AN OVERVIEW: THE KEYBOARD AND THE MOUSE( INPUT DEVICE) If the CPU is the computer’s brain, then the

input devices are its eyes and ears. From the user’s point of view, input devices are just as important as the CPU- more so, in fact. An input device does exactly what its name suggests: it enables you to input information and commands into the computer.

The most commonly used input devices are the keyboard and the mouse.

The discussion about keyboard and mouse are given below.

KEYBOARD The keyboard was one of the first peripherals to be used with computers, and it is still the primary input device for entering text and numbers. A standard keyboard includes about 100 keys: each key sends a different signal to the CPU. we can say that a keyboard is a typewriter like device which uses an arrangement of buttons or keys, to act as a mechanical levers or electronic switchs.

HISTORY OF KEYBOARD:

While typewriters are the definitive ancestor of all key based text entry device, the computer keyboard as a device for mechanical data entry and communication devices largely from the utility of two devices teleprinters and keypunches. It was through such devices that modern computer keyboards inherited their layouts.

As early as the 1870s teleprinterlike devices were used to simultaneously type and transmit stock market text data from the keyboard across telegraph lines to stock ticker machine to be immediately copied and displayed onto ticker tape. Until mouse was invented the keyboard was the main input device for all purpose computing.

Earliest keyboard

KEYS TYPE

KEYS TYPEA typical computer keyboard comprises sections with

different types of keys.A computer keyboard comprises alphanumeric or character

keys for typing, modifier keys for altering the functions of other keys, navigation keys for moving the text cursor on the screen, function keys and system command keys – such as Esc and Break – for special actions, and often a numeric keypad to facilitate calculations.

Character keys The core section of a keyboard comprises character

keys, which can be used to type letters and other characters. Typically, there are three rows of keys for typing letters and punctuation, an upper row for typing digits and special symbols, and the Spacebar on the bottom row. The positioning of the character keys is similar to the keyboard of a typewriter.

Modifier keys Besides the character keys, a keyboard incorporates special keys

that do nothing by themselves but modify the functions of other keys. For example, the ⇧ Shift key can be used to alter the output of character keys, whereas the Ctrl (control) and Alt (alternate) keys trigger special operations when used in concert with other keys.

Dead keys A dead key is a special kind of a modifier key that, instead of

being held while another key is struck, is pressed and released before the other key. The dead key does not generate a character by itself, but it modifies the character generated by the key struck immediately after, typically making it possible to type a letter with a specific diacritic. For example, on some keyboard layouts, the grave accent key ` is a dead key; in this case, striking ` and then A results in à (a with grave accent), whereas ` followed by E results in è (e with grave accent). A grave accent in isolated form can be typed by striking ` and then Space bar.

Compose key A Compose key can be characterized as a generic

dead key that may in some systems be available instead of or in addition to the more specific dead keys. It allows access to a wide range of predefined extra characters by interpreting a whole sequence of keystrokes following it. For example, striking Compose followed by ' (apostrophe) and then A results in á (a with acute accent), Compose followed by A and then E results in æ (ae ligature), and Compose followed by O and then C results in © (circled c, copyright symbol).

The Compose key is supported by the X Window System (used by most Unix-like operating systems, including most GNU/Linux distributions). Some keyboards have a key labelled “Compose”, but any key can be configured to serve this function. For example, the otherwise redundant right-hand ⊞ Win key may, when available, be used for this purpose.

A normal computer keyboard is composed of around 110 keys. Although on the basis of key arrangements there are four major layouts being used worldwide, QWERTY, AZERTY, QWERTZ and HCESAR, but they can be classified in many more different categories depending on types of computer connector, size, number of keys etc.  Among the various types listed below, keyboards can be based on multiple types. For instance, an ergonomic keyboard can have a PS2 interface and be an internet keyboard too.

TYPES OF KEYBOARD

ERGONOMIC KEYBOARD The artifact of this keyboard is slightly broader and

different in shape, when compared       with the normal keyboard. In this key board certain space will be existing between the two sets of keys and the countered shape of this key board allow the users to place their hands in the natural position to type. These key boards are mostly used by the people who often work with the key board as their usage is easier and is less stressful for the wrist. The following figure: Ergonomic keyboard shows how the set of keys are separated with gaps in between.

