An output device is any piece of
computer hardware
Computer hardware includes the physical parts of a computer, such as the computer case, case, central processing unit (CPU), Random-access memory, random access memory (RAM), Computer monitor, monitor, Computer mouse, mouse, Computer keyboard, ...
equipment which converts information into a human-perceptible form or, historically, into a physical machine-readable form for use with other non-computerized equipment. It can be
text
Text may refer to:
Written word
* Text (literary theory), any object that can be read, including:
**Religious text, a writing that a religious tradition considers to be sacred
**Text, a verse or passage from scripture used in expository preachin ...
,
graphics
Graphics () are visual images or designs on some surface, such as a wall, canvas, screen, paper, or stone, to inform, illustrate, or entertain. In contemporary usage, it includes a pictorial representation of data, as in design and manufacture ...
,
tactile
Tactile may refer to:
* Tactile, related to the sense of touch
* Haptics (disambiguation)
* Tactile (device), a text-to-braille translation device
See also
* Tangibility, in law
* Somatosensory system, where sensations are processed
* CD96
CD ...
,
audio
Audio most commonly refers to sound, as it is transmitted in signal form. It may also refer to:
Sound
*Audio signal, an electrical representation of sound
*Audio frequency, a frequency in the audio spectrum
*Digital audio, representation of sound ...
, or
video
Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) syste ...
. Examples include
monitors
Monitor or monitor may refer to:
Places
* Monitor, Alberta
* Monitor, Indiana, town in the United States
* Monitor, Kentucky
* Monitor, Oregon, unincorporated community in the United States
* Monitor, Washington
* Monitor, Logan County, West Vir ...
,
printers
Printer may refer to:
Technology
* Printer (publishing), a person or a company
* Printer (computing), a hardware device
* Optical printer for motion picture films
People
* Nariman Printer ( fl. c. 1940), Indian journalist and activist
* Jam ...
,
speakers
Speaker may refer to:
Society and politics
* Speaker (politics), the presiding officer in a legislative assembly
* Public speaker, one who gives a speech or lecture
* A person producing speech: the producer of a given utterance, especially:
** In ...
,
headphones
Headphones are a pair of small loudspeaker drivers worn on or around the head over a user's ears. They are electroacoustic transducers, which convert an electrical signal to a corresponding sound. Headphones let a single user listen to an au ...
,
projectors
A projector or image projector is an optical device that projects an image (or moving images) onto a surface, commonly a projection screen. Most projectors create an image by shining a light through a small transparent lens, but some newer types ...
,
GPS device
A satellite navigation device (satnav device) is a user equipment that uses one or more of several global navigation satellite systems (GNSS) to calculate the device's geographical position and provide navigational advice.
Depending on the s ...
s,
optical mark reader
Optical mark recognition (also called optical mark reading and OMR) is the process of reading information that people mark on survey (human research), surveys, test (assessment), tests and other paper documents.
OMR is used to read Questionnaire ...
s, and braille readers.
In an industrial setting, output devices also include "printers" for
paper tape
Five- and eight-hole punched paper tape
Paper tape reader on the Harwell computer with a small piece of five-hole tape connected in a circle – creating a physical program loop
Punched tape or perforated paper tape is a form of data storage ...
and
punched cards
A punched card (also punch card or punched-card) is a piece of stiff paper that holds digital data represented by the presence or absence of holes in predefined positions. Punched cards were once common in data processing applications or to d ...
, especially where the tape or cards are subsequently used to control industrial equipment, such as an industrial loom with electrical robotics which is not fully computerized.
Visual
![Ecran plat wikipedia](https://upload.wikimedia.org/wikipedia/commons/9/95/Ecran_plat_wikipedia.jpg)
A display device is the most common form of output device which presents output visually on computer screen. The output appears temporarily on the screen and can easily be altered or erased.
With all-in-one PCs, notebook computers, hand held PCs and other devices; the term display screen is used for the display device. The display devices are also used in home entertainment systems, mobile systems, cameras and video game systems.
