Lesson 4 - Operating Systems

Introduction

An operating system (OS) is the software component of a computer system that is responsible for the management and coordination of activities and the sharing of the resources of the computer. The OS acts as a host for application programs that are run on the machine. As a host, one of the purposes of an OS is to handle the details of the operation of the hardware. This relieves application programs from having to manage these details and makes it easier to write applications. Almost all computers use an OS of some type.

The Big 3

Common contemporary Os's include MicrosoftWindows, Mac Os X, and Linux.

Microsoft Windows has a significant majority of market share in the desktop and notebook computer markets, while the server and embedded device markets are split amongst several Os's.

Linux

Linux (also known as GNU/Linux) is one of the most prominent examples of free software and open source development which means that typically all underlying source code can be freely modified, used, and redistributed by anyone.

The name “Linux” comes from the Linux kernel, started in 1991 by Linus Torvalds. 

The system’s utilities and libraries usually come from the GNU operating system (which is why it is also known as GNU/Linux).

Linux is predominantly known for its use in servers. It is also used as an operating system for a wide variety of computer hardware, including desktop computers, supercomputers, video game systems, and embedded devices such as mobile phones and routers.

Windows

Windows (created by Microsoft) is the most dominant OS on the market today. The two most popular versions of Windows for the desktop are XP and Vista (Vista being the latest version). 

There is also a mobile version of Windows as well as a server version of Windows (the latest being Windows Server 2008).

 Windows is all proprietary, closed-source which is much different than Linux licenses. Most of the popular manufacturers make all of their hardware compatible with Windows which makes Windows operate and almost all kinds of new hardware. Windows has historically been a tempting target for virus creators because of its world market dominance. Security holes are often invisible until they are exploited, making preemptive action difficult. Microsoft has stated that the release of patches to fix security holes is often what causes the spread of exploits against those very same holes, as crackers figured out what problems the patches fixed, and then launch attacks against unpatched systems. It is recommended to have automatic updates turned on to prevent a system from being attacked by an unpatched bug.

OS X

OS X is the major operating system that is created by Apple Inc. Unlike its predecessor (referred to Classic or OS 9), OS X is a UNIX based operating system. Currently OS X is in version 10.5, with 10.5.3 being the last major software update and plans for 10.6 having been announced. Apple has chosen to name each version of OS X after a large cat with 10.0 being Cheetah, 10.1 as Puma, 10.2 as Jaguar, 10.3 as Panther, 10.4 as Tiger, 10.5 as Leopard, and the unreleased 10.6 named Snow Leopard.

Apple also develops a server OS X that is very similar to the normal OS X, but is designed to work on Apple’s X-Serve hardware. Some of the tools included with the server OS X are workgroup management and administration software that provide simplified access to common network services, including a mail transfer agent, a Samba server, an LDAP server, a domain name server, a graphical interface for distributed computing (which Apple calls Xgrid Admin), and others.

OS X is a UNIX based OS built on top of the XNU kernel, with standard Unix facilities available from the CLI. Apple has layered a number of components over this base, including their own GUI. The most notable features of their GUI are the Dock and the Finder.

QUIZ