Overview of comp system

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COMPUTER SYSTEM

• Combination of components designed to process data and store files

• Consists of four major hardware components input devices, output devices, processor and storage devices

• Needs hardware, software and a user to fully function

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*input devices*processor*output devices*storage devices

COMPUTER HARDWARE

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Input devices

Output devices

hardware

software

Computer system

COMPUTER HARDWARE COMPUTER HARDWARE BLOCK DIAGRAMBLOCK DIAGRAM

Input devices

processor

Storage devices

output devices

An Input device feeds raw data to the processor. A processor processes raw data and turns it into useful information. A storage device keeps or stores both process and unprocessed data for later usage. An output device shows or display the processed data

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Any questions so far?

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Human uses the brain to think, make decisions and

process information. A computer has a brain too,

and the brain of a computer is the processor or the central processing unit (CPU) that processes

information

THE CENTRAL PROCESSING UNIT

All processing activities are done in the CPU

It utilizes the computer memory to execute instructions from the application software and accomplish a task

The processor must be connected to input devices, output devices and storage devices to carry out the tasks

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THE INFORMATION PROCESSING CYCLE

Input processor

Storage

output

User will input the data to be processed by the

processor.The storage holds

databases, files and programs. The output of the processed data will

be displayed by the output devices present as useful information products for the user

The Information Processing Cycle

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Draw the computer hardware block diagram

and the information processing cycle. Explain

briefly each diagram

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Information processing cycle

Any data or instructions that we enter into the computer system for processing

Input

A location which data, instruction and information are held for future use

Storage

Data that has been processed into a useful form information

Output

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Machine cycle that consist four basic operations, that’s are fetching, decoding, executing and storing

Process

Fetching

DecodingStoring

Executing

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FetchingThe process of obtaining a program instructions or data item from memory

Decoding The process of translating a program instruction into signals that the computer can execute

StoringThe process of writing the result to the storage or memory

Executing The process of implementing the instructions in a program.

process

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Any questions?

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DATA REPRESENTATI

ON

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Computers recognize only two discrete states on & offThese states can be represented by two digits 0 & 1Each 0 or 1 is called a bit in the binary system.

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BINARY DIGIT

The smallest unit of data a computer can process The binary system has a base of 2 with the two digits (0 and 1) Combinations of 0s and 1s represent larger numbers

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BYTE

• Unit of information built from bits

• 1 byte = 8 bits• One byte represents a single character (3, B or #)

• Unit of information built from bits

• 1 byte = 8 bits• One byte represents a single character (3, B or #)

CHARACTER

• One byte represents one character such as A, 7, 9 and +

• F = 01000110 (binary code)

• One byte represents one character such as A, 7, 9 and +

• F = 01000110 (binary code)

00111001 = 900101011 = +

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æThree character codes to represent characters

æASCII, EBCDIC, Unicode

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* ASCII (American Standard Code for Information Interchange)* Proposed by ASA (American Standard Association)

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To achieve compatibility between various types of data processing equipment making it possible for the components to communicate with each other successfully

Enables manufacturers to produce components that are assured to operate correctly in a computer

Enables human to interact with a computer

Enables users to purchase components that are compatible with their computer configurations

FUNCTIONS OF ASCII

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HOW ASCII WORKS IN A COMPUTER SYSTEM?

When you press a key, for example the letter D on your keyboard, the electronic signal is sent to the CPU for the computer to process and store in memory. Every character is converted to its corresponding binary form. The computer the processes the letter as a byte, which actually a series of on and off of electrical states. When the computer is finished processing the byte, the software installed in the system convert the byte back which is then displayed in the screen. Example, the letter D is converted to 01000100

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DATA DATA MEASUREMENTMEASUREMENT

Bit Bytes Kilobytes (1 KB = 210 bytes) Megabyte (1 MB = 220 bytes) Gigabyte (1 GB = 230 bytes) Terabyte (1 TB = 240 bytes)

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EVOLUTION OF

COMMUNICATION

Computer’s “speed = how fast computer can process data

Every microprocessor contains a system clock

The system clock controls the speed of all the operations within a computer

The speed of the clock = how many cycles per second the clock makes

CLOCK SPEED MEASUREMENT

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The units of clock speed measurement

Hertz (Hz)

æ The clock speed unit is measured in hertz

æ A hertz is one cycle per second

Megahertz (MHz)

æMega = millionæMegahertz (MHz) = 1

million cycles of the system clock

æA computer that operates at 933 MHz has 933 million clock cycles in one second

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Gigahertz (GHz)

æGiga = billionæ1GHz = 1000 MHzæE.g. a microprocessor that runs at 200 GHz

executes 200 billion cycles per second

The units of clock speed measurement

Processing Speed

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»The system clock major factors that influence

the computer speed

»CPU with a higher clock speed can process

more instructions per second than a CPU with a

lower clock speed

»E.g. A 1 GHz CPU is faster than a CPU operating

at 800 MHz

Speed and path

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The combination of speed and number of paths

determines the total processing speed or

channel bandwidth

Different processors often use different

architectures

e.g. a 1.4 GHz Pentium 4 performs better than a

1.4 GHz Pentium 3, but it is not as fast as a 1.4

GHz Power PC G4 processor.