Display devices form images by illuminating a desired configuration of
pixel
In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device.
In most digital display devices, pixels are the smal ...
s. Raster display devices are organized in the form of a 2-dimensional matrix with rows and columns. This is done many times within a second, typically 60, 75, 120 or 144Hz on consumer devices.
Interface
![MSI MS-V328 outputs 20181231](https://upload.wikimedia.org/wikipedia/commons/e/e6/MSI_MS-V328_outputs_20181231.jpg)
The interface between a computer's CPU and the display is a
Graphics Processing Unit
A graphics processing unit (GPU) is a specialized electronic circuit designed to manipulate and alter memory to accelerate the creation of images in a frame buffer intended for output to a display device. GPUs are used in embedded systems, mobi ...
(GPU). This processor is used to form images on a
framebuffer
A framebuffer (frame buffer, or sometimes framestore) is a portion of random-access memory (RAM) containing a bitmap that drives a video display. It is a memory buffer containing data representing all the pixels in a complete video frame. Modern ...
. When the image is to be sent to the display, the GPU sends its image through a
video display controller
A video display controller or VDC (also called a display engine or display interface) is an integrated circuit which is the main component in a video-signal generator, a device responsible for the production of a TV video signal in a computing ...
to generate a
video signal
Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) systems ...
, which is then sent to a
display interface such as
HDMI
High-Definition Multimedia Interface (HDMI) is a proprietary audio/video interface for transmitting uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant source device, such as a display controller, ...
,
VGA
Video Graphics Array (VGA) is a video display controller and accompanying de facto graphics standard, first introduced with the IBM PS/2 line of computers in 1987, which became ubiquitous in the PC industry within three years. The term can no ...
,
DisplayPort
DisplayPort (DP) is a digital display interface developed by a consortium of PC and chip manufacturers and standardized by the Video Electronics Standards Association (VESA). It is primarily used to connect a video source to a display device su ...
, or
DVI
Digital Visual Interface (DVI) is a video display interface developed by the Digital Display Working Group (DDWG). The digital interface is used to connect a video source, such as a video display controller, to a display device, such as a comp ...
.
GPUs can be divided into
discrete
Discrete may refer to:
*Discrete particle or quantum in physics, for example in quantum theory
* Discrete device, an electronic component with just one circuit element, either passive or active, other than an integrated circuit
*Discrete group, a ...
and
integrated units, the former being an external unit and the latter of which is included within a CPU die. Discrete graphics cards are almost always connected to the host through the
PCI Express
PCI Express (Peripheral Component Interconnect Express), officially abbreviated as PCIe or PCI-e, is a high-speed serial computer expansion bus standard, designed to replace the older PCI, PCI-X and AGP bus standards. It is the common ...
bus, while older graphics cards may have used
AGP or
PCI
PCI may refer to:
Business and economics
* Payment card industry, businesses associated with debit, credit, and other payment cards
** Payment Card Industry Data Security Standard, a set of security requirements for credit card processors
* Pro ...
. Some mobile computers support an external graphics card through
Thunderbolt
A thunderbolt or lightning bolt is a symbolic representation of lightning when accompanied by a loud thunderclap. In Indo-European mythology, the thunderbolt was identified with the 'Sky Father'; this association is also found in later Hell ...
(via PCIe).
Form factors
Monitor
A monitor is a standalone display commonly used with a
desktop computer
A desktop computer (often abbreviated desktop) is a personal computer designed for regular use at a single location on or near a desk due to its size and power requirements. The most common configuration has a case that houses the power supply ...
, or in conjunction to a
laptop
A laptop, laptop computer, or notebook computer is a small, portable personal computer (PC) with a screen and alphanumeric keyboard. Laptops typically have a clam shell form factor with the screen mounted on the inside of the upper li ...
as an external display. The monitor is connected to the host through the use of a display cable, such as
HDMI
High-Definition Multimedia Interface (HDMI) is a proprietary audio/video interface for transmitting uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant source device, such as a display controller, ...
