systems software 1.5 Flashcards
functions of the OS 6 points
-communicate with internal and external hardware via the device drivers
-provide a UI, allowing a user to interact with the computer and vice versa
-provides a platform for different applications to run
-allows the computer to multi-task by controlling memory resources and the CPU
-deal with file management and disk management
-manage system security and user accounts
what do device drivers do
drivers are pieces of software that allow the OS and hardware to communicate with each other
what does a UI do
allows the user to interact with a computer system
what are GUIs
-most common UI type
-designed to be easy for everyday users by making them visual, interactive and intuitive
-optimised for input methods, GUIs have been WIMP-based (windows, icons, menus and pointers, android and iOS were created for touchscreen devices
what is the command line interface
-text-based
-user enters specific commands to complete tasks
-less resource heavy
benefits of using command line interface
-more efficient and more powerful than a GUI.
-can be used to automate processes using scripts
-command line interfaces give more control/options than GUIs
what are multi-tasking OSs
-OS that can run multiple applications at the same time
-help CPU carry out multi-tasking by efficiently managing memory and CPU processing time
how does an OS help the CPU carry out multi-tasking by managing memory and CPU processing time(7 points)
-when programs are opened, the OS moves the necessary parts to memory
-the OS will remove unneeded data from memory (if they have been closed or not used recently)
-OS divides memory into segments, when different programs are used, their data is placed into different segments so that running apps cannot overwrites or interfere with each other
-organises the movement of data to and from virtual memory
-OS divides CPU time between running apps as it can only process one at a time
-OS can prioritise CPU time for different programs in order for them to be processed in the most efficient order
How does OS handle file and disk management 4 points
-computers store data as files. File extensions tell the computer which type of file it is
-the OS does file management, organising data into a usable hierarchical structure. It also deals with the naming, movement, editing and deletion of data
-OS manages the hard disk, it splits the physical disk into storage sectors, decides which sectors to write data to, and keep track of free space on the disk (the data for a single file would be placed in adjacent sectors ideally, but this isn’t always possible)
-OS organises and maintains the hard disk with utility software like defragmentation software
how does OS deal with user management 4 points
-The OS is also responsible for user account control-user accounts allow different users to be granted access to a specific data or resources on a computer system
-on most desktop OS each user has access to their own personal data and desktop, but cannot access other user’s personal data
-OS may have anti-theft measures to prevent other users from accessing locked devices or accounts to steal information
-User accounts may be password or PIN protected
why does a disk become fragmented
-files are stored on a hard disk in available spaces
-as files are moved, deleted and change size,
lots of small gaps appear on the disk
-when writing files to the disk, the OS splits files into smaller blocks to fill up the gaps
problems caused by fragmented disks
-Reading and writing files will be slower as the read/write head has to move back and forth across the disk
-this may slow down the computer
what does defragmentation software do
-defragmentation software reduces fragmentation by moving files on the hard disk
-the empty spaces/gaps are collected together
-different bits of the same file are moved to be stored together
-this means the read/write heads will not need to move as far across the disk, improving the read/write speed
why don’t SSDs need defragging
-SSDs use flash storage with no moving parts, fragmentation does not cause them any problems- they can access data just as quickly however its arranged
-SSDs have a limited number of read/writes, defragging them can shorten their lifespan
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-compression software reduces the size of files by permanently or temporarily removing data from them
-compressed files take up less disk space and are quicker to download
-standard file formats include .zip and .rar
-compressed files need to be extracted before they can be used