ADB (Apple Desktop Bus) ADB refers to a special type of

port which is enabled in some computers such as Apple computers. The ADB key boards can be connected only to the ADB jack enabled computers, but with the use of the adapter, the ADB key boards can also be inserted over a USB port.

ADB connected keyboard

XT KEYBOARD: An obsolete type, these keyboards only support the

older computers such as IBM 8086/8088, XT-286. Not supported by present computers, keyboards are much larger than the modern keyboards and the “Enter” key is backward-”L” shaped.

PERSONAL SYSTEMS (PS/2) CONNECTED KEYBOARD:

In the late 1990, most of the computers are integrated with standard PS/2 connector, rather than USB ports, there by the keyboards used for these computers are usually round pin that fits into the PS/2 keyboard jack. For this reason these keyboards are named as PS/2 keyboards.

Xt keyboardPS/2 connector

MULTIMEDIA KEYBOARD: The multimedia keyboard is specially designed for the people who

are much into multimedia designing. This keyboard is just like the standard key board, but composed of additional keys for the multimedia purposes such as multimedia application launch, volume control and mute button.

INTERNET KEYBOARD: The Internet keyboards are designed for wider range of

multimedia applications, these keyboards are specially designed for the intense Internet user. The special keys included in this keyboard are the home key, back and forward key, e-mail launch key, and browser launch key etc. these keys carry out the same functionality as of the buttons on the webpage. In order use these extra keys the computer must be embedded with right operating system.

Multimedia keyboardInternet keyboard

WIRELESS KEYBOARD: A wireless keyboard, the name itself doles the meaning that this keyboard

can be operated without addressing a wired connection to the processor. The wireless keyboards are also referred as Cordless keyboards; these keyboards require batteries to provide the electricity which usually delivered through a PS/2 or USB cable. “AA” or “AAA” batteries are most widely used standard batteries for wireless keyboards.  Apple Macs are known to revolutionize the wireless keyboard by making them thinner than the wired ones. These keyboards usually work at 2.4 GHz frequency and come with a dongle that connects and makes them communicate with the computer.

GAMING KEYBOARD: As the name suggest, gaming keyboards are those who are into gaming and

need easy access to the keys that are usually utilized in gaming. These keyboards are composed of particular gaming-oriented features such as key lighting, programmable keys, and/or extra controls of volume and brightness. These keyboards are available in wired and wireless, in case if wired, it usually supports the USB port.

Gaming keyboardWireless keyboard

MEMBRANE KEYBOARD: Membrane keyboards are one of the

keyboard types, which are used very rarely. The keys integrated in this keyboard are non-moving pressure-sensitive keys. The keys in this keyboard are so close, so that there is no scope for spilling liquids into the keyboard.  Such keyboard types are also used in mobile phones and old landline phones.

Laser computer keyboard The future of computer keyboard is laser computer keyboard. I didn’t find out its

brand and manufacturers; let’s just call it Bluetooth laser keyboard. It’s another laser computer keyboard, and its dimensions approximately are 35*92*25 mm. It’s connected by Bluetooth v1.1 class 2. It has a Project 295*95 mm virtual keyboard with full size and QWERT layout.

Roll Up QWERTY Keyboard It is a flexible and virtually indestructible QWERTY keyboard. The moisture-

resistant silicone allows to spill as much as you like with no effect on function. Dropping donut crumbs into more traditional keyboards requires tediously removing keys to clean out the mess. The bendable silicon allows for easy transportation and the material creates a soundless typing experience. It is perfect for industrial or wet areas such as factories, labs, workshops, restaurants, shops and food preparation areas. As it rolls up into a compact bundle, it's also ideal for travelers. It can even be used in sandstorms.

Laser keyboardRoll up keyboard

Dome-switch keyboard Dome-switch keyboards are a hybrid of flat-panel membrane and mechanical

keyboards. They bring two circuit board traces together under a rubber or silicone keypad using either metal "dome" switches or polyester formed domes. The metal domes switches are formed pieces of stainless steel that, when compressed, give the user a crisp, positive tactile feedback. These metal types of dome switches are very common, are usually reliable to over 5 million cycles, and can be plated in nickel, silver or gold. The rubber dome switches, most commonly referred to as polydomes, are formed polyester domes where the inside bubble is coated in graphite. While polydomes are typically cheaper than metal domes, they lack the crisp snap of the metal domes, and usually have a lower life specification. Polydomes are considered very quiet, but purists tend to find them "mushy" because the collapsing dome does not provide as much positive response as metal domes. For either metal or polydomes, when a key is pressed, it collapses the dome, which connects the two circuit traces and completes the connection to enter the character. The pattern on the PC board is often gold-plated.