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A Pentium 4 running at 2.4 GHz isone-third faster than

a Pentium 4 running at 1.8 GHz

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Input devices

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Any data or instructions that we enter into the computer system for processing

Input

text

audio

Graphic

video

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OUTPUT DEVICES

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Data that has been processed into a useful form information

Output

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MOTHERBOARD

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Motherboard main circuit board of the system unit

Consist of some electronic components attached to it and others built into it

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CPUExpansion

slot

RAM

Components of a Motherboard

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RAM•Memory of the computer•Placed on the RAM slot

expansion card•Plugged into an expansion slot•Used to add new devices or capabilities to a computer

Components of a Motherboard

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Ports and connectors• The point at which a peripheral attaches to a system unit so that the peripheral can send data to or receive information from the computer

• Serial port• Parallel port• Universal Serial Bus (USB) port• FireWire port• Spécial purpose ports - MIDI port - SCSI port - IrDA port

Components of a Motherboard

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PORTS AND CONNECTORS

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Serial port

A socket on a computer used to connect a modem, data acquisition terminal or other serial devices via a slow-speed serial interface

Connect a device to the system unit by transmitting data one bit at a time

Example = COM (communication) port

A socket on a computer used to connect a modem, data acquisition terminal or other serial devices via a slow-speed serial interface

Connect a device to the system unit by transmitting data one bit at a time

Example = COM (communication) port

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Parallel port

A devices by transferring information more than one bit at a time socket on a computer used to connect

Transfer eight bits of data (one byte) simultaneously through eight separate lines in a single cable

Many printers connect to the system unit using a parallel port

A devices by transferring information more than one bit at a time socket on a computer used to connect

Transfer eight bits of data (one byte) simultaneously through eight separate lines in a single cable

Many printers connect to the system unit using a parallel port

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USB port

• A socket on a computer or peripheral devices into which a USB cable is plugged in

• Can connect up to 127 different peripherals together with a single connector

• Transfer data to a speed of 12 megabits per second

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Fire Wire port

• Previously the FireWire port is called IEEE 1394 port, a personal computer (and digital audio/video) serial bus interface standard

• Similar to a USB port in that it can connect multiple types of devices that require faster data transmission speeds

• Data can move across the port at up to 400 megabits per second

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Special purpose

port

MIDI portconnect the system unit to a musical instrument (electronic keyboard)

SCSI portspecial high-speed parallel port used to attach peripheral devices

IrDA porttransmit data via infrared light waves

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CENTRAL PROCESSING

UNIT

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CPU

an integrated circuit chip that is capable of processing electronic signals

CPU interprets instructions given by the software and carries out those instructions by processing data and controlling the rest of the computer’s components

Control Unit (CU)

Arithmetic Logic Unit (ALU)

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Control Unit (CU)

æMain function to direct the CPU to process data

æExtracts instructions from memory and decodes and executes them

æManages a four-step basic operation machine cycle @ processing cycle

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Arithmetic Logic Unit (ALU)

• Perform all arithmetic and logical operations

• Arithmetic operation is an operation that forms a function of two numbers

• Logic operation is an operation on logical values

• 16 logic operations over one or two operands (AND, OR, NOT, NAND, NOR, XOR and equivalence)

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STORAGE

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FUNCTIONS OF COMPUTER STORAGE1.Store programs and data to be used at a later time2.Keep current data while being processed by the processor until the information is saved in a storage media3.Stores instructions from a computer program

Primary storage

Secondary storage

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Primary storage • main memory in a computer

• stores data and programs that can be accessed directly by the processor

• Installed inside computers

• The data in RAM can be read (retrieved) or written (stored)

• RAM is volatile the programs and data in RAM are lost when the computer is powered off

• Stores data during and after processing

RAM

• Permanently stored inside the computer

• ROM is non-volatile• Programs in ROM

have been pre-recorded (It can only be stored by the manufacturer once it is done, it cannot be changed)

• Many complex functions

• All the contents in ROM can be accessed and read but cannot be changed

ROM

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Secondary storage

• alternative storage to keep work and documents

•useful to store programs and data for future use

•non-volatileMagnetic Medium•Non-volatile•Can be any type of storage medium that utilizes magnetic patterns to represent information• Magnetic disk (floppy disk, hard disk)•Magnetic tape (video cassette, audio storage reel-to-reel tape etc)

Optical Medium•Non-volatile•Holds content in digital form that are written and read by a laser (CDs, DVDs, CD-R, DVDR etc)

Flash Memory•Solid-state, non-volatile, rewritable memory that functions like RAM & a hard disk drive combined•Store bits of electronic data •Fast reading access times•Thumb drives, pen drives, flash drives etc

COMPUTER SOFTWARE

A program which consists of a set of instructions that tells the computer how to perform specific tasks

