2. Computers: Information Technology in Perspective By Long and Long Copyright 2002 Prentice Hall, Inc. Encoding J. Holvikivi 2012

3. Quit OUTPUTOUTPUT Information Data PROCESSPROCESS Data vs. Information INPUTINPUT

4. Quit 2.3 Electronic Signals Analog Digital

5. Quit 2.4 Binary Digits (Bits) Only 2 states possible On Off Fiber Optic Cable } Light Pulse No Light Pulse Permanently stored on CD-ROM } Pitted Not Pitted Inside the computer’s memory (RAM) } Electronic pulse present Electronic pulse absent Permanently stored on disks } Positive magnetic field Negative magnetic field } Human readable symbols On 1 Off 0

6. Quit 2.5 001001110001 Digital Digitizing Data Analog

7. Quit 2.6 Encoding Systems “A” is represented by this bit pattern 1 byte= 8 bits “A” is represented by this bit pattern 1 byte= 8 bits 01000001 A A Encoding

8. Quit 2.7 ASCII Chart 7 bits Other Systems: ANSI (8 bit) Unicode (16 bit) Hexadecimal display A is 41

9. Quit 2.8 Encoding Systems  ASCII American Standard Code for Information Interchange  7 bit 2 7 = 128  8 bit 2 8 = 256, including control characters  ANSI, ISO Latin-1: 8 bit codes  Unicode (IBM, Microsoft, Sun)  16 bit encoding: 2 16 = 65 536   ISO 10646 four bytes   email, main frame systems   keyboards, codepages

10. Hexadecimal notation 2 4 =16 BinaryOctalDecimalHexadecimal 0001 0010 0011 0100 0101 0110 0111 1000 1 2 3 4 5 6 7 10 1234567812345678 1234567812345678 1001 1010 1011 1100 1101 1110 1111 11 12 13 14 15 16 17 9 10 11 12 13 14 15 9ABCDEF9ABCDEF 10000201610

11. Quit 2.10 Use of hex and octal numbers  Unix access codes  Web color codes  Unicode code values  Memory addresses  Machine language

12. Result AND000 100 010 111 OR000 101 011 111 NOT1 0 0 1 Logical operations