Data representation
- 2. Data Representation refers to the methods used internally to represent information stored in a computer. Computers store lots of different types of information: Numbers Text Graphics of many varieties (stills,video, animation) Sound
- 3. All types of information stored in a computer are stored internally in the same simple format: a sequence of 0's and 1's. Computers use numeric codes to represent all the information they store.
- 4. Memory consists of bits (0 or 1) › a single bit can represent two pieces of information bytes (=8 bits) › a single byte can represent 256 = 2x2x2x2x2x2x2x2 = 28 pieces of information words (=2,4, or 8 bytes) › a 2 byte word can represent 2562 pieces of information (approximately 65 thousand). Byte addressable - each byte has its own address.
- 5. Binary numbers is 0's and 1's. Numbers in this form are said to be in base 2 and they are called binary numbers.
- 6. • (1011)2 = 1x23 + 0x22 + 1x21 + 1x20 = (11)10
- 7. Hexadecimal numbers are made of 16 symbols: › (0,1,2,3,4,5,6,7,8,9,A, B, C, D, E, F) Convert a hexadecimal number to decimal › (3A9F)16 = 3x163 + 10x162 + 9x161 + 15x160 = 1499910
- 8. Text can be represented easily by assigning a unique numeric value for each symbol used in the text. For example, the widely used ASCII code (American Standard Code for Information Interchange) Uses 7 bits to represent most symbols used in English text
- 9. Decimal(base 10) Octal(base 8) Binary(base 2) Hexadecimal (base16)
- 10. Graphics that are displayed on a computer screen consist of pixels: the tiny "dots" of color that collectively "paint" a graphic image on a computer screen. The pixels are organized into many rows on the screen.