,
DisplayPort
DisplayPort (DP) is a digital display interface developed by a consortium of PC and chip manufacturers and standardized by the Video Electronics Standards Association (VESA). It is primarily used to connect a video source to a display device su ...
,
VGA
Video Graphics Array (VGA) is a video display controller and accompanying de facto graphics standard, first introduced with the IBM PS/2 line of computers in 1987, which became ubiquitous in the PC industry within three years. The term can no ...
, and more.
Older monitors use
CRT technology, while modern monitors are typically
flat panel display
A flat-panel display (FPD) is an electronic display used to display visual content such as text or images. It is present in consumer, medical, transportation, and industrial equipment.
Flat-panel displays are thin, lightweight, provide better li ...
s using a plethora of technologies such as
TFT-LCD
A thin-film-transistor liquid-crystal display (TFT LCD) is a variant of a liquid-crystal display that uses thin-film-transistor technology to improve image qualities such as addressability and contrast. A TFT LCD is an active matrix LCD, in con ...
,
LED
A light-emitting diode (LED) is a semiconductor Electronics, device that Light#Light sources, emits light when Electric current, current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy i ...
,
OLED
An organic light-emitting diode (OLED or organic LED), also known as organic electroluminescent (organic EL) diode, is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound that emits light i ...
, and more.
Internal display
Almost all mobile devices incorporate an internal display. These internal displays are connected to the computer through an internal display interface such as
LVDS
Low-voltage differential signaling (LVDS), also known as TIA/EIA-644, is a technical standard that specifies electrical characteristics of a differential, serial signaling standard. LVDS operates at low power and can run at very high speeds ...
or
eDP. The chief advantage of these displays is their portability.
Terminal
![Colossal Cave Adventure on VT100 terminal](https://upload.wikimedia.org/wikipedia/commons/d/d8/Colossal_Cave_Adventure_on_VT100_terminal.jpg)
Prior to the development of modern pixel-oriented displays,
computer terminals were used, composed of a character-oriented display device known as a VDU and a
computer keyboard
A computer keyboard is a peripheral input device modeled after the typewriter keyboard which uses an arrangement of buttons or keys to act as mechanical levers or electronic switches. Replacing early punched cards and paper tape technology ...
.
These terminals were often monochromatic, and could only display text. Rudimentary graphics could be displayed through the use of
ASCII art
ASCII art is a graphic design technique that uses computers for presentation and consists of pictures pieced together from the 95 printable (from a total of 128) characters defined by the ASCII Standard from 1963 and ASCII compliant chara ...
along with
box-drawing character
Box-drawing characters, also known as line-drawing characters, are a form of semigraphics widely used in text user interfaces to draw various geometric frames and boxes. Box-drawing characters typically only work well with monospaced fonts. In ...
s.
Teleprinter
A teleprinter (teletypewriter, teletype or TTY) is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point and point-to-multipoint configurations. Initia ...
s were the precursors to these devices.
Projector
![LED Projector machine](https://upload.wikimedia.org/wikipedia/commons/c/c1/LED_Projector_machine.jpg)
A projector is a display that projects the computer image onto a surface through the use of a high power lamp. These displays are seen in use to show slideshow presentations or in movie screenings.
Technologies
Display technologies can be classified based on working principle, lighting (or lack thereof), pixel layout, and more.
;
Cathode ray tube
A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms ( oscilloscope), pictu ...
(CRT) : CRT screens produce an image using electron tube, which fires electrons at a phosphorous coated screen to light up pixels in order to display images.
;
Liquid crystal display
A liquid-crystal display (LCD) is a flat panel display, flat-panel display or other Electro-optic modulator, electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers. Liqui ...
(LCD) : An LCD is a display technology employing the use of
liquid crystal
Liquid crystal (LC) is a state of matter whose properties are between those of conventional liquids and those of solid crystals. For example, a liquid crystal may flow like a liquid, but its molecules may be oriented in a crystal-like way. T ...
s to form images.
