A standard keyboard has around 110 keys in a QWERTY layout. It can produce characters through pressing keys which the keyboard controller detects and sends to the computer via an interrupt. A computer mouse is a common input device that was invented in 1968 and uses optical, mechanical, or other methods to track movement and send it to the computer.

1. • A standard computer keyboard has about 110 keys.
• Most keyboards use the QWERTY layout, named for the
first six keys in the top row of letters.
• Can produce all characters in the common character sets
such as ASCII.
Standard Keyboard Layout

2. 5. Cursor-movement keys
4. Modifier keys
3. Function keys
2. Numeric keypad
1. Alphanumeric keys
Most keyboards have keys arranged in five
groups:
Standard Keyboard Layout

4. • The keyboard controller detects the keystroke.
• The controller places a scan code in the
keyboard buffer, indicating which key was
pressed.
• The keyboard sends the computer an interrupt
request, telling the CPU to accept the keystroke.
When you press a key:
Keyboard Working Principle

6. The most common keyboard connectors are:
5-pin DIN (Deustche Industrie Norm) connector
6-pin IBM PS/2 mini-DIN connector
4-pin USB connector

7. Ctrl-Alt-Delete: Reboot.
Alt – f: Opens the File menu in a Windows application.
F1: Help
CTRL+ESC: Open Start menu
ALT+TAB: Switch between open programs
ALT+F4: Quit program
SHIFT+DELETE: Delete item permanently
Windows Logo+L: Lock the computer
Some Keyboard Shortcuts

8.  Hall effect keyboards use magnets and Hall effect sensors instead of an
actual switch.
 When a key is depressed, it moves a magnet, which is detected by the
solid-state sensor.
 These keyboards are extremely reliable
Hall effect keyboards

9. Hall Effect Key Switch

10. Capacitive Key Switch

11. Keyboard Matrix Scanner

12. Computer Mouse
• The computer mouse is considered an input device.
With a click of a button, the mouse sends
information to the computer.
• The computer mouse is an interesting device that
offers an alternative way to interact with the
computer beside a keyboard.
• It looks like real mouse with the cord is the tail and
the part we hold is the body.

14. In 1968, a man named
Douglas Engelbart created
this special tool to help
people control their
computers. It was a small
wooden block on wheels,
and there was a long
cable sticking out of the
back, kind of like a tail!
Inventor of Mouse

15. Types of Mouse
1. Mechanical
2. Optomechanical
3. Optical

16. Basic Parts of a Mouse
1. A Ball
2. Two rollers
3. An infrared LED and an infrared sensor
4. On-board processor chip
5. A shaft

17. 1. A ball inside the mouse touches the desktop
and rolls when the mouse moves.

18. 2. Two rollers inside the mouse touch the ball. One of the
rollers is oriented so that it detects motion in the X direction,
and the other is oriented 90 degrees to the first roller so it
detects motion in the Y direction. When the ball rotates, one
or both of these rollers rotate as well. The following image
shows the two white rollers on this mouse:
The rollers that
touch the ball and
detect X and Y
motion

19. 3. The rollers each connect to a shaft, and the shaft spins a disk
with holes in it. When a roller rolls, its shaft and disk spin. The
following image shows the disk:
Typical optical
encoding disk: This
disk has 36 holes
around its outer
edge.

20. 4. On either side of the disk there is an infrared LED and an
infrared sensor. The holes in the disk break the beam of light
coming from the LED so that the infrared sensor sees pulses
of light. The rate of the pulsing is directly related to the speed
of the mouse and the distance it travels.
There is an
infrared LED
(clear) on one
side of the disk
and an infrared
sensor (red) on
the other.

21. 5. An on-board processor chip reads the pulses from the
infrared sensors and turns them into binary data that the
computer can understand. The chip sends the binary data to
the computer through the mouse's cord.

22. Mechanical Mouse
This is a type of computer mouse that has a rubber or metal
ball on its underside and it can roll in every direction.
There are sensors within the mouse, which are mechanical,
detect the direction in which the ball is moving and moves
the pointer on the screen in the same direction. A mouse
pad should be used under the mouse to run on

23. Working Principle
 A mechanical mouse incorporates an internal ball that
comes in contact with the surface on which the mouse has
been placed.
 The ball automatically rotates, when a user moves the
mouse on the surface or desktop.
 Two wheels are used for detecting the rolling. Both the
wheels are placed at 90 degree angles from each other for
detecting mouse movements and its direction.
 Here one wheel can detect up and down movements,
whereas, other is used for left and right movements.
 Furthermore, the guide wheel (third wheel) that comes
loaded with spring pushes the ball against the two sensor
wheels for its functioning.

24. Opto-mechanical Mouse
 This is the same as the mechanical mouse except that it
uses optical sensors to the motion of the ball. It
demands a mouse pad under the mouse to run on.

25. With advances in mouse technology, now-preferred device
for pointing and clicking is the optical mouse.
Developed by Agilent Technologies and introduced to the
world in late 1999, the optical mouse actually uses a tiny
camera to take 1,500 pictures every second.
Optical Mouse

26. Working Principle
 Optical mouse has a small and red light-emitting diode (LED)
that bounces light off that surface onto a (complimentary metal-
oxide semiconductor) CMOS sensor.
 The CMOS sensor sends each image to a digital signal
processor (DSP) for analysis.
 The DSP operates at 18 MIPS (million instructions per second),
is able to detect patterns in the images and see how those
patterns have moved or changed since the previous image.
 Based on the change in patterns over a sequence of images, the
DSP determines how far the mouse has moved and sends the
corresponding coordinates to the computer.
 The computer moves the cursor on the screen based on the
coordinates received from the mouse. This happens hundreds of
times each second, making the cursor appear to move very
smoothly.

27. Optical mice have several benefits over wheeled mice:
1.Able to work on almost any surface
2.No moving parts means less wear and a lower chance of
failure.
3.There's no way for dirt to get inside the mouse and
interfere with the tracking sensors.
4.Increased tracking resolution means smoother response.
5.They don't require a special surface, such as a mouse
pad.
Advantages of Optical Mouse