<s>
The	O
Video	B-Protocol
Graphics	I-Protocol
Array	I-Protocol
(	O
VGA	B-Protocol
)	O
connector	O
is	O
a	O
standard	O
connector	O
used	O
for	O
computer	O
video	O
output	O
.	O
</s>
<s>
Originating	O
with	O
the	O
1987	O
IBM	B-Device
PS/2	I-Device
and	O
its	O
VGA	B-Protocol
graphics	I-Protocol
system	O
,	O
the	O
15-pin	O
connector	O
went	O
on	O
to	O
become	O
ubiquitous	O
on	O
PCs	O
,	O
as	O
well	O
as	O
many	O
monitors	O
,	O
projectors	O
and	O
high-definition	B-Device
television	I-Device
sets	O
.	O
</s>
<s>
Other	O
connectors	O
have	O
been	O
used	O
to	O
carry	O
VGA-compatible	O
signals	O
,	O
such	O
as	O
mini-VGA	B-Protocol
or	O
BNC	O
,	O
but	O
"	O
VGA	B-Protocol
connector	I-Protocol
"	O
typically	O
refers	O
to	O
this	O
design	O
.	O
</s>
<s>
Devices	O
continue	O
to	O
be	O
manufactured	O
with	O
VGA	B-Protocol
connectors	I-Protocol
,	O
although	O
newer	O
digital	O
interfaces	O
such	O
as	O
DVI	B-Protocol
,	O
HDMI	B-Protocol
and	O
DisplayPort	B-Protocol
are	O
increasingly	O
displacing	O
VGA	B-Protocol
,	O
and	O
many	O
modern	O
computers	O
and	O
other	O
devices	O
do	O
not	O
include	O
it	O
.	O
</s>
<s>
The	O
VGA	B-Protocol
connector	I-Protocol
is	O
a	O
three-row	O
,	O
15-pin	O
D-subminiature	B-Protocol
connector	I-Protocol
referred	O
to	O
variously	O
as	O
DE-15	O
,	O
HD-15	B-Protocol
or	O
DB-15	B-Protocol
.	O
</s>
<s>
DE-15	O
is	O
the	O
most	O
accurate	O
common	O
nomenclature	O
under	O
the	O
D-sub	B-Protocol
specifications	O
:	O
an	O
"	O
E	O
"	O
size	O
D-sub	B-Protocol
connector	I-Protocol
,	O
with	O
15	O
pins	O
in	O
three	O
rows	O
.	O
</s>
<s>
All	O
VGA	B-Protocol
connectors	I-Protocol
carry	O
analog	O
RGBHV	O
(	O
red	O
,	O
green	O
,	O
blue	O
,	O
horizontal	B-General_Concept
sync	I-General_Concept
,	O
vertical	O
sync	O
)	O
video	O
signals	O
.	O
</s>
<s>
In	O
both	O
its	O
modern	O
and	O
original	O
variants	O
,	O
VGA	B-Protocol
utilizes	O
multiple	O
scan	O
rates	O
,	O
so	O
attached	O
devices	O
such	O
as	O
monitors	O
are	O
multisync	B-General_Concept
by	O
necessity	O
.	O
</s>
<s>
The	O
VGA	B-Protocol
interface	O
includes	O
no	O
affordances	O
for	O
hot	B-Device
swapping	I-Device
,	O
the	O
ability	O
to	O
connect	O
or	O
disconnect	O
the	O
output	O
device	O
during	O
operation	O
,	O
although	O
in	O
practice	O
this	O
can	O
be	O
done	O
and	O
usually	O
does	O
not	O
cause	O
damage	O
to	O
the	O
hardware	O
or	O
other	O
problems	O
.	O
</s>
<s>
The	O
VESA	O
DDC	O
specification	O
does	O
,	O
however	O
,	O
include	O
a	O
standard	O
for	O
