CTIS 155 – Information Technologies I

Chapter 4 “System Software”

System Software

System software includes ALL of the programs

needed to keep a computer + its peripheral

(çevre birim) devices running smoothly.

Same of the system software works behind thescene, some of it requires user guidence and control.

System Software has 2 major components

Operating Systems (OS)

System Utilities provide various maintenance functions

2CTIS 155 – Fall 2009-2010

System Software

The more you know about and understand the operating system, the better your computer will serve you.

Thus, it is NOT usual to set up/reinstall OSs so frequently.

3CTIS 155 – Fall 2009-2010

The Operating System (OS):

The operating system is a set of programs that perform certain basic functions with a specific type of computer.

Its most important role lies in coordinating the various functions of the computer’s hardware.

An operating system performs 5 basic functions. 1. starts the computer,

2. manages applications, (i.e., Application Software)

3. manages memory,

4. handles messages from input and output devices,

5. provides the user interface (i.e., GUI, CLI)

The OS is most often found on a hard disk.4CTIS 155 – Fall 2009-2010

Can you give an example of an OS that is NOT found on a hard disk?

CTIS 155 – Fall 2009-2010 5

The Operating System (OS):

1. Function Starting the computer

When you start a computer, it loads the OS into the computer’s RAM. (To load = transfer something from a storage device to memory)

RAM is a form of temporary storage that is very fast, but that is volatile.

The process of loading the operating system to memory is called booting. 2 types of booting:

With a cold boot, you start a computer that is NOT already on.

With a warm boot, you restart a computer that is already on. Warm boots are often necessary after installing new software or after an application crashes or stops working.

6CTIS 155 – Fall 2009-2010

1. Function Starting the computer

Cold Boot

CTIS 155 – Fall 2009-2010 7

Warm Boot

Ctrl+Alt+Del in Windows Sysems

or reset button

1. Function Starting the computer

8CTIS 155 – Fall 2009-2010

or +

The kernel is the central part of the OS that starts applications,

manages devices and memory and performs other essential functions.

Resides in memory at all times, so it must be kept as small as possible.

1. Function Starting the computer Cold/Warm

Boot

Step-by-Step Process

9CTIS 155 – Fall 2009-2010

BIOS is

loaded

Power-on

Self-test is

completed

Operating

System is

loaded

System

configuration

is

accomplishedSystem

Utilities are

loaded

Users are

authenticated

1. Function Starting the computer Cold/Warm

Boot

Step 1:the BIOS and setup program

When you first turn on or reset a PC, electricity flows from the power supply through the CPU, which resets and searches for the BIOS (basic input/output system) .

The BIOS is the part of the system software that equips the computer with the instructions needed to accept keyboard input and display information on the screen.

CTIS 155 – Fall 2009-2010 10

1. Function Starting the computer Cold/Warm

Boot

The BIOS is encoded, or permanently written, in the computer’s ROM. ROM (read only memory), is a kind of memory that is nonvolatile.

Programs such as the BIOS that are encoded in ROM are meant to be reliably used over and over again.

BIOS screen: a text-only screen that provides information about the BIOS.

You can access the computer’s setup program by pressing a special key, such as Del or F8. The setup program includes settings that control the computer’s hardware.

You should NOT alter or change any of these settings unless you are instructed to do so.

CTIS 155 – Fall 2009-2010 11

1. Function Starting the computer Cold/Warm

Boot

CTIS 155 – Fall 2009-2010 12

1. Function Starting the computer Cold/Warm

Boot

Step 2: The power on self test (POST)

After the BIOS instructions are loaded into memory, a series of tests are conducted to make sure that the computer and associated peripherals are operatingcorrectly. These tests are known as the POST.

Among the components tested are the computer’s main memory (RAM), keyboard, mouse, disk drives and hard disk.

CTIS 155 – Fall 2009-2010 13

1. Function Starting the computer Cold/Warm

Boot

If any of the power-on self-tests fail, you will hear a beep, see an onscreen error message and the computer will stop.

You often correct such problems by making sure that components, such as keyboards, are plugged securely.

Some failures are so serious that the computer cannot display an error message; instead it sounds a certain number of beeps. If this happens, call for technical support. Write down any error message appear in the screen.

CTIS 155 – Fall 2009-2010 14

1. Function Starting the computer Cold/Warm

Boot

Step 3: The operating system loads

Once the POST is successfully completed, the BIOS initiate a search for the operating system.

Options (or settings) in the setup program determine where the BIOS looks for the OS.

