1. Bits & Bytes: How Computers Represent Data

2. Data Representation How do computers represent data?
Computers are digital and use electricity
Recognize only two discrete states: on or off
Use a binary system to recognize two states
Use Number system with two unique digits: 0 and 1, called bits (short for binary digits)

3. Data Representation What is a byte?
Eight bits grouped together as a unit
Provides enough different combinations of 0s and 1s to represent 256 individual characters
Numbers
Uppercase and lowercase letters
Punctuation marks

4. Kilo, Mega, Giga, Tera … Roughly 1,000; actually 210 (1,024)
Storage of data (bits & bytes) is often categorized as:
Kilo (KB)
Roughly 1,000; actually 210 (1,024)
Mega (MB)
Roughly 1,000,000; actually 220 (1,048,576)
Giga (GB)
Roughly 1,000,000,000; actually 230 (1,073,741,824)
Tera (TB)
Roughly 1,000,000,000,000; actually 240 (1,099,511,627,776)

5. Text Representation
What are the popular coding systems to represent text?
ASCII (8 bit) - American Standard Code for Information Interchange - most common today
EBCDIC (8 bit) - Extended Binary Coded Decimal Interchange Code – IBM mainframes
Unicode (16 bit) – newer coding scheme capable of representing all world’s languages

6. Representing Images Pixels - picture element Two Methods
Grid of small points (dots) that make up an image
More pixels results in clearer /more precise image
Two Methods
Bit-mapped graphics
Representing images using bytes – each pixel represented by an array of bits
Vector graphics
Use mathematical formulas to define and store image