hot-swapping	B-Device
.	O
</s>
<s>
In	O
the	O
original	O
IBM	B-Protocol
VGA	I-Protocol
implementation	O
,	O
refresh	O
rates	O
were	O
limited	O
to	O
two	O
vertical	O
(	O
60	O
and	O
70Hz	O
)	O
and	O
three	O
horizontal	O
frequencies	O
,	O
all	O
of	O
which	O
were	O
communicated	O
to	O
the	O
monitor	O
using	O
combinations	O
of	O
different	O
polarity	O
H	O
and	O
V	O
sync	O
signals	O
.	O
</s>
<s>
The	O
IBM	B-Device
PS/55	I-Device
Display	B-Device
Adapter	I-Device
redefined	O
pin	O
9	O
as	O
"	O
+12V	O
"	O
,	O
which	O
signals	O
the	O
monitor	O
to	O
turn	O
on	O
when	O
the	O
system	O
unit	O
is	O
powered	O
on	O
.	O
</s>
<s>
In	O
order	O
to	O
advertise	O
display	O
capabilities	O
VESA	O
has	O
introduced	O
a	O
scheme	O
to	O
redefining	O
VGA	B-Protocol
connector	I-Protocol
pins	O
9	O
,	O
12	O
,	O
and	O
15	O
as	O
a	O
serial	O
bus	O
for	O
a	O
Display	O
Data	O
Channel	O
(	O
DDC	O
)	O
.	O
</s>
<s>
The	O
same	O
VGA	B-Protocol
cable	I-Protocol
can	O
be	O
used	O
with	O
a	O
variety	O
of	O
supported	O
VGA	B-Protocol
resolutions	O
,	O
ranging	O
from	O
320×400px	O
@70Hz	O
,	O
or	O
320×480px	O
@60Hz	O
(	O
12.6MHz	O
of	O
signal	B-Algorithm
bandwidth	I-Algorithm
)	O
to	O
1280×1024px	O
(	O
SXGA	O
)	O
@85Hz	O
(	O
160MHz	O
)	O
and	O
up	O
to	O
2048×1536px	O
(	O
QXGA	O
)	O
@85Hz	O
(	O
388MHz	O
)	O
.	O
</s>
<s>
While	O
shorter	O
VGA	B-Protocol
cables	I-Protocol
are	O
less	O
likely	O
to	O
introduce	O
significant	O
signal	O
degradation	O
,	O
good-quality	O
cable	O
should	O
not	O
suffer	O
from	O
signal	O
crosstalk	O
(	O
whereby	O
signals	O
in	O
one	O
wire	O
induce	O
unwanted	O
currents	O
in	O
adjacent	O
wires	O
)	O
even	O
at	O
greater	O
lengths	O
.	O
</s>
<s>
Some	O
high-end	O
monitors	O
and	O
video	B-Device
cards	I-Device
use	O
multiple	O
BNC	B-Protocol
connectors	I-Protocol
instead	O
of	O
a	O
single	O
standard	O
VGA	B-Protocol
connector	I-Protocol
,	O
providing	O
a	O
higher	O
quality	O
connection	O
with	O
less	O
crosstalk	O
by	O
utilizing	O
five	O
separate	O
75ohm	O
coaxial	O
cables	O
.	O
</s>
<s>
Some	O
laptops	O
and	O
other	O
portable	O
devices	O
use	O
a	O
two-row	O
mini-VGA	B-Protocol
connector	O
that	O
is	O
much	O
smaller	O
than	O
the	O
three-row	O
DE-15	O
connector	O
,	O
as	O
well	O
as	O
five	O
separate	O
BNC	B-Protocol
connectors	I-Protocol
.	O
</s>
<s>
Various	O
adapters	O
can	O
be	O
purchased	O
to	O
convert	O
VGA	B-Protocol
to	O
other	O
connector	O
types	O
.	O
</s>
<s>
One	O
common	O
variety	O
is	O
a	O
DVI	B-Protocol
to	O
VGA	B-Protocol
adapter	I-Protocol
