The Linux operating system was originated in 1991, as a project of "Linus Torvalds" from a university student of Finland. He posted information about his project on a newsgroup for computer students and programmers. He received support and assistance from volunteers who succeeded in creating a complete and functional operating system. Linux is similar to UNIX operating system.

The security modules of an Operating System protect the resources and information of a computer system against destruction and unauthorized user access. It is a process of ensuring OS integrity, confidentiality and availability.

In order to optimize the CPU time, the operating system employs two techniques - Buffering and Spooling.

(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.

(a) Device Management
(b) Memory Management
(c) Process Management

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

(a) Real Time OS
(b) Single user OS
(c) Distributed OS

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

(i) CISC stands for Complex Instruction Set Computers.
(ii) They support hundreds of instructions. Computers supporting CISC can accomplish a wide variety of tasks, making them ideal for personal computers.
(iii) Examples of CISC processors are Intel 386 & 480 Pentium, Pentium II and Ill, and Motorola 68000

(i) The address bus is used to point a memory location.
(ii) A decoder, a digital circuit is used to point to the specific memory location where the word can be located.
(iii) The address register is connected with the address bus, which provides the address of the instruction.
(iv) A data bus is used to transfer data between the memory and the CPU.
(v) The data bus is bidirectional and the address bus is unidirectional.
(vi) The control bus controls both read and write operations.
(vii) The system bus is a bunch of wires which is the collection of address bus, data bus and control bus that serves as communication channels between the microprocessor and other devices.

(i) Data transfer
(ii) Arithmetic operations
(iii) Logical operations
(iv) Control flow
(v) Input/output

 1)  0 x 0 = 0
 2)  1 x 1 = 1
 3)  1 x 0 = 0
 4)  0 x 0 = 0

100 , 101 , 110, 111, 1000, 1001, 1010

    1 1 0 1 0 1
+  1 0 1 1 1 1
   __________
    11 0 0 1 0 0
   __________

The 2's complement of 10011011 is 01101010 This represents a 101₁₀
Therefore 10011011₂ = - 101₁₀

(300)₁₀ \(\rightarrow \)(100101100)₂ \(\rightarrow \) (454)₈ \(\rightarrow \) (12C)₁₆

The number conversion is necessary because us enters the data into the computer in decimal fon only and the computer is then expected to convert the decimal number to other number systems which it understands.

The XNOR (exclusive - NOR) gate is a combination XOR gate followed by an inverter. Its output is "true" if the inputs are the same, and "false" if the inputs are different. In simple words, the output is 1 if the input is the same, other wise the output is O.

(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.

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.