Dome switch keyboard

Scissor-switch keyboard A special case of the computer keyboard dome-switch is the scissor-

switch. The keys are attached to the keyboard via two plastic pieces that interlock in a "scissor"-like fashion, and snap to the keyboard and the key. It still uses rubber domes, but a special plastic 'scissors' mechanism links the keycap to a plunger that depresses the rubber dome with a much shorter travel than the typical rubber dome keyboard. Typically scissor-switch keyboards also employ 3-layer membranes as the electrical component of the switch. They also usually have a shorter total key travel distance (2 mm instead of 3.5 – 4 mm for standard dome-switch key switches). This type of key switch is often found on the built-in keyboards on laptops and keyboards marketed as 'low-profile'. These keyboards are generally quiet and the keys require little force to press.

Scessor switch keyboard Switch as like a scissor

Buckling-spring keyboard Many typists prefer buckling spring keyboards. The buckling spring mechanism

(expired U.S. Patent 4,118,611) atop the switch is responsible for the tactile and aural response of the keyboard. This mechanism controls a small hammer that strikes a capacitive or membrane switch. In 1993, two years after spawning Lexmark, IBM transferred its keyboard operations to the daughter company. New Model M keyboards continued to be manufactured for IBM by Lexmark until 1996, when Unicomp purchased the keyboard technology. Today, new buckling-spring keyboards are manufactured by Unicomp. Unicomp also repairs old IBM and Lexmark keyboards.

Hall-effect keyboard Hall effect keyboards use magnets and Hall effect sensors instead of an actual

switch. When a key is pressed, it moves a magnet, which is detected by the solid-state sensor. These keyboards are extremely reliable, and are able to accept millions of keystrokes before failing. They are used for ultra-high reliability applications, in locations like nuclear powerplants or aircraft cockpits. They are also sometimes used in industrial environments. These keyboards can be easily made totally waterproof. They also resist large amounts of dust and contaminants. Because a magnet and sensor is required for each key, as well as custom control electronics, they are very expensive.

Buckling-spring keyboardHall effect keyboard

Thumb-sized keyboard: Smaller external keyboards have been introduced for devices without a built-in keyboard,

such as PDAs, and smart phones. Small keyboards are also useful where there is a limited workspace. A chorded keyboard allows pressing several keys simultaneously. For example, the GKOS keyboard has been designed for small wireless devices. Other two-handed alternatives more akin to a game controller, such as the Alpha Grip, are also used as a way to input data and text. A thumb keyboard (thumb board) is used in some personal digital assistants such as the Palm Treo and BlackBerry and some Ultra-Mobile PCs such as the OQO.

Numeric keyboard: Numeric keyboards contain only numbers, mathematical symbols for addition, subtraction,

multiplication, and division, a decimal point, and several function keys. They are often used to facilitate data entry with smaller keyboards that do not have a numeric keypad, commonly those of laptop computers. These keys are collectively known as a numeric pad, numeric keys, or a numeric keypad, and it can consist of the following types of keys:

1.arithmetic operators such as +, -, *, / 2.numeric digits 0–9 3.cursor arrow keys 4.Navigation keys such as Home, End, Page Up, Page Down, etc. 5.Num Lock button, used to enable or disable the numeric pad 6.enter key

Thumb sized keyboard Numerc keyboard

• CHORDED KEYBOARD: While other keyboards generally associate one action with each key, chorded

keyboards associate actions with combinations of key presses. Since there are many combinations available, chorded keyboards can effectively produce more actions on a board with fewer keys. Court reporters' stenotype machines use chorded keyboards to enable them to enter text much faster by typing a syllable with each stroke instead of one letter at a time. The fastest typists (as of 2007) use a stenograph, a kind of chorded keyboard used by most court reporters and closed-caption reporters. Some chorded keyboards are also made for use in situations where fewer keys are preferable, such as on devices that can be used with only one hand, and on small mobile devices that don't have room for larger keyboards. Chorded keyboards are less desirable in many cases because it usually takes practice and memorization of the combinations to become proficient.

