1. Introduction to Computer and Computer Networking: Part I Xiangming Mu 9/16/2004

2. What Is a Computer and What Does It Do? A computer is a programmable electronic device that accepts data and performs operations on that data. Input—entering data into the computer. Processing—performing operations on the data. Output—presenting the results. Storage—saving data, programs, or output for future use.

3. Computers to Fit Every Need Five basic categories –Mobile devices –Personal computers –Midrange servers –Mainframe computers –Supercomputers

4. Operating Systems System software acts as a mediator between application programs and the hardware resources of the computer system. Application software provides the tools to perform particular tasks on a PC, such as writing a letter, processing orders, playing games, composing and e-mail, and so forth. Most programs use a graphical user interface (GUI). The most common operating systems for PCs today is Microsoft Windows. Other GUI operating systems are Mac OS and Linux.

6. And more…

7. Data and Program Representation Computers today are mostly digital computers—devices that can only understand two states. The two states of a digital computer are typically represented by 0s and 1s; that is, in binary form. Computers do all processing and communications in binary form, so natural-language input and output are translated to and from binary by the computer.

9. Coding Systems for Text-Based Data ASCII and EBCDIC –Fixed-length codes that can represent any single character of data as a string of eight bits. Unicode –A longer (32 bits per character is common) code that can be used to represent text-based data in virtually any written language. Graphics data —often stored as a bitmap which the color to be displayed at each pixel stored in binary form. Audio data —waveform audio is common; MP3 compression makes audio files much smaller. Video data —requires a great deal of storage space, but can be compressed.

10. Inside the System Unit The system unit of a PC is the case that houses processing hardware and other hardware. All of the hardware contained within the system unit is connected to the system board or motherboard. The CPU (central processing unit) does the vast majority of processing for a computer. Buses are electronic paths that data travels around on a computer system. RAM (random access memory) is the computer’s main memory and is used to temporarily storage programs and data with which it is working. Expansion cards can be inserted into expansion slots on the motherboard. Some external devices can be plugged into existing USB or FireWire ports without adding another expansion card.

11. Inside the System Unit The system unit of a PC is the case that houses processing hardware and other hardware. All of the hardware contained within the system unit is connected to the system board or motherboard. The CPU (central processing unit) does the vast majority of processing for a computer. Buses are electronic paths that data travels around on a computer system. RAM (random access memory) is the computer’s main memory and is used to temporarily storage programs and data with which it is working. Expansion cards can be inserted into expansion slots on the motherboard. Some external devices can be plugged into existing USB or FireWire ports without adding another expansion card.

12. Storage Magnetic disk storage systems Optical disc storage systems Other types of storage, such as flash memory, magnetic tape, remote storage, and smart cards

15. Input Input devices convert data from the user into a form understood by the computer.

16. Output Output devices convert the processed 0s and 1s into a form that the user can understand. –Hard copy—permanently recorded, such as on paper. –Soft copy—temporarily recorded, such as on a computer screen.

17. Computer Networks and the Internet A computer network links computers together so that users can share hardware, software, and data, as well as electronically communicate with each other. Network servers manage resources on a network. Clients are computers on the network that access resources via the network server.

18. What Is a Browser? A Web browser is a program used to view Web pages. Common browsers: Microsoft Internet Explorer Netscape Navigator MSN Explorer Opera Wireless phones and other small devices use microbrowsers.

19. Internet Addresses An Internet address identifies a resource available through the Internet, such as a person, computer, or Web page. IP addresses (e.g. 207.46.134.222) and domain names (e.g. microsoft.com) identify computers available through the Internet. URLs (e.g. www.course.com) identify a Web page on the Internet. E-mail addresses (e.g. jsmith@course.com) identify a person on the Internet.