Alternative Titles: computer
peripheral, input–output device, input/output device, peripheral
also known as peripheral, computer
peripheral,input-output device, or input/output
device, any of various devices (including sensors) used to enter
information and instructions into a computer for storage
or processing and to deliver the processed data to a human operator or, in some
cases, a machine controlled
by the computer. Such devices make up the peripheral equipment
of modern digital computer systems.
READ MORE ON THIS TOPIC
peripherals are devices used to input information and instructions into a
computer for storage or processing and to output the processed data. In
addition, devices that enable the transmission and reception of data between
computers are often classified as peripherals.
commonly divided into three kinds: input devices, output devices, and storage
devices (which partake of the characteristics of the first two). An input
device converts incoming data and instructions into a pattern of electrical signals
in binary code
that are comprehensible to a digital computer. An output device reverses the
process, translating the digitized signals into a form intelligible to the
user. At one time punched-card and paper-tape readers were extensively used for
inputting, but these have now been supplanted by more efficient devices.
devices include typewriter-like keyboards; handheld devices such as the mouse,
trackball, joystick, trackpad, and special pen with pressure-sensitive pad;
microphones, webcams, and digital cameras. They also include sensors that
provide information about their environment—temperature, pressure, and so forth—to
a computer. Another direct-entry mechanism is the
scanners used with point-of-sale terminals in retail stores) that can read
bar-coded data or optical character fonts.
equipment includes video display terminals, ink-jet and laser printers,
loudspeakers, headphones, and devices such as flow valves that control
machinery, often in response to computer processing of sensor input data. Some
devices, such as video display terminals and USB hubs, may provide
both input and output. Other examples are devices that enable the transmission and
reception of data between computers—e.g., modems and network
Encyclopædia Britannica, Inc.
Most auxiliary storage
devices—as, for example, CD-ROM and DVD drives, flash memory drives,
and external disk drives also double as input/output devices (seecomputer memory).
Even devices such as smartphones, tablet computers,
and wearable devices like fitness trackers and smartwatches can
be considered as peripherals, albeit ones
that can function independently.
standards for connecting peripherals to computers exist. For example, enhancedintegrateddrive electronics (EIDE)
and serial advanced technology attachment (SATA) are common interfaces,
or buses, for magnetic disk drives. A bus (also
known as a port) can be either serial or parallel,
depending on whether the data path carries one bit at a time (serial) or many
at once (parallel). Serial connections, which use relatively few wires, are
generally simpler and slower than parallel connections. Universal serial bus (USB)
is a common serial bus. A common example of a parallel bus is the SATA bus.