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.
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Input—entering data into the computer.
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Processing—performing operations on the data.
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Output—presenting the results.
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Storage—saving data, programs, or output for future use.
Computers to Fit Every Need
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Five basic categories
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Mobile devices
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Personal computers
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Midrange servers
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Mainframe computers
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Supercomputers
Operating Systems
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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
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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
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The system unit of a PC is the case that houses processing hardware and other
hardware.
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All of the hardware contained within the system unit is connected to the system
board or motherboard.
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The CPU (central processing unit) does the vast majority of processing for a
computer.
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Buses are electronic paths that data travels
around on a computer system.
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RAM (random access memory) is the
computer’s main memory and is used
to temporarily storage programs and
data with which it is working.
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Expansion cards can be inserted into
expansion slots on the motherboard.
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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
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Magnetic disk storage systems
Optical disc storage systems
Other types of storage, such as flash memory, magnetic
tape, remote storage, and smart cards
Input
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Input devices convert data from the user into a form understood by the
computer.
Output
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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
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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?
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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
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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.