# The Computer Revolution/Peripherals/Pointers
### Pointing devices
#### Joy-stick

A Joystick is a general control device that transmits it's angle with two or three dimensions to a computer. It consists of a handheld stick that pivots and how it works is similar to that of a mouse. It also consists of a base and a trigger. You connect the Joystick into the "Joystick input" of your computer for use. They are used usually for games but also are used for things like cranes and trucks. They were especially popular in the mid-90's for control games like Flight Simulator, a flying game.A joystick is very popular and even today some kids use joysticks to play there everyday game.(pac man)etc.

#### Mouse

The computer mouse was invented by Douglas Engelbart of Stanford Research Institute. He conceived the idea of the mouse in 1950 but only published it in 1963. Xerox refined his prototype in 1974 and showed it to Apple's Steve Jobs that quickly applied the concept to his graphical Macintosh computer. It took another ten years for the mouse to gain worldwide acceptance.
Today the mouse is a widely used input device, a hand-held pointing device that can connect to a computer, wirelessly or with a cable that attaches to the USB/OS2/Serial port on the computer system. It is designed to sit under one hand of the user so as to detect movement. It usually has buttons and/or other devices which allow the user to perform different system-dependent operations.
The name "mouse" was derived from its' resemblance of early models to the rodent by the same name. These early models had a cord attached to the rear part of the device, which looked like the tail of the mouse. The older mice used a track ball, that used 2 gear-wheels perpendicular to each other that rolled across the surface, today most mouses are optical: which uses light to detect movement.
Since those early days, several types of mouses have evolved. One of these types is the mechanical mouse. The so-called ball mouse was invented in the early 1970s and became the predominant form used with personal computers throughout the 1980s and 1990s. Another type of mechanical mouse had two plastic "feet" on the bottom which sensed movement.
Optical mice which used a light-emitting diode and photodiodes to detect movement were developed in the early 1980s. Due to the eventual ability to embed more powerful image processing chips in the mouse, the mouse was able to detect motion on a wide variety of surfaces, which also eliminated the need for a special mouse-pad. Nowadays, optical mice work by using an optoelectronic sensor to take pictures of the surface on which the mouse operates.
Laser mice came out as early as 1998. In 2004, Logitech and Agilent Technologies introduced a laser mouse that used a small laser, which increases the resolution of the image taken by the mouse. Laser mice are wireless, which conserves on power.
3D mice were introduced in the late 1990s. It was wireless and was worn on a ring around a finger. It was discontinued because it did not provide sufficient resolution.
Cabled mice typically use a thin electrical cord to transmit their input. Cordless mice transmit data through infrared radiation or radio.
The mouse's buttons have changed very little over the years, varying mostly in shape, number and placement. Most mice usually have between one and three buttons. Two-button mice are the most common. The primary button is located on the left hand side of the mouse, for the benefit of right-hand users. The second button is usually used to invoke a contextual menu in the computer's software user interface, and is located on the right side. A third button located in the middle often maps a commonly-used action or macro. Mice with five or more buttons have also been manufactured, and these extra buttons may allow forward and backward web navigation, scrolling through a browser's history, or other functions. However, the extra buttons are generally more beneficial in computer games.
The widespread usage of graphical user interfaces in the 1980s and 1990s made mice indispensable for computer use. It was estimated in 2000 that mice sales worldwide totaled roughly US$1.5 billion. And with computer usage on the rise, it can only be said that sales will continue to rise, making it a very profitable endeavor to be in the "mouse" manufacturing business.

