<s>
An	O
output	B-Device
device	I-Device
is	O
any	O
piece	O
of	O
computer	B-Architecture
hardware	I-Architecture
that	O
converts	O
information	O
into	O
a	O
human-perceptible	O
form	O
or	O
,	O
historically	O
,	O
into	O
a	O
physical	O
machine-readable	O
form	O
for	O
use	O
with	O
other	O
non-computerized	O
equipment	O
.	O
</s>
<s>
It	O
can	O
be	O
text	B-Device
,	O
graphics	O
,	O
tactile	B-Device
,	O
audio	O
,	O
or	O
video	O
.	O
</s>
<s>
Examples	O
include	O
monitors	B-Device
,	O
printers	O
,	O
speakers	B-Device
,	O
headphones	B-Device
,	O
projectors	B-Application
,	O
GPS	O
devices	O
,	O
optical	B-Application
mark	I-Application
readers	I-Application
,	O
and	O
braille	O
readers	O
.	O
</s>
<s>
In	O
an	O
industrial	O
setting	O
,	O
output	B-Device
devices	I-Device
also	O
include	O
"	O
printers	O
"	O
for	O
paper	O
tape	O
and	O
punched	B-Architecture
cards	I-Architecture
,	O
especially	O
where	O
the	O
tape	O
or	O
cards	O
are	O
subsequently	O
used	O
to	O
control	O
industrial	O
equipment	O
,	O
such	O
as	O
an	O
industrial	O
loom	O
with	O
electrical	O
robotics	O
which	O
is	O
not	O
fully	O
computerized	O
.	O
</s>
<s>
A	O
display	O
device	O
is	O
the	O
most	O
common	O
form	O
of	O
output	B-Device
device	I-Device
which	O
presents	O
output	O
visually	O
on	O
computer	B-Device
screen	I-Device
.	O
</s>
<s>
With	O
all-in-one	O
PCs	O
,	O
notebook	B-Device
computers	I-Device
,	O
hand	O
held	O
PCs	O
and	O
other	O
devices	O
;	O
the	O
term	O
display	O
screen	O
is	O
used	O
for	O
the	O
display	O
device	O
.	O
</s>
<s>
Display	O
devices	O
form	O
images	O
by	O
illuminating	O
a	O
desired	O
configuration	O
of	O
pixels	B-Algorithm
.	O
</s>
<s>
The	O
interface	O
between	O
a	O
computer	O
's	O
CPU	B-General_Concept
and	O
the	O
display	O
is	O
a	O
Graphics	B-Architecture
Processing	I-Architecture
Unit	I-Architecture
(	O
GPU	B-Architecture
)	O
.	O
</s>
<s>
This	O
processor	O
is	O
used	O
to	O
form	O
images	O
on	O
a	O
framebuffer	B-Algorithm
.	O
</s>
<s>
When	O
the	O
image	O
is	O
to	O
be	O
sent	O
to	O
the	O
display	O
,	O
the	O
GPU	B-Architecture
sends	O
its	O
image	O
through	O
a	O
video	B-General_Concept
display	I-General_Concept
controller	I-General_Concept
to	O
generate	O
a	O
video	B-Application
signal	I-Application
,	O
which	O
is	O
then	O
sent	O
to	O
a	O
display	B-Protocol
interface	I-Protocol
such	O
as	O
HDMI	B-Protocol
,	O
VGA	B-Protocol
,	O
DisplayPort	B-Protocol
,	O
or	O
DVI	B-Application
.	O
</s>
<s>
GPUs	B-Architecture
can	O
be	O
divided	O
into	O
discrete	B-Device
and	O
integrated	O
units	O
,	O
the	O
former	O
being	O
an	O
external	O
unit	O
and	O
the	O
latter	O
of	O
which	O
is	O
included	O
within	O
a	O
CPU	B-General_Concept
die	O
.	O
</s>
<s>
Discrete	B-Device
graphics	I-Device
cards	I-Device
are	O
almost	O
always	O
connected	O
to	O
the	O
host	O
through	O
the	O
PCI	B-Protocol
Express	O
bus	O
,	O
while	O
older	O
graphics	B-Device
cards	I-Device
may	O
have	O
used	O
AGP	B-Architecture
or	O
PCI	B-Protocol
.	O
</s>
<s>
Some	O
mobile	O
computers	O
support	O
an	O
external	O
graphics	B-Device
card	I-Device