When the BIOS finds the operating system, it loads the operating system’s kernel into the memory. At that point, the OS takes control of the computer and begins loading system configuration

information. CTIS 155 – Fall 2009-2010 15

1. Function Starting the computer Cold/Warm

Boot

Step 4: System Configuration

In Microsoft Windows, configuration information about installed peripherals and software is stored in a database called the registry. The registry also contains information about your system configuration choices, such as background graphics and mouse settings.

Once the operating system’s kernel has been loaded, it checks the system’s configuration to determine which drivers and other utility programs are needed.

CTIS 155 – Fall 2009-2010 16

1. Function Starting the computer Cold/Warm

Boot

A driver is a utility program that makes a peripheral device function correctly.

If a peripheral device that is already installed on the system requires a driver to operate, that peripheral’s driver will be installed and loaded automatically. If the driver is missing, you may be prompted to insert a disk containing the needed driver.

Operating systems are equipped with Plug-and-Play (PnP) capabilities, which automatically detect new “PnP-compatible” peripherals that you may installed while the power was switched off, load the necessary drivers, and

check for conflicts with other devices. (i.e., USB, Firewire)

CTIS 155 – Fall 2009-2010 17

1. Function Starting the computer Cold/Warm

Boot

Step 5: Loading System Utilities

Once the operating system has detected and configured all of the system’s hardware, it loads system utilities such as speaker volume control, antivirus software.

You can access additional “system configuration choices” in the Control Panel in MS Windows Systems.

CTIS 155 – Fall 2009-2010 18

1. Function Starting the computer Cold/Warm

Boot

Step 6: Authenticating Users

When the operating system finishes loading, you may see a dialog box asking you to type a username and a password.

This process

authentication (or login), you verify that you are indeed the person who is authorized to use the computer.

CTIS 155 – Fall 2009-2010 19

1. Function Starting the computer Cold/Warm

Boot

In OSs you can set up profiles. Associated with a username and optionally a password, a profile is a record of a specific user’s preferences for the desktop theme, icons and menu styles.

You can also enable other users to create and log on to their profiles, and they will see their preferences without disturbing yours.

On multi-user computer systems such as in a university lab, you must have an account to access a computer. Your account consists of your username and password and your storage space, which is called a home directory.

The account is usually created by the computer’s system administrator, the person who is responsible for managing the use of the computer in multi user systems.

At the end of this process, the user interface starts, enabling user interaction with computer programs.

CTIS 155 – Fall 2009-2010 20

2. Function Managing Applications

When you start an application,

Application @ storage Application @ RAM

In the old days, single-tasking operating systems run one application program at a time.

You have to wait that application to be completed

Today, multi-tasking operating systems have the ability to run more than one application program at a time.

CTIS 155 – Fall 2009-2010 21

2. Function Managing Applications

In multi-tasking, the computer does NOT actually run two applications at once, RATHER, it switches between them as need.

The satibility of an OS How it handles the multi-

tasking

Multitasking is accomplished by:

A foreground application – The active program or program in use

One or more background applications – Inactive program(s) or program(s) not in use

CTIS 155 – Fall 2009-2010 22

2. Function Managing Applications

A better and a recent multitasking technique

Preemptive multitasking – Enables the operating system to regain control if an application stops working

Lose the unsaved data

But it prevents that the entire system would be down

CTIS 155 – Fall 2009-2010 23

What is the access rate (speed) of a typical RAM (say DDR2) and a typical hard drive (say SATA disk)?

And compare them.

CTIS 155 – Fall 2009-2010 24

The Operating System (OS):

3. Function Managing Memory

CTIS 155 – Fall 2009-2010 25

3. Function Managing Memory

Computers use a temporary storage medium, called memory, to function as a buffer (tampon,

arabellek).

The OSs are responsible for managing memory.

The OS allocates memory areas for each running program; it keeps programs from interferingwith each other.

The OS uses virtual memory (VM), a method of using the computer’s hard disk as an extension of random access memory (RAM).

CTIS 155 – Fall 2009-2010 26

3. Function Managing Memory Virtual Memory

In VM, program instructions & data are divided into units of fixed size called pages.

If memory is full, the OS starts storing copies of pages in a hard disk file called the swap file, which is a temporary storage space for bits & bytes.

When the pages are needed, they are copied back into memory. The transferring of files from storage to memory & back is called paging.

It is better to upgrade the computer’s RAM, because disks are slower than RAM so, paging slows down the computer.