;
Thin-film transistor
A thin-film transistor (TFT) is a special type of field-effect transistor (FET) where the transistor is thin relative to the plane of the device. TFTs are grown on a supporting (but non-conducting) substrate. A common substrate is glass, becaus ...
(TFT) : A TFT refers to the thin layer of transistors used with an LCD.
;
LED-backlit LCD
An LED-backlit LCD is a liquid-crystal display that uses LEDs for backlighting instead of traditional cold cathode fluorescent (CCFL) backlighting. LED-backlit displays use the same TFT LCD (thin-film-transistor liquid-crystal display) technol ...
: An LCD display which uses
LED
A light-emitting diode (LED) is a semiconductor Electronics, device that Light#Light sources, emits light when Electric current, current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy i ...
s as a
backlight
A backlight is a form of illumination used in liquid crystal displays (LCDs). As LCDs do not produce light by themselves—unlike, for example, cathode ray tube (CRT), plasma (PDP) or OLED displays—they need illumination ( ambient light or a ...
. Prior to the use of LED based backlighting,
Cold Cathode Fluorescent (CCFL) tubes were used.
;
LED display
A LED display is a flat panel display that uses an array of light-emitting diodes as pixels for a video display. Their brightness allows them to be used outdoors where they are visible in the sun for store signs and billboards. In recent y ...
: LED displays use an array of LEDs to form an image.
;
Organic Light Emitting Diode
An organic light-emitting diode (OLED or organic LED), also known as organic electroluminescent (organic EL) diode, is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound that emits light i ...
(OLED) : Unlike an LED display, an OLED display does not use a backlight.
;
Electronic paper
Electronic paper, also sometimes electronic ink, e-ink or electrophoretic display, are display devices that mimic the appearance of ordinary ink on paper. Unlike conventional flat panel displays that emit light, an electronic paper display ref ...
(e-ink) : An e-ink display uses encapsulated pigment to form an image resembling printed paper, commonly used in
e-book readers
An e-reader, also called an e-book reader or e-book device, is a mobile electronic device that is designed primarily for the purpose of reading digital e-books and periodicals.
Any device that can display text on a screen may act as an e-read ...
.
Color output
Monochromatic display
A monochrome display is a type of
CRT common in the early days of
computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, e ...
, from the 1960s through the 1980s, before color monitors became popular.
They are still widely used in applications such as computerized cash register systems. Green screen was the common name for a monochrome monitor using a green "P1" phosphor screen.
Colored display
Color monitors, sometimes called
RGB
The RGB color model is an additive color model in which the red, green and blue primary colors of light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three addi ...
monitors, accept three separate signals (red, green, and blue), unlike a monochromatic display which accepts one. Color monitors implement the RGB color model by using three different phosphors that appear red, green, and blue when activated. By placing the phosphors directly next to each other, and activating them with different intensities, color monitors can create an unlimited number of colors. In practice, however, the real number of colors that any monitor can display is controlled by the
video adapter
A graphics card (also called a video card, display card, graphics adapter, VGA card/VGA, video adapter, display adapter, or mistakenly GPU) is an expansion card which generates a feed of output images to a display device, such as a computer moni ...
.
Auditory
![CREATIVE GIGAWORKS T40 ii AUX input](https://upload.wikimedia.org/wikipedia/commons/e/e4/CREATIVE_GIGAWORKS_T40_ii_AUX_input.jpg)
A speaker is an output device that produces sound through an oscillating
transducer
A transducer is a device that converts energy from one form to another. Usually a transducer converts a signal in one form of energy to a signal in another.
Transducers are often employed at the boundaries of automation, measurement, and contr ...
called a driver. The equivalent input device is a
microphone
A microphone, colloquially called a mic or mike (), is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and public ...
.
