Friday, 1 April 2016

Unit 2 - P2 - Explain the purpose of operating systems


Operating system
An operating system is software which supports the basic functions for a computer, such as any scheduling tasks or the peripherals being controlled. The majority of times, people will use the OS that is already with the computer. In some cases, it is possible to upgrade or change the operating system in the computer. Microsoft Windows, Apple Mac OS X, and Linux are the most common operating systems for personal computers. Then there is android and IOS for smart phones
Machine Management

When on a mobile phone, or computing device and the user clicks on one of the program icons, the OS will run the program either by selecting and opening the program chosen or by typing an instruction into the command line. The OS will have to find the files of the program on the storage drive, where it then loads it to the main memory and instructs the device to start executing the program from the beginning. Every time a new program is opened, the OS performs a series of steps, which is always the same. The steps are: The program code will be found in the storage drive, where a part of the RAM will be saved free so the program can run and there is space within the RAM for the programs data to be stored. The code of the program will be copied from where it is stored to the space which is saved for it in the memory and the device will have the first instructions as a key point for the programme to be working fully. This helps the user as it means that software is able to be used on the computing devices easily as the computer is using it’s hardware to use the programs to the full potential.

Peripheral Management
The peripherals of a computer is any device which can be input or output, where information is put into or comes out of the computer. Each of these peripherals have their own machine coded to it as well as rules which determines the way the data values is transferred between the computer and device. A protocol is made up from the rules, so  the device can be controlled and be communicated with, where if the protocol of different peripherals are the same, the different peripherals can be controlled by the same driver. Then if the identical item, like multiple game controllers are plugged in, each controller will have its data stored separately, so there isn’t any interference. This will help the user as it means that multiple people can use a computer at the same time, where their controller is able to control a different part of the computer. Also, this means that information can be transferred from computer to peripheral or peripheral to computer.
Device drivers
There are programs called device drivers, which the operatingg system uses to manage the connections between the computer and the peripherals. The device driver will handle the understanding of requests between a device and the computers, a process determines where outgoing data  is put before it is sent and the incoming messages that are received are stored. The device drive also ensures that the device is ‘a wake’ when it is needed and the device is ‘a sleep’ of the device is not needed. In most cases, the Operating System will have common device drivers, where the more common peripheral s will be recognised and connectable. However, in some cases, the peripherals have their own device drivers, which are required to be installed before the peripheral is used. This helps the user as it means that the peripherals that are used can be recognised easily and the drivers are used to gather or store information on the device.


File management

Files will be organised on storage files by the Operating System. The data is retrieved from a file by the computer knowing what storage file the file is on, the organisation of the files on the device, the amount of data in the file and how to communicate with the file.  The Operating System has a job of maintaining the information for other programs, where a file system is provided. This means that programs with a specific way of storing and retrieving data is provided.  The Operating System also  manages how the data is organised, as well as how files are stored, deleted, read, found and repaired which makes it easier for the users when using programs the Windows File Explorer or Mac OS X Finder.  The Operating System finally detects and makes repairs on errors like missing disks or incorrect file names, and if or when their is an error, the user is informed.

Security
On computers, there is multiple ways in which security is kept, which is controlled by the operating system. The security methods are User accounts, encryption, anti-virus software and firewalls. The user accounts mean that if a public computer is used, or a computer where there is more than one user, then specific files, which will be personal accounts, can be allocated, and it means that the system is able to authorise or unauthorised certain activities. The encryption is the way that information is written when files are stored or transmitted over a network. Anti-virus software will protect the computer by detecting and blocking viruses and firewalls will prevent untrusted programs through ports, or that are downloaded and the trusted programs will run smoothly. This will hep the users as it means that their documents will be protected as well as the computer, meaning the computer should be able to be used without being damaged.

Multitasking
The Operating System allows the computer to have several programs running at the same time. The programs will be stored on the RAM whilst they are open, at the same time, where the CPU processes the programs. A program can either be in a running state, a waiting state or a runnable state. There can only be one process running at one time and CPU’s are very quick, meaning it can process a program in a short time where the OS will decide the best way to switch between the three processes. It  will control which process is going to be executed by the CPU at what point in time. The term for the working out of when to swap processes is known as scheduling. The swapping of processes happens very fast so it seems that all of the processes are running simultaneously. If there are too many processes running at similar times, or the CPU is working harder than normal, it can seem as if some or all of them have stopped. This will help the user as it means that the priorities of the running programs is running well, where the programs the user wants to use more than others are prioritised higher.





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