drives,a portable hard disk can be easily damaged if the user accidentally drops it or does not shut it down correctly after use.

11.Distinguish between fixed hard disk and portable hard disk drive?

Fixed hard disk drives are available on all computer and are the main method used for data storage.On a PC this is usually a fixed hard disk  with read/write heads allowing data to be written to or read from the disk surface.In case of portable hard disk drive work in much the same way as fixed hard disk drives but are usually connected to the computer via a USb port and can be disconnected and used on different computers.

Fixed hard disk drives are used to store the operating system,working data,applications software that needs fast retrieval and storage of data.In case of portable hard disk ,can be used as back-up system to prevent loss of data and it can used to transfer data,files and software between computers.

12.Define Floppy disk drives.

Floppy Disk Consist of a thin disk of plastic which is housed in a plastic case with a window where the disk can be accessed.As the disk rotates,a read/write head is used to add or read data stored on the surface.Floppy disks are still used on some computer systems.

13.What are the main uses of Floppy disk drives?

Floppy are still used where small files need to be transferred/stored.Some older computer system still make use of this method of storage.

14.Write down the advantages and disadvantages of floppy disk?

Advantages:-

•Using a CD to store a small file is often regarded as wasteful-especially if CD-R is used.

•It is a very simple technology.

•Floppy disk drives are also extremely low cost items to buy.

Disadvantages:-

•Floppy disk have a very low memory capacity

•Very few modern computers have floppy disk drives

•The data transfer rate is slow

•Floppy disks are not very robust

15.Explain Magnetic tapes.

Magnetic tapes is a very thin strip of plastic which is coated in a magnetic layer.They are read and written to by a read/write head.the data is stored in magnetic areas which represent 1s and 0s.Data is written to and read from the tape in sequence.Magnetic tapes is a good example of serial access.magnetic tape have very slow access speed.

16.Write any two uses of Magnetic taps.

Main uses are as follows:-

a) Magnetic tapes are used in applications where batch processing is used,for example in clearing bank cheques,utility billing like gas,electricity,water billing and producing pay slips.In these applications,there is no need for any specific processing order and speed of data access is not important.

b) They are used as a back up media since all the data needs to be stored.

17.Merits and Demerits of magnetic tapes.

The main Merits and Demerits are as follows:-

Merits:-

a)They are generally less expensive than the equivalent capacity hard disk.

b)It is a very robust technology

c)The data transfer rate is fast

Demerits:-

a)Access time is very slow.

b)When updating,another tap is need.

18.What do you mean by Optical Storage Media?

Optical Storage devices all use optical read/write methods,A laser beam is used to write to and read from the optical media.A very thin layer of metal.A very thin layer of metal or organic dye is used as the recording media.The big advantages of there storage media is that they are portable and can store large data files.

19.Define CD-ROM and DVD-ROM?

CD-ROMS and DVD-ROMS are read only memory which means they cannot be written over and can only be read.The data is stored as a series of pits and lands in the metallic optical layer:The pits are formed by a laser beam  the surface at the manufacturing stage.Only a single track exists which spirals out from the centre of the disk.

20.Write down any two uses of CD-ROMS and DVD ROMS?

CD.ROMS are used by manufactures to store music files and software,computer games and reference software.

DVD ROMS have much larger storage capacity than CD ROMS and are used to store films.They are now increasingly used to store computer data and ever more sophisticated computer and arcade games.