1.5: systems software

define systems software

• software that governs the computer system

properties of systems software (4)

• controls the hardware (including peripherals)

• allows other programs to run

• provides an interface for the user to interact with the computer

• maintains the system

• what is a peripheral?

• give one example

• hardware that connects to a computer

• mouse, keyboard, scanner, etc.

what are the 2 types of systems software

• operating system

• utility software

define operating system

a collection, or suite, of programs that manages and controls the computer

functions of an operating system

• controlling hardware components

• providing a platform for software to run on

• providing a user interface

• multitasking facilities (running more than 1 program simultaneously)

• managing computer’s memory, peripherals, files and users

give 3 examples of operating systems

any one from:

• microsoft windows

• apple OS X

• linux

• iOS

• android

define user interface

a program or suite of programs that allows a user to intercat with a computer

give the 3 types of user interface

• graphical user interface (GUI)

• mobile user interface (Mobile UI)

• command line interface (CLI)

give common features of a GUI

WIMP

• windows

• icons

• menus

• pointers

GUIs feature a desktop where e______________ i_ d______________

everything is displayed

in a GUI, where do applications run in

where are these accessible through

windows

menus

in a GUI, what are all apps and files represented by

icons

how do users interact with the GUI

with a mouse and on screen pointer

2 advantages of GUIs

• powerful

• easy to use

1 disadvantage of GUI

require a lot of processing power

how do Mobile UIs differ from GUIs

they respond to touch

ways users can use a mobile UI through touch

• fingers are used to open programs / interact with them

• swiping = used to scroll within documents

• pinching / stretching = used to zoom in and out, e.g. to resize images

1 advantage of mobile UIs

very intuitive and suitable for most users

1 disadvantage of mobile UIs

can take longer to type text up with

CLIs are t___- b________

text-based

how do users controlt he computer with a CLI

they type in commands

2 advantages of CLIs

• require little processing power

• extremely powerful

2 disadvantages of CLIs

• difficult to use

• only trained experts can efficiently make use of it as it is very complicated

MORE FEATURES OF OPERATING SYSTEMS!

what is multitasking

give an example

• being able to run more than one program simultaneously

• e.g. user can stream music while making a backup of files

what 2 conditions are needed for multitasking to be possible

• operating system needs to support multitasking

• computer needs enough memory to hold more than one program in primary memory at the same time

how can the cpu process programs

if they are temporarily stored in ram

when processing is required, from where does the operating system in and out of?

virtual memory

when programs arew closd, where do they get removed from and why

• RAM

• to free up space for other tasks

how many tasks can the OS perform at a time

1

what is multitasking

when it appears that the OS is executing more than on process at a time

(switches so rapidly between performing tasks it appears they are happening at the same time)

during peripheral management, what does the OS manage?

the transfer of data between peripherals and the processor

what is the program the OS uses to operate a peripheral called

device driver

what does the device driver control

the peripheral

what does it help the OS to do with the peripheral

interact and communicate with it

what does the device driver do with the OS’ instructions for the peripherals

translates it into a format the specific hardware can understand (remember, each peripheral has its own driver)

what is user management (common sense)

when the OS manages users

the OS allow users to:

• create / manage / delete individual accounts

• be given access rights, e,g, administrator / guest rights

3 ways the OS manages security by managing users

• auditing (keeping a log of) files a user creates/accesses/edits/deletes

• allows passwords to be reset

• monitors login activity

what is one of the most important tasks of an OS?

file management

file handling software allows files to be: (give like 5 there’s so many)

• created

• modified

• named/renamed

• deleted

• searched for

• opened

• closed

• copied

• moved

• restored

• saved

• sorted into different orders according to name, file type, date created, etc

• allocated to folders

• allows access rights to be set to files, e.g. read only / edit

define utility software

what kind of tasks could you say it performs?

• helps maintain and organise the computer system

• performs ‘housekeeping’ tasks

what are utilities required to run?

additional tasks not performed by the OS

give 3 things utility software includes

• encryption software

• data compression

• defragmentation

encryption disguises the content of files. why?

so they can only be descrambled and therefore understood by authorised users

what encodes or decodes encrypted data

the encryption key

how is a file stored on a hard disk

as a series of segments, not a whole file

the segments are split up and scattered over the disk

what is this called

fragmentation

when does fragmentation occur

when there is limited contiguous (continous, sequential, uninterrupted) space to store a file

explain why there would be limitd space on a hard disk (3)

• data may be stored and later deleted on the hard drive

• when new files are created = may be bigger than the spaces left by deleted files

• these new files have to be split up

why does a fragmented disk take longer to load, read from and write to

so the computer runs…

because of the distance between the segments/fragments (?) of the file

so the computer runs slower

how does DEfragmentation work (2)

• empty spaces are collected together

• fragmented files are rearranged to be stored contiguously

what does defragemtation do to access/read/write time and why

decreases access/read/write time because data is stored contigously

why does defragmentation make it quicker to save new files

• there is more free space together

• files don’t need to be split up - they can just be stored contiguously

why are compressed files easier to transmit across a network

• the files are smaller

• so they require fewer packets to be sent

give 4 other utilities

• backup software

• disk checkers

• disk formatters

• auto-update