##### Wireless Mouse

The classical wired mouse, although it has changed connectors to the computer, is still the most used type of mouse. However, the new wireless technologies are allowing for wireless mice to become more prevalent.
Most wireless mice use radio frequency (RF) technologies to communicate information to your computer. The RF technology used is frequently the Bluetooth technology. It doesn't matter whether the mouse uses normal RF technology or the standards associated with Bluetooth. Each requires two main components: a transmitter and a receiver. Here's how they work:
1. The transmitter is housed in the mouse. It sends an electromagnetic (radio) signal that encodes the information (possibly by Bluetooth) about the mouse's movements and the buttons you click.
2. The receiver, which is connected to your computer, accepts the signal, decodes it and passes it on to the mouse driver software and your computer's operating system.
3. The receiver can be a separate device that plugs into your computer, a special card that you place in an expansion slot, or a built-in component. Many laptop computers now come with built-in Bluetooth capabilities.
One of the biggest advantages of radio frequency over another well tested technology for short distance wireless communications, infrared, is the lack of need for a line-of-site transmission. Radio frequencies work in a sphere from the transmitter.
An important note to wireless mice is the necessity of being "paired" with it's receiver. Pairing means that the devices are both operating on the same frequency, same channel, and use a common identification code. The reason pairing is so important is to filter out interference from RF devices and other sources.

#### Light-pen

An input device that utilizes a light-sensitive detector to select objects on a display screen. A light pen is similar to a mouse, except that with a light pen you can move the pointer and select objects on the display screen by directly pointing to the objects with the pen.

#### Touch-screen

How to use a touch screen; Touch screen/Pads are devices that are used by a person by simply touching the screen and controlling the mouse with his or her fingers tips along the screen. End users are able to scroll up and down and side to side to find information they are looking for. Touch Pads usually come in the shape of a rectangle and are becoming very common stand alone devices.
Touch Screens are display screens that are sensitive to the touch of a finger or a pointing device. This removes the keyboard and/or the mouse as the primary input device for interacting with the display's content. A basic touchscreen has three main components: a touch sensor, a controller, and a software driver. A touch screen sensor is a clear glass panel with a touch responsive surface. The controller is a small PC card that connects between the touch sensor and the PC. The driver is a software update for the PC system that allows the touchscreen and computer to work together. Touchscreen computer systems are perfect for multi-media applications, kiosks, restaurants, computer based training, ATMs (automated teller machines), PDAs (personal digital assistants), retail settings, handicapped, real-estate, executive information systems, and much more.
There are a number of types of touch screen technology: A resistive touch screen panel is coated with a thin metallic electrically conductive and resistive layer that causes a change in the electrical current which is registered as a touch event and sent to the controller for processing. Surface wave technology uses ultrasonic waves that pass over the touch screen panel when the panel is touched. A capacitive touch screen panel is coated with a material, typically indium tin oxide that conducts a continuous electrical current across the sensor. Capacitive sensors must be touched with a conductive device being held by a bare hand or a finger, unlike resistive and surface wave panels that can use anything that can point, such as a finger or stylus. An infrared touch screen panel employs one of two very different methodologies. One method used thermal induced changes of the surface resistance. This method was sometimes slow and required warm hands. Another method is an array of vertical and horizontal IR sensors that detected the interruption of a modulated light beam near the surface of the screen IR touch screens have the most durable surfaces and are used in many military applications that require a touch panel display. In a strain gauge configuration the screen is spring mounted on the four corners and strain gauges are used to determine deflection when the screen is touched. Optical Imaging: A relatively-modern development in touch screen technology, two or more image sensors are placed around the edges (usually the corners) of the screen. Infrared backlights are placed in the camera's field of view on the other sides of the screen. A touch shows up as a shadow and each pair of cameras can then be triangulated to locate the touch and Dispersive Signal Technology: is the newest technology, introduced in 2002. It uses sensors to detect the mechanical energy in the glass that occur due to a touch. Complex algorithms then interpret this information and provide the actual location of the touch. The technology claims to be unaffected by dust and other outside elements, including scratches. Since there is no need for additional elements on screen, it also claims to provide excellent optical clarity. Also, since mechanical vibrations are used to detect a touch event, any object can be used to generate these events, including fingers and styluses. The technology is still quite new and is not currently widely available. http://en.wikipedia.org/wiki/Touchscreen http://encyclopedia.thefreedictionary.com/Touch+screen