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Unit 2: Data Processing

It rotates with very high speed inside the computer drive. Data is stored on both the surfaces Notes
of the disk. Magnetic disks are most popular as direct access storage device. Each disk
consists of a number of invisible concentric circles called tracks. Information is recorded
on tracks of a disk surface in the form of tiny magnetic spots. The presence of a magnetic
spot represents one bit and its absence represents zero bit. The information stored in a disk
can be read many times without affecting the stored data. So the reading operation is non-
destructive. But if you want to write a new data, then the existing data is erased from the
disk and new data is recorded.

Figure 2.7: Magnetic Disk

From Computer Desktop Encyclopedia
c 1998 The computer language co. Ino
Tracks

One sector

Tracks

2.3.2.3 Floppy Disk
It is similar to magnetic disk discussed above. It is 3.5 inch in diameter. These come in
single or double density and recorded on one or both surface of the diskette. The capacity
of a high-density 3.5 inch floppy it is 1.44 mega bytes. It is cheaper than any other storage
devices and is portable. The floppy is a low cost device particularly suitable for personal
computer system.

Figure 2.8: Floppy Disk

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