4.6.1.3 System software and 4.6.1.4 Role of an operating system (OS) Flashcards
What is the role of the Operating System?
Hides the complexities of the machine to the user, providing a ‘virtual machine’.
What sort of things is the Operating System used for?
Resource management through using hardware drivers, system software and task management
Provides a platform that application software can run on and deals with software issues.
Handles communication between devices using protocols
Manages memory such as virtual memory and paging
Job scheduling - provides instructions access to the processor , interrupt handling
Provides security through passwords
Management of peripherals
What is utility software?
Programs that perform a common task that help the running of software, such as disk defragmenters
What is library software?
Previously written program code available from third parties which saves time taken to write the program.
How does an interpreter work?
Analyses the code line by line and translates each statement if the line is error free. It calls the appropriate routines to carry out the statement.
What’s the difference between a compiler and interpreter?
A compiler produces object code but an interpreter doesn’t
Interpreted code will execute slower than the object code produced by the compiler
The interpreter is required to translate the program but once the compiler produces object code it is no longer needed.
Compiled code can only be executed on that processor type whereas an interpreter is more portable
When would you use a compiler?
When you need to execute the program faster. It is useful when distributing software as once the object code is produced it can’t be tampered with by the user. It is used when development of the program is finished.
When would you use an interpreter?
When you need to debug and test your program as correcting mistakes will take less time
What has to be done to assembly code to allow it to be executed by the computer?
It has to be translated into machine code by an assembler
Describe two differences between the operating system that is installed on the smartphone and an operating system that would be used on a desktop computer
Will not have to support as wide a range of hardware devices / peripherals / / may not support external storage devices;
Will not / less likely to need to support the addition of new hardware devices to the system;
Will have minimising power consumption as a higher priority;
Will run application software in a sandbox / / will (more tightly) restrict access to resources by application software;
Must be capable of running on a device with less processing power / / less RAM / memory / / smaller memory footprint;
Needs to work with specialised hardware devices eg GPS receiver, accelerometer
