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Arithmetic Logic Unit: The Arithmetic Logic Unit or ALU performs arithmetic, comparison
and logical operations.
Control Unit: The Control Unit or CU controls all the functions of a computer. It also checks
the result given by ALU.
Memory Unit: The Memory Unit or MU holds the data that needs to be processed as well as the
data that has been processed by the CPU.
OUTPUT DEVICES
We have already learnt about some basic output devices like monitors, printers, etc. Let us now
learn about a few more output devices.
Printer
A printer is an output device that gives the output on paper. The result printed on paper is called
a hardcopy or printout. Printers can be classified into two categories: impact and non-impact.
Printers that have direct contact between the print head and paper are known as impact printers.
The printers that do not have direct contact between the print head and paper are known as
non-impact printers.
Laser Printer
This is a non-impact printer that uses laser technology to print text or
images on paper. It is expensive and gives the best quality output. The
speed of the laser printer is measured in pages per minute (ppm).
Inkjet Printer
This is a non-impact printer that outputs text and images by
spraying ink on the paper. The speed of this printer is measured in
lines per minute (lpm). They are comparatively cheaper than laser
printers and the quality of output is also a little lower.
Dot Matrix Printer
This printer is an impact printer that contains a movable print head with
pins that strike the ribbon, placing a dot on the paper. These printers are
very noisy, less expensive, and slow to work. The speed of these printers is
measured in characters per second (cps).
Plotter
A Plotter is used for printing vector graphics, visual charts, tables and
diagrams. Different types of plotters are:
Inkjet Plotter: It sprays small droplets of ink onto a piece of paper,
thereby creating an image.
Flatbed Plotter: The pen or the inkjet moves in horizontal and vertical
directions over a fixed horizontal flat surface on which the paper is
mounted.
14 Trackpad (Version 1.0)-VI

