An operating system acts as an intermediary between the user of a computer and the computer hardware. An Operating System (OS) is software that manages the computer hardware.
Structure of Operating System:
- Hardware: It provides the basic computing resources for the system. It consists of CPU, memory and input/output (I/O) devices.
- Software (Operating System): Software includes process management routines, memory management routines, I/O control routines, file management routines.
- System programs: This layer consists of compilers, Assemblers, linkers etc.
- Application Programs: Define the ways in which these resources are used to solve users' computing problems. e.g., word processors, spreadsheets, Railway reservation systems, Bank database management, web browsers etc.
Operating System Objectives:
- Convenience: This makes the computer more convenient to use.
- Efficiency: Allows computer system resources to be used in an efficient manner.
- Ability to Evolve: Permit effective development, testing, and an introduction of new system functions without interfering with service.
Characteristics of Operating System:
- Memory Management - keeps track of primary memory i.e. what part of it is in use by whom, what part is not in use etc. and allocates the memory when a processor program requests it.
- Processor Management - allocates the processor(CPU) to a process and de-allocates the processor when it is no longer required.
- Device Management - keeps track of all devices. This is also called the I/O controller that decides which process gets the device, when, and for how much time.
- File Management -- allocates and de-allocates the resources and decides who gets the resources.
- Security -- prevents unauthorized access to programs and data by means of passwords and similar other techniques.
- Job accounting -- keeps track of time and resources used by various jobs and/or users.
- Control over system performance -- records delays between the request for a service and from the system.
- Interaction with the operators -- The interaction may take place via the console of the computer in the form of instructions. Operating System acknowledges the same, does the corresponding action and informs the operation by a display screen.
- Error-detecting aids -- Production of dumps, traces, error messages and other debugging and error-detecting methods.
- Coordination between other software and users -- Coordination and assignment of compilers, interpreters, assemblers and other software to the various users of the computer systems.
Types of Operating Systems
- Batch Operating System: The users of the batch operating system do not interact with the computer directly. Each user prepares his job on an off-line device like punch cards and submits it to the computer operator.
- Multiprogramming: It is a technique that enables many people, located at various terminals, to use a particular computer system at the same time.
- Timesharing / Multitasking: Time-sharing is a technique that enables many people, located at various terminals, to use a particular computer system at the same time. Time-sharing or multitasking is a logical extension of multiprogramming.
- Single User Operating System: It is a type of operating system (OS) that is developed and intended for use on a computer or similar machine that will only have a single user at any given time.
- Multiuser Operating System: It is a computer operating system (OS) that allows multiple users on different computers or terminals to access a single system with one OS on it.
- Real-Time Operating System: It is defined as a data processing system in which the time interval required to process and respond to inputs is so small that it controls the environment. It is always online whereas the online systems need not be real-time.
MS-Windows is a GUI based operating system. In Windows Operating system multiple applications can be simultaneously run in different windows.
- In MS Windows, the screen upon which icons, windows, too are displayed is known as an icon is a graphic symbol that represents a window element like, file, folder, or shortcut.
- Loading up operating system files into the computer’s memory is called booting up.
- The taskbar is a bar, which is usually located at the bottom of the screen.
- My computer is helpful for viewing the contents of a single folder or drive.
- Windows Explorer is another way of seeing what is on your computer. It shows the computer’s contents as a hierarchy.
- File: A program or document stored on a disk.
- Toolbar: A set of the button you click to perform common tasks.
- A folder is a location in which you can store files and other folders.
- To create a new folder, File—New—Folder commands are clicked in My Computer windows.
- To find files or folders, Start---Find---Files or Folder commands are clicked.
- To create a shortcut to a file, firstly select the file or folder, whose shortcut is to be created. Then drag the file icon through right mouse button to the desired location where the shortcut to be placed, and then select create the shortcut(s).
- To shut down the computer, Start—Shut Down commands are clicked.
Boot: When the computer starts, the operating system is first loaded (as it is essential for running all other programs), this process is known as booting.
Cold Boot: When you turn the computer ON from an OFF position.
Warm Boot: When you reset the computer that is already ON.
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