Speakers are plugged into a computer's
sound card
A sound card (also known as an audio card) is an internal expansion card that provides input and output of audio signals to and from a computer under the control of computer programs. The term ''sound card'' is also applied to external audio i ...
via a myriad of interfaces, such as a
phone connector for analog audio, or
SPDIF
S/PDIF (Sony/Philips Digital Interface) is a type of digital audio interface used in consumer audio equipment to output audio over relatively short distances. The signal is transmitted over either a coaxial cable (using RCA or BNC connectors) ...
for digital audio. While speakers can be connected through cables,
wireless speaker
Wireless speakers are loudspeakers that receive audio signals using radio frequency (RF) waves rather than over audio cables. The two most popular RF frequencies that support audio transmission to wireless loudspeakers include a variation of Wi ...
s are connected to the host device through radio technology such as
Bluetooth
Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances and building personal area networks (PANs). In the most widely used mode, transmission power is limi ...
.
Speakers are most often used in pairs, which allows the speaker system to produce
positional audio
3D audio effects are a group of sound effects that manipulate the sound produced by stereo speakers, surround-sound speakers, speaker-arrays, or headphones. This frequently involves the virtual placement of sound sources anywhere in three-dimensio ...
. When more than one pair is used, it is referred to as
surround sound
Surround sound is a technique for enriching the fidelity and depth of sound reproduction by using multiple audio channels from speakers that surround the listener ( surround channels). Its first application was in movie theaters. Prior to sur ...
.
Certain models of computers includes a built-in speaker, which may sacrifice audio quality in favor of size. For example, the built-in speaker of a smartphone allows the users to listen to media without attaching an external speaker.
Interface
![Creative SoundBlaster Audigy 2 (SB0400)-4](https://upload.wikimedia.org/wikipedia/commons/6/6d/Creative_SoundBlaster_Audigy_2_%28SB0400%29-4.jpg)
The interface between an auditory output device and a computer is the
sound card
A sound card (also known as an audio card) is an internal expansion card that provides input and output of audio signals to and from a computer under the control of computer programs. The term ''sound card'' is also applied to external audio i ...
. Sound cards may be
included on a computer's
motherboard
A motherboard (also called mainboard, main circuit board, mb, mboard, backplane board, base board, system board, logic board (only in Apple computers) or mobo) is the main printed circuit board (PCB) in general-purpose computers and other expand ...
, installed as an
expansion card
In computing, an expansion card (also called an expansion board, adapter card, peripheral card or accessory card) is a printed circuit board that can be inserted into an electrical connector, or expansion slot (also referred to as a bus slo ...
, or as a
desktop unit.
The sound card may offer either an analog or
digital
Digital usually refers to something using discrete digits, often binary digits.
Technology and computing Hardware
*Digital electronics, electronic circuits which operate using digital signals
**Digital camera, which captures and stores digital i ...
output. In the latter case, output is often transmitted using
SPDIF
S/PDIF (Sony/Philips Digital Interface) is a type of digital audio interface used in consumer audio equipment to output audio over relatively short distances. The signal is transmitted over either a coaxial cable (using RCA or BNC connectors) ...
as either an electrical signal or an
optical
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviole ...
interface known as
TOSLINK
TOSLINK (from ''Toshiba Link'') is a standardized optical fiber connector system. Also known generically as optical audio, its most common use is in consumer audio equipment (via a "digital optical" socket), where it carries a digital audio st ...
. Digital outputs are then decoded by an
AV receiver
An audio/video receiver (AVR) is a consumer electronics component used in a home theater. Its purpose is to receive audio and video signals from a number of sources, and to process them and provide power amplifiers to drive loudspeakers and ro ...
.
In the case of wireless audio, the computer merely transmits a
radio signal
Radio waves are a type of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum, typically with frequencies of 300 gigahertz (GHz) and below. At 300 GHz, the corresponding wavelength is 1 mm (shor ...
, and responsibility of decoding and output is shifted to the speaker.
