Introduction to Computer and Computer Networking: Part I

Xiangming Mu

9/16/2004

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.

Computers to Fit Every Need • Five basic categories

– Mobile devices

– Personal computers

– Midrange servers

– Mainframe computers

– Supercomputers

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.

And more…

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.

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.

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.

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.

Storage

• Magnetic disk storage systems• Optical disc storage systems• Other types of storage, such as flash memory, magnetic

tape, remote storage, and smart cards

Input • Input devices convert data from the user into a form understood by the

computer.

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.

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.

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.

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.