unit notes - kingscliff & murwillumbah it...what an operating system is, what it can do for the...

Unit Notes

ICAICT302A Install and optimise operating system software

Topic 1 – Determine the functions of

operating systems

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© Copyright, 2012 by TAFE NSW - North Coast Institute

Date last saved: 31 August 2012 by Tracy Norris Version: 1.1 # of Pages = 5

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Acknowledgements:

Project Manager: Julie Board

Instructional Design: Tracy Norris

Graphic Design: Mark Keevers (Template design)

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Table of Contents Table of Contents ............................................................................................................... 3

Getting Started ................................................................................................................... 4

Using these notes ................................................................................................................ 4

Introduction ........................................................................................................................ 4

Topic 1 – Determine the functions of operating systems ............................................... 5

The User Interface .............................................................................................................. 5

Identify and describe the functions ....................................................................................... 6

Operating system functions .............................................................................................. 6

Classes of Operating Systems ............................................................................................. 7

More Detailed OS Functions ............................................................................................. 8

The Boot Process ................................................................................................................ 8

Memory management .......................................................................................................... 9

Virtual memory ................................................................................................................... 10

Learning Activity 1: Changing Virtual Memory .............................................................. 10

File Management ............................................................................................................... 11

Partitioning ......................................................................................................................... 11

Example ...................................................................................................................... 12

Formatting .......................................................................................................................... 13

High-level formatting ................................................................................................... 13

Summary .......................................................................................................................... 14

Check your understanding ................................................................................................. 14

Learning Activity 1.2: Practice ............................................................................................ 15

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Getting Started These unit notes have been developed to provide a learning pathway to competence in ICAICT302A Install and optimise operating system software.The notes contain all the skills and knowledge learning required to achieve competence.

Using these notes

Icons and symbols are used throughout this guide to provide quick visual references. They indicate the following:

Icon Meaning Icon Meaning

ACTIVITY: An activity is listed to be completed

ACTIVITY: A Learning activity requiring some physical action

WWW: A web link is listed REFLECTION: A point is to be considered and thought about more deeply

IMPORTANT: A pivotal point is detailed

SEARCH: A particular item / book etc needs to be found and applied

Introduction Welcome to ICAI3020B - Install and optimise operating system software. This unit will help you to understand the purposes, functions and types of operating system (OS) used in the computing industry today. There are two types of software: system software and application software. An important part of the system software is the set of programs called the operating system. The operating system controls how the computer functions, whereas application software is used to perform particular tasks e.g. word processing, spreadsheet, etc. The operating system loads, stores, executes programs and transfers data among devices and memory. For a computer to operate, an operating system must be stored in its memory.

You will become familiar with various terms and technical specifications to allow you to recommend various operating systems. You‘ll learn how to install one and to optimise it to work more efficiently. You‘ll also be introduced to user training regarding operating systems and learn how to evaluate the acceptance of a new system by the end-users.

You‘ll do some tasks for a Case Study IT company, BIOS Solutions, which will allow you to demonstrate your skills and knowledge in installing and optimising operating system software. You will have the choice of your own case study as well.

To do these tasks you‘ll need these elements:

1. Determine function of operating systems. 1.1. Identify and demonstrate understanding of the purposes of the operating system 1.2. Distinguish between batch system, real-time system, multi-tasking system 1.3. Compare and contrast different operating systems and their features 1.4. Identify and demonstrate understanding of the basic functions of operating system,

including file system, memory management, process scheduling 1.5. Identify and demonstrate management of virtual memory

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2. Obtain an operating system. 2.1. Contact operating system vendors to obtain technical specifications and system

requirements 2.2. Identify the process and steps required to install and configure the operating system

using installation components 2.3. Document adjustment recommendations and provide to appropriate person 2.4. Determine and apply knowledge of licensing, hardware and security requirements

3. Install, configure and optimise an operating system. 3.1. Install, configure and test operating system using installation components and boot-

utility 3.2. Use the relevant operating system user interface to correctly configure the

installation 3.3. Optimise the system to meet organisational requirements 3.4. Document the system according to organisational requirements 3.5. Install the operating system with minimal disruption to client or users

4. Provide instruction to meet new software requirements. 4.1. Provide one-to-one instruction about changes to the client or users as required 4.2. Obtain client evaluation about new system to ensure requirements are met, using

appropriate feedback mechanism

Topic 1 – Determine the functions of operating systems After completing this topic you will be able to:

Identify and demonstrate understanding of the purposes of the operating system.

