Operating systems (OS) Flashcards
What is an OS?
Set of software programs desgined to manage the hardware of the system
What purposes does it have?
controls the hardware of the system through software like resource manageent, hardware drivers, systems software, task management, scheduling, memory management, paging, segmentation and virtual memory
acts as a platfrom on which application software can run and deal with issues that the sotware may have such as storage of files
provided operator with a suitable Human User Interface to allow communcation bewteen users and hardware (for example command line interface)
handles communications between computer devices using rules and protocols to govern communication (such as across a netwrk)
handles translation of code through compiles, interpreters, assemblers to translate high/low level language into machine code
has many utilitt software programs used to carry out housekeeping tasks on the system to mantain the hardware
uses job scheduling to provide fair access to preocessor according to set of rules
What is memory management?
process of controlling and coordinating a computers main memory
How does memory management work?
organises use of main memory by converting logical adresses into physical adressed
partitions programs into chunks to ensure no space is wasted
ensures programs cant access each others memories without access/unless required to
allocates memory to allow seperate processes to run simaltaneously and reallocated memory when necessary
allows programs that are larger than main memory to run
provides security to protect the OS
What is paging?
partitioning of memory into fixed physical divisions made to fit sections of memory
What is segmentation?
partitioning of memory into variable sized logical divisions which hold complete sections of programs
What are the similarities between paging and segmentation?
both assigned to memory when needed to allow programs to run despite insufficient memory
stored on backing store disk to swap parts of programs used for virtual memory
allows programs to be stored in memory away from each toher
may cause disk threshing when more time spent swapping pages than processing
