operating systems Flashcards
application software
for the user benefit eg word processors , internet browser and game
system software
performs the task needed to operate the hardware , and provide services for other software eg Os ,game engines ,utility programs
operating software
-The essential software links the hardware and other software together and generally manages the computer system
purposes:
-manages the hardware (only the os can interact directly with it)
- manages the application installed(inc utility software)
- creates a user interface(an abstraction from the hardwrae
- provides a layer of security
memory management
- when a user opens a program , it needs to be loaded into the ram
- The os overseas the allocation and management of ram space
- if there is no space left ,virtual memory may be used
- Different program data/instructions are kept separate = security
paging
Paging is when memory is split up into equal-sized
sections known as pages.. These can then be
swapped between main memory and the hard disk as
needed.
segmentation
Segmentation is the splitting up of memory into
logical sized divisions, known as segments, which
vary in size. These represent the structure and
logical flow of the program
virtual memory
Virtual memory uses a section of the hard drive to act as RAM when the space in main memory is insufficient to store programs being used. Sections of programs not currently being used are temporarily moved into virtual memory through paging, freeing up memory for other programs in RAM.
interrupts
Interrupts are signals generated by software or hardware to indicate to the processor that
a process needs attention.
distributed system
Run across multiple devices, allowing the load to be spread across multiple computer processors when a task is run.
embedded system
Built to perform a small range of specific tasks and catered towards a
specific device such as a household appliance. T
multi-tasking
Multi-tasking operating systems enable the user to carry out tasks seemingly
simultaneously. This is done by using time slicing to switch quickly between programs and applications in memory.
real time
Commonly used in time-critical computer systems, a real time OS is designed to perform a task within a guaranteed time frame