CHAPTER 11 KEYBOARD AND MOUSE

	Introduction :
	The keyboard and mouse are the principal input devices of a computer. The keyboard and mouse help the user to communicate with the computer.
11.1 Keyboard
	Keyboard is the primary input device of the PC. You use the keyboard to enter commands and type text. The keyboards on computers are similar to typewriters. However, a computer has many additional keys. Computer keyboards have not changed a lot since they were introduced. The only changes have been additions to the number of keys in the original keyboards. Present day keyboards have 101 or more keys. Each of these keys performs a different operation. The main types of keys on a Windows keyboard are: _ Alphanumeric -Allow users to enter text and numbers. _ Punctuation - Enables users to punctuate sentences and add additional characters. _ Navigation - Used to move the cursor between different places on a screen. _ Special - Perform some special functions on the data. _ Windows - Open Windows-specific items like the Start menu. _ Function - Used to perform certain functions like provide help. _ Numeric - Allows users to perform numerical operations on the data. _ Modification - Enables users to use additional features like capitalizing letters.
11.2 Types of Keyboards
	There are several types of keyboards that are in use today. All these keyboards differ slightly in layout. The PC/AT keyboard was a part of the PC/AT computer introduced by IBM. It did not have many of the features that you see on modern keyboards. It had 84 keys and is not much in use today. The PC/AT keyboard has been replaced with the enhanced keyboard that has 101 keys.
	11.2.1 101-Key Enhanced Keyboards
	IBM introduced the 101-key enhanced keyboard in 1986, as part of the IBM PC/AT Model 339. Enhanced keyboards with 101 keys are in use even in the present. Present day fancy versions of a computer keyboard are based on this layout.
	101-Key Enhanced Keyboard
	_ Additional Ctrl and Alt keys - Featured two sets of Ctrl and Alt keys. The positions of these keys were also altered. _ Extra keys in the numeric keypad - Introduced the Enter and/keys in the keyboard. The division key (/) had been missing in previous keyboards. _ Additional function keys - Featured the F11 and F12 keys in the keyboard that were not present in previous versions. _ Movement of function keys - Introduced a change in the placement of the function keys. In the previous version, the function keys were on the left of the keyboard. In this version, the function keys were shifted to the top. Also, the keys were grouped in four to increase convenience. _ Separate Cursor and navigation keys - Introduced dedicated cursor and navigation keys for the first time. The previous version of the keyboard had the cursor keys as part of the numeric keypad. _ Movement of Esc and Caps Lock keys - Featured a change in the position of the Esc and Caps Lock keys. The 101-key enhanced keyboard proved to be very popular amongst all users. However, it had one major drawback - a small Enter key. Despite this drawback amongst other smaller ones, the 101- key enhanced keyboard layout continues to be used even today. :
	11.2.2 102-Key Enhanced Keyboards
	The 102-key enhanced keyboards were introduced to make the usage of keyboards easier for non- English users. There are several versions of this layout, all of which are almost identical to the 101- key enhanced keyboard.
	11.2.3 104-Key Windows Keyboard
	Microsoft introduced the 104-key Windows keyboard as an improvement over the 101-key enhanced keyboard. These two types of keyboards are almost identical. The 104-key Windows keyboard only had an addition of three special keys that initiated Windows related functions. These three keys included two identical keys to open the Start menu and one key to perform the right-click operation using the keyboard. The 104-key Windows keyboard offers additional features and ease of operation that the 101-key enhanced keyboard does not. It has therefore replaced the 101-key enhanced keyboard on most personal computers.
	11.2.4 Ergonomic Keyboards
	A regular keyboard does not offer a user total comfort of use. This is because the shape of a regular keyboard does not properly align with the shape of the human hand. As a result, when you are in the process of typing, your hands bend or tilt slightly to align themselves to the keys. This happens without the knowledge of the user. Because of this, prolonged use of a regular keyboard leads to hand-related stress injuries. The ergonomic keyboard was designed as an answer to the above problem. The word ergonomic refers to a family of computer keyboards that are designed keeping in mind the comfort of the user. Ergonomic keyboards have their keys angled in a manner that the hand aligns perfectly with the keys. This reduces strain on the hands of the typist. Ergonomic keyboards are also known as natural keyboards.