Chorded keyboard

THE INTERNAL CIRCUIT OF A KEYBOARD:

Internal Keyboard Circuitry The "brain" of the keyboard is the circuitry within the unit that handles the processing of keystrokes and exchanging

information with the host system (the rest of the PC). While keyboards are fairly simple devices, you might be surprised at just how complex the internal circuitry is in a keyboard. In some ways it's like another whole computer in there...

In fact, the keyboard has within it small versions of several components you find within the PC as a whole. It has its own microprocessor, which "runs the show" so to speak. (This is of course a tiny CPU like the 8048, not a full-fledged CPU as the main PC hardware uses.) There is also some read-only memory (ROM) that runs this small processor, similar to the system BIOS code on the motherboard. Programmable keyboards also contain some EEPROM memory to hold programming information; this functions as if it were a tiny hard disk, in a way. Sort of. ;^)

This internal circuitry has two fundamental jobs. First, it is responsible for sensing the raw signals created by the keyswitches as they make electrical contact, and translating them into signals that can be sent to the PC. Due to the electrical characteristics of keystrokes, this is not as simple as it sounds. Second, it handles the actual interfacing between the keyboard and the rest of the PC system. The interface between the PC and the keyboard is a full bi-directional serial communications line, with its own special protocols and commands.

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ON MOUSE

MOUSE

Mouse is a device that controls the movement of the cursor or pointer on a display screen. A mouse is a small object you can roll along a hard, flat surface. Its name is derived from its shape, which looks a bit like a mouse, its connecting wire that one can imagine to be the mouse's tail, and the fact that one must make it scurry along a surface. As you move the mouse, the pointer on the display screen moves in the same direction. Mice contain at least one button and sometimes as many as three, which have different functions depending on what program is running. Some newer mice also include a scroll wheel for scrolling through long documents.

For most of their history, computers were the province of scientists and mathematicians. You needed a math degree just to understand the manual and you could only tell them what to do by feeding in a stack of index cards punched with holes. All that started to change when a brilliant US computer scientist namedDouglas Engelbart (1925–) invented the computer mouse.

Engelbart realized computers were far too useful just for boffins: he could see they had the power to change people's lives. But he could also see that they needed to be much easier to use. So, during the 1960s, he pioneered most of the easy-to-use computer technologies that we now take for granted, including on-screen word processing, hypertext (the way of linking documents together used in web pages like these), windows (so you can have more than one document or program in view at a time), and video conferencing.

But he's still best known for inventing the mouse, or the "X-Y Position Indicator" as it was originally known. That stuffy name was dropped when someone spotted that the cable hanging out looked just like a mouse's tail. From then on, Engelbart's invention was known simply as the "mouse".

HISTORY OF MOUSE

Early mouse patent. The first computer mouse

TYPES OF MOUSE: There are three basic types of mice: 1.Mechanical: Has a rubber or metal ball on its

underside that can roll in all directions. Mechanical sensors within the mouse detect the direction the ball is rolling and move the screen pointer accordingly.

2.Optomechanical: Same as a mechanical mouse, but uses optical sensors to detect motion of the ball.

3.Optical: Uses a laser to detect the mouse's movement. You must move the mouse along a special mat with a grid so that the optical mechanism has a frame of reference. Optical mice have no mechanical moving parts. They respond more quickly and precisely than mechanical and optomechanical mice, but they are also more expensive.

OPTO-MECHANICAL MOUSE

Opto-Mechanical mouse: Houses a hard rubber ball that rolls as the mouse is moved. Sensors inside the mouse body detect the movement and translate it into information that the computer interprets.

This is the internal view of a opto-mechanical mouseOpto-mechnical mouse

Operating an opto-mechanical mouse. 1.moving the mouse turns the ball. 2.X and Y rollers grip the ball and transfer

movement 3.Optical encoding disks include light holes. 4.Infrared LEDs shine through the disks. 5.Sensors gather light pulses to convert to X and Y

vectors

WORKING PRINCIPLE:

OPTICAL MOUSE

Optical mouse: Uses a laser to detect the mouse's movement. You must move the mouse along a special mat with a grid so that the optical mechanism has a frame of reference. Opticalmice have no mechanical moving parts. They respond more quickly and precisely than mechanical and optomechanical mice, but they are also more expensive.

