There are different set of keys available in the keyboard such as character keys, modifier keys, system and GUI keys, enter and editing keys, function keys, navigation keys, numeric keypad and lock keys.

Booting a computer is to load an operating system into the computer's main memory or random access memory (RAM).

These printers do not use striking mechanism for printing. They use electrostatic and laser technology. Quality and speed of these printers is better than Impact printers. For example, Laser printers and Inkjet printers are non-impact printers.

It captures images / videos directly in the digital form. It uses a CCD (Charge Coupled Device) electronic chip. When light falls on the chip through the lens, it converts light rays into digital format.

The scanner converts any type of printed or written information including photographs into digital pulses, which can be manipulated by the computer.

Primary Memory	Secondary memory
It is directly accessed by CPU.	It is not directly accessed by CPU.
The access of memory is done by making use of addresses or data buses.	Here the Memory access is done through the input and output channels.
The Primary memory is embedded with 2 types of technologies. They are RAM and ROM.	The secondary memory are stored in mass storage units like CD ROM, CD, DVD, Floppy disk storage.
Volatile in nature.	Non-Volatile in nature.
Much faster than the secondary Memory.	Slower than the Primary Memory.
Costlier than secondary memory.	Cheaper than the Primary Memory.
It is temporary memory.	Secondary memory is permanent.

Dot Matrix Printer	Laser printer
Printing speed is slow	Printing speed is high.
Suitable for black and white printing.	Suitable of colour printing.
It makes noise while printing.	It is silent while printing.

(i) Super Large Scale Integrated chips
(ii) Parallel Processing
(iii) Superconductors
(iv) Computers very small in size
(v) Acts more faster
(vi) Usage of High-level languages
(vii) Can recognize Images and Graphs
(viii) Introduction of Artificial Intelligence Software
(ix) Able to solve high complex problems including decision making and logical reasoning.

Fingerprint Scanner:
Fingerprint Scanners is a fingerprint recognition device used for computer security equipped with the fingerprint recognition module feature that uses biometric technology. Fingerprint Reader/Scanner is very safe and convenient device for security instead of password, that is vulnerable to fraud and is hard to remember.

(i) POST (Power-On Self-Test) is the diagnostic testing sequence that a computer's basic input! output system runs to determine if the computer keyboard, random access memory, disk drives and other hardware are working correctly.
(ii) If the necessary hardware is detected and found to be operating properly, the computer begins to boot.

(a) Natural Language Processing
(b) Development of Robotics
(c) Parallel and Distributed computing
(d) Artificial Intelligence
(e) Development of Robotics

Optical Mouse	Laser Mouse
It is less sensitive towards the surface	Highly sensitive
Tracking power is less	Tracking power is more
Old technology	Latest technology
This uses the light source instead of ball to judge the motion of the pointer.	This uses Laser light
Optical mouse has 3 buttons	No. of buttons will vary from 3 to many

Booting of computer:
(i) An Operating system (OS) is a basic software that makes the computer to work. When a computer is switched on, there is no information in its RAM.
(ii) At the same time, in ROM, the pre-written program called POST (Power on Self Test) will be executed first. This program checks if the devices like RAM, keyboard, etc., are connected properly and ready to operate. If these devices are ready, then the BIOS (Basic Input Output System) gets executed. This process is called Booting.
(iii) Thereafter, a program called "Bootstrap Loader" transfers OS from hard disk into main memory. Now the OS gets loaded (Windows/Linux, etc.,) and will get executed. Booting process is of two types.
1) Cold Booting
2) Warm Booting
(iv) Cold Booting:
When the system starts from the initial state i.e. it is switched on, we call it cold booting or Hard Booting. When the user presses the power button, the instructions are read from the ROM to initiate the booting process.
(v) Warm Booting:
When the system restarts or when Reset button is pressed, we call it Warm Booting or Soft Booting. The system does not start from the initial state and so all diagnostic tests need not be carried out in this case. There are chances of data loss and system damage as the data might not have been stored properly.

Non-Impact Printers:
(i) These printers do not use striking mechanism for printing. They use electrostatic or laser technology.
(ii) Quality and speed of these printers are better than Impact printers. For example, Laser printers and Inkjet printers are non-impact printers.
Laser Printers:
(i) Laser printers mostly work with similar technology used by photocopiers.
(ii) It makes a laser beam scan back and forth across a drum inside the printer, building up a pattern. It can produce very good quality of graphic images.
(iii) One of the chief characteristics of laser printer is their resolution - how many Dots per inch(DPI). The available resolution range around 1200 DPI. Approximately it can print 100 pages per minute(PPM).

