Representação de Caracteres

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1 Representação de Caracteres IFBA Instituto Federal de Educ. Ciencia e Tec Bahia Curso de Analise e Desenvolvimento de Sistemas Introdução à Ciência da Computação Prof. Msc. Antonio Carlos Souza Coletânea York University - ITEC 1011

Desenvolvimento de Sistemas Introdução à Ciência da

2 Introdução Exemplos Real World Data Input device Computer Data Dear Mom: Keyboard Digital camera

3 Formatos Apropriados A representação interna deve ser apropriada para o tipo de processamento (texto, imagem e som)

4 Tipos de Dados Números Inteiro ou ponto fixo Ponto Flutuante Número Decimal (BCD) Caracteres ACSII (American Standard Code for Information Interchange) EBCDIC (Extended binary Coded Decimal Interchange Code) Dados Lógicos Endereços

Standard Code for Information Interchange) EBCDIC

5 Convenções Formatos Apropriados Unique to a product or company E.g., Microsoft Word, Corel Word Perfect, IBM Lotus Notes Padrões Evolve two ways: Proprietary formats become de facto standards (e.g., Adobe PostScript, Apple Quick Time) Committee is struck to solve a problem (Motion Pictures Experts Group, MPEG)

ways: Proprietary formats become de facto standards (e.g.

6 Organizações Padrões ISO International Standards Organization CSA Canadian Standards Association ANSI American National Standards Institute IEEE Institute for Electrical and Electronics Engineers Etc.

ANSI American National Standards Institute IEEE

7 Exemplos de Padrões Type of Data Standards Alphanumeric Image Motion picture Sound Outline graphics/fonts ASCII, EBCDIC, Unicode JPEG, GIF, PCX, TIFF MPEG-2, Quick Time Sound Blaster, WAV, AU PostScript, TrueType, PDF

8 Por que Padrões? Padrões são arbitrary Eles existem porque são: Convenient Efficient Flexible Appropriate Etc.

9 Representação de Caracteres Em geral, usa-se códigos alfanuméricos Código de 6 bits Código de 7 bits (ASCII) EBCDIC ASCII estendido ISO Latin - 1 Caracteres ANSI Caracteres Unicode

10 Dados Alfanuméricos Problema: Distinguir entre o número 123 (one hundred and twenty-three) and the characters 123 (one, two, three) Quatro padrões para representar letras (alpha) and números BCD Binary-coded decimal ASCII American standard code for information interchange EBCDIC Extended binary-coded decimal interchange code Unicode

representar letras (alpha) and números BCD Binary-coded decimal ASCII American

11 Código de 6 bits Permite representar de caracteres 26 letras maiúsculas 10 algarismos ( ) 28 caracteres especiais, incluindo Space

12 7 bits (ASCII)

13 Binary-Coded Decimal (BCD) 4 bits por dígito Note: the following bit patterns are not used: Digit Bit pattern

1100 1101 1110 1111 Digit 0 1 2 3 4 5 6 7 8 9 Bit

14 Example ? (in BCD)

15 Standard Alphanumeric Formats BCD ASCII EBCDIC Unicode Next 22 slides

16 The Problem Representing text strings, such as Hello, world, in a computer

17 Codes and Characters Each character is coded as a byte Most common coding system is ASCII (Pronounced ass-key) ASCII American National Standard Code for Information Interchange Defined in ANSI document X

ass-key) ASCII American National Standard Code for

18 ASCII Features 7-bit code 8 th bit is unused (or used for a parity bit) codes Two general types of codes: 95 are Graphic codes (displayable on a console) 33 are Control codes (control features of the console or communications channel)

Graphic codes (displayable on a console) 33 are Control

19 ASCII Chart NULL DLE P ` p 0001 SOH DC1! 1 A Q a q 0010 STX DC2 " 2 B R b r 0011 ETX DC3 # 3 C S c s 0100 EDT DC4 $ 4 D T d t 0101 ENQ NAK % 5 E U e u 0110 ACK SYN & 6 F V f v 0111 BEL ETB ' 7 G W g w 1000 BS CAN ( 8 H X h x 1001 HT EM ) 9 I Y i y 1010 LF SUB * : J Z j z 1011 VT ESC + ; K [ k { 1100 FF FS, < L \ l 1101 CR GS - M ] m } 1110 SO RS. > N ^ n ~ 1111 SI US /? O _ o DEL

