Aula 2 - Paridade - Iris.sel.eesc.sc.usp.br
Aula 2 - Paridade - Iris.sel.eesc.sc.usp.br
Aula 2 - Paridade - Iris.sel.eesc.sc.usp.br
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<strong>Aula</strong> 2<<strong>br</strong> />
Outras Funções Lógicas e<<strong>br</strong> />
<strong>Paridade</strong><<strong>br</strong> />
SEL 0414 - Sistemas Digitais<<strong>br</strong> />
Prof. Dr. Marcelo Andrade da Costa Vieira
Outras Funções Lógicas
Funções Lógicas<<strong>br</strong> />
PORTA NÃO-INVERSORA (Buffer)<<strong>br</strong> />
TABELA VERDADE<<strong>br</strong> />
S = A<<strong>br</strong> />
A S<<strong>br</strong> />
0 0<<strong>br</strong> />
1 1<<strong>br</strong> />
A S<<strong>br</strong> />
• Aumentar o fan-out de uma dada porta lógica;<<strong>br</strong> />
• Linhas de atraso, com vários buffers conectados em ca<strong>sc</strong>ata<<strong>br</strong> />
• Portas Tri-state (três estados possíveis: zero, um ou de alta<<strong>br</strong> />
impedância): o buffer controla a saída ou não do sinal presente<<strong>br</strong> />
na entrada da porta. Diferente das portas AND ou OR que<<strong>br</strong> />
colocam um estado alto ou baixo na saída.
BUFFERS TRISTATE
BUFFERS TRISTATE
Funções Lógicas<<strong>br</strong> />
FUNÇÃO OU-EXCLUSIVO (“X-OR”)<<strong>br</strong> />
S = AB + AB<<strong>br</strong> />
S = A ⊕ B<<strong>br</strong> />
S = 1 quando A ≠ B S = 1 apenas<<strong>br</strong> />
quando A OU B = 1<<strong>br</strong> />
S = 1 quando o número de 1’s for<<strong>br</strong> />
ímpar S = 0 quando o número de 1’s<<strong>br</strong> />
for par<<strong>br</strong> />
TABELA VERDADE<<strong>br</strong> />
A B S<<strong>br</strong> />
0 0 0<<strong>br</strong> />
0 1 1<<strong>br</strong> />
1 0 1<<strong>br</strong> />
1 1 0
Funções Lógicas<<strong>br</strong> />
FUNÇÃO OU-EXCLUSIVO (“X-OR”)<<strong>br</strong> />
A<<strong>br</strong> />
A<<strong>br</strong> />
A.B<<strong>br</strong> />
A.B+ A.B<<strong>br</strong> />
B<<strong>br</strong> />
B<<strong>br</strong> />
A.B
Funções Lógicas<<strong>br</strong> />
FUNÇÃO OU-EXCLUSIVO (“X-OR”)<<strong>br</strong> />
l Símbolo Equivalente:<<strong>br</strong> />
A<<strong>br</strong> />
B<<strong>br</strong> />
S<<strong>br</strong> />
A B S<<strong>br</strong> />
0 0 0<<strong>br</strong> />
0 1 1<<strong>br</strong> />
1 0 1<<strong>br</strong> />
1 1 0<<strong>br</strong> />
Todas as portas XOR tem apenas duas entradas! Não<<strong>br</strong> />
existem portas XOR de três, quatro ou mais entradas.
Funções Lógicas<<strong>br</strong> />
FUNÇÃO COINCIDÊNCIA (“X-NOR”)<<strong>br</strong> />
A<<strong>br</strong> />
B<<strong>br</strong> />
S<<strong>br</strong> />
S = AB + AB<<strong>br</strong> />
S = A ⋅ B<<strong>br</strong> />
S = 1 somente quando A = B ou<<strong>br</strong> />
S=1 quando o número de 1’s for par<<strong>br</strong> />
S = A ⊕ B<<strong>br</strong> />
TABELA DA VERDADE<<strong>br</strong> />
A B S<<strong>br</strong> />
0 0 1<<strong>br</strong> />
0 1 0<<strong>br</strong> />
1 0 0<<strong>br</strong> />
1 1 1
Funções Lógicas<<strong>br</strong> />
FUNÇÃO COINCIDÊNCIA (“X-NOR”)<<strong>br</strong> />
l Símbolo Equivalente:<<strong>br</strong> />
A<<strong>br</strong> />
B<<strong>br</strong> />
S<<strong>br</strong> />
A B S<<strong>br</strong> />
0 0 1<<strong>br</strong> />
0 1 0<<strong>br</strong> />
1 0 0<<strong>br</strong> />
1 1 1<<strong>br</strong> />
Todas as portas XNOR tem apenas duas entradas! Não<<strong>br</strong> />
existem portas XNOR de três, quatro ou mais entradas.
