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Operating System


1.       What is an Operating System?

An operating system is the most important software that runs on a computer. It manages the computer's memory and processes, as well as all of its software and hardware. It also allows you to communicate with the computer.


Function of an Operating System – use DIV Scrollers

1.       Receives inputs

Decoding keyboards, mice, webcam communication and scanners.

2.       Manage resources

CPU memory – has to decide what to do for operating system and manage it out of the ram.

3.       Sends outputs – emails, printouts

4.       File management

Word, excel, PowerPoint

5.       Memory management

Hard disk, SSD

Components/Functions of the Operating Systems – use DIV Scrollers

1.       Kernel

The kernel is a computer program that is the core of a computer's operating system, with complete control over everything in the system. On most systems, it is one of the first programs loaded on start-up (after the bootloader). It handles the rest of start-up as well as input/output requests from software, translating them into data-processing instructions for the central processing unit. It handles memory and peripherals like keyboards, monitors, printers, and speakers.


2.       Program execution

Execution in computer and software engineering is the process by which a computer or a virtual machine performs the instructions of a computer program. The instructions in the program trigger sequences of simple actions on the executing machine. Those actions produce effects according to the semantics of the instructions in the program.

Programs for a computer may execute in a batch process without human interaction, or a user may type commands in an interactive session of an interpreter. In this case the "commands" are simply programs, whose execution is chained together.


3.       Interrupts

In system programming, an interrupt is a signal to the processor emitted by hardware or software indicating an event that needs immediate attention. ... Hardware interrupts are used by devices to communicate that they require attention from the operating system.


4.       Modes

A processor in a computer running Windows has two different modes: user mode and kernel mode. The processor switches between the two modes depending on what type of code is running on the processor. Applications run in user mode, and core operating system components run in kernel mode.


5.       Memory management

Memory management is the process of controlling and coordinating computer memory, assigning portions called blocks to various running programs to optimize overall system performance. Memory management resides in hardware, in the OS (operating system), and in programs and applications.

6.       Virtual memory

A computer can address more memory than the amount physically installed on the system. This extra memory is actually called virtual memory and it is a section of a hard disk that's set up to emulate the computer's RAM.


7.       Multi-tasking

Multitasking, in an operating system, is allowing a user to perform more than one computer task (such as the operation of an application program) at a time. The operating system is able to keep track of where you are in these tasks and go from one to the other without losing information.


8.       File access

An access method is a function of a mainframe operating system that enables access to data on disk, tape or other external devices.


9.       Networking

A network operating system (NOS) is a computer operating system that is designed primarily to support workstation, personal computer, and, in some instances, older terminal that are connected on a local area network.


10.   Security

Operating system security is the process of ensuring OS integrity, confidentiality and availability. OS security refers to specified steps or measures used to protect the OS from threats, viruses, worms, malware or remote hacker intrusions.

Associated files – use DIV Scrollers

1.       Device drivers

Device driver is a small piece of software that tells the operating system and other software how to communicate with a piece of hardware.

For example, printer drivers tell the operating system, and by extension whatever program you have the thing you want to print open in, exactly how to print information on the page.


2.       Compiler

A compiler is a special program that processes statements written in a particular programming language and turns them into machine language or "code" that a computer's processor uses. Typically, a programmer writes language statements in a language such as Pascal or C one line at a time using an editor. The file that is created contains what are called the source statements. The programmer then runs the appropriate language compiler, specifying the name of the file that contains the source statements.


3.       Link editor

In computing, a linker or link editor is a computer program that takes one or more object files generated by a compiler and combines them into a single executable file, library file.

A simpler version that writes its output directly to memory is called the loader, though loading is typically considered a separate process


4.       Utilities

a.       Antivirus

A software designed to detect and destroy computer viruses.


b.      Anti-spyware/malware

 Smarter detection. Specialized ransomware protection. It's the cybersecurity computer pros recommend.


c.       Backup/restore

Backup and Restore (formerly Windows Backup and Restore Center) is a component of Microsoft Windows introduced in Windows Vista and included in later versions that allow users to create backups and restore from backups created earlier.


d.      File management

A file manager or file browser is a computer program that provides a user interface to manage files and folders.


e.      Disk repair/defragmenter

System errors can occur if hard disks contain damaged sectors or fragmented files. To prevent Disk Defragmenter from moving files to bad sectors of a disk, run the Error-checking tool before running Disk Defragmenter.


f.        Screensavers

A screensaver is a computer program that blanks the screen or fills it with moving images or patterns when the computer is not in use.


User Interfaces – use DIV Scrollers

1.       Command Line Interface – CLI

A command-line interface or command language interpreter, also known as command-line user interface, console user interface and character user interface, is a means of interacting with a computer program.


2.       Menu Driven

Is a program or computer used by making selections from menus.


3.       Graphical User Interface – GUI

The graphical user interface (GUI) is a type of user interface that allows users to interact with electronic devices through graphical icons and visual indicators such as secondary notation, instead of text-based user interfaces, typed command labels or text navigation.


4.       Alternative Interfaces

Alternative PubMed interfaces refers to a range of alternate search tools and interfaces that can search PubMed - MEDLINE in such a way that newer information patterns or insights into the medical literature can be ascertained.


Types of Operating System – use DIV Scrollers

1.       Open Source

Open source refers to a program or software in which the source code (the form of the program when a programmer writes a program in a programming language) is available to the general public for use and/or modification from its original design free of charge. Open source code is typically created as a collaborative effort in which programmers improve upon the code and share the changes within the community.


2.       Original Equipment Manufacturer – OEM

An Original Equipment Manufacturer is a company that produces parts and equipment that may be marketed by another manufacturer. For example, if Acme Manufacturing Co. makes power cords that are used on IBM computers, Acme is an OEM.


3.       Proprietary

Proprietary Software is something owned by a specific company or individual. In the computing world, proprietary is often used to describe software that is not open source or freely licensed. Examples include operating systems, software programs, and file formats.


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