Form factors
Computer speakers
![Creative T4 Wireless 2](https://upload.wikimedia.org/wikipedia/commons/6/6f/Creative_T4_Wireless_2.1_Speakers.jpg)
While speakers can be used for any purpose, there are computer speakers which are built for computer use. These speakers are designed to sit on a desk, and as such, cannot be as large as conventional speakers.
Computer speakers may be powered via
USB
Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad ...
, and are most often connected through a 3.5mm phone connector.
PC speaker
The PC speaker is a simple loudspeaker built into
IBM PC
The IBM Personal Computer (model 5150, commonly known as the IBM PC) is the first microcomputer released in the IBM PC model line and the basis for the IBM PC compatible de facto standard. Released on August 12, 1981, it was created by a team ...
compatible computers. Unlike a speaker used with a sound card, the PC speaker is only meant to produce
square wave
A square wave is a non-sinusoidal periodic waveform in which the amplitude alternates at a steady frequency between fixed minimum and maximum values, with the same duration at minimum and maximum. In an ideal square wave, the transitions b ...
s to produce sounds such as
beeping.
Modern computers utilize a
piezoelectric buzzer or a small speaker as the PC speaker.
PC speakers are used during
Power-on self-test
A power-on self-test (POST) is a process performed by firmware or software routines immediately after a computer or other digital electronic device is powered on.
This article mainly deals with POSTs on personal computers, but many other embed ...
to identify errors during the computer's boot process, without needing a video output device to be present and functional.
Studio monitor
![Andrew Pilling's 2011 Recording Equipment](https://upload.wikimedia.org/wikipedia/commons/3/39/Andrew_Pilling%27s_2011_Recording_Equipment.jpg)
A Studio monitor is a speaker used in a
studio
A studio is an artist or worker's workroom. This can be for the purpose of acting, architecture, painting, pottery (ceramics), sculpture, origami, woodworking, scrapbooking, photography, graphic design, filmmaking, animation, industrial design ...
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
In public relations and communication science, publics are groups of individual people, and the public (a.k.a. the general public) is the totality of such groupings. This is a different concept to the sociological concept of the ''Öffentlichkei ...
,
office
An office is a space where an Organization, organization's employees perform Business administration, administrative Work (human activity), work in order to support and realize objects and Goals, plans, action theory, goals of the organizati ...
or other quiet environments.
Noise-cancelling headphones Noise-cancelling headphones reduce unwanted ambient sounds using active noise control. This is distinct from passive headphones which, if they reduce ambient sounds at all, use techniques such as soundproofing.
Noise cancellation makes it possible ...
are built with
ambient noise reduction capabilities which may employ
active noise cancelling.
Technology
Loudspeakers are composed of several components within an
enclosure
Enclosure or Inclosure is a term, used in English landownership, that refers to the appropriation of "waste" or " common land" enclosing it and by doing so depriving commoners of their rights of access and privilege. Agreements to enclose land ...
, such as several
drivers,
active amplifiers,
crossover
Crossover may refer to:
Entertainment
Albums and songs
* ''Cross Over'' (Dan Peek album)
* ''Crossover'' (Dirty Rotten Imbeciles album), 1987
* ''Crossover'' (Intrigue album)
* ''Crossover'' (Hitomi Shimatani album)
* ''Crossover'' (Yoshino ...
s, and other electronics. Multiple drivers are used to reproduce the full frequency
range of human hearing
Hearing range describes the range of frequencies that can be heard by humans or other animals, though it can also refer to the range of levels. The human range is commonly given as 20 to 20,000 Hz, although there is considerable variati ...
, with
tweeter
A tweeter or treble speaker is a special type of loudspeaker (usually dome, inverse dome or horn-type) that is designed to produce high audio frequencies, typically deliver high frequencies up to 100 kHz. The name is derived from the high ...
s producing high pitches and
woofer
A woofer or bass speaker is a technical term for a loudspeaker driver designed to produce low frequency sounds, typically from 50 Hz up to 1000 Hz. The name is from the onomatopoeic English word for a dog's bark, " woof" (in contrast to th ...
s producing low pitches.
