Computer Science OS Aqa A-level

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  • Created by: roshan231
  • Created on: 15-01-20 12:30
What is system software? What does it do?
System software acts as an interface between the hardware of the computer and the application software that users need to run on the computer.
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What does a OS do overall?
It's designed to act as an inteface between the hardware and the user. This can also be reffered to as a virtual-machine. In other words, it hides the complexity of the computer from the user.
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What are some tasks that the OS preforms?
Start-up, input recognition (mouse movements), Memory management, ETC.
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What is recource allocation?
This is the process undertaken by the OS in which recources are alolocated to certain programs depending in the OS.
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Why is recource management important?
Users tend to run multiple progrmas at the same time, deciding and dividing up recources can be complex in order to achive the best user experience
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What is the Scheduler?
The scheduler is the operating system module responsible for ensuring that processor time is used as efficiently as possible
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What is the round robin algorithm is a OS?
This is a scheduler algorithm wich makes sure each program has a slice of CPU processing time.
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Explain memory management.
An os has to mange the data in primary memory, while keeping track of the memory locations. or it is free in the heap.
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what is memory swapping?
Programs which is a sequence of instruction are transferred from a backing store to main memory. Then programs are stroed in memory fetched in sequence decoded and executed. these progrmas can be replaced by another program at any time.
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How does virtual memory work? part 1
Virtual memory is broken into 'pages' and RAM is broken into "page frames". these pages take 4 kilobytes of storage,
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How does virtual memory work? part 2
There is a "page table" stroed in RAM. this is an array on entries , each entry is a page. This table checks is the page is loaded into a frame of RAM and if so where. The CPU uses this table to find data in virtual memory.
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Other cards in this set

Card 2

Front

What does a OS do overall?

Back

It's designed to act as an inteface between the hardware and the user. This can also be reffered to as a virtual-machine. In other words, it hides the complexity of the computer from the user.

Card 3

Front

What are some tasks that the OS preforms?

Back

Preview of the front of card 3

Card 4

Front

What is recource allocation?

Back

Preview of the front of card 4

Card 5

Front

Why is recource management important?

Back

Preview of the front of card 5
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