Chapter 5

Chapter 5: Type of Utility Programs and Operating Systems

In a computer, we need a system software to control operations of computer. It is defined as a type of computer program that is designed to run a computer's hardware and application programs.

Types of system software:
A) Operating system (OS)- software that support a computer's basic functions and coordinate all activities among computer hardware resources.
For example:
1) Start and shut down a computer- process of it is called booting and contain two types which is cold boot (turn on a computer that has been powered off completely) and warm boot (using the operating system to restart a computer). Also include different shut down options such as sleep mode (saves any open documents and programs to RAM, turns of all unneeded functions and places the computer in low power state) and hibernate mode (saves any open documents and programs to hard disk before removing power from computer). How a pc boot can be refer below.
2) Provide a user interface- control how user enter data and instructions and how information is displayed on the screen. Such as graphical user interface (GUI) (allows interaction by menu and visual images) and command line interface (uses the keyboard to enter data and instructions shown in text only).
3) Manage programs- allow single user and multi user, single tasking and multitasking, foreground and background, preemptive multitasking and multiprocessing.
4) Manage memory- optimises the use of RAM and virtual memory (a portion of storage medium functioning as additional RAM).
5) Coordinate tasks- determines the order in which tasks are processed.
6) Configure devices- by the means of driver (a small program that tells operating system how to communicate with a specific device) and plug and play (automatically configures new devices as user install them).
7) Establish an internet connection- provide a means to establish an internet connection.
8) Monitor performance- a program that assesses and reports information about various computer resources and devices.
9) Provide utilities- provide utilities such as file manager, search utility.
10) Automatic update- automatically provides update to the program.
11) Control a network- contain server operating system (organise and coordinate how multiple users access and share resources on a network).
12) Administer security- allows user to create multiple user account with or without password.

B) Utility programs- a type of system software that allows a user to perform maintenance type tasks.
For example:
1) File manager- a utility that perform function related to file management.
2) Search utility- a program that locate a file on computer based on criteria that user specify.
3) Image viewer- allows user to display, copy and print graphics file.
4) Uninstaller- removes a program and its associated entries in the system file.
5) Disk cleanup- searches and removes unnecessary files such as downloaded program files, temporary internet files, deleted files and unused program files.
6) Disk defragmenter- reorganises the files and unused spaces on hard disk for better performance.
7) Backup utility- allow users to copy file to another storage medium.
8) Restore utility- returns backed up files to their original form.
9) Screen saver- show moving image or blank screen after a period of inactivity.
10) Firewall- detects and protects computer from unauthorised intrusions.
11) Antivirus- protects a computer against viruses such as worm (replicate itself and will take up hard disk space and internet bandwidth), virus (intend to damage a computer) and trojan horse (hides itself from antivirus detection and steal information).
12) Spyware remover- detects and deletes spyware (program placed on a computer without the user's knowledge that secretly collects information about the user)
13) Adware remover- detects and deletes adware (display an online advertisement in a banner or pop-up window).
14) Filters- programs that remove or block certain items from being displayed. For example, web filtering software, anti-spam programs, phishing filters and pop-up blockers.
15) File compression- shrink the size of a file in the format of zip. or rar.
16) Media player- view image, animation, listen to audio and watch video files on computer.
17) Disc burning software- write text, graphics, audio and video files on a recordable or rewritable optical disc.
18) Personal computer maintenance utility- identifies and fixes operating system problems, disk problems and improving a computer's performance.

Types of operating system:
A) Stand alone operating system- a complete operating system.
For example:
1) Windows 7
2) Mac OS X
3) UNIX
4) Linux

B) Server operating system- specifically designed to run on servers.
For example:
1) Windows server 2008
2) UNIX
3) Linux
4) Solaris
5) NetWare

C) Embedded operating system- specialised OS for use in computers built into larger systems.
For example:
1) Windows Embedded CE
2) Windows Phone 7
3) Palm OS
4) iPhone OS
5) BlackBerry
6) Google Android
7) Embedded Linux
8) Symbian OS

Continue from start and shut down a computer, we will talk about how a pc boot step by step.
1) Power supply send signal to the component in system unit.
2) Processor find the ROM chip that contain BIOS (Basic Input/ Output System).
3) The BIOS performs the POST (Power On Self Test) which checks components such as mouse, keyboard and adapter cards.
4) Results of POST are compared with data in a CMOS (Complementary Metal-Oxide Semiconductor).  This is to ensure that the condition of the components are in good condition to prevent any failure of component. Because if certain components are not in good condition when POST, the computer will failed to boot into operating system to ensure safety.
5) The BIOS may look for system files on a USB flash drive or on an optical disc or may look directly on drive C (hard disk). Normally the system files are saved on hard disk.
6) The system files and kernel (a computer program that constitutes the central core of a computer's operating system, it act as an interface between application software and hardware of computer such as device, CPU and memory) of the operating system load into memory RAM from storage.
7) The operating system loads configuration information, may request user information, starts several background processes and display the desktop on the screen.