CTIS 155 – Fall 2009-2010 27

least recently

used data or

program instructions

page

swapped

out

swap

file

Virtual memory

management

hard disk

page

swapped

in

most recently

transferred data or

program instructions

memory

3. Function Managing Memory Virtual Memory

CTIS 155 – Fall 2009-2010 28

In a Windows System, you can change the size of the paging files

4. Function Handling Input and Output

OS should handle input/output and enable communication with input/output devices. Most OS come with the drivers to for the most popular I/O devices.

If not, you can find the associated drivers within the box you purchased or the web sites.

I/O devices generate interrupts (signals, that tell the operating system that something has happened).

A key stroke or a movement of the mouse Interrupts

The OS provides interrupt handlers (mini-programs that are invoked when an interrupt occurs).

CTIS 155 – Fall 2009-2010 29

4. Function Handling Input and Output

The communications between I/O devices and the CPU are handled by Interrupt request (IRQ) lines. Most PCs have 16 IRQs (from 0 to 15)

IRQ conflict may occur if two devices are configured to use the same IRQ

To remedy an IRQ conflict you may need to shut down the computer & remove peripheral devices, one by one, until you determine which one is causing the conflict.

CTIS 155 – Fall 2009-2010 30

5. Function Providing the User Interface

The user interface is that part of the operating system with which the user/human interacts with a computer.

User interfaces helps you:

Start application programs

Manage disks and files,

Shut down the computer safely

CTIS 155 – Fall 2009-2010 31

5. Function Providing the User Interface

Types of User Interfaces

1. Graphical User Interfaces (GUI)

2. Menu Driven

3. Command line (CLI)

CTIS 155 – Fall 2009-2010 32

5. Function Providing the User Interface

Graphical user interface (GUI):

Uses graphics to create a desktop environment

Icons (small pictures) represent computer resources

Programs run within on-screen windows

You can give commands

Mouse clicks, drag-and-drop movements, pull-down menus, dialog boxes

CTIS 155 – Fall 2009-2010 33

5. Function Providing the User Interface

Graphical user interface (GUI):

CTIS 155 – Fall 2009-2010 34

4. Function Providing the User Interface

Command-line:

The user is required to type keywords or commandsin order to enter data or give instructions

You must observe complicated rules of syntax that specify exactly what you can type in a given place.

CTIS 155 – Fall 2009-2010 35

4. Function Providing the User Interface

Menu-driven User Interface:

Text-based menus are used to show all of the options available to the user

CTIS 155 – Fall 2009-2010 36

Exploring Popular Operating Systems

CTIS 155 – Fall 2009-2010 37

WINDOWS XP

MAC OS XWINDOWS NT

WINDOWS CE

Exploring Popular Operating Systems

CTIS 155 – Fall 2009-2010 38

MS-DOSLINUXUNIX

Microsoft Windows

CTIS 155 – Fall 2009-2010 39

Windows 1.0 (1985)Windows 2.0 (1987)Windows 3.x (1990-1992)Windows NT (1993)Windows 95 (1995)Windows 98 (1998)Windows 2000 (2000)Windows ME (2000)Windows XP (2001)

Microsoft Windows XP

CTIS 155 – Fall 2009-2010 40

Released in 2001 by Microsoft

XP is short for “experience”, reflecting Microsoft’s view that users want computers with rich audio and visual features.

Uses the same underlying code for all versions

Replaces all previous versions of Windows

Three versions:

Windows XP Home Edition

Windows XP Professional

Windows XP Server

Microsoft Windows NT

CTIS 155 – Fall 2009-2010 41

Released in 1993 by Microsoft

Designed for client/server systems

2 components:

Windows NT Workstation

Designed for individual desktop computers.

Windows NT Server

Oriented to business needs

Offers

security,

remote administration,

directory services,

Web server

Microsoft Windows CE

CTIS 155 – Fall 2009-2010 42

Light version of Windows for simplified versions of Office applications

For mobile Computing

Released in 1996 by Microsoft

Windows Embedded Compact

System used in PDAs or palmtops

Runs simplified versions of Windows programs

Data can be transferred to PCs

Includes handwriting and voice recognition

Mac OS

CTIS 155 – Fall 2009-2010 43

Released in 1984

1st OS to use GUI

Easiest operating system for beginners

Could not be capitalized on its lead

@year 2000 Mac

OS X

UNIX

CTIS 155 – Fall 2009-2010 44

Developed by AT&T in 1970s

Is a pioneering OS that continues to define what an OS should do & how it should work

Included first preemptive multitasking system, designed to work efficiently in a secure computer network.

Developed concepts of file management and path names

Facilitates client/server networking

Widely used by corporations

Lack of compatibility among the many different versions. It’s difficult to use.

Linux

Introduced by Linus Torvalds (Finnish Student) in 1991.

Expecting that Linux would be free alternative to UNIX.

Is then further developed by thousands of programmers.

Linux is open-source software

Powerful like UNIX

But free

CTIS 155 – Fall 2009-2010 45

Linux

CTIS 155 – Fall 2009-2010 46

Screenshot of Debian 5.0

System Utilities: Tools for Housekeeping

System utilities (=utility programs) are programs that help the operating system manage the computer system’s resources.

Keep the system running smoothly

Types of utilities:

Backup software

Antivirus software

File-searching software & File management

Disk scanning

Disk defragmentation

File compression

CTIS 155 – Fall 2009-2010 47

Backup software

Includes programs that enable the user to copy data from the hard disk to another storage medium. If the hard disk fail, you can recover the data from the backup disk.

Types of backups:

Full backup: “a mirror image” is made of the entire hard disk’s contents

Incremental backup: the backup software copies only those files that have been createdor changed since the last backup occurred

CTIS 155 – Fall 2009-2010 48

Backup software

Even if you do NOT have backup software, you can still make backup copies of your important files.

Assignments

Projects

Previously written code segments

etc

CTIS 155 – Fall 2009-2010 49

Antivirus Software

Antivirus software protects the computer from computer viruses.

Such software uses a pattern-matchingtechnique that examines all of the files on a disk, looking for virus code “signatures”.

One limitation of antivirus software is that they can detect only those viruses whose “signatures” are in their databases

Most antivirus programs enable you to download the signatures of new viruses from the web site, if your system becomes infected by a virus that’s not in the system’s database, it may not be detected

CTIS 155 – Fall 2009-2010 50

Antivirus Software

CTIS 155 – Fall 2009-2010 51

Searching and Managing Files

CTIS 155 – Fall 2009-2010 52

“My Computer” in Windows

“File Manager” in Mac OS X

Searching and Managing Files

CTIS 155 – Fall 2009-2010 53

Scanning and Cleanup

Disk-scanning utilities are programs that detect and fix physical and logical problemson storage devices.

Scanning programs look for a physical problem involving an irregularity on the disk’s surface that results in a bad sector, which is a portion of the disk that is unable to store data reliably.

The scanner can fix the problem by locking out the bad sector so that it’s no longer used.

CTIS 155 – Fall 2009-2010 54

Scanning and Cleanup

Logical problems are usually caused by a power outage that occurs before the computer is able to finish writing the data to the disk.

Disk cleanup utilities are programs that remove files that are no longer needed.

In Windows Systems

Start Programs Accessories System Tools

CTIS 155 – Fall 2009-2010 55

Disk defragmentation

As you use the computer, it creates & erases files on the hard disk. The result is that the disk is soon becomes a patchworkof files, with portions of files scattered here and there.

This slows disk access because the system must look in several locations to find all of a file’s segments

CTIS 155 – Fall 2009-2010 56

Disk defragmentation

A disk defragmentation program moves data on a storage device to improve performance.

CTIS 155 – Fall 2009-2010 57

A file compression utility

A file compression utility reduces the size of a file by as much as 80% without harming the data lossless

Compression enables faster downloads, but you must decompress a file after downloading it.

Most compression utilities can create archives, which is a single file stored in a special format.

CTIS 155 – Fall 2009-2010 58

Data Compression Techniques:

1. Lossless and 2. Lossy compression

25.888888888

In a lossy system, using

25.[9]8 Interpreted as, "twenty five point 9 eights", the original string is perfectly recreated, just written in a smaller form.

In a lossy system, using

26 instead, the exact original data is lost, at the benefit of a smaller file size.

CTIS 155 – Fall 2009-2010 59

A file compression utility

CTIS 155 – Fall 2009-2010 60

System Update

Windows Update keeps the operating system up to date with any fixes or protections against external environment changes.

windowsupdate.microsoft.com

The updates will fix problems with the original version of the OS & will oftentimes provide protection against viruses and worms

CTIS 155 – Fall 2009-2010 61

Troubleshooting (sorun giderme )

System slowdown:

But not limited to...

Scan for viruses.

Check the CPU fan.

Check BIOS options.

Defragment the hard disk

CTIS 155 – Fall 2009-2010 62