computer science 1.5 !

what does an operating system do?

manages hardware and provides a user interface (so they can interact with hard ware)

examples of operating systems?

android os, mac os, ios, linux

what is a GUI?

graphical user interface

what is in a GUI?

windows, icons, menus, pointers

what do pointers do in a GUI?

click on windows and icons

what do icons do in a GUI?

represent complex functions

what do menus do in a GUI?

organise data and bring up context sensitive menus

what is a menu driven interface?

displays data in a series of linked menus

advantages of menu driven interface?

user friendly (easy as commands dont need to be memorised)

disadvantages of menu driven interface?

tedious as there can be many menus to go through

examples of where menu driven interfaces are used?

TVs, ipods, older nokias

what is a command line interface?

users interact by typing commands

disadvantages of a command line interface?

many programs to learn and mistakes can delete data (mostly only for professionals)

what is a voice activated/natural language interface?

hardware controlled by speaking commands to a listening device

advantages of a natural language interface?

hands free and speeds up process

disadvantages of a natural language interface?

instructions are limited and can be misheard

how does the OS manage users?

allocates accounts, organises user log ins and passwords

what are access rights?

users can only view their own files and only some can read without editing files

how does the OS manage files?

lets you see properties of files, makes sure files aren’t overwritten and manages where files are so can be retrieved

what does the OS do with peripherals?

recieve input/sends output, copy files from disk to main memory and copy files to secondary storage

what does a data buffer do and why?

in the ram or os, it manages and it gives load at the peripheral’s speed as it isn’t as fast as the CPU

what are drivers?

small programs that act as instruction manuals for a peripheral

what do drivers do?

allow for communicating with OS and allowing control of the peripheral

what happens if the incorrect driver is used?

the OS cannot communicate with the device and it will not work

how does OS manage RAM?

it keeps track of available locations in RAM to store data or new instructions

how does the OS manage memory?

ensures there’s enough space to run without interfering with other processes!

how does the OS enable multitasking?

it tracks active programs by giving each one access to the memory it needs when required

what does utility software do?

performs a specific task and is related to maintenance / optimisation of a computer system

what is encryption ?

scrambling data into unreadable format using a key so attackers cant understand if intercepted during transmission

how does the HDD become slower over time (fragmentation) ?

files are split and stored wherever possible, so when retrieved the read/write head has to physically move more to retrieve all parts of file

how does defragmentation work?

this software reorders files so it is stored consecutively + orders free space together so new files aren’t fragmented

what is other examples of utility software ?

firewalls, backups, compression, anti-malware