UNIT 2UNIT 2

Dissecting the ultimate Machine Dissecting the ultimate Machine Parts of a PC - Hardware, Software, Data, Users Parts of a PC - Hardware, Software, Data, Users The Information Processing CycleThe Information Processing Cycle Interface- GUI,CLIInterface- GUI,CLI Operating System Operating System Single user / single taskingSingle user / single tasking Single user/ multitaskingSingle user/ multitasking Multi-user / multitaskingMulti-user / multitasking Software types – System Software , Application Software types – System Software , Application

Software Software

PARTS OF A COMPUTER PARTS OF A COMPUTER SYSTEMSYSTEM

A complete computer system A complete computer system consists of four parts:-consists of four parts:-

a)a) HardwareHardware

b)b) SoftwareSoftware

c)c) Data Data

d)d) useruser

a) Hardwarea) Hardware

Mechanical device/physical device Mechanical device/physical device that make up the computerthat make up the computer

You can touch hardwareYou can touch hardware A computer hardware consists of A computer hardware consists of

interconnected electronic devices interconnected electronic devices that you is used to control the that you is used to control the computer’s operation, input and computer’s operation, input and output.output.

c) Data c) Data

Consist of individual facts or pieces Consist of individual facts or pieces of information that by themselves of information that by themselves may not make much sense to a may not make much sense to a personperson

Computer’s primary job is to process Computer’s primary job is to process these tiny pieces of data in various these tiny pieces of data in various ways, converting them into useful ways, converting them into useful informationinformation

d) userd) user

User are computer operators User are computer operators It can be argued that some computer It can be argued that some computer

systems are complete without a systems are complete without a person’s involvement; however no person’s involvement; however no computer is totally autonomous. computer is totally autonomous. even if a computer can do its job even if a computer can do its job without a person sitting in front of it, without a person sitting in front of it, people still design , build, program people still design , build, program and repair computer system.and repair computer system.

DIFFERENCE B/N DATA & DIFFERENCE B/N DATA & INFORMATIONINFORMATION

DATA – describes informationDATA – describes information Data consist of raw numbers that Data consist of raw numbers that

computers organize to produce computers organize to produce information.information.

Data is a collection of facts – Data is a collection of facts – unorganized but able to be organized unorganized but able to be organized into useful information.into useful information.

INFORMATION – it is an data INFORMATION – it is an data arranged in an order and form that is arranged in an order and form that is useful to the people who receive ituseful to the people who receive it

Useful in decision makingUseful in decision making Meaningful information such as Meaningful information such as

spreadsheets , charts and reports.spreadsheets , charts and reports.

INFORMATION PROCESSING INFORMATION PROCESSING CYCLECYCLE

Computer converts data into information Computer converts data into information by performing various actions on the data by performing various actions on the data e.g. Mathematical operations on two e.g. Mathematical operations on two numbers , perform logical operation such numbers , perform logical operation such as comparing two numbers.as comparing two numbers.

These operations are part of a process These operations are part of a process called information processing cycle, which called information processing cycle, which is a set of steps the computer follows to is a set of steps the computer follows to receive data, process the data according receive data, process the data according to instructions from a program, display the to instructions from a program, display the resulting information to the user, aand resulting information to the user, aand store the results.store the results.

Processing cycle have four parts Processing cycle have four parts :-:-

a)a) Input - Input -

b)b) ProcessingProcessing

c)c) OutputOutput

d)d) StorageStorage

a)a) Input Input The collection of raw data from the outside world The collection of raw data from the outside world

so it can be put into an information system. so it can be put into an information system. putting the acquired data into the information putting the acquired data into the information system.system.

e.g. the payroll clerk collects workers timecards e.g. the payroll clerk collects workers timecards so she knows how many hours each person so she knows how many hours each person worked that week and types the hours from the worked that week and types the hours from the timecards into a spreadsheetstimecards into a spreadsheets

Input devices used are – keyboard, mouse, bar Input devices used are – keyboard, mouse, bar code readers , joysticks, digital data tablets, code readers , joysticks, digital data tablets, electronic cash registerselectronic cash registers

b) Processing b) Processing

During this phase, computer’s During this phase, computer’s processing components perform processing components perform actions on the data, based on actions on the data, based on instructions from the user or a instructions from the user or a programprogram

c) Outputc) Output

Is the process of transmitting the Is the process of transmitting the processing information .processing information .

Output is the presentation of any Output is the presentation of any data exiting a computer system.data exiting a computer system.

It can be in printed form, video, It can be in printed form, video, audio on monitor or any other audio on monitor or any other alternate devicealternate device

d) Storage d) Storage

In this step , the computer In this step , the computer permanently stores the results of tis permanently stores the results of tis processing on a disk, tape or some processing on a disk, tape or some other kind of storage medium. other kind of storage medium.

SOFTWARESSOFTWARES Refers to a set of programsRefers to a set of programs The ingredients that enables a The ingredients that enables a

computer to perform a specific task is computer to perform a specific task is software, which consists of instructions.software, which consists of instructions.