Distinguish between batch systems, real time systems and multi-tasking systems.

Identify and demonstrate understanding of the basic functions of an operating system, including file systems, memory management, process scheduling and virtual memory.

The User Interface The user interface determines how you will interact with the computer. It controls how information is presented to you on screen and how you enter data and commands. Most operating systems use a graphical user interface (GUI) which provides visual clues such as icons to help a user. Otherwise there is a command line interface which requires knowledge of commands to use the computer.

Figure 1 – The GUI (pronounced ―gooee‖) or Graphical User Interface of MS Windows 7 operating system

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Figure 2 - a Command Line Interface

Identify and describe the functions

When you have turned on the switch to activate or ―boot‖ your computer, it probably made various noises, displayed information on the computer screen that indicated what the computer was doing and eventually stopped at a screen that was familiar to you such as Microsoft Windows®, Linux, MAC OS, Ubuntu or your game console screen.

It is the Operating System which causes your computer to work and run through these routines which interact with attached devices and perform shared functions such as to print a document when you choose ―print‖ button in your application software. The operating system does disk management tasks, too, such as saving or retrieving files to/from your computer disks and external storage devices. It can also analyse problems with your computer.

Examples of popular modern operating systems for personal computers are Microsoft Windows Vista, Windows 7, Mac OS X and the Linux-based Ubuntu. Examples of popular operating systems for networked computers are Unix, Novell, NetWare and Microsoft Windows Server 2008.

Nearly every computer needs some way of communicating between the user of the computer and the various devices the computer has, such as a keyboard, mouse, modem, pointing device, CD/DVD drive, etc. This is one of the tasks of the Operating System.

Regardless of the IT area you may decide to specialise in, you will need some knowledge of what an operating system is, what it can do for the end user, what its various features are, and how it functions. You will also need to know why some operating systems are better suited to some industries and not to others.

Operating system functions While you work in your computer‘s applications, the operating system works in the background and provides the resources such as memory, disk space and processing time. Here are some of an operating system‘s functions:-

It allocates resources to the applications that are running.

It provides the utility programs required to manage the hardware by analysing, configuring, optimizing and maintaining the computer

It facilitates communication between the hardware (such as the keyboard, disk drives, internal memory, video monitors and other

Figure 3 - the operating system is an interface between a user and the hardware

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peripheral devices like your digital camera or your MP3 player or smartphone.

It manages the scheduling of tasks (such as an automatic backup you might set off to run at a particular time).

It facilitates communication with other computers on a network or the Internet.

Classes of Operating Systems

There are also various classes of operating systems, each with its own characteristics.

Real-time Operating System

It is a multitasking operating system that aims at executing real-time applications. Real-time operating systems often use specialized scheduling algorithms so that they can achieve a deterministic nature of behaviour. The main object of real-time operating systems is their quick and predictable response to events. They either have an event-driven or a time-sharing design. An event-driven system switches between tasks based on their priorities while time-sharing operating systems switch tasks based on clock interrupts.

Multi-user and Single-user Operating Systems

The operating systems of this type allow multiple users to access a computer system concurrently. Time-sharing system can be classified as multi-user systems as they enable a multiple user access to a computer through the sharing of time. Single-user operating systems, as opposed to a multi-user operating system, are usable by a single user at a time. Being able to have multiple accounts on a Windows operating system does not make it a multi-user system. For a Unix-like operating system, it is possible for two users to login at a time and this capability of the Unix OS makes it a multi-user operating system.