	Ergonomic Keyboard
	The main typing keys on an ergonomic keyboard are split into two typing areas. This split enables proper alignment of the right and left hands on either part. Many ergonomic keyboards include features like wrist rests, to enhance user comfort. Also, the angle between the two halves can be adjusted in some types of ergonomic keyboards. However, the ergonomic keyboard is difficult to use if you are not an experienced typist. These keyboards are also expensive as compared to the regular keyboards. They also consume much more space, as they tend to be large in size.
	11.2.5 Programmable Keyboards
	A programmable keyboard is one whose functions and operation can be modified by the user. This type of keyboard has additional keys that control the operation of other keys. An important key on a programmable keyboard is the Remap keyboard. If you press the Remap key first and then press two other keys, the function of the first key is transferred to the second key. A user can thus in effect, swap keys around. These changes are made within the keyboard and will be in effect even if the keyboard is connected to another computer. A programmable keyboard can also create macros, which are a string of sequences that are activated at the press of a single button. Programmable keyboards are not very popular, as most users consider the additional features unnecessary. Also, if the keyboard is not used carefully, it could change the functions of important keys without the user even realizing it. It is, however possible to reset a programmable keyboard.
	11.2.6 Cordless Keyboards
	Cordless keyboards are the latest addition to the family of keyboards. The usage of cordless keyboards has a lot of advantages. You can place the keyboard according to your convenience and comfort. Cordless keyboards run on batteries.
11.3 Keyboard connectors
	The keyboard can be connected to the keyboard port or the USB port of the computer. The connection between the keyboard and the computer carries power to the keyboard. Data from the keyboard is also sent to the computer through the cable. The keyboard controller on the computer monitors the port on the computer to which the keyboard is connected. The keyboard controller is an integrated circuit that processes data coming from the keyboard and forwards it to the computer. There are different types of keyboard connectors.
	11.3.1 5-pin DIN Connector
	The 5-pin DIN connector was widely in use in the past. The DIN stands for Deustche Industrie Norm. This type of connector is rarely used nowadays.
	11.3.2 6-pin PS/2 connector
	IBM introduced the PS/2 port on the back of PCs to connect devices such as the mouse and the keyboard. The PS/2 port supports the 6-pin PS/2 connector, which is very popular in the present. It has replaced most of the 5-pin DIN connectors. The 6-pin PS/2 connector is also known as the 6-pin mini DIN connector.
	6-pin PS/2 Connector
	_ Modern day PCs have two PS/2 ports, to connect the mouse and the keyboard. These two ports look identical, but are not interchangeable. The two ports are usually colored or labeled to indicate the difference.
	PS/2 Ports
	PS/2 keyboard port PS/2 mouse port
	11.3.3 4-pin USB connector
	The 4-pin USB connector for keyboards is fast replacing the 6-pin PS/2 port as the most widely used connector for keyboards. The USB keyboard is connected to the USB port on the back of the computer and tends to be the fastest.
	11.4 Working of the Keyboard
	The computer keyboard has a microprocessor that studies the state of each key on the keyboard and sends the appropriate signal to the computer. There is a grid of circuits underneath the keys on the keyboard. It is known as the key matrix. In most keyboards, the circuits below all the keys are broken. When you press a key, the circuit is closed and a current flows. The keyboard microprocessor detects the closed circuit and notes the position of the circuit on the key matrix. The keyboard microprocessor has a character map of the keyboard in its ROM. It compares the location of the closed circuit to the same location in the character map. The character map is a comparison chart that tells the processor which key is present at a particular location. If you press a combination of characters, the keyboard processor compares the combination to the character map to see if there is any designation for that particular combination. The keyboard processor analyses the key matrix and decides on the characters to be sent to the computer. These characters are maintained in a memory buffer and then sent in a stream to the computer. The data stream is sent through a connector that connects the keyboard to the computer.
