Operating System (JSS2 FIRST TERM)

 

Operating System

Introduction:

An operating system performs these services for applications:

 1. The OS determines which applications should run in what order and how much time should be allowed for each application before giving another application a turn during multitasking.

2. The OS manages the sharing of internal memory among multiple applications.

3. It handles input and output to and from attached hardware devices, such as hard disks, printers, and dial-up ports.

4. The OS sends messages to each application or interactive user (or to a system operator) about the status of operation and any errors that may have occurred.

5. It can offload the management of what are called batch jobs (for example, printing) so that the initiating application is freed from this work.

The application programs make use of the operating system by making requests for services through a defined application program interface (API).

In addition, users can interact directly with the OS through a user interface such as a command language or a graphical user interface (GUI). The OS controls the basic input and output, allocates system resources, manage storage space, maintain security and delete equipment failure. It controls the flow of data.

Examples of operating systems include:

1.      UNIX                                             4. Linux

2.      Microsoft Windows                     5. Mac OS

3.      OS/2                                             6. Solaris

7.     Chrome OS

The examples below are for mobile devices

1.    Android             2.       iOS               

3. Blackberry OS     4.       Symbian OS

    5.   Java OS

 Functions of an Operating System

 1. Boot process: When the computer is switched on, the boot program that is resided in ROM initialize the setup of the computer, the then load the rest of the OS from the banking storage (hardware) in the RAM.

2. The OS does the work of sharing and accounting of the computer resources.

3. It handles the input and output of data and information.

4. The OS handles the management of memory.

5. It handles the management of the hardware.

6. The OS handles multitasking and multiprogramming.

7. It handles protection and error trending.

8. The operating system acts as an interface between the user and the computer

9. It controls interaction and program control 

Types of operating system

1.           Network Operating Systems: this OS runs on servers and provides the server the capability to manage data, users, groups, security, applications and other networking functions.

·         Designed to optimize the networked computers ability to respond to service requests.

·         Servers run on a network operating system.

Examples of NT operating systems:

1.    Windows NT/2000/2003

2.    UNIX

3.    Linux

4.    Novel Netware.

2.           Desktop O.S.

The control program in a user's machine (desktop or laptop). Also called a "client operating system," Windows is the overwhelming majority while the Macintosh comes second. There are also several versions of Linux for the desktop.

Categories of Operating systems

1.      Single-user, single task OS: this type of OS is designed to manage the computer so that the user can effectively do one thing at a time. The Palm OS for Palm handheld computer and Microsoft Disk Operating System (MS-DOS) are good examples of single-user, single task OS.

2.      Single-user, multi-tasking OS: this OS allows a single-user to run several programs at the same time. They are common on desktops, laptops and even latest mobile phones. For example, it’s entirely possible for a Windows user to be typing in a word processor, while downloading a file from the internet and printing the text of an email message. Microsoft Windows, Mac OS, and Linux are three well-known examples of this type of system.

3.      Multi-user, multi-tasking OS: this OS allows many users to take advantage of the computer’s resources simultaneously. UNIX, Xenix, Virtual Memory System (VMS) are examples of multi-user operating systems.

FUNCTIONS OF AN OPERATING SYSTEM

Resource Allocation:

 The Operating System ensures the proper use of all the resources available by deciding which resource to be used by whom for how much time. All the decisions are taken by the Operating System.

 Control over system performance:

The OS monitors overall system health to help improve performance, records the response time between service requests and system response to having a complete view of the system health. This can help improve performance by providing important information needed to troubleshoot problems.

 

Security:

The operating system uses password protection to protect user data and similar other techniques. it also prevents unauthorized access to programs and user data.

 

Coordination between other software and users:

Operating systems also coordinate and assign interpreters, compilers, assemblers and other software to the various users of the computer systems.

Device Management:

 An OS manages device communication via their respective drivers. It performs the following activities for device management.

 1. Keeps tracks of all devices connected to the system.

2. Designates a program responsible for every device known as the Input/output controller.

3. Decides which process gets access to a certain device and for how long.

4. Allocates devices in an effective and efficient way.

5. De-allocates devices when they are no longer required.