<s>
A	O
framebuffer	B-Algorithm
(	O
frame	B-Algorithm
buffer	I-Algorithm
,	O
or	O
sometimes	O
framestore	O
)	O
is	O
a	O
portion	O
of	O
random-access	B-Architecture
memory	I-Architecture
(	O
RAM	B-Architecture
)	O
containing	O
a	O
bitmap	O
that	O
drives	O
a	O
video	O
display	O
.	O
</s>
<s>
It	O
is	O
a	O
memory	B-General_Concept
buffer	I-General_Concept
containing	O
data	O
representing	O
all	O
the	O
pixels	B-Algorithm
in	O
a	O
complete	O
video	O
frame	O
.	O
</s>
<s>
Modern	O
video	B-Device
cards	I-Device
contain	O
framebuffer	B-Algorithm
circuitry	O
in	O
their	O
cores	O
.	O
</s>
<s>
This	O
circuitry	O
converts	O
an	O
in-memory	O
bitmap	O
into	O
a	O
video	B-Application
signal	I-Application
that	O
can	O
be	O
displayed	O
on	O
a	O
computer	B-Device
monitor	I-Device
.	O
</s>
<s>
In	O
computing	O
,	O
a	O
screen	B-Algorithm
buffer	I-Algorithm
is	O
a	O
part	O
of	O
computer	B-General_Concept
memory	I-General_Concept
used	O
by	O
a	O
computer	O
application	O
for	O
the	O
representation	O
of	O
the	O
content	O
to	O
be	O
shown	O
on	O
the	O
computer	B-Device
display	I-Device
.	O
</s>
<s>
The	O
screen	B-Algorithm
buffer	I-Algorithm
may	O
also	O
be	O
called	O
the	O
video	B-Algorithm
buffer	I-Algorithm
,	O
the	O
regeneration	B-Algorithm
buffer	I-Algorithm
,	O
or	O
regen	B-Algorithm
buffer	I-Algorithm
for	O
short	O
.	O
</s>
<s>
Screen	B-Algorithm
buffers	I-Algorithm
should	O
be	O
distinguished	O
from	O
video	O
memory	B-General_Concept
.	O
</s>
<s>
To	O
this	O
end	O
,	O
the	O
term	O
off-screen	B-Algorithm
buffer	I-Algorithm
is	O
also	O
used	O
.	O
</s>
<s>
The	O
information	O
in	O
the	O
buffer	B-General_Concept
typically	O
consists	O
of	O
color	O
values	O
for	O
every	O
pixel	B-Algorithm
to	O
be	O
shown	O
on	O
the	O
display	O
.	O
</s>
<s>
Color	O
values	O
are	O
commonly	O
stored	O
in	O
1-bit	O
binary	B-Algorithm
(	O
monochrome	O
)	O
,	O
4-bit	O
palettized	B-Data_Structure
,	O
8-bit	O
palettized	B-Data_Structure
,	O
16-bit	O
high	O
color	O
and	O
24-bit	O
true	O
color	O
formats	O
.	O
</s>
<s>
An	O
additional	O
alpha	B-Algorithm
channel	I-Algorithm
is	O
sometimes	O
used	O
to	O
retain	O
information	O
about	O
pixel	B-Algorithm
transparency	O
.	O
</s>
<s>
The	O
total	O
amount	O
of	O
memory	B-General_Concept
required	O
for	O
the	O
framebuffer	B-Algorithm
depends	O
on	O
the	O
resolution	B-General_Concept
of	O
the	O
output	O
signal	O
,	O
and	O
on	O
the	O
color	O
depth	O
or	O
palette	B-Data_Structure
size	O
.	O
</s>
<s>
Computer	O
researchers	O
had	O
long	O
discussed	O
the	O
theoretical	O
advantages	O
of	O
a	O
framebuffer	B-Algorithm
,	O
but	O
were	O
unable	O
to	O
produce	O
a	O
machine	O
with	O
sufficient	O
memory	B-General_Concept
at	O
an	O
economically	O
practicable	O
cost	O
.	O
</s>
<s>
In	O
1947	O
,	O
the	O
Manchester	B-Device
Baby	I-Device
computer	O
used	O
a	O
Williams	B-General_Concept
tube	I-General_Concept
,	O
later	O
the	O
Williams-Kilburn	B-General_Concept
tube	I-General_Concept
,	O
to	O
store	O
1024	O
bits	O
on	O
a	O
cathode-ray	B-Device
tube	I-Device
(	O
CRT	O
)	O
memory	B-General_Concept
and	O
displayed	O
on	O
a	O
second	O
CRT	O
.	O
</s>
<s>
A	O
color	O
scanned	O
display	O
was	O
implemented	O
in	O
the	O
late	O
1960s	O
,	O
called	O
the	O
Brookhaven	O
RAster	O
Display	O
(	O
BRAD	O
)	O
,	O
which	O
used	O
a	O