Funções Lógicas<<strong>br</strong> />
A + B<<strong>br</strong> />
= A B<<strong>br</strong> />
A B<<strong>br</strong> />
A + B A B<<strong>br</strong> />
0 0 0 1<<strong>br</strong> />
0 1 1 0<<strong>br</strong> />
1 0 1 0<<strong>br</strong> />
1 1 0 1
Portas Lógicas - Resumo
<strong>Paridade</strong>
Bit de <strong>Paridade</strong><<strong>br</strong> />
Transmissão de Dados Digitais<<strong>br</strong> />
l Menos sujeitos à ruídos do que sistemas<<strong>br</strong> />
analógicos;<<strong>br</strong> />
l Detecção de erros por paridade.
Bit de <strong>Paridade</strong><<strong>br</strong> />
BIT DE PARIDADE<<strong>br</strong> />
l Utilizada em transmissão para minimizar<<strong>br</strong> />
erros;<<strong>br</strong> />
l Bit extra anexado ao conjunto de bits para<<strong>br</strong> />
informar a sua paridade;<<strong>br</strong> />
l O bit de paridade pode ser 0 ou 1,<<strong>br</strong> />
dependendo do número de 1´s contido no<<strong>br</strong> />
conjunto de bits do código (par ou ímpar);
Bit de <strong>Paridade</strong><<strong>br</strong> />
<strong>Paridade</strong> Par e <strong>Paridade</strong> Ímpar<<strong>br</strong> />
l <strong>Paridade</strong> Par: o bit anexado serve para<<strong>br</strong> />
tornar o número total de 1´s par;<<strong>br</strong> />
Ex. 01001 001001<<strong>br</strong> />
10110 110110<<strong>br</strong> />
l<<strong>br</strong> />
<strong>Paridade</strong> Ímpar: o bit anexado serve para<<strong>br</strong> />
tornar o número total de 1´s ímpar;<<strong>br</strong> />
Ex. 01001 101001<<strong>br</strong> />
10110 010110
Bit de <strong>Paridade</strong><<strong>br</strong> />
GERAÇÃO DE PARIDADE PAR<<strong>br</strong> />
- Informação possui número PAR de bits 1 bit de paridade = 0<<strong>br</strong> />
- Informação possui número ÍMPAR de bits 1 bit de paridade = 1<<strong>br</strong> />
Dados<<strong>br</strong> />
P<<strong>br</strong> />
Dados<<strong>br</strong> />
P<<strong>br</strong> />
0000<<strong>br</strong> />
0001<<strong>br</strong> />
0010<<strong>br</strong> />
0011<<strong>br</strong> />
0100<<strong>br</strong> />
0101<<strong>br</strong> />
0110<<strong>br</strong> />
0111<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1000<<strong>br</strong> />
1001<<strong>br</strong> />
1010<<strong>br</strong> />
1011<<strong>br</strong> />
1100<<strong>br</strong> />
1101<<strong>br</strong> />
1110<<strong>br</strong> />
1111<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0
Bit de <strong>Paridade</strong><<strong>br</strong> />
GERADOR / VERIFICADOR DE PARIDADE PAR<<strong>br</strong> />
l Porta OU-EXCLUSIVO (X-OR):<<strong>br</strong> />
A<<strong>br</strong> />
B<<strong>br</strong> />
S<<strong>br</strong> />
A B S<<strong>br</strong> />
0 0 0<<strong>br</strong> />
0 1 1<<strong>br</strong> />
1 0 1<<strong>br</strong> />
1 1 0
GERADOR / VERIFICADOR DE PARIDADE PAR<<strong>br</strong> />
ASSOCIAÇÃO DE PORTAS X-OR<<strong>br</strong> />
l <strong>Paridade</strong> em palavras com<<strong>br</strong> />
maior número de bits;<<strong>br</strong> />
A<<strong>br</strong> />
0<<strong>br</strong> />
B<<strong>br</strong> />
0<<strong>br</strong> />
C<<strong>br</strong> />
0<<strong>br</strong> />
S<<strong>br</strong> />
0<<strong>br</strong> />
l Associam-se n portas X-OR de<<strong>br</strong> />
duas entradas<<strong>br</strong> />
l Não existem portas X-OR de<<strong>br</strong> />
mais de duas entradas!<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
A<<strong>br</strong> />
S<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
B<<strong>br</strong> />
