Operating systems

Operating systems are the force behind most computers, acting as the central hub for managing hardware and software. They handle all the behind-the-scenes tasks, allowing users to interact with the computer without needing to understand complex technical details.  Essentially, operating systems provide a user-friendly interface and environment for running applications. The main functions performed by an operating system are:

• File management
• Process management
• Memory management
• Hardware management
• User interface management
• Security 
• Networking

Common operating systems include:

• Microsoft Windows
• macOS
• Linux
• Android
• iOS

Multitasking

This means running multiple programs on the same computer. Since computers can generally do only one or two things, time sharing accomplishes this.

Device drivers

The operating system is responsible for the management of peripherals such as printers, monitors, graphics cards etc. This is often done through device drivers which are programs that allow the OS to control the hardware.

Memory management

The operating system is responsible for managing the memory of the system to ensure that there are no conflicts of memory usage between all the currently running programs and processes.

This can sometimes involve using virtual memory where a portion of the disk drive is used as primary memory. This has major drawbacks as the speed of a hard disk is several orders slower than the main memory.

File management

This is a central feature to operating systems allowing files to be stored in a hierarchy of directories or folders in a directory tree.

Common systems include NTFS, FAT32, ext3.

User interface

The most common forms of interface are the Graphical User interface (GUI) and the command line interface (CLI).

GUI

A GUI is normally built around visual (graphical) elements and is characterised by the acronym:

WIMP

W - Windows are used to display information

I - Icons are small pictures used to graphically represent an element eg. a folder

M - Menus provide the user with choices eg File>Save as.

P - A pointer is an arrow (or similar) that can be moved around the screen to select things.

CLI

Command line interfaces were most prevalent some time ago when computers were not as powerful. The advantage of such interfaces is that they use very little memory compared to a GUI and the commands can offer a greater range of control than most GUIs the disadvantage is that they require a more expert approach as all commands for even simple operations need to be known.

Security

Operating systems handle security in several ways.

1. Account privileges can be set up to provide different users access to varying levels and authenticated with such methods as username and password/biometrics/smart cards etc.

2. Recording of user activity e.g. who opened what file and when.

Networking

Modern OSs support a variety of networking protocols, hardware and applications so that they can communicate with different OSs.

Word processors

A program for storing, manipulating, and formatting text entered from a keyboard and providing a printout. They can generally add a range of formatting including images. Software examples are Microsoft Word, Google Docs, and Libre Office Writer. File formats include .rtf .doc. 

Spreadsheets

A spreadsheet is an electronic document in which data is arranged in the rows and columns of a grid and can be manipulated and used in calculations. They are mainly used for modelling and calculations. Software examples are Microsoft Excel, Google Sheets, and Libre Office Calc. File formats include .xls. 

Database management systems

Database management systems (DBMS) provide users and programmers with a systematic way to create, retrieve, update and manage data. This is generally done by inputting the data in forms, storing data in tables manipulating data with queries and outputting data in a variety of report formats. Software examples include Microsoft Access, MySQL, and Libre Office Base. 

Email

An email client is a program that provides a user interface to download, store, organise and send email. Examples are Mozilla Thunderbird and Microsoft Outlook. 

Web browsers

A web browser (commonly referred to as a browser) is a software application for retrieving, presenting, and traversing information resources on the World Wide Web. Examples are Chrome, Internet Explorer, Opera and Safari. 

Computer-aided design (CAD)

CAD, or computer-aided design and drafting (CADD), is the use of computer technology for design and design documentation. Examples include Autodesk, SketchUp and Sculptris. 

Graphic processing software.

An image editor or photo editor is a software program used to edit or otherwise manipulate an image, picture or other graphic. Examples include Adobe Photoshop, Gimp, and Pixlr. 

There are a variety of features that are common to many applications. These are described below.

Toolbars

A toolbar is a GUI widget containing icons menus buttons or text. toolbars are seen in many types of software such as browsers and graphic manipulation software.

Dialogue Boxes

In a graphical user interface, the dialogue box is a window that allows the user to interact. It may be in the form of an alert or provide information or request for the user to make a choice.

GUI components

"GUIs use a consistent visual language to represent information in computers."

This is generally conveyed by the acronym WIMP. Windows, Icons, Menus, Pointing devices.