through	O
Thunderbolt	B-Protocol
(	O
via	O
PCIe	O
)	O
.	O
</s>
<s>
A	O
monitor	O
is	O
a	O
standalone	O
display	O
commonly	O
used	O
with	O
a	O
desktop	B-Device
computer	I-Device
,	O
or	O
in	O
conjunction	O
to	O
a	O
laptop	B-Device
as	O
an	O
external	O
display	O
.	O
</s>
<s>
The	O
monitor	O
is	O
connected	O
to	O
the	O
host	O
through	O
the	O
use	O
of	O
a	O
display	O
cable	O
,	O
such	O
as	O
HDMI	B-Protocol
,	O
DisplayPort	B-Protocol
,	O
VGA	B-Protocol
,	O
and	O
more	O
.	O
</s>
<s>
Older	O
monitors	B-Device
use	O
CRT	B-Device
technology	O
,	O
while	O
modern	O
monitors	B-Device
are	O
typically	O
flat	B-General_Concept
panel	I-General_Concept
displays	I-General_Concept
using	O
a	O
plethora	O
of	O
technologies	O
such	O
as	O
TFT-LCD	B-Device
,	O
LED	O
,	O
OLED	B-Device
,	O
and	O
more	O
.	O
</s>
<s>
These	O
internal	O
displays	O
are	O
connected	O
to	O
the	O
computer	O
through	O
an	O
internal	O
display	B-Protocol
interface	I-Protocol
such	O
as	O
LVDS	B-Architecture
or	O
eDP	O
.	O
</s>
<s>
Prior	O
to	O
the	O
development	O
of	O
modern	O
pixel-oriented	O
displays	O
,	O
computer	B-General_Concept
terminals	I-General_Concept
were	O
used	O
,	O
composed	O
of	O
a	O
character-oriented	O
display	O
device	O
known	O
as	O
a	O
VDU	O
and	O
a	O
computer	B-Device
keyboard	I-Device
.	O
</s>
<s>
These	O
terminals	O
were	O
often	O
monochromatic	O
,	O
and	O
could	O
only	O
display	O
text	B-Device
.	O
</s>
<s>
A	O
projector	B-Application
is	O
a	O
display	O
that	O
projects	O
the	O
computer	O
image	O
onto	O
a	O
surface	O
through	O
the	O
use	O
of	O
a	O
high	O
power	O
lamp	O
.	O
</s>
<s>
Display	O
technologies	O
can	O
be	O
classified	O
based	O
on	O
working	O
principle	O
,	O
lighting	O
(	O
or	O
lack	O
thereof	O
)	O
,	O
pixel	B-Algorithm
layout	O
,	O
and	O
more	O
.	O
</s>
<s>
Cathode	B-Device
ray	I-Device
tube	I-Device
(	O
CRT	B-Device
)	O
CRT	B-Device
screens	I-Device
produce	O
an	O
image	O
using	O
electron	O
tube	O
,	O
which	O
fires	O
electrons	O
at	O
a	O
phosphorous	O
coated	O
screen	O
to	O
light	O
up	O
pixels	B-Algorithm
in	O
order	O
to	O
display	O
images	O
.	O
</s>
<s>
Liquid	B-Device
crystal	I-Device
display	I-Device
(	O
LCD	B-Device
)	O
An	O
LCD	B-Device
is	O
a	O
display	O
technology	O
employing	O
the	O
use	O
of	O
liquid	B-Device
crystals	I-Device
to	O
form	O
images	O
.	O
</s>
<s>
Thin-film	B-Device
transistor	I-Device
(	O
TFT	O
)	O
A	O
TFT	O
refers	O
to	O
the	O
thin	O
layer	O
of	O
transistors	O
used	O
with	O
an	O
LCD	B-Device
.	O
</s>
<s>
LED-backlit	O
LCD	B-Device
An	O
LCD	B-Device
display	I-Device
which	O
uses	O
LEDs	O
as	O
a	O
backlight	O
.	O
</s>
<s>
Organic	B-Device
Light	I-Device
Emitting	I-Device
Diode	I-Device
(	O
OLED	B-Device
)	O
Unlike	O
an	O
LED	O
display	O
,	O
an	O
OLED	B-Device
display	I-Device
does	O
not	O
use	O
a	O
backlight	O
.	O
</s>
<s>
A	O
monochrome	O
display	O
is	O
a	O
type	O
of	O
CRT	B-Device
common	O
in	O
the	O
early	O
days	O
of	O
computing	O
,	O
from	O
the	O
1960s	O
through	O
the	O
1980s	O
,	O
before	O
color	B-Device
monitors	I-Device
became	O
popular	O
.	O
</s>
<s>
