Operating System
What is an Operating System?
An operating system (OS) is a program that, after being initially loaded into the computer by a boot program, manages all the other programs in a computer. These other programs are called applications. The applications make use of the operating system by making requests for services through a defined application program interface (API).
What are some examples of Operating Systems?
Some examples of operating systems include Microsoft Windows, Apple's MacOS, Linux distributions like Ubuntu, and mobile systems like Android and iOS.
What are the main functions of an Operating System?
The main functions of an operating system are managing the computer's resources, such as the central processing unit, memory, disk drives, and printers, providing an interface for users to interact with the computer, running applications, and ensuring security and ease of use.
How does an Operating System manage resources?
The operating system manages the hardware resources of a system, including the CPU, memory and storage, by controlling how they are allocated to applications. It also manages tasks, ensuring that they are executed efficiently and securely.
What is a Kernel in an Operating System?
The kernel is the core part of an operating system. It interacts directly with the system's hardware and manages the system's resources. Its many functions include managing memory, handling system calls, and managing input and output devices.
What's the difference between a monolithic kernel and a microkernel?
A monolithic kernel is an operating system architecture where the entire operating system is working in the kernel space and is alone in the supervisor mode. On the other hand, in a microkernel, the kernel is broken down into separate processes, known as servers. Some of the servers run in kernel space and some run in user-space.
What is Multitasking in an Operating System?
Multitasking is the concurrent execution of multiple tasks, also known as processes, over a certain period of time. Multitasking allows more than one task to be part of the computer's CPU's busy cycle.
What's the difference between preemptive and non-preemptive multitasking?
Preemptive multitasking involves the use of an interrupt mechanism which suspends the currently executing process and invokes a scheduler to determine which process should execute next. Non-preemptive multitasking, on the other hand, ensures a process relinquishes control of the CPU once it enters a waiting state, allowing another process to run.
What is Virtual Memory in an Operating System?
Virtual memory is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine". It allows a program to be designed as though there is only one kind of memory, "single-level storage".
Why is virtual memory important?
Virtual memory is important because it allows programs to run even if they need more memory than the system has available. It does this by using part of the computer's hard disk space as extra memory, called swap space. This also enables multitasking, where multiple programs are running concurrently.
What is paging in Operating Systems?
Paging is a memory management scheme by which a computer stores and retrieves data from secondary storage for use in main memory. In this scheme, the operating system retrieves data from disk storage as needed and stores it in 'pages'.
What's the difference between paging and segmentation?
The difference between paging and segmentation is that paging is an allocation technique which involving dividing physical memory into small pieces called pages, while segmentation is another memory management technique that divides a user program into its logical parts or segments.
What are drivers in the context of an Operating System?
In the context of operating systems, a driver is a special type of software that controls a specific hardware connected to a computer. The driver communicates between the hardware and the operating system, ensuring that the hardware functions properly.
What happens when a driver is outdated or incompatible with the OS?
When a driver is outdated or incompatible with the operating system, it may cause the hardware to function improperly or not function at all. It can also cause system instability, reducing the performance of the operating system, or even causing it to crash.
What is an Application Programming Interface (API)?
An Application Programming Interface, or API, is a set of protocols and tools for building software applications. It specifies how software components should interact and behave. Operating Systems provide APIs for developers to interact with the system hardware and software resources.
Can you give an example of how an API is used in a real-world application?
An example of an API in a real-world application is a weather application on a smartphone. The application uses an API to retrieve weather data from a remote server. The API defines how the application requests the data and how the data is returned to the application.
What is a shell in an Operating System?
A shell in an operating system acts as an interface between the user and the kernel. It takes commands from the user and executes them. It can be graphical (like the Windows interface) or command-based (like the UNIX shell).
Can you explain the difference between a shell and a kernel?
The shell and the kernel are two core components of an operating system, but they serve different purposes. The kernel is the core of the operating system and directly interacts with the hardware, while the shell is an interface that allows users to interact with the kernel.
What is a file system in an Operating System?
A file system is a method and data structure that an operating system uses to control how data is stored and retrieved. The file system manages the positions of the bits on the storage device, whether it's a hard disk or flash drive.
What are some examples of file systems?
Some examples of file systems include NTFS and FAT used in Windows, ext4 and Btrfs used in Linux, and HFS used in Apple systems.