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Unformatted text preview: EEL 3801 EEL 3801 Computer Organization Computer Organization Spring 2010 Spring 2010 Chapter 2 Chapter 2 Machine Instructions and Machine Instructions and Programs Programs Hamacher et al , Computer Organization Acknowledgment and appreciation for various slide materials from Dr. Philip Wilsey, Dr. Randy Katz, Dr. Philip Leong Numbers, Arithmetic Operations, and Characters s Binary numbers (0, 1) are used in computers as they are easily represented as on/off electrical signals s Consider an nbit vector B = b n1 b 1 b 0 or , s This vector can represent unsigned integer values V in the range 0 to 2 n1, where V(B) = b n1 2 n1 ++b 1 2 1 +b 0 2 s MSB= M ost S ignificant B it (leftmost digit in a binary vector) s LSB= L east S ignificant B it (rightmost digit in a binary vector) s Obviously need to represent both positive and negative numbers 1 = i b 1 n i Negative Numbers s Signandmagnitude s Most significant bit determines sign, remaining unsigned bits represent magnitude s 1s complement s Most significant bit determines sign. To change sign from unsigned to negative, invert all the bits s 2s complement s Most significant bit determines sign. To change sign from unsigned to negative, invert all the bits and add 1 s This is equivalent to subtracting the positive number from 2 n Addition of Positive Numbers (1bit) Carryout 1 1 + 1 1 1 + + 1 1 + 0000 0111 0011 1011 1111 1110 1101 1100 1010 1001 1000 0110 0101 0100 0010 0001 +0 +1 +2 +3 +4 +5 +6 +7 0 1 2 3 4 5 6 7 0 100 = + 4 1 100 = 4 Sign and Magnitude s Assume a 4 bit machine word s One bit dedicate to sign (positive or negative) s sign: 0 = positive (or zero)...
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This note was uploaded on 04/02/2010 for the course EEL 3801 taught by Professor Froosh during the Spring '08 term at University of Central Florida.
 Spring '08
 FROOSH

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