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“Read” Head. Signal. 0. 0. 1. 0. 1. 0. 0. 1. 1. 0. _. _. “Bits” of information. Magnetic Data Storage. A computer hard drive stores your data magnetically. “Write” Head. S. N. Disk. N. S. direction of disk motion. 25 DVDs on a disk the size of a quarter, or
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“Read” Head Signal 0 0 1 0 1 0 0 1 1 0 _ _ “Bits” of information Magnetic Data Storage A computer hard drive stores your data magnetically “Write” Head S N Disk N S direction of disk motion
25 DVDs on a disk the size of a quarter, or all Library of Congress books on a 1 sq ft tile! Scaling Down to the Nanoscale Increases the amount of data stored on a fixed amount of “real estate” ! Now ~ 50 billion bits/in2, future target more than 1 trillion bits/in2
4 choices two bits 00, 01, 10, 11 000, 001, 010, 011, 100, 101, 110, 111 three bits 8 choices Binary Representation of Data only 2 choices one bit “1” or “0” n bits has 2n choices For example, 5 bits has 52 = 32 choices... more than enough to represent all the letters of the alphabet
Binary representation of lower case letters 5-bit Science Saturday code: ex: k = 01011