1.2.1 Operating systems Flashcards Preview

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Flashcards in 1.2.1 Operating systems Deck (83)
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1

Operating systems

Define 'kernel'

The kernel loads and unloads software into main memory

2

Operating systems

Define 'driver'

Controls and communicates with hardwaere

3

Operating systems

Define 'utilities'

Programs that perform background tasks

4

Operating systems

Define 'user interface'

A way to allow users to interact with the computer system

5

Operating systems

Define 'operating system'

Software which controls how a computer operates

6

Operating systems

Define 'scheduling'

The process of assigning resources to tasks

7

Memory management

Describe the process of memory management

Ensuring programs cannot access each other's data

Ensuring the RAM's free space is being used efficiently

8

Memory management

What are the two methods of managing the space used in main memory?

Paging

Segmentation

9

Memory management

What is memory segmentation?

The allocation of segments of memory to a process, to allow it to run

10

Memory management

What sections are found within each segment during memory segmentation?

Stack segment

Free memory

Data segment

Code segment

11

Memory management

What is the role of the code segment?

Where the program instructions for the process reside

12

Memory management

What is the role of the data segment?

Memory space for the variables the program will use

13

Memory management

What is the role of the stack segment?

Stores the address of the line in the program the processor was on when it got interrupted by a subroutine

14

Memory management

What is the role of the free memory?

Available memory space put aside for the stack overflow

15

Memory management

What is virtual memory?

An area on the hard disk that has been marked as additional main memory, to increase the size of RAM temporarily

16

Memory management

How does the CPU access data held in virtual memory?

The memory manager swaps data between RAM and virtual memory for the CPU to access, as it can only reach data stored in RAM

17

Memory management

What is meant by 'disk thrashing'?

When the hard disk is excessively used for virtual memory storage, and data is being transferred repeatedly between RAM and virtual memory

18

Memory management

What is a 'page'?

A fixed sized area of memory

19

Memory management

How does the memory manager keep track of pages?

Each page has an associated number, kept track of in a page table

20

Memory management

What happens when RAM is getting full, in regards to memory being stored as pages?

The memory manager identifies less used pages and cuts them to virtual memory

21

Memory management

Describe what pagination is and when it is used

Pagination is the process of separating memory into pages

It is used when managing and using virtual memory

22

Memory management

What are the similarities between segmentation and pagination?

Both are a way of dividing up memory

Both are assigned and managed by the memory manager

23

Memory management

What are the differences between segmentation and pagination?

Segmentation is used to load and unload processes, whereas paging is used when swapping data to virtual memory

The size of a segment always varies, whereas a page is a fixed size

24

Memory management

What is a 'memory leak', and what can happen because of one?

A memory leak is when segments contained finished with processes aren't remarked as free, and therefore prevent more data from being stored in memory

Due to a memory lea, the system can eventually run out of memory

25

Memory management

What is a 'stack overflow'?

When the stack section in a segment has run out of free memory to expand into, causing the program to crash with a stack overflow error

26

Interrupts and scheduling

What is meant by 'polling'?

The regular checking of devices or software to ensure it doesn't have problems

27

Interrupts and scheduling

What is an advantage and disadvantage of polling?

 

Advantage:

Simple and predictable as it only occurs at specific points

 

Disadvantage:

Can be inefficient as it uses up CPU processing time

28

Interrupts and scheduling

What is meant by the term 'interrupt'?

A signal for the CPU to stop what it is doing and carry out the interrupt task

Afterwards it will go back to what it was originally doing

29

Interrupts and scheduling

Explain the process for the CPU upon receiving an interrupt

  • An interrupt arrives while the CPU is running its current program
  • It comes with a priority label telling how important it is
  • If it is more important than the current process, the CPU will jump to the task the interrupt is asking the CPU to carry out, an ISR (Interrupt Service Routine)

30

Interrupts and scheduling

What happens to the values in the registers when a higher priority interrupt comes in

All the values in the registers are copied to the stack segment whilst the CPU executes the ISR

After it is completed the stored values are loaded back into the registers