Agenda

• Character representation– ASCII– EBCDIC

• Numerical Conversions– Between Upper & Lower Case Characters– From Upper Case Character to Control

Character

Character Representation

• Since computers are only designed to interpret binary data, textual information must somehow be converted to binary.

• In other words, a binary number is associated with each possible character

Character Representation

There are two commonly recognized standards for data formats:

• EBCDIC (Extended Binary Coded Decimal Interchange Code)

• ASCII (American Standard Code for Information Interchange)

EBCDIC

Characteristics:

• Used on IBM mini and mainframe computers

• 8 bit binary code associated with each character

ASCII

Characteristics:• Used on most “other” computers. System

designed from a variety of computer manufacturers

• 7 bit code associated with each character• Also, an 8 bit code used to provide an

additional 128 characters (additional character set - printable & nonprintable characters)

ASCII & EBCDIC Tables

• We can represent various representation of characters by either standard by referring to tables.

• Note that tables are organized as hexadecimal numbers for reference

• Check my website for ASCII and EBCDIC Tables

Numerical Conversions (ASCII)

• To convert uppercase character to lowercase character:– add 2016 to uppercase character or– add 3210 to uppercase character

• To convert uppercase character to lowercase character:– subtract 2016 to lowercase character or– subtract 3210 to lowercase character

Uppercase Letter to Control Character

• To convert uppercase character to corresponding control character– add 4016 to uppercase character or– add 6410 to uppercase character