Optical mouse

WORKING PRINCIPLE: Optical mice make use of one or more light-emitting

diodes (LEDs) and an imaging array of photodiodes to detect movement relative to the underlying surface, rather than internal moving parts as does a mechanical mouse. A laser mouse is an optical mouse that uses coherent (laser) light.

The earliest optical mice detected movement on pre-printed mousepad surfaces, whereas the modern optical mouse works on most opaque surfaces; it is unable to detect movement on specular surfaces like glass. Laser diodes are also used for better resolution and precision. Battery powered, wireless optical mice flash the LED intermittently to save power, and only glow steadily when movement is detected.

SOME OTHER TYPES OF MOUSE:

1. Inertial and gyroscopic mice2. 3D mice3. Tactile mice4. Ergonomic mice5. Gaming mice6. Trackball mice7. Stylus mice 8. Chordless 3D mice9. Foot mice10. Rotational mice11. LED mice12. LASER mice

INERTIAL AND GYROSCOPIC MICE

Often called "air mice" since they do not require a surface to operate, inertial mice use a tuning fork or other accelerometer (US Patent 4787051) to detect rotary movement for every axis supported. The most common models (manufactured by Logitech and Gyration) work using 2 degrees of rotational freedom and are insensitive to spatial translation. The user requires only small wrist rotations to move the cursor, reducing user fatigue or "gorilla arm".

Usually cordless, they often have a switch to deactivate the movement circuitry between use, allowing the user freedom of movement without affecting the cursor position. A patent for an inertial mouse claims that such mice consume less power than optically based mice, and offer increased sensitivity, reduced weight and increased ease-of-use. In combination with a wireless keyboard an inertial mouse can offer alternative ergonomic arrangements which do not require a flat work surface, potentially alleviating some types of repetitive motion injuries related to workstation posture.

Inertial mouse

3D MICE

Also known as bats, flying mice, or wands, these devices generally function through ultrasound and provide at least three degrees of freedom. Probably the best known example would be 3Dconnexion/Logitech's SpaceMouse from the early 1990s. In the late 1990s Kantek introduced the 3D RingMouse. This wireless mouse was worn on a ring around a finger, which enabled the thumb to access three buttons. The mouse was tracked in three dimensions by a base station. Despite a certain appeal, it was finally discontinued because it did not provide sufficient resolution.

A recent consumer 3D pointing device is the Wii Remote. While primarily a motion-sensing device (that is, it can determine its orientation and direction of movement), Wii Remote can also detect its spatial position by comparing the distance and position of the lights from the IR emitter using its integrated IR camera (since the nunchuk accessory lacks a camera, it can only tell its current heading and orientation). The obvious drawback to this approach is that it can only produce spatial coordinates while its camera can see the sensor bar.

3D mice

TACTILE MICE

In 2000, Logitech introduced the "tactile mouse", which contained a small actuator that made the mouse vibrate. Such a mouse can augment user-interfaces with haptic feedback, such as giving feedback when crossing a window boundary. To surf by touch requires the user to be able to feel depth or hardness; this ability was realized with the first electrorheological tactile mice but never marketed.

Tactile mouse

ERGONOMIC MICE

As the name suggests, this type of mouse is intended to provide optimum comfort and avoid injuries such as carpal tunnel syndrome, arthritis and other repetitive strain injuries. It is designed to fit natural hand position and movements, to reduce discomfort.

Ergonomic mouse

GAMING MICE

These mice are specifically designed for use in computer games. They typically employ a wide array of controls and buttons and have designs that differ radically from traditional mice. It is also common for gaming mice, especially those designed for use in first-person shooter games, to have a relatively high sensitivity, measured in dots per inch (DPI). Ergonomic quality is also an important factor in gaming mice, as extended gameplay times may render further use of the mouse to be uncomfortable.

Gaming mouse

Trackball mouse: Like an upside-down mouse. Rather

than roll the mouse around, you use your thumb or index finger to roll a ball on top of the mouse. The whole contraption stays stationary, so it doesn’t need a lot of room, and its cord never gets tangled.

Stylus mouse: Another mouse mutation enjoyed by the artistic type is the stylus mouse, which looks like a pen and draws on a special pad.

Cordless 3-D mouse: This kind of mouse can be pointed at the computer screen like a TV remote.