Full-range speaker
A full-range loudspeaker drive unit is defined as a driver which reproduces as much of the audible frequency range as possible, within the limitations imposed by the physical constraints of a specific design. The frequency range of these driv ...
s 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
Visual impairment, also known as vision impairment, is a medical definition primarily measured based on an individual's better eye visual acuity; in the absence of treatment such as correctable eyewear, assistive devices, and medical treatment†...
individuals as an alternative to a
screen reader
A screen reader is a form of assistive technology (AT) that renders text and image content as speech or braille output. Screen readers are essential to people who are blindness, blind, and are useful to people who are visual impairment, visually ...
.
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 controller
A game controller, gaming controller, or simply controller, is an input device used with video games or entertainment systems to provide input to a video game, typically to control an object or character in the game. Before the seventh generation ...
s, 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
An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple fruit tree, trees are agriculture, cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, wh ...
added haptic technology in various devices, marketed as 3D Touch and
Force Touch
Force Touch is a haptic technology developed by Apple Inc. that enables trackpads and touchscreens to distinguish between various levels of force being applied to their surfaces. It uses pressure sensors to add another method of input to Apple's ...
. 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
A touchpad or trackpad is a pointing device featuring a tactile sensor, a specialized surface that can translate the motion and position of a user's fingers to a relative position on the operating system that is made output to the screen. Touchp ...
, 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
Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distributed ...
. Printers operate by transferring ink onto this medium in the form of the image received from the host.
Early printers could only print text, but later developments allowed printing of graphics. Modern printers can receive data in multiple forms like
vector graphics
Vector graphics is a form of computer graphics in which visual images are created directly from geometric shapes defined on a Cartesian plane, such as points, lines, curves and polygons. The associated mechanisms may include vector display a ...
, as an
image
An image is a visual representation of something. It can be two-dimensional, three-dimensional, or somehow otherwise feed into the visual system to convey information. An image can be an artifact, such as a photograph or other two-dimensiona ...
, a program written in a
page description language
In digital printing, a page description language (PDL) is a computer language that describes the appearance of a printed page in a higher level than an actual output bitmap (or generally raster graphics). An overlapping term is printer control la ...
, or a string of characters.
Multiple types of printers exist:
;
Inkjet printer
Inkjet printing is a type of computer printing that recreates a digital image by propelling droplets of ink onto paper and plastic substrates. Inkjet printers were the most commonly used type of printer in 2008, and range from small inexpensi ...
s : An inkjet printer injects tiny droplets onto the printing medium via a series of nozzles on a printing head.
;
Laser printer
Laser printing is an electrostatic digital printing process. It produces high-quality text and graphics (and moderate-quality photographs) by repeatedly passing a laser beam back and forth over a negatively-charged cylinder called a "drum" to d ...
s : A laser printer uses a
laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The fir ...
to charge a drum of
toner
Toner is a powder mixture used in laser printers and photocopiers to form the printed text and images on paper, in general through a toner cartridge. Mostly granulated plastic, early mixtures only added carbon powder and iron oxide, however, ...
in order to mark points where the toner would stick onto the medium.
;
Thermal printer
Thermal printing (or direct thermal printing) is a digital printing process which produces a printed image by passing paper with a thermochromic coating, commonly known as thermal paper, over a print head consisting of tiny electrically heated ...
s : A printer which heats up a thermally sensitive roll of paper to reveal ink. Most often seen in retail stores to print
receipts
A receipt (also known as a packing list, packing slip, packaging slip, (delivery) docket, shipping list, delivery list, bill of the parcel, manifest, or customer receipt) is a document acknowledging that a person has received money or propert ...
.
;
Dot matrix printer
A dot matrix printer is an impact printer that prints using a fixed number of pins or wires. Typically the pins or wires are arranged in one or several vertical columns. The pins strike an ink-coated ribbon and force contact between the ribbon ...
