lec-1 [introduction to computer- omt-i]

8/6/2019 Lec-1 [Introduction to Computer- OMT-I]

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Office Mana ement Tool - I Institute of Management Sciences

Muhammad Shahzad AliLecture 1: Introduction to Computer

L E C T U R E

1 INTRODUCTIONTO COMPUTER


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What is Computer?

A computer is a programmable machine that receives

input, stores and manipulates data, and provides output

in a useful format.

It responds to a specific set of instructions in a well-defined manner.

It can execute a prerecorded list of instructions (a

program).


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What is Computer?

A device that computes, especially a programmable

electronic machine that performs high-speed

mathematical or logical operations or that assembles,

stores, correlates, or otherwise processes information.


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The actual machinery -- wires, transistors, and circuits

-- is called hardware;

the instructions and data are called software.


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Basic Computer Model

All computers perform four basic operations

Input Data

Process Data

Store Data

Output Data


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Basic Operations

Input data is to feed information which can be supplied by any

person, environment or other computer.

Processing data is manipulating data by performing

calculations, sorting lists of words or numbers, drawing

pictures.

Storing data is for future retrieval and processing. Memory

holds data that is waiting to be processed, and storage areas

hold data permanently until the data is deleted.

Output data is the result produced by a computer, which

includes reports, documents, music, graphs and pictures.


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Hardware Components

All general-purpose computers require the following

hardware components:

memory : Enables a computer to store, at least

temporarily, data and programs.

mass storage device :Allows a computer to

permanently retain large amounts of data. Common

mass storage devices include disk drives and tape

drives.


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input device : Usually a keyboard and mouse, the

input device is the conduit(pipe or channel) throughwhich data and instructions enter a computer.

output device :A display screen, printer, or other

device that lets you see what the computer hasaccomplished.

central processing unit (CPU): The heart of the

computer, this is the component that actually executesinstructions.


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Classification of Computers

personal computer : A small, single-user computer

based on a microprocessor.

In addition to the microprocessor, a personal computer

has a keyboard for entering data, a monitor for

displaying information, and a storage device for saving

data.

w

orkstation : A powerful, single-user computer.

A workstation is like a personal computer, but it has a

more powerful microprocessor and a higher-quality

monitor.


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minicomputer : A multi-user computer capable of

supporting from 10 to hundreds of users

simultaneously.

mainframe : A powerful multi-user computer capableof supporting many hundreds or thousands of users

simultaneously.

supercomputer : An extremely fast computer that can

perform hundreds of millions of instructions per

second.


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Applications of Computer Systems

In Education

Multimedia-Facilitated Learning

Simulation-Based Education

Intelligent Machine-Based Training

Interactive Learning


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In Business

Supply Chain Management

Project Management

Customer Relationship Management

Sales and Marketing UsingE

lectronic Commerce

Manufacturing Research


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In Entertainment

Movies

Video Games

Music

Digital Photography

Travel

Wearable Computer Systems


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Why Use Computers?

S

peed Accuracy

Consistency

Reliability

Communications

Memory


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Components ofComputer Systems


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Components of Computer Systems

Input

Output

Storage

Processor


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Input Systems

Keyboard

Most common input device

QWERTY


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Mouse

Cursor manipulation device

Trackball


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Touch Screens


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Pens

Stylus


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Magnetic InkCharacter Recognition (MICR)


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Bar Code Readers


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Optical Character Recognition systems

Book readers for the blind

Automated input of text

Can do typewritten text and

handwritten block capital

Problems with cursive handwriting recognition


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Sensors

Digital thermometers

Accelerometers

Strain gauges (weighing scales)

....