Color	B-Device
monitors	I-Device
,	O
sometimes	O
called	O
RGB	B-Device
monitors	I-Device
,	O
accept	O
three	O
separate	O
signals	O
(	O
red	O
,	O
green	O
,	O
and	O
blue	O
)	O
,	O
unlike	O
a	O
monochromatic	O
display	O
which	O
accepts	O
one	O
.	O
</s>
<s>
Color	B-Device
monitors	I-Device
implement	O
the	O
RGB	O
color	O
model	O
by	O
using	O
three	O
different	O
phosphors	O
that	O
appear	O
red	O
,	O
green	O
,	O
and	O
blue	O
when	O
activated	O
.	O
</s>
<s>
By	O
placing	O
the	O
phosphors	O
directly	O
next	O
to	O
each	O
other	O
,	O
and	O
activating	O
them	O
with	O
different	O
intensities	O
,	O
color	B-Device
monitors	I-Device
can	O
create	O
an	O
unlimited	O
number	O
of	O
colors	O
.	O
</s>
<s>
In	O
practice	O
,	O
however	O
,	O
the	O
real	O
number	O
of	O
colors	O
that	O
any	O
monitor	O
can	O
display	O
is	O
controlled	O
by	O
the	O
video	B-Device
adapter	I-Device
.	O
</s>
<s>
A	O
speaker	O
is	O
an	O
output	B-Device
device	I-Device
that	O
produces	O
sound	O
through	O
an	O
oscillating	O
transducer	B-Algorithm
called	O
a	O
driver	O
.	O
</s>
<s>
The	O
equivalent	O
input	B-Device
device	I-Device
is	O
a	O
microphone	B-Application
.	O
</s>
<s>
Speakers	B-Device
are	O
plugged	O
into	O
a	O
computer	O
's	O
sound	B-Device
card	I-Device
via	O
a	O
myriad	O
of	O
interfaces	O
,	O
such	O
as	O
a	O
phone	B-Device
connector	I-Device
for	O
analog	O
audio	O
,	O
or	O
SPDIF	O
for	O
digital	O
audio	O
.	O
</s>
<s>
While	O
speakers	B-Device
can	O
be	O
connected	O
through	O
cables	O
,	O
wireless	B-Device
speakers	I-Device
are	O
connected	O
to	O
the	O
host	O
device	O
through	O
radio	O
technology	O
such	O
as	O
Bluetooth	B-Protocol
.	O
</s>
<s>
Speakers	B-Device
are	O
most	O
often	O
used	O
in	O
pairs	O
,	O
which	O
allows	O
the	O
speaker	O
system	O
to	O
produce	O
positional	B-Application
audio	I-Application
.	O
</s>
<s>
The	O
interface	O
between	O
an	O
auditory	O
output	B-Device
device	I-Device
and	O
a	O
computer	O
is	O
the	O
sound	B-Device
card	I-Device
.	O
</s>
<s>
Sound	B-Device
cards	I-Device
may	O
be	O
included	O
on	O
a	O
computer	O
's	O
motherboard	B-Device
,	O
installed	O
as	O
an	O
expansion	B-Device
card	I-Device
,	O
or	O
as	O
a	O
desktop	O
unit	O
.	O
</s>
<s>
The	O
sound	B-Device
card	I-Device
may	O
offer	O
either	O
an	O
analog	O
or	O
digital	O
output	O
.	O
</s>
<s>
In	O
the	O
latter	O
case	O
,	O
output	O
is	O
often	O
transmitted	O
using	O
SPDIF	O
as	O
either	O
an	O
electrical	O
signal	O
or	O
an	O
optical	B-Architecture
interface	O
known	O
as	O
TOSLINK	B-Protocol
.	O
</s>
<s>
While	O
speakers	B-Device
can	O
be	O
used	O
for	O
any	O
purpose	O
,	O
there	O
are	O
computer	B-Device
speakers	I-Device
which	O
are	O
built	O
for	O
computer	O
use	O
.	O
</s>
<s>
These	O
speakers	B-Device
are	O
designed	O
to	O
sit	O
on	O
a	O
desk	O
,	O
and	O
as	O
such	O
,	O
cannot	O
be	O
as	O
large	O
as	O
conventional	O
speakers	B-Device
.	O
</s>
<s>
Computer	B-Device
speakers	I-Device
may	O
be	O
powered	O
via	O
USB	O
,	O
and	O
are	O
most	O
often	O
connected	O
through	O
a	O
3.5mm	O
phone	B-Device
connector	I-Device
.	O
</s>
<s>
The	O