drum	B-General_Concept
memory	I-General_Concept
and	O
a	O
television	O
monitor	O
.	O
</s>
<s>
In	O
1969	O
,	O
A	O
.	O
Michael	O
Noll	O
of	O
Bell	O
Labs	O
implemented	O
a	O
scanned	O
display	O
with	O
a	O
frame	B-Algorithm
buffer	I-Algorithm
,	O
using	O
magnetic-core	O
memory	B-General_Concept
.	O
</s>
<s>
In	O
the	O
early	O
1970s	O
,	O
the	O
development	O
of	O
MOS	B-Architecture
memory	I-Architecture
(	O
metal	B-Architecture
–	I-Architecture
oxide	I-Architecture
–	I-Architecture
semiconductor	I-Architecture
memory	B-General_Concept
)	O
integrated-circuit	O
chips	O
,	O
particularly	O
high-density	O
DRAM	O
(	O
dynamic	O
random-access	B-Architecture
memory	I-Architecture
)	O
chips	O
with	O
at	O
least	O
1kb	O
memory	B-General_Concept
,	O
made	O
it	O
practical	O
to	O
create	O
,	O
for	O
the	O
first	O
time	O
,	O
a	O
digital	B-Architecture
memory	I-Architecture
system	O
with	O
framebuffers	B-Algorithm
capable	O
of	O
holding	O
a	O
standard	O
video	O
image	O
.	O
</s>
<s>
This	O
led	O
to	O
the	O
development	O
of	O
the	O
SuperPaint	B-Application
system	O
by	O
Richard	O
Shoup	O
at	O
Xerox	O
PARC	O
in	O
1972	O
.	O
</s>
<s>
Shoup	O
was	O
able	O
to	O
use	O
the	O
SuperPaint	B-Application
framebuffer	B-Algorithm
to	O
create	O
an	O
early	O
digital	O
video-capture	O
system	O
.	O
</s>
<s>
By	O
synchronizing	O
the	O
output	O
signal	O
to	O
the	O
input	O
signal	O
,	O
Shoup	O
was	O
able	O
to	O
overwrite	O
each	O
pixel	B-Algorithm
of	O
data	O
as	O
it	O
shifted	O
in	O
.	O
</s>
<s>
Shoup	O
also	O
experimented	O
with	O
modifying	O
the	O
output	O
signal	O
using	O
color	B-Data_Structure
tables	I-Data_Structure
.	O
</s>
<s>
These	O
color	B-Data_Structure
tables	I-Data_Structure
allowed	O
the	O
SuperPaint	B-Application
system	O
to	O
produce	O
a	O
wide	O
variety	O
of	O
colors	O
outside	O
the	O
range	O
of	O
the	O
limited	O
8-bit	O
data	O
it	O
contained	O
.	O
</s>
<s>
This	O
scheme	O
would	O
later	O
become	O
commonplace	O
in	O
computer	O
framebuffers	B-Algorithm
.	O
</s>
<s>
In	O
1974	O
,	O
Evans	O
&	O
Sutherland	O
released	O
the	O
first	O
commercial	O
framebuffer	B-Algorithm
,	O
the	O
Picture	O
System	O
,	O
costing	O
about	O
$	O
15,000	O
.	O
</s>
<s>
It	O
was	O
capable	O
of	O
producing	O
resolutions	O
of	O
up	O
to	O
512	O
by	O
512	O
pixels	B-Algorithm
in	O
8-bit	O
grayscale	O
,	O
and	O
became	O
a	O
boon	O
for	O
graphics	O
researchers	O
who	O
did	O
not	O
have	O
the	O
resources	O
to	O
build	O
their	O
own	O
framebuffer	B-Algorithm
.	O
</s>
<s>
The	O
New	O
York	O
Institute	O
of	O
Technology	O
would	O
later	O
create	O
the	O
first	O
24-bit	O
color	O
system	O
using	O
three	O
of	O
the	O
Evans	O
&	O
Sutherland	O
framebuffers	B-Algorithm
.	O
</s>
<s>
Each	O
framebuffer	B-Algorithm
was	O
connected	O
to	O
an	O
RGB	O
color	O
output	O
(	O
one	O
for	O
red	O
,	O
one	O
for	O
green	O
and	O
one	O
for	O
blue	O
)	O
,	O
with	O
a	O
Digital	O
Equipment	O
Corporation	O
PDP	O
11/04	O
minicomputer	B-Architecture
controlling	O
the	O
three	O
devices	O
as	O
one	O
.	O
</s>
<s>
In	O
1975	O
,	O
the	O
UK	O
company	O
Quantel	O
produced	O
the	O
first	O
commercial	O
full-color	O
broadcast	O
framebuffer	B-Algorithm
,	O
the	O
Quantel	O
DFS	O
3000	O
.	O
</s>
<s>
The	O
rapid	O
improvement	O
of	O
integrated-circuit	O
technology	O
made	O
it	O
possible	O
for	O
many	O
of	O
the	O
