Operating system

Question 1

Define OS

Answer 1

this is the software that manages and controls all the computer’s hardware.

Question 2

describe the OS

Answer 2

• it is loaded into RAM once the computer is switched on.
• it runs the entire time the computer is turned on.
• it is the platform on which all application software runs.

Question 3

list the communication link in order

Answer 3

userapplicationOShardware

• the OS serves as a link between application software and the computer’s hardware
• the OS provides a platform on which application software can run.

Question 4

list the functions and services of the OS

Answer 4

• memory management
• process/task management
• device management
• file management
• security
• user interface

Question 5

describe memory management

Answer 5

• the OS assigns a certain amount of memory to running programs.
• if there is not sufficient RAM then the OS will use part of the hard disk (a space allocated for Virtual memory)

Question 6

define virtual memory

Answer 6

memory that appears to exist as main storage although most of it is supported by data held in secondary storage, transfer between the two being made automatically as required.

Question 7

describe process management.

part 1

Answer 7

• multiple software are normally executed at once (by users and in backgrounds)
• the OS assign resources (such as printers and hard disk) in a controlled manner to processes currently running.

Question 8

describe process management

part 2

Answer 8

• protects one program from corrupting another program’s data
• if a program crashes, the OS will kill it or shut it down without affecting other programs.
• the OS assigns each program a certain amount of CPU time (to users it may appear that several programs are running at the same time.)

Question 9

describe security

Answer 9

• provides security by requiring users to authenticate themsevles [username and password]
• the OS manages a user’s home directories, by keeping them safe from other users.
• the OS maintains a list of permissions controls user access- applies to shared files, folders and peripheral devices.
• the OS will have firewall systems on networks to :
  1. restrict incoming and outgoing traffic
  2. prevent unauthorised access

Question 10

describe user interface

Answer 10

• the OS provides an interface to allow the user to interact with and operate the computer.
• allows for the starting and stopping of programs, switching between programs, and management of files. (create, move, copy and delete.)

Question 11

list the main types of interfaces.

Answer 11

• command line interface (CLI) [user types a series of commands using a keyboard
• graphical user interface (GUI) [user uses a mouse or pointing device]

Question 12

describe device management

Answer 12

• transparently controls all hardware devices (disk drives, printers, screens.)
• the OS schedules when a device can be used by a process and for how long. for example, a printing of one file can start only when another is completed.

Question 13

describe file management

Answer 13

• the OS keeps a tract of where different files can be found using an index
• the OS controls the disk by telling it which data to save and in what sector.
• the user tells the OS logically what folder to save the file in and what to name the file.

Question 14

how RAM and Virtual memory work with each other

Answer 14

research this

Question 15

different process states

Answer 15

research this

Question 16

explain the pre-emptive process scheduling- Round Robin

Answer 16

research this

Question 17

explain the pre-emptive process scheduling- Shorting job first

Answer 17

research this

Question 18

explain the non-preemptive process scheduling-

first come first serve

Answer 18

research this.