APPLICATIONSOFTWARE

SYSTEMSOFTWARE

SYSTEMSOFTWARE

Any software used to control and manage computer devices

and operations

APPLICATIONSOFTWARE

Any software used to help user perform specific tasks

OS, Utility program

Spreadsheet, web browser

Usage

Need

NumberOf software

Dependency

Function

System software Application software

Enable computer to function properly

Enable user to work efficiently

Compulsory Optional

One More than one

Independent

Provides environment for

application to run

Dependent

Provides environment enable user to do

specific tasks

SYSTEMSOFTWARE

OPERATING SYSTEM

A set of program that coordinates all the activities

among the computer

hardware devices

-LINUX

-Mac OS

-UNIX

-Windows XP

UTILITY PROGRAM

A type of system software that allows user to

perform maintenance type tasks to manage a computer, devices

or its program

-Antivirus

-Screen savers

-File manager

Function of OS

Starting a computer

Providing user interface

Managing data and programs

Managing memory

Configuring devices

Starting a computerOS function

❋ Booting – Loading and initialize OS into the computer’s

memory

❋ Two ways of booting

Warm boot Cold boot- Restarting a computer that is

already on

- After installing new software

or hardware / after

application stops working

- Starting a computer that is

already off

- Computer that is completely

powered off

Providing user interface

OS function

- Controls how user enters data and

instructions and how information

is displayed

- Interface enables users to;

- start an application program

- manage disks and files

- shut down computer safely

Command Line

Menu-Driven

GUI

CommandLine

➤Requires user to type command or press special

keys on the keyboard to enter data and

instructions to tell the OS what to do

➤Typed one line at a time

➤Difficult to use exact spelling, syntax or a set

of rules of entering commands

➤Advantage helps user to operate computer

quickly after memorizing the keywords and

syntax

Menu-Driven

➤ No need to memorize

keywords and syntax

➤ Provide menu to enter

commands

➤ shows all the option

available at a given point

in a form of text based

menu

➤ Easy to learn

GUI

• Friendly user, commonly used

• Operates after OS finishes loading into

memory

• Interacts with the menus and visual

images to issue commands

• On desktop can initiate many actions

by clicking icons that represents

computer resources

THE IMPORTANCE OF

USER INTERFACE✺Assists user to interact with OS

✺Control how user enters data and

instructions

✺Control how information is displayed

OS function

Managing data and programs

- CPU loads the application from storage into

memory

- Multitasking OS enable users to work

with two or more application at the same

time

Managing memory

OS function

- Optimizing the use of RAM

- Allocating data and instruction to an area

of memory while being processed- Monitoring the contents of memory

- Releasing data and instructions from

being monitored in memory when the

process is done

Configuring devices

OS function

- Handling input/output as

well as enabling

communication with i/o

devices

- Most OS comes with

drivers for popular

i/o devices

OS PLATFORMS• manufacturers produce unique

software version for each platform

ApplePlatform OS

PCPlatform OS

Cross-platformOS

ApplePlatform OS

• Used on Apple platform- Mac OS- Mac OS X

• Closed source software• For use with home desktop and

workstations

ApplePlatform OS

• Used in IBM compatible computers• Examples:

- Disk Operating System (DOS)- Microsoft Windows XP

• Closed source software• DOS - use command line interface• MS Windows XP – GUI interface

PCPlatform OS

PCPlatform OS

• UNIX Multitasking OS» Most versions of UNIX use GUI and some

use command line

Cross-platformOS

• LINUX Multitasking OS» Open source software» Free and UNIX-like GUI OS» Best known for its support of IBM-Intel

PC-based hardware

Cross-platformOS

APPLICATIONSOFTWARE

WORD PROCESSING

SPREADSHEET

PRESENTATION

GRAPHICS EDITING

• An office application enables user to create, edit, format and print textual document

WORD PROCESSING

• A program that processes information in the form of grid of columns and rows (table)

• Holds values or mathematical formulas• Indispensable if working with numbers

SPREADSHEET

• Enables user to create transparencies, slides and handouts for presentation

• Create visual aids for presentation to communicate ideas, messages and other information to a group

PRESENTATION

• A program that can edit digital representation or non-text information (drawings, charts or photographs)

GRAPHICS EDITING

APPLICATIONSOFTWARE

WORD PROCESSING

SPREADSHEET

PRESENTATION

GRAPHICS EDITING

SOFTWARE SUITE• A collection of individual programs sold as a

single package• Designed to enhance work performance • Word processing, spreadsheet, presentation and e-mail• Microsoft Office

• closed source software • stable system with support if

the software fails or malfunctions

PROPRIETARY SOFTWARE

• Provided for use, modification and redistribution

• Can download from the Internet for free and modify into better quality software

• The only qualification changes can't be copyrighted

OPEN SOURCE SOFTWARE

OPEN SOURCE SOFTWARE

OpenOffice.org, PHP-Nuke, The GIMP, Mozilla, ClamAV, OpenLDAP, Audacity and RedHat

LINUX version