Number Systems
By : Ms. Kalpani ManatungaGCE (A/L) ICT Training for Teachers
Representation of NumbersGCE (A/L) ICT Training for Teachers
Integer + & - whole numbers4251 -582
Real All numbers including everything between integers0.23, 0, 5, -2.3,
Least significant bitMost significant bit
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Fixed Point Representation12.548
Floating Point RepresentationScientific Notation12.054 1.2054 * 101Computer Notation12.65 0.1265*102
Floating Point NumbersGCE (A/L) ICT Training for Teachers
Mantissa
15.23 * 10 4Radix /baseExponent
IEEE 754 32bit Floating Point RepresentationGCE (A/L) ICT Training for Teachers
Data Representation in ComputersGCE (A/L) ICT Training for Teachers
BCD (Binary Coded Decimal)
4 bit code for numeric values only9 1001
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ASCII (American Standard Code for Information Interchange)7 bit code for all 128 charactersA=1000001
EBCDIC (Extended BCD Interchange Code)8 bit ASCII
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ASCII (American Standard Code for Information Interchange)7 bit code for all 128 characters
A =1000001 65
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Unicode provides a unique number for every character, no matter what the platform, no matter what the program, no matter what the language.Fundamentally, computers just deal with numbers. They store letters and other characters by assigning a number for each one. 8, 16 or 32 bits per character
Binary AdditionGCE (A/L) ICT Training for Teachers
Rules of Binary Addition0 + 0 = 0 0 + 1 = 1 1 + 0 = 1 1 + 1 = 0, and carry 1 to the next more significant bit
Try out these additions:00011010 + 00001100 = ?00010011 + 00111110 = ?
Binary SubtractionGCE (A/L) ICT Training for Teachers
Rules of Binary Subtraction0 - 0 = 0 0 - 1 = 1, and borrow 1 from the next more significant bit 1 - 0 = 1 1 - 1 = 0
Try out these subtractions:00100101 - 00010001 = ?00110011 - 00010110 = ?
1s & 2s ComplementsGCE (A/L) ICT Training for Teachers
Store the integer -70 in a byte using the two's complement notation.
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