B.A. (Mahayana Studies)
000-209 Introduction to Computer Science
November 2005 - March 2006
1. What is a Computer?
 An
overview of what a
computer is, the different types,
and how we communicate with
them.
Overview

What is a Computer?
 look

at the basic elements that make up a computer
Types of Computer
 micros,

minis, mainframes, supercomputers
The User Interface
 how
000-209 Intro. to CS. 1/computer?
do we communicate with the computer?
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1. What is a Computer?

Before 1940, a computer was a person who did
calculations.

The modern definition of the term computer
emerged in the 1940’s.
 due
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to World War II military needs
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1.1. Von Neumann’s Definition

Von Neumann, leading
mathematician, wrote a report
describing plans for the
first computer, the EDVAC.

A computer is a device that:




accepts input
processes data
stores data
produces output
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1.2. Computer Diagram (v.1)
Input
Device
Central Processing
Unit (CPU)
Output
Device
Data
Storage
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1.3. Input

Input means to send information (data)
into a computer.
 words
from a document
 numbers for a calculation
 pictures, sounds, video, ...
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1.4. Processing

Processing is the way that a computer
manipulates data.
 performing
calculations
 sorting lists and numbers
 drawing graphs
 making movies, ...
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1.5. Storage



A computer stores data so that it will always be
available for processing.
Storage is the area where data can be left on a
permanent basis.
Memory is an area of a computer that holds data
that is waiting to be processed.
 e.g.
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RAM
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1.5. Output

Computer output is the results produced by the
computer.
 reports,

documents, music, graphs, pictures
An output device displays, prints or transmits
the processing results.
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1.6. Computer Diagram (v.2)
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1.7. Peripherals

Hardware refers to the physical things that go
together to make a computer.

Peripheral devices are hardware components that
handle the computer’s input, output, and storage
capabilities.
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1.8. Software

A computer needs software to tell it how to
interact with the user, and how to process the
user’s data.

There are many types of software
 see
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part 2
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2. Types of Computer

Computers can be separated into four groups,
from least to most powerful:
 microcomputers
 minicomputers

(rapidly disappearing)
also known as minis
 mainframes
 supercomputers
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2.1. Microcomputers





Also known as personal computers, PCs, and
micros.
Typically found in homes and small businesses.
Cost about US $800-4000.
Speed can exceed 1,500 million operations per
second.
May be stand-alone, or may be connected to
other computers, in order to share data and
software.
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Microcomputers
A laptop computer is
light, and runs on
batteries or electricity
A personal digital
assistant (PDA)
accepts info
on a touch-sensitive
screen
Desktop
microcomputer
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Desktop Microcomputers

Two major types:
 PCs


originally created by IBM
now also Compaq, Dell, HP, Acer, ...
 Macintoshs

(Macs)
made by Apple Computers
The iMac
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2.2. Mainframes





Large, fast, and fairly
expensive computers.
Used by business and government.
Storage, processing, and management of large
amounts of data.
Can support thousands of users.
Often uses several central processing units
(CPUs).
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2.3. Supercomputers





Fastest and most
expensive type of computer.
Cost between US $500,000 and $35 million.
Now used in business markets to handle large
amounts of data.
Processes more than 1 trillion instructions per
second.
Applications:
 weather
forcasting, military simulations,
cartoons like Shrek
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3. The User Interface

The means by which
humans and computers
communicate.

A good user interface is
easy to learn and use.

User interfaces are still
improving.
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3.1. GUIs

Graphical objects are a key element of the
Graphical User Interfaces, or GUIs, found on
most of today’s microcomputers.
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3.2. Microsoft Windows GUI
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Mac OS X GUI
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3.3. Computer Commands


A command is an instruction you input to tell the
computer to carry out a task.
Command words are often English words, such
as print, begin, save, and erase, but they can also
be harder to remember.
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3.4. GUI Elements

A menu displays a list of commands or options.
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continued
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
Submenus are additional sets of commands that
the computer displays after you
make a selection from the
main menu.
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continued
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
Dialog boxes display the options associated with
a command.
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continued
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Icons


Graphical objects are small pictures on
the screen that you can manipulate
using a mouse or other input device.
Graphical objects include icons,
buttons, and windows.
Selected icon
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