Multi-tasking and Single-tasking Operating Systems

When a single program is allowed to run at a time, the system is grouped under a single-tasking system, while in case the operating system allows the execution of multiple tasks at one time, it is classified as a multi-tasking operating system. Multi-tasking can be of two types:- namely pre-emptive or co-operative. In pre-emptive multitasking, the operating system slices the CPU time and dedicates one slot to each of the programs. Unix-like operating systems such as Solaris and Linux support pre-emptive multitasking. Cooperative multitasking is achieved by relying on each process to give time to the other processes in a defined manner.

Distributed Operating System

An operating system that manages a group of independent computers and makes them appear to be a single computer is known as a distributed operating system. The development of networked computers that could be linked and communicate with each other, gave rise to distributed computing. Distributed computations are carried out on more than one machine. When computers in a group work in cooperation, they make a distributed system.

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Embedded System

The operating systems designed for being used in embedded computer systems are known as embedded operating systems. An embedded system is a computer system designed to perform one or a few dedicated functions often with real-time computing constraints – an Automatic Teller Machine is an example. Embedded systems include PDAs (Personal Digital Assistants), cash registers, GPS devices, MP3 players, traffic lights – all systems with less autonomy. They are able to operate with a limited number of resources. They are compact and extremely efficient by design. Windows CE, FreeBSD and Minix 3 are some examples of embedded operating systems.

Batch Systems and Real-Time Systems

Batch processing is the process in which data is collected, and at some later time, all the data that has been collected is processed as a group. An example of batch processing is the case of a business which processes its accounts on weekly or monthly intervals.

Real-time processing refers to systems that perform one task at a time and update a central database instantly. Automatic Teller Machines are real-time systems. If you make a withdrawal, your balance is debited immediately. Airline booking systems are real-time too.

More Detailed OS Functions We have discussed the purpose and types of an operating system. We now need to discuss in more detail the different functions that an operating system can perform.

The Boot Process

One of the more critical functions of the operating system is in ‗booting up‘ (starting) your computer. Let‘s look (briefly) at the steps in this process in relation to a personal computer using the older MS-DOS operating system. (In other operating systems the process is basically the same; however some of the file names used are different and may perform extra or other functions.)

When your computer is first turned on, it uses a special piece of hardware/software called the BIOS (Basic Input Output System). The BIOS is generally stored on a ROM (Read Only Memory) microprocessor chip stored on your computer‘s motherboard. This chip has instructions on it to tell the computer to perform a Power On Self-Test (POST). The POST tests for the existence of various devices on your computer and ensures that they are working properly. (That is why you see the lights on your keyboard light up momentarily when the computer is first turned on.)

Once the POST has finished, and assuming that everything to this point is working correctly, the BIOS looks for a small program called a Bootstrap Loader stored on a hard disk or even on a ‗bootable‘ Compact Disk (CD) or any other bootable medium, such as USB devices. The order of where to look for an operating system is stored in the CMOS (Complementary Metal Oxide Semiconductor). The CMOS is accessed by a user pressing certain keys on their keyboard while the computer is booting (generally <DEL> or <F1>). To determine what key to press, watch your computer screen during its start up. It will generally display something such as ‗Press DEL to access setup‘. Once you have accessed your CMOS you can change certain settings that will affect your computer‘s behaviour. A word of warning: Changing some items can cause your computer to stop working, so be careful!

The Bootstrap Loader program has basically one function: to load other parts of the operating system into the computer‘s memory so that it can be used. Eventually the

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

http://en.wikipedia.org/wiki/Real-time_computing

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Bootstrap Loader gives control of the computer to the rest of the operating system. These other parts of the OS include the File Management schemes, the Memory Management schemes and loading the different software drivers that communicate with the various devices.

The Bootstrap Loader program will then tell the system where to look for the first file in the (DOS) operating system, called IO.SYS. IO.SYS is then loaded into memory and it now takes over the boot process. It then looks for an operating system file called MSDOS.SYS. This is then loaded into memory and the system now looks for a programme called CMD.EXE, which then takes permanent control of the computer.

