Operating System Fundamentals: Definitions, Types, and Functions
Operating System Definition
An operating system (OS) is a suite of software designed to allow communication between a computer user and the hardware, managing the computer’s resources in a comfortable and efficient manner.
What is a transmission medium?
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What is POST?
POST stands for Power-On Self-Test. It is a diagnostic testing sequence that a computer’s basic input/output system (BIOS) runs to determine if the computer keyboard, random access memory, disk drives, and other hardware are working correctly.
What are the functions of an operating system?
- Managing Hardware: Efficiently manages the machine’s resources (CPU, memory, storage devices, input/output devices).
- Facilitating User Work: Enables communication between the user and the machine’s devices through interfaces (command-line or graphical).
- Abstraction: Hides the complexity of the hardware and provides programmers with a more convenient set of instructions to work with.
- Running Modes: The core of the OS (kernel) runs in a privileged kernel or monitor mode, with top priority and hardware protection. Compilers, editors, and other user programs run in user mode with fewer privileges.
What is the purpose of an operating system?
The primary purpose is to allow communication with a computer user and manage the computer’s hardware and software resources comfortably and efficiently, providing a platform for application programs to run.
Resource Definition
In computing, a resource is any physical or virtual component of limited availability within a computer system. Examples include CPU time, memory space, network bandwidth, and I/O devices. Resource management, a key OS function, involves allocating these resources to programs and users, often handling concurrent access.
Program Definition
A sequence of instructions that a computer can interpret and execute to perform a specific task.
Process Definition
A program in execution. It is an instance of a computer program that is being executed by one or many threads.
System Definition
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What is a batch operating system?
Batch systems are an early type of operating system, introduced around 1956 to increase processing capacity. They process a large amount of work (jobs) with little or no interaction between users and the running programs. Jobs with similar needs are batched together and run sequentially to optimize resource utilization, avoiding the wait times associated with serial processing.
What is a distributed operating system?
A distributed operating system manages a group of distinct computers and makes them appear to be a single computer. It allows the distribution of jobs, tasks, or processes among a set of processors, which may reside in different physical computers. This distribution is typically transparent to the user.
What is a network operating system?
A network operating system (NOS) runs on a server and provides the capability to manage data, users, groups, security, applications, and other networking functions. It connects two or more computers through a communication medium (physical or wireless) with the primary objective of sharing resources and information.
What is a multiprogramming operating system?
Multiprogramming operating systems are distinguished by their ability to handle the execution of two or more active jobs (processes) concurrently. By keeping several jobs in main memory simultaneously, the CPU always has a task to execute, maximizing its utilization. When one job needs to wait (e.g., for I/O), the OS switches to another job. This concept is central to modern operating systems, even on single-CPU machines.
General classification of operating systems (structure, feature, function, tasks)
What is an interface?
In this context, an interface often refers to the physical connection (port) and protocol used to connect a peripheral device (like a printer, keyboard, or monitor) to the computer. It can also refer to a user interface (command-line or graphical) or an application programming interface (API).
Operating System Generations
- Generation Zero (1940s): Early computers without operating systems. Programming was done directly with machine hardware, often using plugboards.
- First Generation (1945-1955): Vacuum Tubes and Connections. Computers were large and unreliable. Programming was in machine language.
- Second Generation (1955-1965): Transistors and Batch Systems. Transistors replaced vacuum tubes, making computers smaller, faster, and more reliable. Batch processing improved efficiency.
- Third Generation (1965-1980): Integrated Circuits and Multiprogramming. ICs further reduced size and cost. Operating systems became more complex, introducing multiprogramming and time-sharing.
- Fourth Generation (1980-Present): Microprocessors and Personal Computers. The advent of microprocessors led to personal computers. Operating systems became user-friendly (GUIs) and supported networking and distributed computing.
What is a monolithic operating system?
A monolithic operating system is structured such that the entire OS code runs as a single program in kernel mode. It consists of an interlocking set of routines where any routine can call any other. While potentially efficient, this structure can be complex to manage and modify. Early versions of Unix and Linux, as well as MS-DOS, are examples.
What is memory cache?
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What is a multitasking operating system?
A multitasking operating system allows a user to perform multiple tasks or run multiple computer programs concurrently. The OS manages how CPU time is shared among these tasks, giving the illusion that they are running simultaneously. For example, a user might be editing source code, compiling another program, and receiving email all at the same time.
What is a uniprocessor system?
A uniprocessor system is a computer that has a single central processing unit (CPU). An operating system designed for uniprocessing is capable of managing only one processor. If installed on a computer with multiple CPUs, it would typically only utilize one of them. Examples of early systems primarily designed for uniprocessing include MS-DOS and classic MacOS.