Operating Systems

Sara Mullan

Johns Hopkins University

Fall 2010

http://depts.alverno.edu/cil/mod1/software/images/syssoftpic.gif

Who is the manager of your computer?

The Operating System

Answer

What is an operating system?

What is an operating system?

• A software program which runs on a computer– Consists of programs and data

• Enables the computer hardware to communicate and operate with the computer software – Manager of resources

• Most important program which runs on a computer

When is an operating system loaded onto a

computer ?

First thingAnswer

How does an operating system help a computer?

• Basic Tasks: – Recognizing input– Sending output– Controlling peripheral devices (printers, disk

drives)

• Keep up with needs

• Interact with users

How does an operating system work?

• Allocation and assignment of system resources: – Input and output devices– Software – Central processing unit

• Scheduling: – Follows priority – Coordinates resources and jobs

• Monitoring: – Monitors and tracks activities in the computer system

What are an operating system’s tasks?

• Memory management

• Processor management

• Storage management

• Device management

• Application interface

• User interface

What are an operating system’s parts?

• Kernel – Controls low-level processes

• How information is sent and received• How to interpret information received • How memory is read and written

• User Interface– Interacts with the computer user directly

• User can control and use programs • May be graphical

• Application Programming Interfaces – Provide services and code libraries

Features

• Multi-user

– Two or more users can run the programs simultaneously

• Multiprocessing

– Enables a program to run on more than one CPU

• Multitasking

– Allows programs to run at the same time

• Multithreading

– Allows multiples parts of a program to run at the same time

• Graphical User Interface

– Contains graphics and icons

• Real Time

– Responds to input right away

History of Operating Systems

• Early computers were similar to a calculator. – Built to perform a series of single tasks– Could only execute one program at a time

• Operating Systems have continually evolved since the 1940s – Consumer needs – Changes in computer capabilities

Examples of Commonly Used Operating Systems

• Windows

• Mac OS

• Linux

• Unix

There are many other examples of operating systems.

Timeline

• 1971 – MULTICS was released by UNIX

• experimental operating system

• 1978 – development of Apple DOS 3.1 – first Apple operating system

• 1985 – Microsoft introduced Windows – overtook Mac OS

• 1991 – Linux began to create a new operating system kernel

Windows

• Developed by Microsoft

• Most popular PC operating system

• Windows 7 is the latest version released

• Security criticized by customers

• Default programs included

• Typical for the general consumer and a software developer

http://www.microsoft.com/windows/default.aspx?icid=winvan

Mac

• Developed by Apple

• Second most popular PC operating system

• Snow Leopard is the latest version released

• Default programs included

• Typical for picture and video editing http://www.findmysoft.com/news/The-Latest-Mac-OS-X-Malware-and-the-Apple-Security-Software-Recommendations/

Linux

• Developed by Linux Torvalds

• Alternative to Windows

• Gaining in popularity

http://www.fashionfunky.com/2007/08/linux_on_dell_in_europe.php

UNIX

• Originally developed in 1969 by a group of AT&T employees at Bell Labs

• Widely used in servers, workstations, and mobile devices

Comparing Apple and Microsoft

Name Creator First Public

Release

Latest Stable

Version

Cost Target System Type

Mac OS Apple Inc. 1984 2002 Yes Workstation, Personal computer

Mac OS X Apple Inc. 2001 2010 Yes Workstation, Personal computer, Embedded system

Mac OS X Server

Apple Inc. 2001 2010 Yes Server

Windows Server

(NT family)

Microsoft 1993 2009 Yes Server, NetApp, Embedded system, HPC

Microsoft Windows

(NT family)

Microsoft 1993 2009 Yes Workstation, Personal computer, Media center, Tablet PC, Embedded system

Microsoft Windows (Classic family)

Microsoft 1985 2000 Yes Personal computer, Media center

http://en.wikipedia.org/wiki/Comparison_of_operating_systems

Statistics on Usage

90% of the market share for operating systems for the personal computer is

Microsoft. Answer

Usage Share of Web Client Operating Systems

http://en.wikipedia.org/wiki/Usage_share_of_operating_systems

Market Share

http://www.moiz.co.uk/windows-7-market-share-up-to-10-percent

Pros

• Keep up with the needs which change over time

• Direct hardware access

• No coding necessary

• Security

• Made out of portable code.– This allows them to be changed or modified.

• Add an application, add a new security update

Cons

• Manufacturing costs increase

• Upgrades often needed

• Takes up memory and processing resources

• Additional security often necessary

Educational Connection

• Can use hardware and software resources • Controls your input and output• Share resources within among a group of users• Makes your job easier• Makes sure different users and programs don’t

interfere with each other when running at the same time

• Security – Makes sure unauthorized users don’t assess the

system

Work Cited

See attached Word document.