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Operating System

Notes The individual segments in a 4+1 RAID-5 array are organized as follows:

Table 9.4: RAID-5 Segments
Drive 0 Drive 1 Drive 2 Drive 3 Drive 4
0 1 2 3 Parity
4 5 6 Parity 7
8 9 Parity 10 11
12 Parity 13 14 15
Parity 16 17 18 19
20 21 22 23 Parity
The above block layout is an example of Linux RAID-5 in left-asymmetric mode.

9.10 Summary

Input is the signal or data received by the system and output is the signal or data sent from
it.
I/O devices are used by a person (or other system) to communicate with a computer.
Keyboard is the one of the main input devices used on a computer, a PC’s keyboard looks
very similar to the keyboards of electric typewriters, with some additional keys.
Mouse is an input device that allows an individual to control a mouse pointer in a graphical
user interface (GUI).
Scanner is a hardware input device that allows a user to take an image and/or text and
convert it into a digital file, allowing the computer to read and/or display the scanned

object.
A microphone is a hardware peripheral that allows computer users to input audio into
their computers.
Web Cam is a camera connected to a computer or server that allows anyone connected to
the internet to view still pictures or motion video of a user.
Digital camera is a type of camera that stores the pictures or video it takes in electronic
format instead of to fi lm.

A computer joystick allows an individual to easily navigate an object in a game such as
navigating a plane in a fl ight simulator.
Monitor is a video display screen and the hard shell that holds it. It is also called a video
display terminal (VDT).
Printer is an external hardware device responsible for taking computer data and generating
a hard copy of that data.
Sound card is a sound card is an expansion card or integrated circuit that provides a
computer with the ability to produce sound that can be heard by the user. It is also known
as a sound board or an audio card.
Speaker is a hardware device connected to a computer’s sound card that outputs sounds
generated by the card.

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