C<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
S = A ⊕ B ⊕ C
GERADOR / VERIFICADOR DE PARIDADE PAR<<strong>br</strong> />
ASSOCIAÇÃO DE PORTAS X-OR<<strong>br</strong> />
l <strong>Paridade</strong> em palavra de 4 bits;<<strong>br</strong> />
l Associam-se 3 portas X-OR;<<strong>br</strong> />
A<<strong>br</strong> />
B<<strong>br</strong> />
S<<strong>br</strong> />
C<<strong>br</strong> />
D
Bit de <strong>Paridade</strong><<strong>br</strong> />
PORTA XOR DE 4 ENTRADAS<<strong>br</strong> />
l Gerador ou Verificador de<<strong>br</strong> />
<strong>Paridade</strong> PAR:<<strong>br</strong> />
Y = A ⊕ B ⊕ C ⊕ D<<strong>br</strong> />
A<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
B<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
C<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
D<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
Y<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0
Bit de <strong>Paridade</strong><<strong>br</strong> />
GERAÇÃO / VERIFICAÇÃO DE PARIDADE PAR<<strong>br</strong> />
Dados<<strong>br</strong> />
P<<strong>br</strong> />
Dados<<strong>br</strong> />
P<<strong>br</strong> />
0000<<strong>br</strong> />
0001<<strong>br</strong> />
0010<<strong>br</strong> />
0011<<strong>br</strong> />
0100<<strong>br</strong> />
0101<<strong>br</strong> />
0110<<strong>br</strong> />
0111<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1000<<strong>br</strong> />
1001<<strong>br</strong> />
1010<<strong>br</strong> />
1011<<strong>br</strong> />
1100<<strong>br</strong> />
1101<<strong>br</strong> />
1110<<strong>br</strong> />
1111<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
A<<strong>br</strong> />
B<<strong>br</strong> />
C<<strong>br</strong> />
D<<strong>br</strong> />
P
Bit de <strong>Paridade</strong><<strong>br</strong> />
GERAÇÃO DE PARIDADE ÍMPAR<<strong>br</strong> />
- Informação possui número PAR de bits 1 bit de paridade = 1<<strong>br</strong> />
- Informação possui número ÍMPAR de bits 1 bit de paridade = 0<<strong>br</strong> />
Dados<<strong>br</strong> />
P<<strong>br</strong> />
Dados<<strong>br</strong> />
P<<strong>br</strong> />
0000<<strong>br</strong> />
0001<<strong>br</strong> />
0010<<strong>br</strong> />
0011<<strong>br</strong> />
0100<<strong>br</strong> />
0101<<strong>br</strong> />
0110<<strong>br</strong> />
0111<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1000<<strong>br</strong> />
1001<<strong>br</strong> />
1010<<strong>br</strong> />
1011<<strong>br</strong> />
1100<<strong>br</strong> />
1101<<strong>br</strong> />
1110<<strong>br</strong> />
1111<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1
Bit de <strong>Paridade</strong><<strong>br</strong> />
GERADOR / VERIFICADOR DE PARIDADE ÍMPAR<<strong>br</strong> />
l Porta NÃO OU-EXCLUSIVO (X-NOR):<<strong>br</strong> />
A<<strong>br</strong> />
B<<strong>br</strong> />
S<<strong>br</strong> />
A B S<<strong>br</strong> />
0 0 1<<strong>br</strong> />
0 1 0<<strong>br</strong> />
1 0 0<<strong>br</strong> />
1 1 1
Bit de <strong>Paridade</strong><<strong>br</strong> />
PORTA X-NOR DE 4 ENTRADAS<<strong>br</strong> />
l Detector de <strong>Paridade</strong> ÍMPAR:<<strong>br</strong> />
Y = A • B • C • D<<strong>br</strong> />
A<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
B<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
C<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
D<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
Y<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
1<<strong>br</strong> />
0<<strong>br</strong> />
0<<strong>br</strong> />
1
FIM