Representing Characters in a computer

• Pressing a key on the computer a code is generated that the computer can convert into a symbol for displaying or printing.

• Standards were required to make sure computers used the same codes for the characters.

• ASCII was set up – American Standard Code for information Interchange.

Representing Characters in a computer

• ASCII Represents:

• 127 Codes – requiring 7 bits

• 8 bit computers allowed an extra bit to store more mathematical characters

• Numerical values allow comparisons to sort data

All the main alphabetic characters, upper and lower case 52 Characters

All the numeric symbols, 0-9 10 Characters

32 punctuation and other symbols, and ‘space’ 33 Characters

32 codes reserved for non-printable control codes 32 Characters

Representing Characters in a computer

• Unicode uses 32 bits allowing 4 billion possibilities – which includes multiple languages and characters. ASCII is a subset of Unicode.

Representing Characters in a computer

• Read page 78 – 79

• Answer questions on page 79