1. DAILY QUESTION April 29, 2009 1. What is the difference between ROM and RAM? Hint: Use your book!

2. Agenda 4/29/09  Daily Question  Turn-in: 18-2 Worksheet  18-3 Notes Assignments: 1. 18-3 Review Worksheet due 4/30

3. Computers  A machine that can receive data, perform high-speed calculations or logical operations, and output the results  They do only what they are programmed to do

4. First computer  Electronic Numerical Integrator and Computer (ENIAC) Developed during WWII As big as a house Weighed 30 tons

5. Four main functions  Input  Storage  Processing  Output

6. Input Devices Keyboard Mouse Scanner Microphones Cameras Modem  All devices provide data in binary form

7. Output devices  Modem  Printer  Speakers  Recording devices

8. Storage devices  Long-term storage Hard-disk drive (hard drive) Read-only memory (ROM)  Compact discs (CD ROMs)  Digital versatile discs (DVD ROMs)  Short-term storage Random access memory (RAM)

9. Hardware  Hardware All of the physical components of a computer Compute and store data only with necessary instructions  Software – computer programs with instructions

10. Operating systems  Coordinates the computer hardware  Handles transfer and organization of computer files  Provides environment for other programs to run in

11. Applications  Word processors  Drawing programs  Spreadsheet programs  Computer games  Internet browsers

12. Central processing unit (CPU)  Carries out computing or data processing  One of many chips found on the motherboard  Arithmetic/logic unit (ALU) Performs calculations and logic decisions  Registers Hold results from previous calculations

13. Central processing unit (CPU)  Logic gates Open or close a circuit depending on the condition of two inputs AND gate: closes circuit, allows current to pass only when both inputs are “on” OR gate: allows current to pass when either inputs are “on”

14. Local area networks (LAN)  All PCs are connected by cables to a central computer called a server A server consists of a computer with lots of memory  Allows sharing of data files Electronic mail (E-mail)

15. Internet  A large computer network that connects many local and smaller networks all over the world  WWW (world wide web) created in Europe in 1989 for scientists to share data

16. Three things you need to use the Internet 1.Modem: modulator/demodulator, a device that codes the output data of your computer 2.Internet/Web browser: interprets signals received from the internet 3.Internet Service Provider: ISP, a company that connects the modem signal to the Internet