: A printer which uses
impact
Impact may refer to:
* Impact (mechanics), a high force or shock (mechanics) over a short time period
* Impact, Texas, a town in Taylor County, Texas, US
Science and technology
* Impact crater, a meteor crater caused by an impact event
* Impac ...
to transfer ink from a ribbon to the medium.
Plotter
A plotter is a type of printer used to print
vector graphics
Vector graphics is a form of computer graphics in which visual images are created directly from geometric shapes defined on a Cartesian plane, such as points, lines, curves and polygons. The associated mechanisms may include vector display a ...
. Instead of drawing pixels onto the printing medium, the plotter draws lines, which may be done with a
writing implement
A writing implement or writing instrument is an object used to produce writing. Writing consists of different figures, lines, and or forms. Most of these items can be also used for other functions such as painting, drawing and technical drawing, ...
such as a pencil or pen.
Teleprinter
A teleprinter or teletypewriter (TTY) is a type of printer meant for sending and receiving messages. Before displays were used to display data visually, early computers would only have a teleprinter for use to access the
system console
One meaning of system console, computer console, root console, computer operator, operator's console, or simply console is the text entry and display device for system administration messages, particularly those from the BIOS or boot loader, the ...
. As the operator would enter commands into its keyboard, the teleprinter would output the results onto a piece of paper. The teleprinter would ultimately be succeeded by a
computer terminal
A computer terminal is an electronic or electromechanical hardware device that can be used for entering data into, and transcribing data from, a computer or a computing system. The teletype was an example of an early-day hard-copy terminal and ...
, which had a display instead of a printer.
Headless operation
A computer can still function without an output device, as is commonly done with
servers, where the primary interaction is typically over a data network. A number of protocols exist over serial ports or LAN cables to determine operational status, and to gain control over low-level configuration from a remote location without having a local display device. If the server is configured with a video output, it is often possible to connect a temporary display device for maintenance or administration purposes while the server continues to operate normally; sometimes several servers are multiplexed to a single display device though a
KVM switch
A KVM switch (with KVM being an abbreviation for "keyboard, video, and mouse") is a hardware device that allows a user to control multiple computers from one or more sets of keyboards, video monitors, and mice.
Name
Switches to connect mu ...
or equivalent.
Some methods to use remote systems are:
; Remote access : The computer's
console
Console may refer to:
Computing and video games
* System console, a physical device to operate a computer
** Virtual console, a user interface for multiple computer consoles on one device
** Command-line interface, a method of interacting with ...
can be accessed through a network connection such as the Internet, using protocols such as
telnet
Telnet is an application protocol used on the Internet or local area network to provide a bidirectional interactive text-oriented communication facility using a virtual terminal connection. User data is interspersed in-band with Telnet control i ...
or
SSH
The Secure Shell Protocol (SSH) is a cryptographic network protocol for operating network services securely over an unsecured network. Its most notable applications are remote login and command-line execution.
SSH applications are based on ...
.
;
Remote desktop
In computing, the term remote desktop refers to a software- or operating system feature that allows a personal computer's desktop environment to be run remotely off of one system (usually a PC, but the concept applies equally to a server or a ...
: Allows a
Graphical User Interface
The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, inste ...
to be accessed through remote access even without a monitor.
;
KVM switch
A KVM switch (with KVM being an abbreviation for "keyboard, video, and mouse") is a hardware device that allows a user to control multiple computers from one or more sets of keyboards, video monitors, and mice.
Name
Switches to connect mu ...
: Multiple computers are connected to a single display device which can be switched between computers.
;
Serial port
In computing, a serial port is a serial communication interface through which information transfers in or out sequentially one bit at a time. This is in contrast to a parallel port, which communicates multiple bits simultaneously in parallel. ...
: A serial console can be connected to access the device's console.
See also
*
Input Device
In computing, an input device is a piece of equipment used to provide data and control signals to an information processing system, such as a computer or information appliance. Examples of input devices include keyboards, mouse, scanners, cameras ...
*
CPU
References
External links
*
{{Basic computer components