CHAPTER 2 resume

To perform a specific task, a special type of computer program, known as an operating system (OS)is required,which controls input and output functions.
In addition, the entered data is manipulated inside of the computer, stored in RAM and processed by the CPU. This internal manipulation and processing is also controlled by the OS. All computerized devices, such as servers, desktops, laptops or handhelds, require an OS in order to function.

PURPOSE OF AN OPERATING SYSTEM

A user interacts with the computer system through an application, such as
word processor
spreadsheet
computer game or instant messaging program
Application programs are designed for a specific purpose, such as word processing, and know nothing of the underlying electronics.

The portion of the OS code that interacts directly with the computer hardware is known as the kernel

The portion that interfaces with the applications and user, is known as the shell

The CLI, the user interacts directly with the system in a text-based environment by entering commands on the keyboard at a command prompt.

The GUI interface allows the user to interact with the system in an environment that uses graphical images, multimedia, and text.

REDIRECTOR
To work with resources that are not directly connected to the computer system, a special piece of software must be added that allows a device to send and receive data from the network.
May either be an integral part of the OS or may need to be installed separately as a network client. When installed, the operating system becomes a network operating system (NOS).

OPERATING SYSTEM REQUIERMENTS
These resources are specified by the manufacturer and include such things as:
Amount of RAM
Hard disk space required
Processor type and speed
Video resolution

Choosing an appropriate OS requires many factors to be considered before deciding which one to use in a given environment.

SECURITY
SUPPORT
POLITICS
COST
AVAILABILITY
RESOURCES
PLATFROM
USE

Types of OS:
Microsoft Windows: XP, Vista, 2003 Server
UNIX-Based: IBM AIX, Hewlett Packard HPUX, and Sun Solaris
BSD - Free BSD
Linux-Based (Many varieties)
Macintosh OS X
Non-Unix Proprietary: IBM OS/400, z/OS

There are several operating systems released under a different type of licensing scheme known as the GNU Public License (GPL).

Windows XP, Mac OS X and UNIX are all examples of commercial OS software.

OS selection

determine the user requiermentes
determine choices and OS
technicaland financial resources available
other restrictions
implement selected OS

OS installation Methods:
CLEAN INSTALL
is done on a new system or in cases where no upgrade path exists between the current OS and the one being installed.

UPGRADE
With an upgrade, system configuration settings, applications and data are preserved. It simply replaces the old OS files with the new OS files.

MULTI-BOOT
It is possible to install more than one OS on a computer to create a multi-boot system.

VIRTUALIZATION
It enables multiple copies of an OS to be run on a single set of hardware, thus creating many virtual machines.

PREPARING OS FOR INSTALLATION

A pre-installation checklist helps ensure that the installation process is successful.

1. Verify that all hardware is certified to work with the selected OS.

2. Verify that the hardware resources meet or exceed the published minimum requirements.

3. Confirm that the appropriate installation medium is available. Due to the file size of current operating systems, they are usually available on both CD and DVD medium.

4. If the OS is to be installed on a system that already contains data: (a) Use system diagnostic tools and utilities to ensure the current OS installation is in good condition, free of malicious or damaging files and codes; (b) Complete a full backup of all important files.

5. If performing a clean-install, verify that all application software is available for installation.
BEFORE IT
One of the techniques available to help protect data is to divide the hard drive into multiple partitions
it's also necessary to determine the type of file system to use.

CONFIFURING FOR A NETWORK
3 parts to the IP configuration, which must be correct for the computer to send and receive information:
IP address - identifies the computer on the network.

Subnet mask - is used to identify the network on which the computer is connected.

Default gateway - identifies the device that the computer uses to access the Internet or another network.

COMPUTER NIC default gateway IP INTERNET


MANUAL IP CONF
network adm.

DYNAMIC IP CONF
server---------- ip adress----------subnet mask-------def gateway-----host

computer naming
A computer name provides a user friendly name, making it easier for users to connect to shared resources such as folders and printers on other computers.

NETWORK NAME AND ADDRESS PLANNING helps them to find you in case.

PATCHES
A patch is a piece of program code that can correct a problem or enhance the functionality of an application program or OS.

Patches to operating systems can be installed in different ways, depending on the OS and the needs of the user. Options for downloading and installing updates include:

Automatic installation
a computer automatically accesses a manufacture'sweb site bightly to check for any OS updates to install.

Prompt for Permission
the suer is available to decide not to install it based on reports of poor computer performance after installation.

Manual
to correct known functionality and security issues within and operating system