BASICS OF COMPUTER APPLICATIONS ASB 102

UNIT 1 Introducing computer system  Number system  What is number system?  Types of number system  Their Conversions  Binary arithmetic ( addition, subtraction, multiplication )

Number system In any number system there is an ordered set of symbols known as DIGITS with rules defined for performing arithmetic operations like +, -, * etc A collection of these digits makes a number which in general has two parts - 1) integer 2) fractional

Set apart by a radix point (.) (N) b = d n-1 d n-2 ….d i ….d 1 d 0. d -1 d -2 …d -f ….d -m Integer portion radix fractional portion Where N – number B – radix or base of the number system n – number of digits in integer portion m- number of digits in fractional portion D n-1 - most significant digit (msd ) D -m - least significant digit ( lsd )

Types of number system Binary number system Octal number system Decimal number system Hexadecimal number system

1. Binary number system Have base/radix 2 (two) Only two symbols are used to represent binary number system 0 and 1 Eg

2. Decimal number system Have base 10 Symbols- 0,1,2,3,4,5,6,7,8,9 Eg

3. Octal number system Have base or radix eight Symbols used to represent numbers- 0,1,2,3,4,5,6,7 Eg

4. Hexadecimal number system Have base 16 which requires 16 distinct symbols to represent the numbers. Symbols used are 0 through 9 and alphabets A and f. This is an alphanumeric number system. Eg- 3FA9.56

Conversions - Decimal to binary Eg1 (13) 10 to ( ?) 2 quotient remainder 13/ / /2 1 1 ½ 0 1 Thus (13) 10 = ( 1101) 2

Eg ( ) 10 to ( ?) 2 (10) * 2 = * 2 = * 2 = ( ) 10 to ( ) 2

Conversion – binary to decimal eg = (1*2 5 ) + (1*2 4 ) + (0*2 3 ) + (1*2 2 ) + (0*2 1 ) + (1*2 0 ) + (1*2-1) + (0*2-2) +(1*2- 3) = = ( 53) 10