Glossary » I/O Devices

isometric joystick

a joystick that doesn’t move when pressure is applied to it; the isometric joystick is sensitive to the force a person is applying. When used to control a pointer, as when embedded in the keyboards of many laptops, the isometric…

joystick

an input device that consists of a user holding a stick in their hand, where movement of the stick from its central position provides both a direction and a quantity that can be used to control pointer movement or other…

keyboard

an input device used to enter alphanumeric data. Keyboards differ widely for different languages, and especially different scripts (writing systems). Keyboards may be physical or may be displayed on the screen, which is common for pen-based systems.

keystroke rollover

the characteristic that in rapid typing a subsequent key will start being pressed before the previous key has been released. Keyboards need to support this by not requiring that only one key be down at a time.

light pen

an input device for selecting regions on a screen or drawing. Light pens are generally held up to the monitor and determine their position by detecting the timing of the monitor refresh at their location. Because of the need for…

locator

a general way of referring to any input device or input method for specifying a location (an x,y position) on a screen. Typically includes devices associated with moving a screen pointer, such as a light pen, mouse, trackball, pen or…

logical input device

a hardware-independent way of expressing the functionality of an input device. Also useful as an abstract way of discussing the functionality of widgets on the screen. Though other logical devices are popular (such as a 3D input device), the 5…

luminance ratio

for displays, the ratio of the brightness of ambient light to screen brightness, which affects the legibility of the display.

membrane keys

mechanical keys that are covered by a membrane to give them a flat surface and keep them clean, used especially in industrial devices.

Meyer’s Law

T = A + B * SQRT(D/W)

T = time to move to a target
D = distance to target
W = width of target
A ~ -13 msec
B ~ 108 msec

Meyer’s Law is…

modifier key

same as qualifier key; a key on the keyboard that modifies the meaning of other keys that are used with it, such as shift, control, command, and alt.

motional input device

a device that detects the motion of a user or an object, such as a motion detector used to detect an intruder or a device planted inside a toy to detect when it is moved. Not normally used to refer…

mouse

an input device used to control the position of a pointer on the screen by detecting relative movement of the device. The typical design uses a ball in the bottom of the mouse that rolls as the mouse is moved…

mouse-button binding

the association of a button on a mouse with a specific functionality, such as the association of a specific tool with the left mouse button after that tool has been selected in a toolbar. Mice range in the number of…

MouseKeys

a feature that allows the pointer position to be controlled with keyboard keys instead of the mouse, intended especially for people with motor disabilities who have difficulty using a mouse.

mouthstick

a device for the physically disabled that enables them to control input through a stick they control with their mouth.

multimodal interaction

interacting with a computer using more than one input or output channel at a time, usually suggesting drastically different input channels being used simultaneously, such as voice input combined with a mouse. The simplest, most common form of multimodal interaction…

OCR

optical character recognition; using image recognition techniques so that a computer can convert an image of text (from a scan or photograph) to the computer-readable alphanumeric representation of that text. The challenge to successful OCR is in correctly interpreting the…

output device

the way a computer conveys messages to a person; computer hardware such as computer monitors and the windowing systems that run on them, and also including speakers and devices that provide tactile feedback (e.g. force-feedback joysticks).

paddle

a small round input device that a user can spin clockwise or counterclockwise (either mounted, or usually held in the opposite hand). The direction and speed of movement, rather than the absolute position, are the relevant measured parameters. Paddles were…

pen-based computing

interacting with computers using a pen, as opposed to a keyboard or mouse. A pen allows fluid handwriting, gestures, and sketching that are difficult with many other input devices, thus enabling a more expressive form of input. Pen-based interfaces are…

pick device

a general way of referring to any input device or input method for selecting an object or selecting information. A wide range of devices can be used for this purpose, including a touch screen, mouse, thumbwheel, or cursor keys.

plug and play

a hardware architecture that enables users to add and remove input and output devices at any time and immediately use them, without software installation or complicated configuration. The computer system recognizes the devices and configures itself, as with the USB…

pointer jumping

when the pointer automatically moves around to the most likely place you’ll want to click next, such as moving the pointer over the default button of a dialog box as soon as the dialog appears. This shortens the average amount…

pointing device

any device used to indicate a position, as a mouse is used to point to a position on a screen. Typical pointing devices include a mouse, pen, lightpen, trackball, touchscreen, touch tablet, touchpad, and possible a joystick or cursor keys.…