Chapter 1.4

Representing Information as Bit Patterns

Representing Information as Bit Patterns

Representing text Representing Numeric Values Representing Images Representing Sound

Representing Text

Information in the form of text is normally represented by means of a code in which each of the different symbols in the text is assigned a unique bit pattern.

The text is then represented as a long string of bits in which the successive patterns represent the successive symbols in the original text.

Representing Text

ASCII American Standard Code for

Information Interchange Appendix A shows a portion of ASCII

in an eight-bit-per-symbol format.

Representing Text

Representing Text

Example: Message “Hello” in ASCII

01001000 01100101 01101100 01101100 01101111 H e l l o

Representing Text

Unicode, was developed through the cooperating of several of the leading manufacturers of hardware and software and is rapidly gaining support in the computing community.

It uses a unique pattern of 16 bits to represent each symbol.

It consists of 65,536 different bit patterns Languages as Chinese, Japanese, and

Hebrew can be represented.

Representing Text

Question 1 on page 40 Here is a message encoded in ASCII

using eight bits per symbol. What does it say?

01000011 01101111 01101101 01110000 01110101 01110100 01100101 01110010 00100000 01010011 01100011 01101001 01100101 01101110 01100011 01100101

Representing Text

Look it up in the ASCII Table

Representing Text

Representing Text

The answer is: Computer Science.

Representing Numeric Values

Binary NotationFractions in Binary

Two’s Complement NotationNegative valuesLength of the Bit pattern

Excess notationLength of the bit pattern

Representing Numeric Values

Floating-Point NotationDifferent fields (sign, exponent,

mantissa)Sign bitIn the book, we only use 1 byte, which

is 8 bits lengthWhere the radix point is

Representing Numeric Values

Floating-Point NotationExtracting floating point

• How to move the radix point • (+->R, - ->L)