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mikemouse@is.cs.nthu.edu.tw

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- OS MS-DOS Windows XP Unix Windows Server

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BMP Bitmap( ) IBM Microsoft (24 bits ) TIFF Tagged Image File Format GIF Graphic Interchange Format Compu Serve GIF87a ( ), GIF89a ( )

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JPG MAC JPEG Joint Photographic Experts Group WWW JPG 100 1 JPEG 25 1 JPG Image Quality Low Medium High Maximum=1 1.4 2.8 5.2 JPEG JEPG GIF (Interlaced)

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(20070226): AVIRA AntiVir PersonalEdition Classic 7.0 ( ): 88.44% BitDefender 8 Free Edition ( ): 86.52% Kaspersky Internet Security 6.0: 84.77% Panda Internet Security 2007: 79.16% Trend Micro Internet Security 2007: 60.53% ESET NOD32 2.7: 49.17%

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- Sunbelt CounterSpy

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BitDefender Internet Security v10: 94.85% ESET NOD32 2.7: 89.12% Kaspersky Internet Security 6.0: 88.86% Grisoft AVG Anti-Spyware 7.5 (ewido anti- spyware 4.0): 88.50% Alwil avast! 4.7 Home Edition (free): 84.47% Sunbelt CounterSpy 1.5: 67.51%

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base radix n n 1 2 1 0 -1 -2 -m n -m n -m

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365.25 10 310 2 610 1 510 0 210 -1 510 -2 365.25 8 38 2 68 1 58 0 28 -1 58 -2 3A.F7 16 316 1 1016 0 1516 -1 716 -2

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2 8 16

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r s t r s 10 10 10 10 t

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EX: Convert the base 16 number C4D.4 to base 5

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BIG-5 IBM-5550

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modolus

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(1) A 1,0 B 1,1 (2) 1 2 (3) (4) 1 9 8 7 6 5 4 3 2 1 P1015277082310152770 8 21 39 18 07 16 55 24 73 72 01 111 111 mod 10 1 9 9 1 0

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Parity check code Odd parity bit Parity bit Data bit + Parity bit 1 Odd parity Even parity bit Parity bit Data bit + Parity bit 1 Even parity

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LRC longitudinal redundancy check VRC vertical redundancy check BCC block check code LRC+VRC error correction

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CRC cyclic redundancy check polynomial code CRC code D X C X R X D X +R X D X +R X C X 0 C X CRC-12 X 12 +X 11 +X 3 +X 2 +X+1 CRC-CCITT X 16 +X 15 +X 5 +1

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hamming code bit 1100001 hamming code 01001010110 7 bit

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2 0 1 1 0 2 0 0 0 1

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flag register

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