Operating Systems

Question 1

what is the purpose of operating systems

Answer 1

provides an interface between the user and the computer

Question 2

what is file management

Answer 2

a function provided by the OS which allows the user to create, organise and rename files

Question 3

what is memory management

Answer 3

a function provided by the OS which allocates and tracks resources to ensure efficient use of memory

Question 4

what is input/output management

Answer 4

involves controlling the exchange of data between the computer and external hardware.

Question 5

how does multitasking work

Answer 5

works by allocating processing time to each program, this happens in a cycle.
this creates an illusion of simultaneous operation

Question 6

what is paging

Answer 6

when memory is divided into fixed sizes and programs are split up to fit these pages

Question 7

what is segmentation

Answer 7

when memory is split up into different sizes (logical divisions)

Question 8

what are the simmilarities of paging and segmentation

Answer 8

both allow programs to run on insufficient memory

Question 9

what are the differences between paging and segmentation

Answer 9

pages are fixed sizes
segments are logical

Question 10

how does an interrupt happen relating to FDE cycles

Answer 10

1.complete the current FDE cycle
2.save the registers to memory
3.determine the interrupt service
4.service the interrupt
5.restore the register values
6.continue the original process

Question 11

what is a device driver

Answer 11

software that tell the operating system how to communicate with a device

Question 12

how do driver routines work

Answer 12

• when a program requests to interact with a hardware device - it calls a routine within the driver software of that device
• the routine causes the hardware to perform a specific task

Question 13

What bus is used for devices to communicate with the processor?

Answer 13

control bus

Question 14

what are the different types of OS

Answer 14

multi tasking OS
multi user OS
Distributed OS
Embedded OS
real time OS

Question 15

what is a distributed OS

Answer 15

where multiple computers work on a single task
the distributed OS coordinates the communication between nodes

Question 16

what is an interrupt

Answer 16

a signal to the processor indicating a device or process needs attention

Question 17

what is polling

Answer 17

where the CPU asks each process if an interrupt is needed

Question 18

what are the steps to handling interrupts

Answer 18

1)the processor completes the current FDE cycle
2) the interrupt flag is checked to see if any interrupts have been raised(if so the priority is checked)
3)the higher priority tasks are executed first
4) the other interrupt tasks are then loaded from the stack to all the processors to be executed

Question 19

how are the non interupt tasks loaded to a stack
and what happens to the interrupts

Answer 19

• the contents of registers are pushedto a stack
  the address
• the addess of the ISR is loaded into the PC(register)
• the ISR is executed

Question 20

what is an ISR

Answer 20

a program that is designed to respond to an interrupt’s request

Question 21

what is the purpose of a schedulling algorithm

Answer 21

to decide how processor time is split between processes

Question 22

what is the difference between pre-emptive and non pre-emptive

Answer 22

pre emptive = a process can be replaced with a higher priority task
non pre emptive = once a job is started it is left alone until finished

Question 23

what data structure is associated to scedulling

Answer 23

QUEUE (FIFO)

Question 24

what does BIOS stand for

Answer 24

basic input output system

Question 25

what are the tasks peformed by the BIOS

Answer 25

keeping track of the system time
testing the hadware that is connected as te computer boots

Question 26

how does an operating system get the device driver of a mouse

Answer 26

the device drvier of the mouse is automatically downloaded by the
OS once the mouse is plugged in

Question 27

what are the different jobs performed by the control bus

Answer 27

interrupts
clock signals
read/write signals

Question 28

what is a virtual machine

Answer 28

a program that has the same functionality as a physical machine

Question 29

what is a hypervisor

Answer 29

a program used to run and manage one o more virtual machine on a computer

Question 30

what are the advantages of virtual machines

Answer 30

allows developers to test software developed for multiple platforms

can be used to test dangerrous code like viruses

Question 31

what is system software

Answer 31

software that controls the hadware

Question 32

what is utility software

Answer 32

software that perfporms a specific task that is usually related to the up keep of the system

Question 33

what is the difference between specific and generic software

Answer 33

generic can be used for masny different tasks
specific is only used for specific tasks (usually takes lots of skill)

Question 34

what is the purpose of disk defragmenters

Answer 34

helps to combine the different parts of the file together in contiguous space