At this point the computer should basically be ready to accept input/output data from the attached devices and the user.

Memory management

One of the most important tasks that an operating system does is manage the memory requirements of your computer. We discussed earlier how current day operating systems are Multi User. This means that many users will be using the facilities of the computer at the same time, including its memory, to run their own tasks. Imagine if you had ten people sitting and working around your desk, and each of those people put their paperwork all over the desk. The desk would soon become unmanageable, with the paperwork hard to find or even lost. Eventually all ten people would probably not be able to complete their tasks. Somebody needs to take control and organise the chaos — on a computer this is one of the jobs of the operating system.

As an example consider the process of using your word processor on your computer. On your computer, you double-click an icon on your desktop to ‗load‘ the program. This double-click sends a signal to the operating system that you want to use this particular program. The operating system then makes a request to the CPU to retrieve a copy of the program from the computer disk. The CPU and operating system then find where on the disk this program resides and start to copy the program code from the disk into the computer‘s memory (RAM). Once the code is stored in memory, the CPU then executes the code and your program runs.

Once you have your word processor working, you may want to open up an existing document. To do this, the same process basically happens, where the document is loaded from the computer‘s hard disk into RAM, so again more storage space is required.

The problem with this scenario is that:

There must be enough memory available to store the program or data when it is retrieved.

The programs and data cannot overlap or use memory that is currently being used by other programs.

This is where the operating system needs to be a memory manager.

Memory chips in your computer are like the mailboxes found at your local post office. The operating system, when storing the data or program‘s bytes, stores them in these boxes. All of these boxes have an address (like the mailboxes). The CPU needs to know these addresses so it can retrieve and store the data when required. However, the operating system cannot store the data in addresses that are already filled. Part of the operating system‘s task is to determine whether the data that is in those boxes is still relevant — does the system or do the programs still require it? If not, then the operating system will discard the data and then use the now empty space. However, if the data is still required, then some other technique must be found.

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When you close a program or save and close a document, the operating system knows that you have finished using the file and/or program, so it automatically purges the program or file data from memory. This means that RAM is a temporary storage area. At some point in time whatever is in RAM will eventually be lost, especially when you turn the computer off.

Virtual memory

If your computer runs out of space to store data in physical RAM, the operating system must compensate for this somehow. (Remember that a multi-tasking system could have many programs and/or files open at once, each needing resource space such as physical memory.) Most operating systems do this by creating a ‗swap file‘ and Microsoft Windows uses this to store its ‗virtual memory‘.

When the computer‘s RAM chips run out of space, the operating system uses one of its programs called a Memory Manager. This Memory Manager sets up a large contiguous (there are no gaps) file on your computer‘s hard disk (Note that sometimes, this file can be fragmented and is called a temporary swap file). As the operating system determines that your physical memory is full, it moves some of the data/programs that it believes are not currently needed, but could be needed later, into the swap file on the hard disk. Because it is contiguous, the operating system knows exactly where this data is, if it needs to retrieve it again very quickly. The size of the amount of space used by the swap file can also grow and shrink, depending on system requirements and no other programme/file/document will ever be saved in the space being reserved as the swap file.

A problem with using a swap file is that it can slow down system performance because the data has be read from the disk when it is required and written to the disk when not needed. (There are not many moving parts within a computer, but there are in a hard disk — the disk itself that spins and the read/write heads that move backwards and forwards across the disk reading and writing the data. These moving parts always slow down access). Another problem with swap files occurs when the available space on a user‘s hard drive shrinks through normal use, e.g. saving programs and files. As the amount of free space on the hard disk reduces, the amount of space available for the swap file is also reduced, thereby degrading system performance significantly.

This virtual memory makes your computer think that it has more memory than it actually has. Fortunately, the average computer user doesn‘t have to worry about this, as it is handled automatically by the operating system and associated software programmes. Windows, Unix and Linux use this technique of having a swap file. Large mainframe computers use a similar technique called paging. The data that is moved in and out in these systems is called ‗pages‘. Linux actually creates an exclusive partition on your drive to use for swapping.