,	O
which	O
is	O
possible	O
because	O
many	O
DVI	B-Protocol
interfaces	O
also	O
carry	O
VGA-compatible	O
analog	O
signals	O
.	O
</s>
<s>
Adapting	O
from	O
HDMI	B-Protocol
or	O
DisplayPort	B-Protocol
to	O
VGA	B-Protocol
without	O
an	O
active	O
converter	O
is	O
not	O
possible	O
because	O
those	O
connectors	O
do	O
n't	O
output	O
analog	O
signals	O
.	O
</s>
<s>
For	O
conversions	O
to	O
and	O
from	O
digital	O
formats	O
like	O
HDMI	B-Protocol
or	O
Displayport	B-Protocol
,	O
a	O
scan	B-General_Concept
converter	I-General_Concept
is	O
required	O
.	O
</s>
<s>
VGA	B-Protocol
outputs	O
to	O
interfaces	O
with	O
different	O
signaling	O
,	O
more	O
complex	O
converters	B-General_Concept
may	O
be	O
used	O
.	O
</s>
<s>
Most	O
of	O
them	O
need	O
an	O
external	O
power	O
source	O
to	O
operate	O
and	O
are	O
inherently	O
lossy	B-General_Concept
.	O
</s>
<s>
However	O
,	O
many	O
modern	O
displays	O
are	O
still	O
made	O
with	O
multiple	O
inputs	O
including	O
VGA	B-Protocol
,	O
in	O
which	O
case	O
adapters	O
are	O
not	O
necessary	O
.	O
</s>
<s>
VGA	B-Protocol
can	O
also	O
be	O
adapted	O
to	O
SCART	B-Protocol
in	O
some	O
cases	O
,	O
because	O
the	O
signals	O
are	O
electrically	O
compatible	O
if	O
the	O
correct	O
sync	O
rates	O
are	O
set	O
by	O
the	O
host	O
PC	O
.	O
</s>
<s>
Many	O
modern	O
graphics	B-Device
adapters	I-Device
can	O
modify	O
their	O
signal	O
in	O
software	O
,	O
including	O
refresh	O
rate	O
,	O
sync	O
length	O
,	O
polarity	O
and	O
number	O
of	O
blank	O
lines	O
.	O
</s>
<s>
Under	O
these	O
restrictive	O
conditions	O
,	O
a	O
simple	O
circuit	O
to	O
combine	O
the	O
VGA	B-Protocol
separate	O
synchronization	O
signals	O
into	O
SCART	B-Protocol
composite	O
sync	O
may	O
suffice	O
.	O
</s>
<s>
A	O
VGA	B-Protocol
extender	I-Protocol
is	O
an	O
electronic	O
device	O
that	O
increases	O
the	O
signal	O
strength	O
from	O
a	O
VGA	B-Protocol
port	I-Protocol
,	O
most	O
often	O
from	O
a	O
computer	O
.	O
</s>
<s>
They	O
are	O
often	O
used	O
in	O
schools	O
,	O
businesses	O
,	O
and	O
homes	O
when	O
multiple	O
monitors	O
are	O
being	O
run	O
off	O
one	O
VGA	B-Protocol
port	I-Protocol
,	O
or	O
if	O
the	O
cable	O
between	O
the	O
monitor	O
and	O
the	O
computer	O
will	O
be	O
excessively	O
long	O
(	O
often	O
pictures	O
appear	O
blurry	O
or	O
have	O
minor	O
artifacts	B-Algorithm
if	O
the	O
cable	O
runs	O
too	O
far	O
without	O
an	O
extender	O
)	O
.	O
</s>
<s>
VGA	B-Protocol
extenders	I-Protocol
are	O
sometimes	O
called	O
VGA	B-Protocol
boosters	O
.	O
</s>