A set of instructions that drive a A set of instructions that drive a computer to perform specific task is computer to perform specific task is called program ( program is a sequence called program ( program is a sequence of instructions written in a language of instructions written in a language that ca be understood by a computer )that ca be understood by a computer )

Types of softwareTypes of software

Most software can be divided into Most software can be divided into two types:two types:

1)1) System software System software

2)2) Application softwareApplication software

1) System software1) System software

Are designed to control the operation Are designed to control the operation and extend the processing capability and extend the processing capability of a computer systemof a computer system

It controls the computer hardware or It controls the computer hardware or is used to maintain the computer in is used to maintain the computer in some way so that it runs more some way so that it runs more efficientlyefficiently

Eg :- operating system, utility Eg :- operating system, utility softwaresoftware

2) Application software2) Application software

Are designed to solve a specific Are designed to solve a specific problem or to do a specific taskproblem or to do a specific task

Eg :- word processing, spreadsheets , Eg :- word processing, spreadsheets , powerpoint, access , windows media powerpoint, access , windows media player , internet explorer ( web player , internet explorer ( web browser ), gamesbrowser ), games

Operating systemOperating system An OS is software program but it is An OS is software program but it is

different from word processing programs , different from word processing programs , spreadsheets and all other software spreadsheets and all other software programs of our computer programs.programs of our computer programs.

Os provides user with the tools Os provides user with the tools (commands) that enables user to interact (commands) that enables user to interact with the PC.with the PC.

When we issue a command, the OS When we issue a command, the OS translates it into code that the machine translates it into code that the machine can use. can use.

The OS ensures that the results of The OS ensures that the results of your actions are displayed on your actions are displayed on screen , printed and so on. screen , printed and so on.

The OS also acts as the primarily The OS also acts as the primarily controlling mechanism for the controlling mechanism for the computer hardware.computer hardware.

Functions of OSFunctions of OS

As programs work with the computer’s As programs work with the computer’s hardware and other software. Loads hardware and other software. Loads programs ( such as word processing, programs ( such as word processing, spreadsheet programs) into the spreadsheet programs) into the computer’s memory so that you can use computer’s memory so that you can use themthem

Manages the way information is stored on Manages the way information is stored on and retrieved from disks ( memory and retrieved from disks ( memory management )management )

Process managementProcess management

File managementFile management

SecuritySecurity

Command interpretationCommand interpretation

Interface Interface

Interface provides an medium to the Interface provides an medium to the user via which he or she can user via which he or she can communicate with the OS.communicate with the OS.

There are two types of OS interfaceThere are two types of OS interface

a) GUIa) GUI

b) CUIb) CUI

CLI/CUICLI/CUI Stands for command line interface/ Stands for command line interface/

command user interfacecommand user interface Users give instructions to computers by Users give instructions to computers by

typing commands in textual interfacetyping commands in textual interface User uses keyboard to type words and User uses keyboard to type words and

symbolssymbols If a user types command incorrectly , If a user types command incorrectly ,

command interpreter responds with a command interpreter responds with a message indicating that it did not message indicating that it did not understand the command. when this understand the command. when this happens , the user has to retype the happens , the user has to retype the command correctly.command correctly.

Involves of typingInvolves of typing Limitation- user needs to remember Limitation- user needs to remember

commands.commands. Eg- DOS, unixEg- DOS, unix

GUIGUI

Stands for graphical user interfaceStands for graphical user interface GUI emphasizes on graphical entities. user GUI emphasizes on graphical entities. user

chooses and selects graphical icons chooses and selects graphical icons positioned on the screenpositioned on the screen

Involves click, double click, drag and dropInvolves click, double click, drag and drop Advantages- need not to remember Advantages- need not to remember

commands. It is user friendly.commands. It is user friendly. Eg windows – 95 , 3.1 , 98 , me,xp,vista Eg windows – 95 , 3.1 , 98 , me,xp,vista

etcetc

Types of OS

OS can be organized into four major types:

1) Real time (special purpose systems)2) Single user/single-tasking3) Single user/multitasking4) Multi-user/multitasking

1) Real time Os

Are very fast, relatively small OS. They are built into circuitry of a

device and are not loaded from a disk drive.

Real time OS need to run real time application

It may support multiple simultaneous tasks, or it may only support single tasking.

A real time application is an application that responds to certain inputs extremely quickly- thousandths or millionths of a second (milliseconds or microseconds resp. )

Real time systems are used when rigid time requirements have been placed on the operation of a processor or the flow of data . sensors bring data to the computer . computer must analyze the data and possibly adjust controls to modify the sensor inputs.

RTS have well defined ,fixed time RTS have well defined ,fixed time constraints. processing must be done constraints. processing must be done within the defined constraints or the within the defined constraints or the system will fail.system will fail.

RTS functions correctly only if it returns RTS functions correctly only if it returns the correct result within its time the correct result within its time constraints.constraints.

E.g. scientific experiments, medical E.g. scientific experiments, medical imaging systems, industrial control imaging systems, industrial control system, automatic-engine fuel-injection system, automatic-engine fuel-injection system ,home appliances control system, system ,home appliances control system, weapon systemweapon system

Also called as real time embedded system

Real time OS are of two type:a) Hard real timeb) Soft real time

Hard real time - A hard real-time system guarantees that critical tasks complete on time. This goal requires that all delays in the system be bounded from the retrieval of the stored data to the time that it takes the operating system to finish any request made of it. E.g. satellites working

Soft real time – when a critical real time task gets priority over other tasks and retains that priority until it completes.