Learning Activity 1: Changing Virtual Memory Changing the virtual memory settings on your computer can cause it to stop working. You should only do this if you really understand the consequences. For this exercise we will simply walk through a process of looking at where it is configured on a Windows operating system. However, note that the process is basically the same for all versions of Windows including Windows 7.

1. Open the Control Panel on your computer by going to Start / Settings / Control Panel.

2. In the Control Panel look for your System icon and double-click it.

3. Click the Advanced tab.

4. Click the Settings button on the Performance option.

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5. Click the Advanced tab within the Performance Options box.

6. At the bottom of the performance box the Virtual Memory option is displayed. Click the Change button.

The resulting screen will display the settings for the virtual memory on your computer - the size of the swap file. Microsoft generally recommends that you allow Windows to control the size of your swap files. Do not change anything in these screens. Click the Cancel buttons until you have closed down the Control Panel.

File Management

One of the most used pieces of an operating system, file management refers to the way that the operating system manipulates, stores, retrieves and saves data on mass storage devices. Each time you install a program onto your computer, open and play a game, create and save a new document, delete an old document or simply copy files from your hard drive to a USB device, CD or DVD, etc, you are using the operating system file management programs. The operating system may also implement security on files and programs such as when a network operating system is used.

When files are stored on a mass storage device, these different devices can vary in their structure, e.g. a CD-ROM, a hard Disk, a tape, a USB flash drive. It is important therefore that the operating system knows how data can be stored on these devices as each has its own characteristics of storing data. However, the operating system will nearly always present the data on those devices to a user in a consistent view. That is, as folders and files in a directory structure.

For a device to be able to store and retrieve data it needs to be ‗set up‘ by the operating system to allow this. The techniques for setting up these devices vary slightly depending on the device. For this discussion, we will concentrate on a hard disk drive and the Microsoft disk operating system (MS-DOS), but note that the concepts for most mass storage devices with other operating systems are similar to what is discussed here.

Partitioning

When a hard disk drive (HDD) is first installed into a computer, and before it can be used, the operating system needs to create a partition/partitions on the drive. A HDD can have either only one partition or many partitions. A partition is simply the physical hard disk having an area or multiple separate areas to hold data. An analogy would be a large roomy office. The room could simply be used as one large office where everybody works together or we could use room partitions and divide the room into separate working areas. The end result is that we still have one physical room, but it is divided into smaller separate areas where each staff person would have their own private space.

Partitioning a hard drive is similar to this. In the DOS and Windows operating systems these

Figure 3 - System Properties for changing virtual memory

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separate areas of the HDD are identified by letters of the alphabet. If we have one physical HDD and only have one partition, then the drive is identified as the C: drive. If we partitioned the HDD into four separate areas, then each is identified by a letter of the alphabet, i.e. C:, D:, E:, F: etc, called logical drives. On a Linux and Unix system, (and generally on Windows NT and Windows Server 2003/8 systems) the separate areas are known as volumes and are identified by names rather than letters.

When the operating system creates these partitions, it creates a ‗partition table‘ on the very first track of the hard drive. During the POST, the operating system checks the partition table and verifies that they exist on the disk. If the operating system finds that the partition information is invalid, then the system normally stops and it will be unusable. If it finds the partition table to be valid, it checks to see which partition has been identified as the ‗active partition‘. The active partition is identified and created during the partitioning process. When an operating system is installed on the HDD, the active partition tells the operating system that this partition is the one to boot the computer from, e.g. if Windows was installed on the active partition then Windows would be the default operating system to load and run. If Linux was installed on the active partition, then Linux would be the operating system loaded. (Note that it is possible to have more than one operating system installed on a HDD in the different partitions. Some operating systems will recognise this and present the user with a menu from which they can select the operating system they want to load.)

Example

The screen below shows the results of running the MS-DOS FDISK program, and that the computer simply has one partition, identified as C: drive and it is marked ‗active‘. It also displays the size of the partition in megabytes and also the type of file system installed (FAT32).