$LF SUB * : J Z j z 1011 VT ESC + ; K [ k { 1100 FF FS, < L \ l 1101 CR GS - M ] m } 1110 SO RS.$

20 NULL DLE P ` p 0001 SOH DC1! 1 A Q a q 0010 STX DC2 " 2 B R b r 0011 ETX DC3 # 3 C S c s 0100 EDT DC4 $ 4 D T d t 0101 ENQ NAK % 5 E U e u 0110 ACK SYN & 6 F V f v 0111 BEL ETB ' 7 G W g w 1000 BS CAN ( 8 H X h x 1001 HT EM ) 9 I Y i y 1010 LF SUB * : J Z j z 1011 VT ESC + ; K [ k { 1100 FF FS, < L \ l 1101 CR GS - M ] m } 1110 SO RS. > N ^ n ~ 1111 SI US /? O _ o DEL

$y 1010 LF SUB * : J Z j z 1011 VT ESC + ; K [ k { 1100 FF FS, < L \ l 1101 CR GS - M ] m } 1110 SO RS.$

21 NULL DLE P ` p 0001 SOH DC1! 1 A Q a q 0010 STX DC2 " 2 B R b r 0011 ETX DC3 # 3 C S c s 0100 EDT DC4 Most $ significant 4 bit D T d t 0101 ENQ NAK % 5 E U e u 0110 ACK SYN & 6 F V f v 0111 BEL ETB ' 7 G W g w 1000 BS CAN ( 8 H X h x 1001 HT EM ) 9 I Y i y 1010 LF SUB * : J Z j z 1011 Least significant VT ESC bit + ; K [ k { 1100 FF FS, < L \ l 1101 CR GS - M ] m } 1110 SO RS. > N ^ n ~ 1111 SI US /? O _ o DEL

22 e.g., a NULL DLE P ` p 0001 SOH DC1! 1 A Q a q 0010 STX DC2 " 2 B R b r 0011 ETX DC3 # 3 C S c s 0100 EDT DC4 $ 4 D T d t 0101 ENQ NAK % 5 E U e u 0110 ACK SYN & 6 F V f v 0111 BEL ETB ' 7 G W g w 1000 BS CAN ( 8 H X h x 1001 HT EM ) 9 I Y i y 1010 LF SUB * : J Z j z 1011 VT ESC + ; K [ k { 1100 FF FS, < L \ l 1101 CR GS - M ] m } 1110 SO RS. > N ^ n ~ 1111 SI US /? O _ o DEL

23 95 Graphic codes NULL DLE P ` p 0001 SOH DC1! 1 A Q a q 0010 STX DC2 " 2 B R b r 0011 ETX DC3 # 3 C S c s 0100 EDT DC4 $ 4 D T d t 0101 ENQ NAK % 5 E U e u 0110 ACK SYN & 6 F V f v 0111 BEL ETB ' 7 G W g w 1000 BS CAN ( 8 H X h x 1001 HT EM ) 9 I Y i y 1010 LF SUB * : J Z j z 1011 VT ESC + ; K [ k { 1100 FF FS, < L \ l 1101 CR GS - M ] m } 1110 SO RS. > N ^ n ~ 1111 SI US /? O _ o DEL

24 33 Control codes NULL DLE P ` p 0001 SOH DC1! 1 A Q a q 0010 STX DC2 " 2 B R b r 0011 ETX DC3 # 3 C S c s 0100 EDT DC4 $ 4 D T d t 0101 ENQ NAK % 5 E U e u 0110 ACK SYN & 6 F V f v 0111 BEL ETB ' 7 G W g w 1000 BS CAN ( 8 H X h x 1001 HT EM ) 9 I Y i y 1010 LF SUB * : J Z j z 1011 VT ESC + ; K [ k { 1100 FF FS, < L \ l 1101 CR GS - M ] m } 1110 SO RS. > N ^ n ~ 1111 SI US /? O _ o DEL

25 Alphabetic codes NULL DLE P ` p 0001 SOH DC1! 1 A Q a q 0010 STX DC2 " 2 B R b r 0011 ETX DC3 # 3 C S c s 0100 EDT DC4 $ 4 D T d t 0101 ENQ NAK % 5 E U e u 0110 ACK SYN & 6 F V f v 0111 BEL ETB ' 7 G W g w 1000 BS CAN ( 8 H X h x 1001 HT EM ) 9 I Y i y 1010 LF SUB * : J Z j z 1011 VT ESC + ; K [ k { 1100 FF FS, < L \ l 1101 CR GS - M ] m } 1110 SO RS. > N ^ n ~ 1111 SI US /? O _ o DEL

26 Numeric codes NULL DLE P ` p 0001 SOH DC1! 1 A Q a q 0010 STX DC2 " 2 B R b r 0011 ETX DC3 # 3 C S c s 0100 EDT DC4 $ 4 D T d t 0101 ENQ NAK % 5 E U e u 0110 ACK SYN & 6 F V f v 0111 BEL ETB ' 7 G W g w 1000 BS CAN ( 8 H X h x 1001 HT EM ) 9 I Y i y 1010 LF SUB * : J Z j z 1011 VT ESC + ; K [ k { 1100 FF FS, < L \ l 1101 CR GS - M ] m } 1110 SO RS. > N ^ n ~ 1111 SI US /? O _ o DEL