11.5 Connecting the Keyboard
	11.5 Connecting the Keyboard Depending on the type of your keyboard, you will connect it to the appropriate port on the back of the computer.
	Best practice
	1. Read the instruction manual of the device thoroughly. 2. After unpacking the device, check it for any signs of damage or missing parts. 3. Check the device and manual thoroughly to find the port that it will connect to. 4. Before connecting the keyboard to the computer, it is safest to turn the computer off and unplug it. If your keyboard is a USB device, your computer may be kept on.
	Hands on exercise
	To connect a PS/2 keyboard : 1. Connect the other end of the keyboard cable to the PS/2 port. Be careful to connect to the correct PS/2 port, since the keyboard and mouse PS/2 ports look identical. If the PS/2 ports on your computer are colored, the keyboard PS/2 port is usually purple in color. To connect a USB keyboard : 1. Connect the other end of the USB keyboard to the USB port on the PC. If there are other USB devices, connect the keyboard to the USB hub. You will have to install the driver for your keyboard if it has additional advanced features. You will also have to install the software for the keyboard in this case. Refer to the keyboard manual.
11.6 Troubleshooting the Keyboard
	The keyboard must be handled with a lot of care. You must not spill liquids or food particles on the keyboard. However, the keyboard is largely a trouble-free device if handled properly
	11.6.1 Computer Displays Keyboard Error
	This type of error mostly occurs when the connection or the configuration of the keyboard is faulty. To solve this problem : 1. Check both the ends of the connection of the keyboard to the computer. 2. Turn the keyboard over and hit gently to dislodge any dirt or hair stuck beneath the keys. 3. Check the internal connections from the keyboard port to the motherboard. Do not try to force the connection, as it can damage the motherboard. 4. Switch the keyboard with another computer and see if it works. Switch the power off when doing this. 5. Make sure that you have not pressed any key when the system is starting up. This will cause the keyboard to register an error. 6. If the keyboard still does not work, it is possible that the keyboard controller on the motherboard is faulty. In this case, you must locate the keyboard controller on the motherboard and examine it for any signs of damage. 7. If the keyboard controller is damaged, you may have to replace it or the entire motherboard. 8. If the keyboard controller looks fine, check its connection to the motherboard. The connection must not be loose.
	11.6.2 Keyboard does not operate properly
	If the keys on the keyboard seem sticky, it is possible that the keyboard is dirty. If you eat or drink around the computer, you may drop substances onto the keyboard. You can clean a keyboard by blowing compressed air under the keys. This will remove any dry particles stuck underneath. It will also dry any spilt liquid. If you spilt any sticky liquid on the keyboard, compressed air will not help much. In this case, the best option is to remove one key at a time and clean underneath.
11.7 Mouse
	Douglas Engelbart invented the computer mouse in 1963. It is a device that enables a computer user to move the cursor or pointer to a specific point on the screen. It was given its name because of its appearance and movement, which are similar to those of a mouse. When you move the mouse, the cursor on the screen also moves in the same direction. A mouse can have one to three buttons, each of which performs a different function. Modern mouse devices also include a scroll button that makes it easier to read long documents. The mouse is the most used input device after the keyboard. The usage of the mouse greatly reduces the extent of usage of the keyboard. The mouse is particularly important for Graphical User Interface (GUI) applications, wherein you point to an option or object on the screen and click the appropriate mouse button. You can also use the mouse for drawing objects on the screen by using the mouse as a pencil or paintbrush.
11.8 Types of Mouse Devices
	There are different types of mouse devices that are widely in use at present. The connected mouse has been replaced to a great extent with cordless and optical mouse devices.