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Camera Systems

Surveillance and monitoring

Visual inspection

Robot guidance

Video conferencing


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Voice

Voice recognition

Hands-free car-phones

Assistance for the disabled


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Output Systems


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Soft Copy

Voice synthesis

Music

CRT (Cathode Ray Tube)

LC

D (LiquidC

rystal Display)


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Modems

Modulator-Demodulator

Allows computers to communicate over telephone lines


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Disks

Magnetic

Floppy

Hard disk

Optical

Storage Device

M h d Sh h d AliL 1 I d i C


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Hard Copy

Plotters

M h d Sh h d AliL t 1 I t d ti t C t


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Hard Copy

Microfilm

M h d Sh h d AliL t 1 I t d ti t C t


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Non-Impact Printers

Laser

Magnetic

Thermal transfer

Thermal and Electrostatic


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Storage Systems



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Primary Memory Types

CacheCache

RAMRAM

ROMROM

PROMPROM



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Memory

Stores the bits and bytes (instructions and data)



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ROM - Read Only Memory

Permanent; user cannot change

Loads Operating System during boot process

PROM, EPROM, EEPROM

Non-volatile

Wont disappear when power is off



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RAM - Random Access Memory

Solid-state electronic circuitry

Holds current data and programs at a RAM address

Temporary or volatile storage

Read/Write Memory

Volatile



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Cache Memory

Faster and more costly than RAM

Much smaller capacity than RAM

Holds next likely instructions

Increases system throughput



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Storage Capacity

Byte - one character

Kilobyte (KB) - 1024 bytes

Megabyte (MB) - about 1 million bytes

Gigabyte (GB) - about 1 billion bytes

Terabyte (TB) - about 1 trillion bytes



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Mass Storage and Files

Programs and information (text, image, audio, video)

are stored:

Temporarily in RAM

Permanently in Mass Storage (disk and tape)



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p

Optical Disks

15,000 tracks per inch

Digital code read by laser

650 Mbytes in a 4.75 plastic platter

CD ROM; WORM;



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p

Write-One Read_Mostly - CDs (WORMS)

Powerful laser burns in the digital code

Not erasable

Lower power laser reads the digital pattern

Eraseable CD

Lasers read and write inofrmation

Also use a magnetic material

To write: a laser beam heats a tiny spot and a magnetic field

is applied to reverse the magnetic polarity



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Magnetic Disk

A circular platter coated with magnetic material

Floppy Disk

3.5; 360kbyte to 2.88Mbytes (1.44 is common)

Hard Disk

1.3, 1.8, 2.5, 3.5, 5.25;

120Mbytes to over 6 Gigabyte (6 Gbyte)



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Software



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What is Software?

Software is a set of computer instructions or data.

Software receives input from the user and processes

this input through the computer to produce output.

Software directs how the computer interacts with the

user.

Software specifies how to process the user's data



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Operating Systems

Operating System is the software that manages the overall

operation of the computer system

Main purpose is to support application programs

Hide details of devices from application programs



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Operating Systems

User interfaces

Software which is responsible for passing information to and from

the person using the program (the user)

Communicates with and controls the computer

Three types of user interface:

Graphic user interfaces

Menu driven interfaces

Command driven interfaces



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Operating Systems

Graphic User Interfaces (GUIs)

Pictures, graphic symbols (icons), to represent commands

Windows: a way of looking in on several applications at once



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Operating Systems

Windows

GUI

Can run DOS programs

Has network services

Has multimedia extensions

Requires large amounts of memory, disk space, powerful processor

Designed for the Intel 80X86 processors



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Operating Systems

Menu-driven interfaces

Menu bar

Pull-down menu for choices



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Command-driven interfaces

A (system) prompt

User types in single letter, word, line which is translated into

an instruction for the computer

For example: cp source destination

Need to be very familiar with the syntax (grammar) of thecommand language



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Operating Systems

DOS (Disk Operating System)

Single-tasking

Command-driven

Huge number of applications written for DOS

Does not require powerful computer

No network services

No multimedia extensions Designed for the Intel 80x86 processor



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Application Software

Special Purpose

Payroll

Accounting

Book-Keeping

Entertainment

Statistical Analysis



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General Purpose

Word Processing (e.g. MS Word)

Desktop Publishing (e.g. Quark Xpress)

Spreadsheets (e.g. MS Excel)

Databases (e.g. MS Access)

Graphics (e.g. MS Powerpoint)

E-mail (e.g. MS Mail)

Internet Browsers (e.g. Firefox, Explorer)



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Computer Viruses

Via Internet when downloading files

Via e-mail as attachments

Via diskette

Via computer networks

Use anti-viral program for your hard disks and

UPDATE IT often!

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