Figure 4 - a screen from the Microsoft FDISK programme used for partitioning a HDD

Figure 5 - a Windows XP partitioning schema

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Figure 6 - an un-partitioned C: drive running Windows 7

Consider Figure 5 - This is a screenshot from the Windows XP partition programme. Note how it shows that the C: drive (where the mouse pointer is) on this system is the ‗system‘ partition and is the equivalent to an active partition in MS-DOS. Also note that the different shades of ‗blue‘ define the different types of partitions with the darker blue being the primary partition and the lighter blue being the logical drives - D: & E:.

Formatting

Once you have partitioned the HDD, the formatting process is now performed. Note that there are two types of formatting: low level and high level. Low level formatting is generally done before the HDD leaves the factory. Low level formatting divides the HDD into sectors (much like the pieces in a pie) and tracks (separate concentric circles on the disk surface). For our purpose, we will concentrate on what the average user can do — high-level formatting.

High-level formatting

High-level formatting of a HDD basically does four tasks:

1. Creates the sectors and tracks that are identified by the low level format. Each sector can hold about 512 bytes (characters) of data per track. Some operating systems allow this value to be increased. The first PC hard disks typically held 17 sectors per track. Today's hard disks can have thousands of sectors in a single track, and make use of zoned recording to allow more sectors on the larger outer tracks of the disk.

2. Creates a master boot record (MBR). The MBR holds data that tells the operating system about the structure of the disk. How many tracks, how many sectors, etc.

3. Creates an area on the first track, (the outside track) called the file allocation table (FAT). The FAT is like the index of a book. It holds information that tells the operating system where the data (your programs and documents) is physically stored on the disk. The format process actually creates two copies of the FAT, in case one of the copies is corrupted. (Each time you save or delete data from your disk, the operating system updates this table.)

4. Creates the first directory (folder) on the disk called the root directory. The root directory is simply the first directory on the disk. It is called the root directory because directory structures are like trees — every other directory that is created

Figure 7 - a disk platter divided into tracks and sectors

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on your disk ‗grows‘ from the root.

So how does the process work? Assume you are using your word processor and you open an existing document on your hard disk. When this happens, the application program tells the operating system that it wants to retrieve this document from the hard drive. The operating system then consults the FAT on the disk to determine the address of the file you want. (The address is basically the track and the sector where it is stored). Once the operating system knows where the file (or first part of the file) is located on the disk, it then directs the ‗actuator arm‘, (the piece of the hard drive that has the read/write heads) to move to that address on the disk and start retrieving the data. As the data is retrieved it is assembled into the correct order and sent to the CPU, which then displays it on the screen. Note that the file may be stored in many different sectors and tracks all over the disk, depending on its size. This is known as fragmentation. When a file is saved on a disk, the operating system looks for addresses which are not in use. Because you may have saved/deleted many files of different sizes over time, the disk will have empty addresses in different places all over the disk and the operating system simply uses these empty addresses to store the data. Non-contiguous sectors are the reason for defragmenting a disk, they slow the retrieval process down.

Summary Having completed topic 1, you should now be able to describe the functions of an operating system:

1. provides an interface for the end user to use their computer

2. manages the various system resources and devices without the end-user needing to manage them

3. brings the computer into an operating state so that it can be used by the end user.

Check your understanding

1. Choose the correct response to the statement: An operating system manages…

a. Computer memory requirements

b. Communication between the various computer devices

c. Storing and retrieving files for your computer

d. All of the above

2. Name at least three well-known operating systems.

3. What is a computer ‗BIOS‘?

4. What is the ‗File Allocation Table‘ (FAT)?

5. What is a ‗swap file‘?

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Learning Activity 1.2: Practice

Check The Windows Experience Index by going to Control Panel\All Control Panel Items\Performance Information and Tools. This measures the capability of your computer's configuration and expresses this measurement as a base score. A higher base score generally means that your computer will perform better and faster than a computer with a lower base score, especially when performing more advanced and resource-intensive tasks.

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