Presentation Topic “Time Sharing System”

JamshaidAli(2011-COE-10)

SohaibAbdullah(2011-COE-19)

TYPES OF OPERATING SYSTEM

Presented By:-

Yousuf Nazir 2011-COE-17

M.Ishfaq Shah 2011-COE-23

WHAT IS OS?Operating System is a software, which makes a

computer to actually work.It is the software the enables all the programs

we use.The OS organizes and controls the hardware.OS acts as an interface between the application

programs and the machine hardware.Examples: Windows, Linux, Unix and Mac OS,

etc.,

What OS does?

An operating system performs basic tasks such as,

controlling and allocating memory, prioritizing system requests, controlling input and output

devices, facilitating networking.

Providing user interface

Two most common types.

1) GUI (Graphical user interface)

2) Command line interface

GUI

A GUI uses windows, icons, and menus to carry out commands such as opening files, deleting files, moving files, etc.

Many GUI Operating Systems are operated by using a mouse, the keyboard can also be used by using keyboard shortcuts

GUI

System 7. xp Windows 98 Apple System 7 and Mac OS X

GUI

CLI

Referred to as the command line interface or a text interface.

Navigated by typing commands at prompts.

Uses a keyboard to navigate by entering commands and does not utilize a mouse.

CLI

Types of o.s

Batch systemReal time o.sSingle-user/single taskingSingle-user/multitaskingMulti user/multitasking Time sharing system

Batch System Such systems in which the user does

not get to interact with his/her jobs and jobs with similar needs are executed in a “batch”, one after the other, are known as batch systems.

drives as input devices are line printers, tape drives, and card punches as output devices.

Batch System All FORTRAN programs were

complied one after the other. The major task of such an operating system was to transfer control automatically from one job to the next.

In this execution environment, the CPU is

often idle because the speeds of the mechanical I/O devices such as a tape drive are slower than that of electronic devices.

Real Time System

A real-time system is one that must process information and produce a response within a specified time.

Real Time System

Any system in which the time at which output is produced is significant.

Time an important factor. That is, in a system with a real-time

constraint it is no good to have the correct action or the correct answer after a certain deadline.

Types of Real Time System Soft Real Time System

all practical systems can be said to be real-time systems because they must produce an output or respond to the user’s commands within a reasonable amount of time.

However a small delay is bearable.

(insurance company responding to letters, word processor displaying what was typed on the screen, mobile phones responding)

Types of Real Time System Hard Real Time System

Systems where failure to meet response time constraints leads to catastrophic system failure.

Modern world interested in these systems.

(aircraft crashing, car skidding, patient dying before corrective action is performed)

Single user/Single tasking OS

One user works on the system

Performs one task at a time

Single user/Single tasking OS

One user works on the systemPerforms one task at a timeMS-DOS and Palm OSTake up little space on diskRun on inexpensive

computers

Single-user/multitasking

User performs many tasks at onceMost common form of OS

Single-user/multitasking

They are popularly associated with Desk Top operating system which run on standalone systems where no user accounts are required.

Single-user/multitasking

They may run different types of

operating systems, including DOS, Windows, and Mac OS. Linux and UNIX operating

Operating System can take control

back from the running process and can give it to other.

Single-user/multitasking

Single-user/multitasking

When one job needs to wait for I/O, the processor can switch to the other job

Multi user/multitasking

Allows two or more users to run

programs at the same time.Many users connect to one computerThe operating system keeps

several jobs in memory simultaneously

Some operating systems permit hundreds or even thousands of concurrent users.

Multi user/multitasking

Each user has a unique session.

Requires a powerful computer

MAINFRAME

Multi user/multitasking

Time sharing System

Time-sharing or multitasking is a logical extension of multiprogramming.

Provide advantage of quick response.

Reduces CPU idle time.

Time sharing System

When the time runs out, the process is interrupted, and another process is

loaded into the CPU.

The act of giving each process a small slice of time to run is called time slicing.

CPU Time Slicing for Time Sharing

CPU

Process 1

Process 3

Main Memory

Process 2CurrentProcess

Repeat until all processes have completed.

Allocate CPU to Process 1

Allocate CPU to Process 2

Allocate CPU to Process 3