A footmouse is a type of computer mouse that gives the users the ability to move the cursor and click the mouse buttons with their feet. It is primarily used by users with disabilities or with high-back or neck problems. It is also promoted as a way to prevent such problems in the future and as a means to increase productivity by not having to move one's hand between the keyboard and mouse

FOOTMOUSE

Footmouse that tilts and rotates.Footmouse that slides in four directions.

ROTATIONAL MIUSE

A rotational mouse is a type of computer mouse which attempts to expand traditional mouse functionality. The objective of rotational mice is to facilitate three degrees of freedom (3DOF) for human-computer interaction by adding a third dimensional input, yaw, to the existing x and y dimensional inputs. There have been several attempts to develop rotating mice, using a variety of mechanisms to detect rotation.

Rotational mice

LED MICE

Optical mice often use LEDs for illumination, even though they are sometimes colloquially referred to as 'lasers'. The color of the optical mouse's light-emitting diodes can vary, but red is most common, as red diodes are inexpensive and silicon photodetectors are very sensitive to red light. Other colors are sometimes used, such as the blue LED of the V-Mouse VM-101 illustrated at right.

Led mouse

LASER MICE

The laser mouse uses an infrared laser diode instead of a LED to illuminate the surface beneath their sensor. As early as 1998, Sun Microsystems provided a laser mouse with their Sun SPARCstation servers and workstations. However, laser mice did not enter the mainstream market until 2004, when Paul Machin at Logitech, in partnership with Agilent Technologies, introduced its MX 1000 laser mouse. This mouse uses a small infrared laser instead of a LED and has significantly increased the resolution of the image taken by the mouse. The laser enables around 20 times more surface tracking power to the surface features used for navigation compared to conventional optical mice.

Laser mouse

CONNECTIVITY AND COMMUNICATION PROTOCOLS

To transmit their input, typical cabled mice use a thin electrical cord terminating in a standard connector, such as RS-232C, PS/2,ADB or USB. Cordless mice instead transmit data via infrared radiation (see IrDA) or radio (including Bluetooth), although many such cordless interfaces are themselves connected through the aforementioned wired serial buses.

While the electrical interface and the format of the data transmitted by commonly available mice is currently standardized on USB, in the past it varied between different manufacturers. A bus mouse used a dedicated interface card for connection to an IBM PC or compatible computer.

Mouse use in DOS applications became more common after the introduction of the Microsoft mouse, largely because Microsoft provided an open standard for communication between applications and mouse driver software. Thus, any application written to use the Microsoft standard could use a mouse with a Microsoft compatible driver (even if the mouse hardware itself was incompatible with Microsoft's). An interesting footnote is that the Microsoft driver standard communicates mouse movements in standard units called "mickeys", as does the Allegro library.

Standard PC mice once used the RS-232C serial port via a D-subminiature connector, which provided power to run the mouse's circuits as well as data on mouse movements. The Mouse Systems Corporation version used a five-byte protocol and supported three buttons. The Microsoft version used a three-byte protocol and supported two buttons. Due to the incompatibility between the two protocols, some manufacturers sold serial mice with a mode switch: "PC" for MSC mode, "MS" for Microsoft mode.

SERIAL INTERFACE AND PROTOCOL

With the arrival of the IBM PS/2 personal-computer series in 1987, IBM introduced the eponymous PS/2 interface for mice and keyboards, which other manufacturers rapidly adopted. The most visible change was the use of a round 6-pin mini-DIN, in lieu of the former 5-pin connector. In default mode (called stream mode) a PS/2 mouse communicates motion, and the state of each button, by means of 3-byte packets. For any motion, button press or button release event, a PS/2 mouse sends, over a bi-directional serial port, a sequence of three bytes, with the following format:

PS/2 INTERFACE AND PROTOCOL

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Byte 1 YV XV YS XS 1 MB RB LB

Byte 2 X movement

Byte 3 Y movement

APPLE DESKTOP BUS

In 1986 Apple first implemented the Apple Desktop Bus allowing the daisy-chaining together of up to 16 devices, including arbitrarily many mice and other devices on the same bus with no configuration whatsoever. Featuring only a single data pin, the bus used a purely polled approach to computer/mouse communications and survived as the standard on mainstream models (including a number of non-Apple workstations) until 1998 when iMac joined the industry-wide switch to using USB. Beginning with the "Bronze Keyboard" PowerBook G3 in May 1999, Apple dropped the external ADB port in favor of USB, but retained an internal ADB connection in thePowerBook G4 for communication with its built-in keyboard and trackpad until early 2005.

