Managing resources
An The software that manages the hardware and software resources in a computer system. is a collection (or suite) of Sequences of instructions for a computer. that manages and controls a computer.
Common operating systems include:
- Microsoft Windows
- macOS
- Linux
- Android
- iOS
Operating systems have many functions.
Managing peripherals
The operating system manages peripheral input and output devices such as keyboards, monitors, printers, scanners and cameras. It controls the sending and receiving of Units of information. In computing there can be different data types, including integers, characters and Boolean. Data is often acted on by instructions..
To achieve this, the operating system uses a program called a Software that controls and communicates with peripherals. Device drivers contain instructions on how to control a device. Each connected device has its own driver.
Using device drivers brings two advantages:
- any device can be used with the operating system as long as a driver is available for it
- drivers can be updated, usually to give better performance or to remove a An error in a program.
Managing printing using spooling
The operating system manages printing and spooling by organising data that is waiting to be printed into a queue. Once the printer becomes available the operating system releases the next data from the queue and prints it. This means that other user and system tasks can continue while the data is in the queue.
Managing backing store
File handling and file maintenance are some of the most important tasks of an operating system. Filing systems such as A simple聽file system聽that organises files by using a table held at the start of a storage device. are often used. These allow users to:
- create, modify and delete files and folders
- copy and duplicate files and folders
- move files and folders
- rename files and folders
- sort items into different orders according to name, file type, date created and more
- search for particular files and folders
- restore deleted files
- set access rights - such as read only or edit - to files
Memory management
Computer The part of a computer that stores data. must be managed to ensure that:
- more than one program can run at the same time
- more than one document can be opened at the same time
One method of memory management is A method of memory management where memory is divided into pages.. Memory is broken up into fixed-size blocks known as In computing, a small portion of memory..
Different operating systems use different page sizes. For example, memory pages in modern operating systems are typically four Kilobyte. in size.
When a program is run it is loaded into memory. The operating system determines how much memory the program requires and allocates enough pages to hold it and its documents. When the program is closed the allocated pages are freed up for use by other programs.
The pages a program occupies may or may not be Running together in sequence, one after another. but this does not matter. The operating system knows how to access each page and Retrieve data from memory. the data held in them when needed.
Consider this example - Program A requires two pages. It is allocated pages 0 and 1. Program B requires three pages. It is allocated pages 2, 3 and 4.
Program A now closes and program C now runs. Program C requires three pages. Pages 0 and 1 are now free, so program C is allocated pages 0, 1 and 5.
Managing processes
The operating system makes sure that different processes can make use of the Central processing unit - the brain of the computer that processes program instructions. without conflicting with each other. Multitasking means to be able to run more than one program simultaneously.
Modern operating systems are multitasking in that they allow several programs to run side by side. It is not uncommon for a user to be Data that is sent in pieces. Each piece is viewed as it arrives, eg a streaming video is watched as it downloads. music while entering text into a An application used to write, edit and format text. or streaming a video while making a A copy of important files that is kept separately in case the original files are lost or damaged. of files.
Multitasking is possible only if:
- the operating system can support multitasking
- the computer has enough memory to hold more than one program in The part of a computer that stores data. at the same time
In the past, computers with A method of running programs and working on a computer using only text. This contrasts with a graphical interface which uses clickable icons and menus. were unable to multitask - the operating systems of the day allowed only one program to run at a time. However, newer CLIs can handle multitasking, for example Linux (Linux is also distributed as a graphical user interface (GUI)).
Managing security
Operating systems also manage user access. They allow:
- individual users to be created and deleted
- access levels to be given to users, such as administrator rights or standard user rights
- auditing (keeping a log) of files a user creates, accesses, edits and deletes
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