COMPUTER ARCHITECTURE
SECONDARY STORAGE DEVICES
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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The laser hits the just the disk
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The laser hits the disk and the light sensor
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The laser hits the mirror and the light sensor
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The laser hits the disk, mirror and light sensor
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Detailed explanation-1: -A bump represents the number zero, so every time the laser burns a bump into the disc, a zero is stored there. The lack of a bump (which is a flat, unburned area on the disc, called a land) represents the number one.
Detailed explanation-2: -A laser is used to transfer digital data (a long sequence of ones and zeros) to this disc by literally burning small ‘pits’ into the surface, with untouched areas (called ‘lands’) representing ones and burned areas representing zeros.
Detailed explanation-3: -The laser produces a narrow beam of light incident on the bottom surface of the CD. The beam goes through the polycarbonate, is reflected by the aluminum, and then comes back through the polycarbonate and exits the CD to reach a photodiode detector.