The industry-standard USB (Universal Serial Bus) protocol and its connector have become widely used for mice; it is among the most popular types.

Cordless or wireless mice transmit data via infrared radiation or radio. The receiver is connected to the computer through a serial or USB port, or can be built in (as is sometimes the case with Bluetooth). Modern non-Bluetooth wireless mice use USB receivers. Some of these can be stored inside the mouse for safe transport while not in use, while other, newer mice use newer "nano" receivers, designed to be small enough to remain plugged into a laptop during transport, while still being large enough to easily remove.

USB AND WIRE LESS

ATARI STANDARD JOYSTICK CONNECTIVITY

The Amiga and the Atari ST use an Atari standard DE-9 connector for mice, the same connector that is used for joysticks on the same computers and numerous 8-bit systems, such as the Commodore 64 and the Atari 2600. However, the signals used for mice are different from those used for joysticks. As a result, plugging a mouse into a joystick port causes the "joystick" to continuously move in some direction, even if the mouse stays still, whereas plugging a joystick into a mouse port causes the "mouse" to only be able to move a single pixel in each direction.

INSIDE A BALL-STYLE COMPUTER MOUSE

Here's the inside of an old-style Logitech ball mouse:1.Switch detects clicks of left mouse button.2.Switch for middle button.3.Switch for right button.4.Old-style connection to PS/2 socket on computer.5.Chip turns back-and-forth (analog) mouse movements into numeric (digital) signals computer can understand.6.X-axis wheel turns when you move mouse left and right.7.Y-axis wheel turns when you move mouse up and down.8.Heavy rubber wheel.9.Spring presses rubber ball firmly against X- and Y-axis wheels so they

register movements properly.10Electrolytic capacitor.11Resistors.

How a ball computer mouse works.

As you move it across your desk, the ball rolls under its own weight and pushes against two plastic rollers linked to thin wheels (numbered 6 and 7 in the photo). One of the wheels detects movements in an up-and-down direction (like the y-axis on graph/chart paper); the other detects side-to-side movements (like the x-axis on graph paper).

INSIDE AN OPTICAL COMPUTER MOUSE

1.An LED at the back generates red light and shines it horizontally, from the back of the mouse toward the front (from the left to the right of this photo).2.A plastic prism bends (refracts) the light from the LED at an angle, down onto the desk.3.A light-detector chip measures light reflected back up from the desk, converting the analog movements of your hand into digital signals that can be sent to your computer.4.The scroll wheel at the front of the mouse is mounted on a switch mechanism

that detects both how much it's rotated and whether you've pressed it (it functions like the central button of a conventional mouse). Rotations of the scroll wheel can be detected in a variety of different ways. Some mice use potentiometers (broadly, variable resistors), similar to the volume control on a radio but able to turn around multiple times. Others use various kinds of rotary switches or optical (rotary) encoders to convertanalog wheel movements to digital signals.

5.A microswitch detects when you press the right mouse button. There's an identical switch on the other side to detect the left mouse button.

6.The USB cable connection carries digital information from the mouse to your computer.

HOW AN OPTICAL MOUSE WORKS An optical mouse works in a completely different way. It shines a bright light down onto your desk from anLED  (light-emitting diode) mounted on the bottom of the mouse. The

light bounces straight back up off the desk into a photocell (photoelectric cell), also mounted under the mouse, a short distance from the LED. The photocell has a lens in front of it that magnifies the reflected light, so the mouse can respond more precisely to your hand movements. As you push the mouse around your desk, the pattern of reflected light changes, and the chip inside the mouse uses this to figure out how you're moving your hand.

Some optical mice have two LEDs. The first one shines light down onto the desk. The light from that is picked up by the photocell. The second LED lights up a red plastic strip along the back of the mouse so you can see it's working. Most optical mice also have a wheel at the front so you can scroll pages on-screen much faster. You can click the wheel too, so it functions like the third (center) button on a conventional ball mouse.

MULTIPLE-MOUSE SYSTEMS Some systems allow two or more mice to be used at

once as input devices. 16-bit era home computers such as the Amiga used this to allow computer games with two players interacting on the same computer. The same idea is sometimes used in collaborative software, e.g. to simulate a whiteboard that multiple users can draw on without passing a single mouse around.

