Representing text Each of different symbol on the text (alphabet letter) is assigned a unique bit patterns the text is then representing as a long string of bits. –ASCII” American standard code for information interchange”: Uses patterns of 7-bits to represent most symbols used in written English text. –Today, it is extended to 8-bits. Islamic University Of Gaza, Nael Aburas2

Figure 1.13 The message “Hello.” in ASCII Islamic University Of Gaza, Nael Aburas3

Representing Text: The American National Standards Institute (ANSI) adapted the American Standard Code for Information Interchange (ASCII) This code uses 7 bits to represent the alphabets (a-z & A-Z) and numbers from 0 to 9 and punctuation symbols.

Unicode: This code uses 16 bits represents each symbols. Unicode consists of different bit patterns enough to allow text written in such languages A file containing a long sequence of symbols encoded using ASCII or Unicode is often called a text file

Representing text Unicode: Uses patterns of 16-bits to represent the major symbols used in languages world side ISO standard: Uses patterns of 32-bits to represent most symbols used in languages world wide Islamic University Of Gaza, Nael Aburas6

The difference between word processors and text file as follows: Word processorsText file Use word applicationUse text editor 1 Contains numbers proprietary codes representing changes in fonts, alignment information, …etc Contains only character-by- character encoding of text 2 Use proprietary code rather than the ASCII or Unicode Use ASCII or Unicode 3

Representing Numeric Values Binary notation is a way of representing numeric values using only digits 0 and 1. Islamic University Of Gaza, Nael Aburas8

Representing Numeric Values A number can be represented differently in different systems. For example, the two numbers (2A) 16 and (52) 8 both refer to the same quantity, (42) 10, but their representations are different. Each number system is associated with a base Islamic University Of Gaza, Nael Aburas9

Representing Numeric Values A number represented as: Each digit carries a certain weight based on its position IntegerFraction Islamic University Of Gaza, Nael Aburas10

Binary system In the binary system, there are only two symbols or possible digit values, 0 and 1. This base-2 system can be used to represent any quantity that can be represented in decimal or other number system Islamic University Of Gaza, Nael Aburas11

Binary system 11001) 2For example, here is ( 11001) 2 in binary (101.11) 2(101.11) 2 Islamic University Of Gaza, Nael Aburas12

Decimal The decimal system is composed of 10 numerals or symbols. These 10 symbols are 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9; using these symbols as digits of a number, we can express any quantity. The decimal system, also called the base-10 system Islamic University Of Gaza, Nael Aburas13

Decimal system (224) 10(224) 10 Note that the digit 2 in position 1 has the value 20, but the same digit in position 2 has the value 200Note that the digit 2 in position 1 has the value 20, but the same digit in position 2 has the value 200 Islamic University Of Gaza, Nael Aburas14

Figure 1.15 The base ten and binary systems Islamic University Of Gaza, Nael Aburas15

Figure 1.16 Decoding the binary representation Islamic University Of Gaza, Nael Aburas16

Exercise Convert each of the following binary representation to its base ten: –0101 –1001 –1011 –0110 –1000 –10010 Islamic University Of Gaza, Nael Aburas17

Figure 1.17 An algorithm for finding the binary representation of a positive integer Islamic University Of Gaza, Nael Aburas18

Figure 1.18 Applying the algorithm in Figure 1.15 to obtain the binary representation of thirteen Islamic University Of Gaza, Nael Aburas19

Binary addition To add two integers represented in binary notation, we follow the same procedure in the traditional base ten except that all sums are computed using the following addition fact. Islamic University Of Gaza, Nael Aburas20

Binary addition Islamic University Of Gaza, Nael Aburas21

Binary addition Islamic University Of Gaza, Nael Aburas22

Binary addition Islamic University Of Gaza, Nael Aburas23

Fraction in binary The digit to the right of radix point represent the fractional part. The positions are assigned fractional quantities The first position is assigned the quantity ½ (which is 2 -1 ), and so on Islamic University Of Gaza, Nael Aburas24

Fraction in binary Islamic University Of Gaza, Nael Aburas25

Decimal fraction to binary Covert to base x 2 = =.1 25 x 2 = = x 2 = =.101 Islamic University Of Gaza, Nael Aburas26