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1.2.1 Systems software

A-Level Computer Science

Learning Objectives Flashcards Quiz Exam Questions

Fill in the blanks with the correct words. Click "Check Answer" to see if you're right!

Term: Operating System

Definition:

Systems that the computer.
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Term: Memory Managment

Definition:

Function of the O.S that ensures efficient use of the computer' memory. Includes loading in RAM when needed, paging, segmentation and virtual memory.
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Term: Paging

Definition:

Separates memory into sized units. Pages are removed from when loaded but idle and transferred back into RAM when needed.
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Term: Segmentation

Definition:

Separating a program into blocks of memory. Each segment is a complete block that separately.
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Term: Virtual memory

Definition:

The O.S will create space on a storage device to store currently loaded programs when the memory has insufficient space.
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Term: Interrupt

Definition:

A signal that causes a halt in the execution of the current routine. Examples include, and output devices or systems software routine. Interrupts are handled in priority order.
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Term: ISR

Definition:

Interrupt Routine. A program that is and executed when an interrupt of higher is signalled. ISR's are executed in priority order.
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Term: Scheduling

Definition:

An that determines how time is allocated between different tasks.
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Term: Round Robin

Definition:

A scheduling algorithm. Each task is added to the round robin. Each task is given an equal of processor time. After the time slice, the CPU to the next task.
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Term: Round Robin

Definition:

A scheduling algorithm. Each task is added to the round robin. Each task is given an equal of processor time. After the time slice, the CPU to the next task.
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Term: First Come First Served

Definition:

The are placed in the ready in the order they arrived.
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Term: Multi-Level Feedback Queue

Definition:

Multiple queues are used. Each queue can have a different algorithm. Tasks can between different queues in order to better prioritise a task. Improves CPU utilisation.
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Term: Shortest Job First

Definition:

The ready queue is by how short a task is to complete. The shorter ones get processed first. Maximises .
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Term: Shortest Remaining Time

Definition:

Scheduling algorithm that orders the ready queue by how long a task has to complete. The order is checked and after each cycle. Maximises throughput.
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Term: Distributed OS

Definition:

.
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Term: Distributed OS

Definition:

An OS that is over different computers, often in different locations. processing power as large tasks can be shared.
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Term: Embedded OS

Definition:

A lightweight OS that is designed to manage a function within a larger machine.
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Term: Multi-tasking OS

Definition:

An OS that is capable of running applications at once. This is achieved by and memory management functions.
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Term: Real time OS

Definition:

An OS that processes as it comes in, . Suitable for time critical systems.
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Term: BIOS

Definition:

Basic Output System. Part of the OS that handles the operating system using a bootloader program, checking using a POST test and System Settings.
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Term: Virtual Machine

Definition:

A software program that emulates a machine.
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Term: Device Drivers

Definition:

Software that allows devices to with the main computer.
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