	11.8.1 Mechanical Mouse
	A mechanical mouse is the oldest type of mouse available today. This type of mouse consists of a rubber or metal ball on the underside. The mouse is placed on a mouse pad. As the mouse is moved, the ball rolls in the appropriate direction. This type of mouse has mechanical sensors that detect the direction of movement of the mouse and send signals to the computer to move the pointer accordingly.
	11.8.2 Optomechanical Mouse
	The Optomechanical mouse is similar to the mechanical mouse. However, this type of mouse makes use of optical sensors instead of mechanical sensors. The optomechanical mouse is more accurate than the mechanical mouse.
	11.8.3 Optical Mouse
	An Optical Mouse uses laser technology to detect the movement of the mouse. It is the most accurate and precise type of mouse. The optical mouse has no moving parts. The optical mouse must be moved along a special mouse pad that has grids on its surface. The grids on the mouse pad provide a frame of reference for the working of the mouse.
	11.8.4 Cordless Mouse
	A cordless mouse establishes an infrared or radio link with a transceiver (transmitter/receiver) that is connected to the computer through a cable. Cordless mouse are very convenient and easy to use. Cordless mouse operate on batteries.
11.9 Mouse Connectors
	You can connect the mouse to the computer through the serial port, PS/2 port or the USB port. There are different types of mouse devices available for connection to each of these ports.
	11.9.1 Serial Connector
	The serial mouse connects to the serial port on the computer. This type of connection offers low speed and hence it is being replaced with other connections like the PS/2 and USB ports.
	11.9.2 PS/2 Connector
	The PS/2 mouse port on the back of the PC connects to the mouse. This port was originally invented so that other devices like modems could use the serial port. The PS/2 port was also known as the mouse port. This is the most widely used port for connection of a mouse to the computer.
	11.9.3 USB Connector
	Some types of mouse devices connect to the computer through the USB port. The USB connection offers good speed.
11.10 Working of the Mouse
	The mouse converts our movements to signals that the computer can use. As a result, we can see the cursor on the screen changing direction as we move the mouse. The mouse has a ball inside its body that rolls around as the user moves the mouse. A part of the mouse ball is exposed on the underside of the mouse. There is a pair of rollers around the mouse ball that touch it and sense its movements. The two rollers are angles in such a way that one senses the movement of the mouse ball in the X-direction and the other in the Y-direction. As the mouse ball moves, one or both of the rollers moves. Each roller is connected to a shaft. As the roller moves along with the mouse ball, the shaft connected to that roller also moves. The shaft moves a disk that has may holes in its periphery. An infrared LED provides light, which shines on the disks. As the disk rotates, the beams of light are broken due to the gaps between the holes on the disk. An infrared sensor senses the pattern of light coming through the holes on the disk. A processor in the mouse receives signals form the sensor and converts these signals to binary data. The mouse cord that connects the mouse to the computer then carries the binary data to the computer.
11.11 Connecting the mouse
	Depending on the type of your mouse, you will connect it to the appropriate port on the back of the computer.
	Best practice
	1. Read the instruction manual of the device thoroughly. 2. After unpacking the device, check it for any signs of damage or missing parts. 3. Check the movement of the mouse by rolling it on the mouse pad. 4. Check the device and manual thoroughly to find the port that it will connect to. 5. Before connecting the mouse to the computer, it is safest to turn the computer off and unplug it. If your mouse is a USB device, your computer may be kept on.
	Hands on exercise
	To connect a serial mouse : 1. Connect the other end of the mouse cable to the serial port. If there are no serial devices connected to the computer and there are two serial ports, take care to connect the mouse to the first serial port. To connect a PS/2 mouse : 1. Connect the other end of the mouse cable to the PS/2 port. Be careful to connect to the correct PS/2 port, since the keyboard and mouse PS/2 ports look identical. If the PS/2 ports on your computer are colored, the mouse PS/2 port is usually green in color. To connect a USB mouse : 1. Connect the other end of the USB mouse to the USB port on the PC. If there are other USB devices, connect the mouse to the USB hub. To configure mouse settings in CMOS : 1. If you installed a serial mouse, check the CMOS settings to ensure that the serial or COM ports are enabled and assigned. 2. If you installed a USB mouse, check the CMOS settings to ensure that the USB is enabled. Also ensure that USB Legacy Support is enabled.
