self-test to identify errors during the computer's boot process, without needing a video output device to be present and functional. Studio monitor A Studio monitor is a speaker used in a studio environment. These speakers optimize for accuracy. A monitor produces a flat (linear) frequency response which does not emphasize or de-emphasize of particular frequencies. Headphones Headphones, earphones, and earpieces are a kind of speaker which is supported either on the user's head, or the user's ear. Unlike a speaker, headphones are not meant to be audible to people nearby, which suits them for use in the public, office or other quiet environments. Noise-cancelling headphones are built with ambient noise reduction capabilities which may employ active noise cancelling. Technology Loudspeakers are composed of several components within an enclosure, such as several drivers, active amplifiers, crossovers, and other electronics. Multiple drivers are used to reproduce the full frequency range of human hearing, with tweeters producing high pitches and woofers producing low pitches. Full-range speakers use only one driver to produce as much of a frequency response as possible. While Hi-Fi speakers attempt to produce high quality sound, computer speakers may compromise on these aspects due to their limited size and to be inexpensive, and the latter often uses full-range speakers as a result. Tactile Braille display A refreshable braille display outputs braille characters through the use of pins raised out of holes on its surface. It is ordinarily used by visually-impaired individuals as an alternative to a screen reader. Haptic technology Haptic technology involves the use of vibration and other motion to induce a sense of touch. Haptic technology was introduced in the late 1990s for use in game controllers, to provide tactile feedback while a user is playing a video game. Haptic feedback has seen further uses in the automotive field, aircraft simulation systems, and brain-computer interfaces. In mobile devices, Apple added haptic technology in various devices, marketed as 3D Touch and Force Touch. In this form, several devices could sense the amount of force exerted on its touchscreen, while MacBooks could sense two levels of force on its touchpad, which will produce a haptic sensation. Printing devices Printer A printer is a device that outputs data to be put on a physical item, usually a piece of paper. Printers operate by transferring ink onto this medium in the form of the image received from the host. Early printers could