Download Computer Systems

Computer Systems
Computer
Software
Operating System
When a computer is switched on, the first
task is to load the OPERATING SYSTEM
into the memory.
The OPERATING SYSTEM (definition
sheet) is a suite of programs that controls
the hardware and software running on the
computer.
Operating Systems (OS)
Two examples of OS are:
Command-line operating system, this
requires the user to memorise and enter
all commands from a command prompts
DOS is an example of Command Line
Graphical User Interface (GUI) this
interface allowed the user to
Launch programs by double clicking with a
mouse
Files to be copies by drag and drop
Much easier to copy and paste
Microsoft office is an example of GUI
Application Programs
An application program is a piece of software that
is designed for a specific task or function:
Word Processing
Spreadsheets
Databases
Presentation
E-Mail
Browsers
Standard File Format
This is when files are compatible over
different computer packages
e.g.You can type something in Microsoft
word and as long as you save it as RTF
you can open it in another word
processing package (Apple Works etc)
Standard File Format
There are lots of different Standard File
Formats for different packages;
– E.g. TEXT- .txt, .ascii, .rtf
– GRAPHICS- .jpeg, .gif
Native File Formats
A native file format is how a file saves
automatically.
– E.g. Microsoft Word files automatically save
as .doc so .doc is the native file format for
Microsoft Word
– Microsoft Excel files automatically save as .exl
so .exl is the native file format for Microsoft
Word
General Purpose Packages (GPPs)
These are application packages that are in
common use and may be supplied with
desktop computer systems.
GPPs are widespread because the data
objects contained in each package fall into
the categories of text, number, data and
graphics. These are the most commonly
used data type in computing.
Four main GPP s
For Example
QUESTION:
– Name one object and one
operation from the
following poster.
ANSWER:
– Object: picture of cake
– Operation: scale
Or
– Object: text “Cake Sale”
– Operation: Bold
Cake Sale
Sunday 21st September
12pm-3pm
in
St. Kentigerns Assembly Hall
Viruses
A viruse is a rouge program that can cause
damage to a computer system, it enters your
system vie e-mail, downloads from the Internet,
infected floppy disks, home made CD’s and fun
websites
The most popular method is for the virus to arrive
as an attachment to an e-mail, which when
opened sends copies to everyone in the users
address book.
Viruses
When a virus program is opened it tends to
perform four actions:
 Replication, copies itself to other files
 Camouflage, attempts to disguise itself to avoid
detection
 Event watching, whenever the virus runs it
checks for certain events, specific dates
 Delivery, this is the purpose of the virus , it may
be a simple jumbling of letters or wiping an
entire hard drive.
Virus Signs
There are a number of tell-tale signs that
can indicate that your computer has been
infected with a virus. They include:
Displaying unwanted messages
Strange sounds or visual effects
Computer keeps rebooting unexpectedly
A flood of unexpected e-mails
Finished
You are now your first unit of work, it is now
time to start revising for you first NAB
Good luck with you revising, remember to
uses Wikkispaces, go over your home
works and ask for help.