Page 64 - DCAP101_BASIC_COMPUTER_SKILLS

Unit 4: Secondary Storage Devices

The most commonly used character set by MICR devices is known as E13B font consisting Notes
of numerals 0 to 9 and four special characters (See Figure 4.12). Coded data in the form of
these fonts are transferred from cheques to a computer by an MICR reader-sorter. As the
cheques enter the reading unit, they pass through a magnetic field causing the particles in
the ink to be magnetized. Read heads then interpret these characters by examining their
shapes. The sorter is used to sort the cheques into different pockets according to their
identification code numbers.
Digitizer

A digitizer is an input device used for converting (digitizing) pictures, maps, and rawings
into digital form forstorage in computers. For example, the x and y coordinates of points
in a drawing may be stored in digital form. This enables re-creation of the drawing from
the stored information and easy incorporation of changes in the drawing, whenever required.
A digitizer consists of a digitizing tablet (also known as graphics tablet) associated with a
stylus (See Figure 4.13). The digitizing tablet is a flat surface that contains hundreds of fine
copper wires forming a grid. Each copper wire receives electric pulses. The digitizing tablet
can be spread over a working table and is connected to a computer. The stylus a like a pen
or a lens-like cursor with a cross hair and button. It is connected to the tablet and can be
pressed down at a point on the tablet to input the (x, y) coordinates of the point. On moving
the stylus on the tablet, a cursor on computer’s screen moves simultaneously to a corresponding
position on the screen to provide visual feedback to the operator. This enables the operator
to draw sketches directly or to input sketched drawings very easily. Inputting drawings or
developing sketches by using a digitizer is further simplified by the fact that poorly sketched
lines, arcs, and other graphical objects are automatically input as mathematically precise
objects like straight lines and smooth curves.
Digitizers are used commonly in the area of Computer Aided Design (CAD) by architects
and engineers to design cars, buildings, medical devices, robots, mechanical parts, etc. They
are also used in the area of Geographical Information System (GIS) for digitizing of maps
available in paper form.

Figure 4.13: Digitizer

4.2.2 Output Devices

An output device is an electromechanical device that accepts data from a computer and
translates them into a form suitable for use by outside world (users). Several output devices
are available today. They can be broadly classified into following categories:
1. Monitors 4. Screen image projector

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