27 Punctuation, etc NULL DLE P ` p 0001 SOH DC1! 1 A Q a q 0010 STX DC2 " 2 B R b r 0011 ETX DC3 # 3 C S c s 0100 EDT DC4 $ 4 D T d t 0101 ENQ NAK % 5 E U e u 0110 ACK SYN & 6 F V f v 0111 BEL ETB ' 7 G W g w 1000 BS CAN ( 8 H X h x 1001 HT EM ) 9 I Y i y 1010 LF SUB * : J Z j z 1011 VT ESC + ; K [ k { 1100 FF FS, < L \ l 1101 CR GS - M ] m } 1110 SO RS. > N ^ n ~ 1111 SI US /? O _ o DEL

28 Hello, world Example Binary Hexadecimal C 6C 6F 2C C 64 Decimal H el l o, w or l d

29 Common Control Codes CR 0D carriage return LF 0A line feed HT 09 horizontal tab DEL 7F delete NULL 00 null Hexadecimal code

30 NULL DLE P ` p 0001 SOH DC1! 1 A Q a q 0010 STX DC2 " 2 B R b r 0011 ETX DC3 # 3 C S c s 0100 EDT DC4 $ 4 D T d t 0101 ENQ NAK % 5 E U e u 0110 ACK SYN & 6 F V f v 0111 BEL ETB ' 7 G W g w 1000 BS CAN ( 8 H X h x 1001 HT EM ) 9 I Y i y 1010 LF SUB * : J Z j z 1011 VT ESC + ; K [ k { 1100 FF FS, < L \ l 1101 CR GS - M ] m } 1110 SO RS. > N ^ n ~ 1111 SI US /? O _ o DEL

31 NULL DLE P ` p 0001 SOH DC1! 1 A Q a q 0010 STX DC2 " 2 B R b r 0011 ETX DC3 # 3 C S c s 0100 EDT DC4 $ 4 D T d t 0101 ENQ NAK % 5 E U e u 0110 ACK SYN & 6 F V f v 0111 BEL ETB ' 7 G W g w 1000 BS CAN ( 8 H X h x 1001 HT EM ) 9 I Y i y 1010 LF SUB * : J Z j z 1011 VT ESC + ; K [ k { 1100 FF FS, < L \ l 1101 CR GS - M ] m } 1110 SO RS. > N ^ n ~ 1111 SI US /? O _ o DEL

32 Standard Alphanumeric Formats BCD ASCII EBCDIC Unicode Next 1 slides

33 EBCDIC Extended BCD Interchange Code (pronounced ebb -se-dick) 8-bit code Developed by IBM Rarely used today IBM mainframes only

34 8 bits (EBCDIC) Extended Binary Coded Decimal Interchange Code

35 8 bits (ASCII Estendido)

36 ISO Latin-1

37 Caracteres ANSI Windows 9x suporta caracteres ANSI American National Standards Institute Representação de 8 bits (256 caracteres) 0 a 255 Valores de 0 a 127: mesmos de ASCII Entre 128 a 255: similar a ISO Latin-1 Tem extensões e incompatibilidades

38 Standard Alphanumeric Formats BCD ASCII EBCDIC Unicode Next 2 slides

39 Unicode 16-bit standard Developed by a consortia Intended to supercede older 7- and 8-bit codes

40 Unicode Version Improves on version 2.0 Includes the Euro sign (20AC 16 ) From the standard: contains 38,887 distinct coded characters derived from the supported scripts. These characters cover the principal written languages of the Americas, Europe, the Middle East, Africa, India, Asia, and Pacifica.

41 Caracteres Unicode Windows NT usa Unicode 16-bits Cobre grande parte das línguas vivas Também linguas mortas (uso escolar) Detalhes

42 Keyboard Input Key ( scan ) codes are converted to ASCII ASCII code sent to host computer Received by the host as a stream of data Stored in buffer Processed Etc.

43 Outras Entradas OCR optical character recognition Bar code readers Voice/audio input Punched cards Images / objects Pointing devices

ASCII Code. Numerous codes were invented, including Émile Baudot's code (known as Baudot

ASCII Code. Numerous codes were invented, including Émile Baudot's code (known as Baudot ASCII Code Data coding Morse code was the first code used for long-distance communication. Samuel F.B. Morse invented it in 1844. This code is made up of dots and dashes (a sort of binary code). It was