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Unformatted text preview: 1 TA C162 Computer Programming I Virendra S Set2 Today’s Agenda c What we have done so far c Representations of Numbers c Arithmetic operations on bits •What’s next… • Logical operations on bits h AND h OR h NOT h XOR 2 TA C162 Computer Programming I Virendra S Set2 Logical Operations •Logical operations operate on logical variables . •Logical variable can have values either 0 or 1 •Basic logical functions: • AND • OR • NOT • XOR( Exclusive OR) •Operations on logical TRUE or FALSE • Two states  takes one bit to represent: h TRUE=1, FALSE=0 •View nbit number as a collection of n logical values • Operation applied to each bit independently 3 TA C162 Computer Programming I Virendra S Set2 Logical AND Operation • Binary logical operation • Needs two operands • Truth Table A B A AND B 1 1 1 1 1 The output is 1 only if both the operands have value 1 Example: Let A =10011001 B =00110011 A AND B = 00010001 Used for Clearing Bits AND with zero b AND with one b no change 4 TA C162 Computer Programming I Virendra S Set2 Logical OR Operation •Binary logical operation • Needs two operands •Truth Table A B A OR B 1 1 1 1 1 1 1 The output is 1 if any of the two operands are 1 Example: Let A =10011001 B =00110011 A OR B = 10111011 Useful for setting the bits OR with 0 b No change OR with 1 b Set the bit to 1 5 TA C162 Computer Programming I Virendra S Set2 Logical NOT Operation •Unary logical operation • Needs only one operand Truth Table: A NOT A 1 1 Example: Let A = 11000101 NOT A = 00111010 c Flips all bits of an operand c Also known as Complement operation c Used to take 1’s complement of a number 6 TA C162 Computer Programming I Virendra S Set2 Logical XOR Operation •Binary logical operation • Needs two operands •Truth Table A B A X OR B 1 1 1 1 1 1 The output is 0 if both operands are same Example Let A= 10011001, B= 11001010 A XOR B = 01010011 c Used to check two numbers are identical or not c If A and B are identical then A XOR B b all bits 0 c If A and B are not identical then A XOR B b all bits 1 7 TA C162 Computer Programming I Virendra S Set2 Transistor: Building Block of Computers • Microprocessors contain millions of transistors • Intel Pentium 4 (2000): 48 million...
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 Spring '09
 SHANTA
 Computer Programming

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