definitions 1.2 Flashcards
basic input-output system
a program that initialises and tests whether system hardware is functional and then loads the operating system from the hard disk into ram when the computer is turned on
device driver
A program supplied with a peripheral device that allows the os to control and communicate with the devices
distributed operating system
the operating system is spread over multiple computer servers on a network, acting as a single system to parallel process a job
embedded operating system
a specialised operating system with limited resources and functionality, built-in to control a single machine
First come first served
a scheduling algorithm where processes are dealt with in the order they arrive (a queue)
intermediate code
code partly transferred between high-level and machine language produced by a compiler
interrupts
a signal from hardware, software or the clock to alert the CPU. in the interrupts is a higher priority than the current task, the current routine pauses and resumes after the interrupts is executed
interrupts service routines
if an interrupt is a higher priority than the current task, register contents are temporarily transferred onto the system stack at the end of the current FDE cycle and the interrupts is handled
Memory management
The efficient organisation and allocation of main memory to the program in use
Multi-level Feedback queues
A scheduling algorithm that uses multiple queues, each with a different priority. jobs can be moved between queues.
Multi-tasking operating systems
an operating system capable of running multiple tasks simultaneously
Multi-user operating systems
an operating system 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
operating systems
a set of programs managing the operation of the computer that is loaded into RAM every time the computer is turned on. it bridges the user to the hardware
paging
partitioning memory into fixed-sized physical divisions called pages. processors in memory will be assigned an appropriate number of pages.
Real-time operating system
an operating system where data is processed as it comes, with responses generated with a guaranteed timeframe
Round-Robin
a scheduling algorithm where each process is given an equal time slice and is dealt with on a first-in-first-out basis. if a process does not finish within a time slice it joins the end of the queue
scheduling
allocating processor time to each application to ensure processor time is used as efficiently as possible when multi-tasking
Segmentation
partitioning memory into variable-sized logical divisions called segments. A large program can be executed by consecutively running its segments
Shortest job first
A scheduling algorithm that picks the process with the shortest estimated running time and runs it until its finished
Shortest Remaining time
A scheduling algorithm that picks the process with the shortest estimated time remaining to finish. if a process with a shorter time is added, the scheduler switches processor
Virtual machines
Any instance where software is used to take on the function of a machine, including intermediate code or running an operating system within another
Virtual Memory
an allocated area of secondary storage where pages of inactive jobs are swapped to free up enough RAM for the current job
Applications
A program that can be run on a computer, allowing the user to carry out specific tasks