Microsoft Windows, since Windows 3.1, has supported multiple simultaneous pointing devices. Because Windows only provides a single screen cursor, using more than one device at the same time requires cooperation of users or applications designed for multiple input devices.

Multiple mice are often used in multi-user gaming in addition to specially designed devices that provide several input interfaces.

Windows also has full support for multiple input/mouse configurations for multiuser environments.

BUTTONS Mouse buttons are microswitches which can be

pressed to select or interact with an element of a graphical user interface, producing a distinctive clicking sound.

The three-button scrollmouse has become the most commonly available design. As of 2007 (and roughly since the late 1990s), users most commonly employ the second button to invoke a contextual menu in the computer's software user interface, which contains options specifically tailored to the interface element over which the mouse cursor currently sits. By default, the primary mouse button sits located on the left-hand side of the mouse, for the benefit of right-handed users; left-handed users can usually reverse this configuration via software.

MOUSE SPEED

Mickey is the unit of measurement for the speed and movement direction of a computer mouse. The speed of the mouse is the ratio between how many pixels the cursor moves on the screen and how many centimeters you move the mouse on the mouse pad. The directional movement is called the horizontal mickey count and the vertical mickey count. One mickey is approximately 1/200th of an inch.

The computer industry often measures mouse sensitivity in terms of counts per inch (CPI), commonly expressed as dots per inch (DPI) – the number of steps the mouse will report when it moves one inch. In early mice, this specification was called pulses per inch (ppi). 

If the default mouse-tracking condition involves moving the cursor by one screen-pixel or dot on-screen per reported step, then the CPI does equate to DPI: dots of cursor motion per inch of mouse motion.

The CPI or DPI as reported by manufacturers depends on how they make the mouse; the higher the CPI, the faster the cursor moves with mouse movement. However, software can adjust the mouse sensitivity, making the cursor move faster or slower than its CPI. Current software can change the speed of the cursor dynamically, taking into account the mouse's absolute speed and the movement from the last stop-point. In most software this setting is named "speed", referring to "cursor precision". However, some software names this setting "acceleration", but this term is in fact incorrect. The mouse acceleration, in the majority of mouse software, refers to the setting allowing the user to modify the cursor acceleration: the change in speed of the cursor over time while the mouse movement is constant.

For simple software, when the mouse starts to move, the software will count the number of "counts" or "mickeys" received from the mouse and will move the cursor across the screen by that number of pixels (or multiplied by a rate factor, typically less than 1). The cursor will move slowly on the screen, having a good precision. When the movement of the mouse passes the value set for "threshold", the software will start to move the cursor more quickly, with a greater rate factor. Usually, the user can set the value of the second rate factor by changing the "acceleration" setting.

Operating systems sometimes apply acceleration, referred to as "ballistics", to the motion reported by the mouse. For example, versions of Windows prior to Windows XP doubled reported values above a configurable threshold, and then optionally doubled them again above a second configurable threshold. These doublings applied separately in the X and Y directions, resulting in very nonlinear response

Mousepads Engelbart's original mouse did not require a mousepad; the

mouse had two large wheels which could roll on virtually any surface. However, most subsequent mechanical mice starting with the steel roller ball mouse have required a mousepad for optimal performance.

The mousepad, the most common mouse accessory, appears most commonly in conjunction with mechanical mice, because to roll smoothly the ball requires more friction than common desk surfaces usually provide. So-called "hard mousepads" for gamers or optical/laser mice also exist.

Most optical and laser mice do not require a pad. Whether to use a hard or soft mousepad with an optical mouse is largely a matter of personal preference. One exception occurs when the desk surface creates problems for the optical or laser tracking, for example, a transparent or reflective surface.

SOME UNUSUAL MICE

Gold brain computer mouse

Aircraft computer mouse with led lights

Wireless mouse – camaro black

The man’s body mouse

Optical ferrari car mouseCyborg r.a.t. gaming mice

Optical mouse skype hands-free pc speakerphone

Eclipse touchmouse

portable finger hand held 4d usb mini trackball mouse

Golf 3d usb optical computer mouse

Wowpen joy vertical computer mouse Creative golf mouse

Handshoe mouse

Another keypad mouse

Hybrid monster naga mouse

Body mouse

Crystal computer mouse

Tortoise-shaped optical usb mouse

A steampunk mouse

THANK YOU FRIENDS.