Let us assume that there are three processes called P₁, P₂, P₃ and time allocated for each process 30,40, 50 minutes. If the process P₁ completes with in 20 minutes then processor takes the next Process P₂ for the execution.
If the process P₂ could not complete within 40 minutes, then the current process P₂ will be paused and switch over to the next process P₃.

1. The operating systems should be robust.
2. When there is a fault, the operating system should not crash, instead the os have fault tolerance capabilities and retain the existing state of system.

A computer consists of a collection of process they are classified as two categories,
1. Operating system process which is executed by system code
2. User processes which is executed by user code.

(i) A float type variable is initialized with a fractional value such as 0.0Lwhere as a double type variable is initialized with a fractional value as 0.0D. The difference between initialized is the suffir L and D respectively
(ii) Eg: float a = 0.0f; double x = 0.0 D.

The parts of an algorithm are known as functions. A function is like a sub-algorithm. It takes an input, and produces an output, satisfying a desired input output relation.

We divide the main algorithm into functions. We construct each function independently of the main algorithm and other functions. Finally, we construct the main algorithm using the functions. When we use the functions, it is enough to know the specification of the function. It is not necessary to know how the function is implemented.

1) 0 \(\div \)  0 = 0
2) 0 \(\div \) 1 = 0
3) 1 \(\div \) 1 = 1
4)  0  \(\div \) 1 = infinite

(i) The octal number system is playing a vital role in digital computer work.
(ii) The octal number system has a base of 8: It means that it has eight unique symbols such as 0,1 ,2,3,4,5,6 and 7.
(iii) Thus, each digit of an octal number can have any value from 0 to 7

(i) The term Decimal is derived from a Latin prefix deci, which means ten.
(ii) The Decimal number system has ten digits ranging from 0-9.
(iii) Because this system has ten digits. It is also called as a base ten number system or denary number system.
(iv) A decimal number should always be written with a subscript 10

Programming language, pseudo code, flowchart are notations for expressing algorithms.

Alternative statement selects and executes exactly one of the two statements, depending on value of the condition.

(i) Establish the loop invariant at the start of the loop.
(ii) The loop body should so update the variables as to progress toward the end and maintain the loop invariant, at the same time.
(iii) When the loop ends, the termination condition and the loop invariant should establish the input-output relation

Let P(m, n) = m + 3n. Then
P(m, n) [m, n := m + 3, n -1]
= m + 3n [m, n := m + 3, n -1]
= (m + 3) + 3(n -1)
= m + 3 + 3n - 3
= m + 3n
= P(m, n)
Since (m + 3n) [m, n : = m + 3, n - 1] = m + 3n, m + 3n an invariant of the assignment m, n := m + 3, n-1.

(i) The absolute value is the magnitude of a digit in a number.
(ii) For example, the digit 5 in 7458 has an absolute value of 5 according to its value in the number line.
(iii) The place value of a digit in a number refers to the position of the digit in that number such as tens, hundreds, and thousands.
(iv) The total value of a number is the sum of the absolute value x place value of each digit that the number consists of.
(v) The base value of a number is also known as the radix, which depends on the type of the number of systems that are being used.

Windows store is designed to unify all Windows platforms across multiple devices, including Windows Phone and tablets, with universal apps that can be downloaded from the Windows Store and run on all Windows devices.

(i) Select the file or folder you wish to delete.
(ii) Click on the File menu and select Delete.
(iii) The file will be moved to Recycle bin.

(i) Optical mouse uses Red, Blue or Green LED whereas Laser mouse uses only infrared LED.
(ii) Optical mouse has three buttons; Laser mouse has as many as 12 buttons and can be programmed by user.
(iii) Optical mouse is less sensitive and sensitive towards surface but Laser mouse is highly sensitive and able to work on any hard surface.

(i) A touch screen is a display device that allows the user to interact with a computer by using the finger.
(ii) It can be quite useful as an alternative to a mouse or keyboard for navigating a graphical user interface (GUI).
(iii) Touch screens are used on a wide variety of devices such as computer and laptop, monitors, smart phones, tablets, cash registers, and information kiosks.
(iv) Some touch screens uses a grid of infrared beams to sense the presence of a finger instead of utilizing touch-sensitive input.

(i) The ALU is a part of the CPU where various computing functions are performed on data.
(ii) The ALU performs arithmetic operations such as addition, subtraction, multiplication, division and logical operations.
(iii) The result of an operation is stored in internal memory of CPU.
(iv) The logical operations of ALU promote the decision-making ability of a computer.

(i) An OS is required to access and use the hardware resources.
(ii) It provides a stable, consistent way for applications to deal with the hardware.
(iii) An OS prepares the computer for taking instructions from the user and converts into machine code and gives into the CPU for execution.
(iv) as only co-ordinates and controls all the activities of a computer system.

(i) This is the operating system that provides a Graphic User Interface (GUI) through which the user can easily navigate and interact.
(ii) The computer responds almost immediately after an instruction has been entered, and the user can enter new instructions after seeing the results of the previous instructions.

Nano-technology is an engineering, science, and technology that develops machines or works with one atom or one molecule that is 100 nanometers or smaller.

(i) IC is short for Integrated Circuit or Integrated Chip.
(ii) The IC is a package containing many circuits, pathways, transistors, and other electronic components all working together to perform a particular function or a series of functions.

(a) Control over system performance.
(b) Job accounting.
(c) Coordination between Software and Users

(i) Single-user operating system
(ii) Multi-user Operating system
(iii) Distributed Operating system
(iv) Operating system
(v) Mobile Operating system.