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Looking Inside the Black Box
Input Output CPU Storage Secondary - Hard Drives Primary - RAM, ROM
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Storing Data Computers store Digital Data Two type of data
Digital – can be compressed Analog Digital data – stored as digital data Text data – stored as ASCII codes (digital) Analog data – converted to digital
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Storing Data – Binary Numbers
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Storing Data – Binary Numbers
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Storing Data – Binary Numbers
Used to store digital data 8 bits 0 = 1 = 2 = ... 254 = 255 = 16 bits 0 = 1 = 2 = ... 65534 = 65535 =
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Storing Data – Hexadecimal
Easy way to represent binary numbers Easy to convert between hex and binary Base 16 0 = 0000 1 = 0001 2 = 0010 3 = 0011 4 = 0100 5 = 0101 6 = 0110 7 = 0111 8 = 1000 9 = 1001 A = 1010 B = 1011 C = 1100 D = 1101 E = 1110 F = 1111
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Storing Data – ASCII Used to store text based DIGIT 1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9 ASCII REPRESENTATION LETTER A B C D E F G H I ASCII REPRESENTATION
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32 blank 65 A 66 B 67 C 68 D 69 E 70 F 71 G 72 I 73 I 74 J 75 K 76 L 77 M 78 N 79 O 80 P 81 Q 82 R 83 S 84 T 97 a 98 b 99 c 100 d 101 e 102 f 103 g 104 h 105 i 106 j 107 k 108 l 109 m 110 n 111 o 112 p 113 q 114 r 115 s 116 t 117 u
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ASCII Full ASCII Table F o u r a n d s e v e n
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Storing Data – Analog Data
Must be converted to Digital Sample demo
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Converting Between Number Systems
Binary to Decimal Decimal to Binary Binary to Hex Hex to Binary
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Converting Between Number Systems
Decimal Binary
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Converting Between Number Systems
Binary >Decimal > decimal > decimal Decimal > Binary 128 > binary 100 > binary Hex > Binary 1A > binary 0F > binary Binary > Hex > hex > hex ASCII > Decimal A > decimal a > decimal Decimal > ASCII > ascii > ascii
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Coding Data for Processing by a Computer
Pixels Data Compression Lossy - examples Lossless - examples ?Examples of file types
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Data Compression Binary Data Compressed Data
\ 12 bytes Compressed Data 4, ,255 5 bytes
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Compression Examples BMP (422kb)
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Compression Examples JPG 10% (66kb)
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Compression Examples JPG 85% (15kb)
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Compression - LZ Lempel – Ziv WinZip
Dictionary to eliminate redundancy From - HowStuffWorks.com
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Compression - LZ Example
"Ask not what your country can do for you -- ask what you can do for your country.“ = 79 chrs Dictionary: ask what your country can do for you “1 not " = 37 chrs From - HowStuffWorks.com
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Compression - LZ Plus Dictionary = 37, Total = 74 vs 79
Real LZ uses patterns not words ask__ what__ you r__country __can__do__for__you "1not__ " = 16 chrs Dictionary = 41, Total = 57 From - HowStuffWorks.com
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