Inkjet Printers:
(i) Inkjet Printers use colour cartridges which combined Magenta, Yellow and Cyan inks to create color tones.
(ii) A black cartridge is also used for monochrome output. Inkjet printers work by spraying ionised ink at a sheet of paper.
(iii) The speed of Inkjet printers generally ranges from 1-20 PPM (Page Per Minute).
(iv) They use the technology offering ink by heating it so that it explodes towards the paper in bubbles or by using piezoelectricity in which tiny electric currents controlled by electronic circuits are used inside the printer to spread ink in jet speed.
(v) An Inkjet printer can spread millions of dots of ink at the paper every single second.

S.No	Type of Mouse	Mechanism	Developed and Introduced
1		1. A small ball is kept inside and touches the pad through a hole at the bottom of the mouse. 2. When the mouse is moved, the ball rolls. 3.This movement of the ball is converted into signals and sent to the computer.	Telefunken, German Company, 0211011968
2		1. Measures the motion and acceleration of pointer. 2. It uses light source instead of ball to judge the motion of the pointer. 3. Optical mouse has three buttons. 4. Optical mouse is less sensitive towards surface.	In 1988, Richard Lyon, Steve Krish independently invented different versions of Optical Mouse.
3		1. Measures the motion and acceleration of pointer. 2. Laser Mouse uses Laser Light. 3. Laser Mouse is highly sensitive and able to work on any hard surface.

(a) Inkjet Printer:
(i) Inkjet printer use colour cartridges which combined magenta, yellow and cyan inks to create colour tones.
(ii) A black cartridge is used for monochrome output. Inkjet printer works by spraying ionised ink at a sheet of paper.
(iii) The speed of inkjet printers generally range from 1-20 ppm (page per minute)
(iv) An inkjet printer can spread millions of dots of ink at the paper every single second.
(v) They use the technology of firing ink by heating it so that it explodes towards the paper in bubbles or by using piezo electricity in which tiny electric currents are controlled by electronic circuits.
(b) Multimedia Projector:
(i) Multimedia projectors are used to produce computer output on a big screen.
(ii) These are used to display presentations in meeting halls or in class rooms.
(c) Barcode/ QR code Reader:
(i) A Bar code is a pattern printed in lines of different thickness.
(ii) The Bar code reader scans the information on the bar codes transmits to the computer for further processing.
(iii) The system gives fast and error free entry of information into the computer.
Quick response (QR) code:
The QR code is the two dimension bar code which can be read by a camera and processed to interpret the image.

Computers size was drastically reduced. S.No	Generation	Period	Main Component used	Merits/ Demerits
1	First Generation	1942-1955		Big in size Consumed more power Malfunction due to overheating Machine Language was used Eg : ENIAC, EDVAC, UNIVAC
First Generation Computer - ENIAC, EDVAC, UNIVAC 1 ENIAC weighed about 27 tons, size 8 feet x 100 feet x 3 feet, and consumed around 150 watts of power
2	Second Generation	1955-1964		Smaller compared to First Generation Generated Less Heat Consumed less power compared to first-generation Punched cards were used. The first operating system was developed Batch Processing and Multiprogramming Operating System Machine language, as well as Assembly language, was used.
Second Generation Computers IBM 1404, IBM 1620, UNIVAC 1108
3	Third Generation	1964-1975		Computers were smaller, faster, and more reliable Consumed less power. High-Level Languages were used.
Third Generation Computers -IBM ·360 series, Honeywell 6000 series
4	Fourth Generation	1975-1980		Smaller and Faster Microcomputer series such as IBM and APPLE was developed Portable Computers were introduced.
5	Fifth Generation	1980-till date		Parallel, Processing Superconductors Computers size was drastically reduced. Can recognize Images and Graphics Introduction of Artificial Intelligence and Expert Systems Able to solve highly complex problems including decision making and logical reasoning.
6	Sixth Generation	In future		Parallel and Distributed computing Computers have become smarter faster and smaller Development of robotics Natural Language Processing Development of Voice Recognition Software.

(i) Basic components of computer :
The Basic components are I/O Unit, CPU, ALU, Control Unit, Storage Unit.
Input unit:
Input unit is used to feed any form of data to the computer. It can be stored in the memory unit for further processing.
Ex. Keyboard, Mouse, Scanner, Retinal scanner, Track ball.
Central processing unit:
CPU is the major component and it controls the operation of all other components such as memory, input and output units. The CPU has three components namely control unit, Arithmetic and logic unit (ALU) and memory unit.
Arithmetic and logic unit:
The ALU is a part of the CPU where arithmetic operations like addition, subtraction, multiplication, divisions and logical operations will takes place.
Control unit:
The control unit controls the flow of data between the CPU, memory and I/O devices. It also controls the entire operation of a computer.
Output unit:
An output device is a hardware component that conveys information to the user in an understandable form.
Ex. Monitor, printer, plotter
Memory unit:
The memory stores everything that computer works with. The memory unit is of two types namely primary memory and secondary memory. The primary memory stores the data and instructions temporarily. Whereas the secondary memory stores the data permanently. The primary memory is volatile and secondary memory is non-volatile.