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operating system software & security (user interface (GUI = graphical…
operating system software & security
software types
System Software
Utility programs
Operating systems
Program translator
Application software
operating system examples
IOS (iPhone/iPad)
OS X (Apples MACs): versions have nicknames such was "mountain Lion" and "snow leopard"
Android OS: versions have nicknames such as jelly bean and Kit Kat
operating system = software that manages hardware a computers hardware and provides a user interface
functions of an OS
provides user interface
manages
peripherals e.g. keyboard & mouse
Getting input and sending output
Copying files from disk to main memory
Copy data files back to secondary storage
files
multitasking
user access rights
memories
user interface
Menu-Driven interface
GUI = graphical user interface controls WIMP = Windows, Icons, Menus, Pointers
User can click on icons using a pointer or cursor Icons representing functions mean less need to type instructions – just click on an icon or menu item Right-clicking brings up context-sensitive menus Different shaped pointers have different uses
CLI = Command Line Interface
just text, like Windows command prompt
All user commands must be typed in as text No graphics Quicker for expert users who know the commands Takes less space on the disk and in RAM
Voice activated
real-time sensors detect inputs, actuators output actions
Interrupts
Interrupts are signals sent to the CPU by external devices to indicate an event that needs immediate attention They tell the CPU to suspend its current activities and execute appropriate instructions Hardware interrupts are generated by hardware devices – for example, printer out of paper Software interrupts are generated by programs, e.g. a divide-by-zero error will cause a calculation to be abandoned and an error message displayed
device driver
.
A device driver is a program that controls a peripheral device such as a printer, VDU, CD-ROM drive etc.
Each device communicates with the OS via its own driver
Many device drivers are built into the operating system but if you buy a brand new type of device,
it will be supplied with a driver, which you will need to install
sending files to a printer
The computer can send data thousands of times faster than the printer can print it
The computer sends the printer output to a print buffer, a special area of memory in either the computer or the printer, at full speed
From here, it is transmitted it to the printer, typically a page at a time
The print buffer may store a number of jobs waiting to be printed
If the printer cannot print, the OS is notified and passes on the message to the user, e.g. “Offline” or “Printer out of paper”