SLR 4 - OPERATING SYSTEMS Flashcards
What is a software?
a program that runs on a computer
What are the 2 main types of software?
- operating systems
- application software
What is an operating system?
a collection of programs that manages the hardware and software of a computer system including sharing the computer’s time, memory, hardware and other resources
What are the functions of an operating system?
- file management
- input/output management
- resource allocation
- process management
- networking management
- user management
- user interface
What is paging?
- partitioning memory into fixed sized physical divisions called pages
- processes in memory will be assigned an appropriate number of pages
What are the 3 features of pages?
- fixed sizes
- made to fit sections of memory
- physical divisions
What is segmentation?
- partitioning memory into variable sized logical divisions called segments
- a large program can be executed by consecutively running its segments
What are the 3 features of segments?
- different sizes
- complete sections of programs
- logical divisions
What are the similarities between paging and segmentation?
- both allow programs to run despite insufficient memory
- both pages and segments are stored on disk and transferred to memory when needed
What are the differences between paging and segmentation?
- pages are fixed sizes whereas segments are different sizes
- pages are physical divisions whereas segments are logical divisions
- pages are made to fit sections of memory whereas segments are complete sections of programs
What is virtual memory?
an allocated area of secondary storage where pages of inactive jobs are swapped into to free up enough RAM for the current job
What are the different types of OS?
- distributed
- multi-tasking
- multi-user
- embedded
- real-time
What is a distributed OS?
a distributed OS is spread over multiple computer servers on a network, acting as a single system to parallel process a job
What uses a distributed OS?
online shopping sites
What is a multi-tasking OS?
- an OS capable of running many tasks simultaneously
- each active program is scheduled to receive a tiny time slice in quick rotation, giving the impression that they are operating at the same time
What is a multi-user OS?
- OS consisting of one mainframe computer with multiple terminals that allow multiple users to access the computer’s resources
- each user is given a time slice of the mainframe processor
- computer will manage user’s various permissions and access rights when they log on
- server OS software will handle the requests of multiple people using diff computers on a network at the same time
What is an embedded OS?
- specialised OS with limited resources and functionality, built in to control a single machine
- tend to run on dedicated hardware so they run with max efficiency using low-powered processors and very little memory
What is a real-time OS?
- an OS that generates responses within a guaranteed time frame
- plenty of redundancy built in so they can handle sudden increases in input
Give 2 examples of uses of a real-time OS?
- self-driving cars
- hospital monitoring machines
What is a device driver?
- a program supplied with a peripheral device that allows the OS to control and communicate with the device
- translates OS instructions into a series of instructions that a specific piece of hardware can understand
