UNIT 2 Dissecting the ultimate Machine  Parts of a PC - Hardware, Software, Data, Users  The Information Processing Cycle  Interface- GUI,CLI  Operating System  Single user / single tasking  Single user/ multitasking  Multi-user / multitasking  Software types – System Software, Application Software

PARTS OF A COMPUTER SYSTEM  A complete computer system consists of four parts:- a) Hardware b) Software c) Data d) user

a) Hardware a) Hardware  Mechanical device/physical device that make up the computer  You can touch hardware  A computer hardware consists of interconnected electronic devices that you is used to control the computer’s operation, input and output.

c) Data  Consist of individual facts or pieces of information that by themselves may not make much sense to a person  Computer’s primary job is to process these tiny pieces of data in various ways, converting them into useful information

d) user  User are computer operators  It can be argued that some computer systems are complete without a person’s involvement; however no computer is totally autonomous. even if a computer can do its job without a person sitting in front of it, people still design, build, program and repair computer system.

DIFFERENCE B/N DATA & INFORMATION  DATA – describes information  Data consist of raw numbers that computers organize to produce information.  Data is a collection of facts – unorganized but able to be organized into useful information.

 INFORMATION – it is an data arranged in an order and form that is useful to the people who receive it  Useful in decision making  Meaningful information such as spreadsheets, charts and reports.

INFORMATION PROCESSING CYCLE  Computer converts data into information by performing various actions on the data e.g. Mathematical operations on two numbers, perform logical operation such as comparing two numbers.  These operations are part of a process called information processing cycle, which is a set of steps the computer follows to receive data, process the data according to instructions from a program, display the resulting information to the user, aand store the results.

Processing cycle have four parts :- a) Input - b) Processing c) Output d) Storage

a)Input  The collection of raw data from the outside world so it can be put into an information system. putting the acquired data into the information system.  e.g. the payroll clerk collects workers timecards so she knows how many hours each person worked that week and types the hours from the timecards into a spreadsheets  Input devices used are – keyboard, mouse, bar code readers, joysticks, digital data tablets, electronic cash registers

b) Processing  During this phase, computer’s processing components perform actions on the data, based on instructions from the user or a program

c) Output  Is the process of transmitting the processing information.  Output is the presentation of any data exiting a computer system.  It can be in printed form, video, audio on monitor or any other alternate device

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

SOFTWARES  Refers to a set of programs  The ingredients that enables a computer to perform a specific task is software, which consists of instructions.  A set of instructions that drive a computer to perform specific task is called program ( program is a sequence of instructions written in a language that ca be understood by a computer )

Types of software  Most software can be divided into two types: 1) System software 2) Application software

1) System software  Are designed to control the operation and extend the processing capability of a computer system  It controls the computer hardware or is used to maintain the computer in some way so that it runs more efficiently  Eg :- operating system, utility software

2) Application software  Are designed to solve a specific problem or to do a specific task  Eg :- word processing, spreadsheets, powerpoint, access, windows media player, internet explorer ( web browser ), games

Operating system  An OS is software program but it is different from word processing programs, spreadsheets and all other software programs of our computer programs.  Os provides user with the tools (commands) that enables user to interact with the PC.  When we issue a command, the OS translates it into code that the machine can use.

 The OS ensures that the results of your actions are displayed on screen, printed and so on.  The OS also acts as the primarily controlling mechanism for the computer hardware.

Functions of OS  As programs work with the computer’s hardware and other software. Loads programs ( such as word processing, spreadsheet programs) into the computer’s memory so that you can use them  Manages the way information is stored on and retrieved from disks ( memory management )  Process management

 File management  Security  Command interpretation

Interface  Interface provides an medium to the user via which he or she can communicate with the OS.  There are two types of OS interface a) GUI a) GUI b) CUI b) CUI

CLI/CUI  Stands for command line interface/ command user interface  Users give instructions to computers by typing commands in textual interface  User uses keyboard to type words and symbols  If a user types command incorrectly, command interpreter responds with a message indicating that it did not understand the command. when this happens, the user has to retype the command correctly.

 Involves of typing  Limitation- user needs to remember commands.  Eg- DOS, unix

GUI  Stands for graphical user interface  GUI emphasizes on graphical entities. user chooses and selects graphical icons positioned on the screen  Involves click, double click, drag and drop  Advantages- need not to remember commands. It is user friendly.  Eg windows – 95, 3.1, 98, me,xp,vista etc

Types of OS   OS can be organized into four major types: 1) 1) Real time (special purpose systems) 2) 2) Single user/single-tasking 3) 3) Single user/multitasking 4) 4) Multi-user/multitasking

1) 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 constraints. processing must be done within the defined constraints or the system will fail.  RTS functions correctly only if it returns the correct result within its time constraints.  E.g. scientific experiments, medical imaging systems, industrial control system, automatic-engine fuel-injection system,home appliances control system, weapon system

  Also called as real time embedded system   Real time OS are of two type: a) a) Hard real time b) b) 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.