PC	O
speaker	O
is	O
a	O
simple	O
loudspeaker	O
built	O
into	O
IBM	B-Device
PC	I-Device
compatible	O
computers	O
.	O
</s>
<s>
Unlike	O
a	O
speaker	O
used	O
with	O
a	O
sound	B-Device
card	I-Device
,	O
the	O
PC	O
speaker	O
is	O
only	O
meant	O
to	O
produce	O
square	O
waves	O
to	O
produce	O
sounds	O
such	O
as	O
beeping	O
.	O
</s>
<s>
PC	O
speakers	B-Device
are	O
used	O
during	O
Power-on	O
self-test	O
to	O
identify	O
errors	O
during	O
the	O
computer	O
's	O
boot	O
process	O
,	O
without	O
needing	O
a	O
video	O
output	B-Device
device	I-Device
to	O
be	O
present	O
and	O
functional	O
.	O
</s>
<s>
These	O
speakers	B-Device
optimize	O
for	O
accuracy	O
.	O
</s>
<s>
Headphones	B-Device
,	O
earphones	O
,	O
and	O
earpieces	O
are	O
a	O
kind	O
of	O
speaker	O
which	O
is	O
supported	O
either	O
on	O
the	O
user	O
's	O
head	O
,	O
or	O
the	O
user	O
's	O
ear	O
.	O
</s>
<s>
Unlike	O
a	O
speaker	O
,	O
headphones	B-Device
are	O
not	O
meant	O
to	O
be	O
audible	O
to	O
people	O
nearby	O
,	O
which	O
suits	O
them	O
for	O
use	O
in	O
the	O
public	O
,	O
office	O
or	O
other	O
quiet	O
environments	O
.	O
</s>
<s>
Noise-cancelling	O
headphones	B-Device
are	O
built	O
with	O
ambient	O
noise	O
reduction	O
capabilities	O
which	O
may	O
employ	O
active	O
noise	O
cancelling	O
.	O
</s>
<s>
Loudspeakers	O
are	O
composed	O
of	O
several	O
components	O
within	O
an	O
enclosure	B-Device
,	O
such	O
as	O
several	O
drivers	B-Device
,	O
active	O
amplifiers	O
,	O
crossovers	B-Algorithm
,	O
and	O
other	O
electronics	O
.	O
</s>
<s>
Multiple	O
drivers	B-Device
are	O
used	O
to	O
reproduce	O
the	O
full	O
frequency	O
range	O
of	O
human	O
hearing	O
,	O
with	O
tweeters	B-Device
producing	O
high	O
pitches	O
and	O
woofers	B-Device
producing	O
low	O
pitches	O
.	O
</s>
<s>
Full-range	B-Device
speakers	I-Device
use	O
only	O
one	O
driver	O
to	O
produce	O
as	O
much	O
of	O
a	O
frequency	O
response	O
as	O
possible	O
.	O
</s>
<s>
While	O
Hi-Fi	O
speakers	B-Device
attempt	O
to	O
produce	O
high	O
quality	O
sound	O
,	O
computer	B-Device
speakers	I-Device
may	O
compromise	O
on	O
these	O
aspects	O
due	O
to	O
their	O
limited	O
size	O
and	O
to	O
be	O
inexpensive	O
,	O
and	O
the	O
latter	O
often	O
uses	O
full-range	B-Device
speakers	I-Device
as	O
a	O
result	O
.	O
</s>
<s>
Haptic	B-Device
technology	I-Device
involves	O
the	O
use	O
of	O
vibration	O
and	O
other	O
motion	O
to	O
induce	O
a	O
sense	O
of	O
touch	O
.	O
</s>
<s>
Haptic	B-Device
technology	I-Device
was	O
introduced	O
in	O
the	O
late	O
1990s	O
for	O
use	O
in	O
game	B-Device
controllers	I-Device
,	O
to	O
provide	O
tactile	B-Device
feedback	O
while	O
a	O
user	O
is	O
playing	O
a	O
video	O
game	O
.	O
</s>
<s>
Haptic	O
feedback	O
has	O
seen	O
further	O
uses	O
in	O
the	O
automotive	O
field	O
,	O
aircraft	B-Application
simulation	I-Application
systems	O
,	O
and	O
brain-computer	B-Application
interfaces	I-Application
.	O
</s>
<s>
In	O
mobile	O
devices	O
,	O
Apple	O
added	O
haptic	B-Device
technology	I-Device
in	O
various	O
devices	O
,	O
marketed	O
as	O
3D	O
Touch	O
and	O
Force	B-Device
Touch	I-Device
