Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Computer Science A level > Chapter 20 System software > Flashcards

Chapter 20 System software Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

What starts the OS?

A

BIOS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a BIOS?

A

Is a code stored in ROM and starts a bootstrap program that loads the OS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does an OS provide?

A

Provides facilities to have moe than one program stored in memory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Which are the two ways in which the purposes of the OS can be considered?

A

Internal viewpoint

External viewpoint

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the internal viewpoint concerned about?

A

Concerns how the activities of the operating system are organised to best use the resources available
Concerns the facilities made available for system usage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the external viewpoint?

A

It is what the user sees

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does the multi-programing algorithm do?

A

Makes sure that only one program can acces the CPU at any given time but others are ready when the oppportunity arises and it is used when a single user is logged in

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the time-sharing system designed for?

A

It is designed to have many users simultaneously logged in

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which are the three fundamental resources in a computer system?

A

the CPU
the memory
the I/O (input/output) system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does the I/O system do?

A 
Makes sure of what goes in and out of the:
    CPU
    Memory
    Disk device driver
        - Disk
    Screen device driver
        - Screen
    Keyboard device driver
        - Keyboard
    Printer device driver
        - Printer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does the file system help with? Give one example.

A

Allowing the program to be created and run without the programmer being familiar with hot the processor functions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does the API stand for?

A

Application Programming Interface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does an API do?

A

Fulfils a specific function such as creating a screen icon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is an API aim?

A

To provide portability for a program

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which are the two modes of operation that the operating system provides?

A

User mode

Kernl mode

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does the user more provide and contain?

A

The User Interface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is kernel mode also known as?

A

Priviliged mode

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the difference between kernel mode and user mode?

A

The difference between user mode and kernel is that kernal has access part of the memory and to certain system functions that user mode cannot access

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is a kernel?

A

Kernel is a computer program that is the core of a computer’s operating system, with complete control over everything in the system.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does a layered structure look like?

A 
Hardware interface
    Kernel
        Utilities
            Application programs
                User interface
21
Q

How does the transition between the states of process scheduling happen?

A

A new process arrives in memory and a PCB is created; it changes to the ready state
A process is the ready state is given access to the CPU by the dispatcher; it changes to the running state
A process in the running state is halted by an interrupt; it returns to the ready state
A process in the running state cannot progress until some event has occured (I/O perhaps); it changes to hte waiting state (sometimes called the ‘suspended’ or ‘blocked’ state)
A process in the waiting state is notified that an event is completed; it returns to hte ready state
A process in the running state completes execution; it changes to the terminated state

22
Q

What is a Process control block (PCB)?

A

Process control block (PCB) is a complex data structure containing all data relevant to the running of a process

23
Q

In the scheduling process which are the five threads?

A 
New 
Ready 
Waiting
Running
Terminated
24
Q

When are interrupts implemented?

A

Used when a process in the running state makes a system call requiring an I/O operation and has to change to the waiting state
A scheduling algorithm decides to halt the process

25
Q

What does FIFO stand for?

A

first-in first-out (FIFO)

26
Q

What can Scheduling algorithms be?

A

Short term
Long term
Preemptive algorithm
Non-preemtive algorithm

27
Q

First come first served (FCFS) non-preemtive or preemtive?

A

Non-preemtive

28
Q

When is FCFS inefficient

A

FCFS is very inefficient if it is the only algorithm employed but it can be used as part of a more complex algorithm

29
Q

Round-robin algorithm is non-preemtive or preemtive?

A

Preemptive

30
Q

How is round-robin used as and how does it work?

A

Allocates time slice to each process
Process will be halted when its time slice has run out
Can be implemented as a FIFO queue
Normally it doesn’t involve any prioritising process
Can be used for shedulling if the processes have different priorities

31
Q

Why is the Priority-based scheduling algorithm more complicated than the other Process scheduling algorithms?

A

Priority-based scheduling algorithm is more complicated because every time a new process enters the ready queue or when a running process is halted, the priorities for the processes may have to be re-evaluated

32
Q

The scheme used to determine priority levels in Priority-based scheduling algorithm needs computation for what criteria?

A

Estimated time of process execution
Estimated remaining time for execution
Length of time already spent in the ready queue
Whether the process is I/O bound or CPU bound

33
Q

Which taskes normally take part first in a Priority-based scheduling algorithm?

A

Normally the smaller tasks take place first since it may not need that much of a CPU usage

34
Q

What is the main task of memory management?

A

Protecting memory space for the OS kernel

35
Q

What is virtual memory?

A

A paging mechanism that allows a program to use more memory addresses than are available in main memory

36
Q

What are the advantages of virtual memory?

A

Large program can be run when an equally large amount of memory is unavailable
Only part of a program needs to be in memory at any one time

37
Q

What are the disadvantages of virtual memory?

A

Disk thrashing
When part of a process on one page requires another page which is on disk
Causing long loading times
Fortunately this happens rarely because there are algorithms made to avoid this

38
Q

How does virtual machine work?

A

A process interacts directly with a software interface provided by the operating system
The kernel of the operating system handles all of teh interactions with the actual hardware of the host system
The software interface provided for the virtual machine provides an exact copy of the hardware

39
Q

What are the advantages of virtual machine?

A

More than one different operating system can be made available on one computer system

40
Q

What are the disadvantages of virtual machine?

A

Takes time and effort for implementation

Will not offer the same level of performance that would be obtained on a normal system

41
Q

What is the front end of a compiler?

A

Performs analysis of the source code and produces an intermediate code that expresses completely the meaning of the source code

42
Q

What is the back end of a compiler?

A

Takes the intermediate code as input and performs synthesis of object code

43
Q

What are the front end analysis stages?

A

Lexical analysis
Syntax analysis
Semantic code generation
Intermediate code generation

44
Q

What happens in lexical analysis?

A

Each line of code is separated into tokens in Lexical analysis

45
Q

What does Syntax analysis do?

A

Syntax analysis makes:
Symbol tables
A data structure in which each record contains the name and attributes of an identifier
Identifies the tokens
The results are recorded as a syntax or parse tree

46
Q

What does Intermediate code generation do?

A 
Intermediate code generation creates the three-address code
    e.x.
        temp := b * C
        temp := temp - d
        temp := temp / e
        y := a + temp
47
Q

How do you represent the grammar of a language in a translation software?

A

::= ||
::= 0|1|2|3|4|5|6|7|8|9
::= |
::= A|B|C|D|E|F|G|H|I|J|K|K|L|M|N|O|P|Q|R|S|T\U|V|W|X|Y|Z
::= a|b|c|d|e|f|g|h|i|j|k|l|m|n|o|p|q|r|s|t|u|v|w|x|y|z

48
Q

What do back-end synthesis stages do?

A

Presentation of a list of errors

Optimisation of the code

Computer Science A level (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions