Computer Operating Systems

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ICT 100: Introduction to Information and Communications Technology Unit 3: Operating Systems
Objectives:        Define the term software Differentiate between system software and application software Define the terms operating system and utility program Identify the types of operating systems Explain the boot process of a computer Describe the functions of an operating system Identify common utility programs

Software, also called a program, consists of a series of related instructions, organized for a common purpose, that tells the computer what tasks to perform and how to perform them. The two categories of software are system software and application software.

System Software
System software consists of the programs that control or maintain the operations of the computer and its devices. System software serves as the interface between the user, the application software, and the computer’s hardware. It includes the following: 1. Operating Systems 2. Library Programs 3. Utility Programs

Operating Systems
An operating system (OS) is a set of programs containing instructions that work together to coordinate all the activities among computer hardware resources. Every computer needs an operating system to act as an interface between the user and the computer hardware. It allows the user to perform tasks without having to know how they are done. For example, a user can give a command to save a file on disk without having to know where the file will be stored or how it will be retrieved again. When a command is given to print a document, the user does not have to be concerned with the details of how the printer works – a program called a device driver takes care of the details.

ICT 100 – Operating Systems

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The operating system that a computer uses sometimes is called the platform. With purchased application software, the package or specifications identify the required platform (operating system). A cross-platform program is one that runs the same on multiple operating systems. Application programs are usually written to work with a particular operating system, so that a word processor, which works with Windows, will not work on an Apple Mac, which has a different operating system. When purchasing application software, ensure that it works with the operating system installed on your computer or mobile device.

The Bootstrap Process
The process of starting or restarting a computer is called booting. When turning on a computer that has been powered off completely, you are performing a cold boot. A warm boot is the process of using the operating system to restart a computer. A warm boot properly closes any running processes and programs; however, it does not save any unsaved work. Thus, always remember to save your work before rebooting (restarting) a computer. Each time you boot a computer, the kernel and other frequently used operating system instructions are loaded, or copied, from storage into the computer’s memory (RAM). The kernel is the core of an operating system that manages memory and devices, maintains the computer’s clock, starts programs, and assigns the computer’s resources, such as devices, programs, data, and information. The kernel is memory resident, which means it remains in memory while the computer is running. Other parts of the operating system are nonresident, that is, these instructions remain on a storage medium until they are needed. When you boot a computer, a series of messages may appear on the screen. The actual information displayed varies depending on the make and type of the computer and the equipment installed. The boot process, however, is similar for large and small computers. The steps of the bootstrap process are given and explained below: Step 1: The power supply sends a signal to the components in the system unit. When you turn on the computer, the power supply sends an electrical signal to the components in the system unit.

Step 2: The processor...
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