.	O
</s>
<s>
In	O
this	O
form	O
,	O
several	O
devices	O
could	O
sense	O
the	O
amount	O
of	O
force	O
exerted	O
on	O
its	O
touchscreen	O
,	O
while	O
MacBooks	B-Device
could	O
sense	O
two	O
levels	O
of	O
force	O
on	O
its	O
touchpad	B-Application
,	O
which	O
will	O
produce	O
a	O
haptic	O
sensation	O
.	O
</s>
<s>
Early	O
printers	O
could	O
only	O
print	O
text	B-Device
,	O
but	O
later	O
developments	O
allowed	O
printing	O
of	O
graphics	O
.	O
</s>
<s>
Instead	O
of	O
drawing	O
pixels	B-Algorithm
onto	O
the	O
printing	O
medium	O
,	O
the	O
plotter	O
draws	O
lines	O
,	O
which	O
may	O
be	O
done	O
with	O
a	O
writing	O
implement	O
such	O
as	O
a	O
pencil	O
or	O
pen	O
.	O
</s>
<s>
Before	O
displays	O
were	O
used	O
to	O
display	O
data	O
visually	O
,	O
early	O
computers	O
would	O
only	O
have	O
a	O
teleprinter	O
for	O
use	O
to	O
access	O
the	O
system	B-Device
console	I-Device
.	O
</s>
<s>
As	O
the	O
operator	O
would	O
enter	O
commands	O
into	O
its	O
keyboard	B-Device
,	O
the	O
teleprinter	O
would	O
output	O
the	O
results	O
onto	O
a	O
piece	O
of	O
paper	O
.	O
</s>
<s>
The	O
teleprinter	O
would	O
ultimately	O
be	O
succeeded	O
by	O
a	O
computer	B-General_Concept
terminal	I-General_Concept
,	O
which	O
had	O
a	O
display	O
instead	O
of	O
a	O
printer	O
.	O
</s>
<s>
A	O
computer	O
can	O
still	O
function	O
without	O
an	O
output	B-Device
device	I-Device
,	O
as	O
is	O
commonly	O
done	O
with	O
servers	B-Application
,	O
where	O
the	O
primary	O
interaction	O
is	O
typically	O
over	O
a	O
data	O
network	O
.	O
</s>
<s>
A	O
number	O
of	O
protocols	O
exist	O
over	O
serial	B-Protocol
ports	I-Protocol
or	O
LAN	O
cables	O
to	O
determine	O
operational	O
status	O
,	O
and	O
to	O
gain	O
control	O
over	O
low-level	O
configuration	O
from	O
a	O
remote	O
location	O
without	O
having	O
a	O
local	O
display	O
device	O
.	O
</s>
<s>
If	O
the	O
server	O
is	O
configured	O
with	O
a	O
video	O
output	O
,	O
it	O
is	O
often	O
possible	O
to	O
connect	O
a	O
temporary	O
display	O
device	O
for	O
maintenance	O
or	O
administration	O
purposes	O
while	O
the	O
server	O
continues	O
to	O
operate	O
normally	O
;	O
sometimes	O
several	O
servers	B-Application
are	O
multiplexed	O
to	O
a	O
single	O
display	O
device	O
though	O
a	O
KVM	B-Device
switch	I-Device
or	O
equivalent	O
.	O
</s>
<s>
Remote	O
access	O
The	O
computer	O
's	O
console	B-Device
can	O
be	O
accessed	O
through	O
a	O
network	O
connection	O
such	O
as	O
the	O
Internet	O
,	O
using	O
protocols	O
such	O
as	O
telnet	B-Protocol
or	O
SSH	B-Protocol
.	O
</s>
<s>
Remote	B-Protocol
desktop	I-Protocol
Allows	O
a	O
Graphical	B-Application
User	I-Application
Interface	I-Application
to	O
be	O
accessed	O
through	O
remote	O
access	O
even	O
without	O
a	O
monitor	O
.	O
</s>
<s>
KVM	B-Device
switch	I-Device
Multiple	O
computers	O
are	O
connected	O
to	O
a	O
single	O
display	O
device	O
which	O
can	O
be	O
switched	O
between	O
computers	O
.	O
</s>
<s>
Serial	B-Protocol
port	I-Protocol
A	O
serial	B-Device
console	I-Device
can	O
be	O
connected	O
to	O
access	O
the	O
device	O
's	O
console	B-Device
.	O
</s>