11.12 Troubleshooting the Mouse
	The mouse is an uncomplicated device, but it can give rise to a lot of problems if it is not handled with care. You must always be careful not to spill liquids or other substances around the mouse. Follow the troubleshooting steps in a systematic manner, to solve problems with the mouse.
	11.12.1 Mechanical Mouse not Moving Properly
	This problem is mostly caused by dirt in the mouse. Dust and particles may accumulate on the inside of the mouse and cause problematic movements. The mouse may also function incorrectly because of problems with the connection or the cable. To solve this problem : 1. Check the cable of the mouse to ensure that it is properly connected to the computer. Also ensure that is it not excessively twisted or bent. 2. If the connection is tight and secure, observe the bottom of the mouse and find out which direction to rotate mouse cover. 3. Rotate the mouse cover in the proper direction and remove it. 4. Remove the mouse ball and clean it with a soft wet cloth. Keep it aside in a clean dry place. Be very careful not to drop it. If the mouse ball falls, it will ruin the functionality of the mouse. 5. Clean the rollers inside the mouse with a cotton swab in a very gentle manner. Clean the rollers in a horizontal manner. Remove as much dirt and particles as possible. 6. Replace the ball inside the mouse and turn the cover back on. 7. Clean the mouse pad with a damp cloth. A clean mouse pad helps the mouse to move in a smoother manner. 8. If the mouse still does not function properly, repeat the cleaning process. 9. Try to connect the mouse to another computer and check if it works. Also, cross-check by connecting another mouse to the computer. 10. If the mouse does not function properly even after repetitive cleaning, it is possible that there is a hardware problem with the mouse. In this case, contact the manufacturer or replace the device.
	11.12.2 Cordless Mouse does not Move Properly
	A cordless mouse may stop working properly because of dirt on the inside or because of a low battery. To solve this problem : 1. Ensure that the mouse transceiver is connected to the proper port. 2. Clean the cordless mouse in the same manner as a mechanical mouse. 3. Remove the cover of the mouse and ensure that the batteries are connected in the proper manner. 4. Replace the battery of the mouse.
	11.12.3 System does not Recognize Mouse
	Sometimes, the computer may stop recognizing the mouse. Any movement of the mouse will not create a response on the screen. 1. Check the connection of the mouse to the computer. 2. If you are using a PS/2 mouse, ensure that it is connected to the proper port. You can check this by seeing if the PS/2 keyboard is working. If the ports are interchanged, both the devices will not work properly. 3. If you have upgraded your motherboard, ensure that you have replaced the cables from the mouse port to the motherboard. The new motherboard may not be able to work properly with the old cables. 4. Check whether there is a loose internal cable that connects the mouse port to the motherboard.
	11.12.4 Mouse does not Move in a Particular Direction
	The mouse may not move in some directions or it may cease movement totally. This can occur even if the mouse is recognized by the system. This problem is most probably a result of restricted roller movement. It can also be caused because of an electrical failure inside the mouse. To solve this problem : 1. Check the mouse ball to see if it rolling in all directions. 2. If the mouse is new, check whether there is a piece of foam placed around the ball. In some cases, this piece of foam is included with the package so that the mouse ball does not roll around during transportation. If the mouse ball does not move, it is possible that the foam is still inside. Remove the cover of the mouse and dislodge the foam if it is there. 3. If there is no foam inside the mouse, remove the mouse ball and check the rollers of the mouse to see if they are moving properly. 4. Try to move the rollers by hand if they are not moving smoothly. 5. Clean the interior of the mouse if it is dirty.