home	O
computers	O
of	O
the	O
late	O
1970s	O
to	O
contain	O
low-color-depth	O
framebuffers	B-Algorithm
.	O
</s>
<s>
Today	O
,	O
nearly	O
all	O
computers	O
with	O
graphical	O
capabilities	O
utilize	O
a	O
framebuffer	B-Algorithm
for	O
generating	O
the	O
video	B-Application
signal	I-Application
.	O
</s>
<s>
Amiga	B-Device
computers	I-Device
,	O
created	O
in	O
the	O
1980s	O
,	O
featured	O
special	O
design	O
attention	O
to	O
graphics	O
performance	O
and	O
included	O
a	O
unique	O
Hold-And-Modify	O
framebuffer	B-Algorithm
capable	O
of	O
displaying	O
4096	O
colors	O
.	O
</s>
<s>
Framebuffers	B-Algorithm
also	O
became	O
popular	O
in	O
high-end	O
workstations	O
and	O
arcade	O
system	O
boards	O
throughout	O
the	O
1980s	O
.	O
</s>
<s>
SGI	O
,	O
Sun	O
Microsystems	O
,	O
HP	O
,	O
DEC	O
and	O
IBM	O
all	O
released	O
framebuffers	B-Algorithm
for	O
their	O
workstation	O
computers	O
in	O
this	O
period	O
.	O
</s>
<s>
These	O
framebuffers	B-Algorithm
were	O
usually	O
of	O
a	O
much	O
higher	O
quality	O
than	O
could	O
be	O
found	O
in	O
most	O
home	O
computers	O
,	O
and	O
were	O
regularly	O
used	O
in	O
television	O
,	O
printing	O
,	O
computer	O
modeling	O
and	O
3D	O
graphics	O
.	O
</s>
<s>
Framebuffers	B-Algorithm
were	O
also	O
used	O
by	O
Sega	O
for	O
its	O
high-end	O
arcade	B-Application
boards	I-Application
,	O
which	O
were	O
also	O
of	O
a	O
higher	O
quality	O
than	O
on	O
home	O
computers	O
.	O
</s>
<s>
Framebuffers	B-Algorithm
used	O
in	O
personal	O
and	O
home	O
computing	O
often	O
had	O
sets	O
of	O
defined	O
modes	O
under	O
which	O
the	O
framebuffer	B-Algorithm
can	O
operate	O
.	O
</s>
<s>
These	O
modes	O
reconfigure	O
the	O
hardware	O
to	O
output	O
different	O
resolutions	O
,	O
color	O
depths	O
,	O
memory	B-General_Concept
layouts	O
and	O
refresh	O
rate	O
timings	O
.	O
</s>
<s>
In	O
the	O
world	O
of	O
Unix	B-Application
machines	O
and	O
operating	O
systems	O
,	O
such	O
conveniences	O
were	O
usually	O
eschewed	O
in	O
favor	O
of	O
directly	O
manipulating	O
the	O
hardware	O
settings	O
.	O
</s>
<s>
This	O
manipulation	O
was	O
far	O
more	O
flexible	O
in	O
that	O
any	O
resolution	B-General_Concept
,	O
color	O
depth	O
and	O
refresh	O
rate	O
was	O
attainable	O
–	O
limited	O
only	O
by	O
the	O
memory	B-General_Concept
available	O
to	O
the	O
framebuffer	B-Algorithm
.	O
</s>
<s>
An	O
unfortunate	O
side-effect	O
of	O
this	O
method	O
was	O
that	O
the	O
display	B-Device
device	I-Device
could	O
be	O
driven	O
beyond	O
its	O
capabilities	O
.	O
</s>
<s>
Modern	O
CRT	B-Device
monitors	I-Device
fix	O
this	O
problem	O
through	O
the	O
introduction	O
of	O
protection	O
circuitry	O
.	O
</s>
<s>
If	O
the	O
monitor	O
is	O
unable	O
to	O
obtain	O
a	O
signal	O
lock	O
,	O
or	O
if	O
the	O
signal	O
is	O
outside	O
the	O
range	O
of	O
its	O
design	O
limitations	O
,	O
the	O
monitor	O
will	O
ignore	O
the	O
framebuffer	B-Algorithm
signal	O
and	O
possibly	O
present	O
the	O
user	O
with	O
an	O
error	O
message	O
.	O
</s>
<s>
Framebuffers	B-Algorithm
have	O
traditionally	O
supported	O
a	O
wide	O
variety	O
of	O
color	O
modes	O
.	O
</s>
<s>
Due	O
to	O
the	O
expense	O
of	O
memory	B-General_Concept
,	O
most	O
early	O
framebuffers	B-Algorithm
used	O
1-bit	O
(	O
2-colors	O
per	O
pixel	B-Algorithm
)	O
,	O
2-bit	O
(	O
4-colors	O
)	O
,	O
4-bit	O
(	O
16-colors	O
)	O
or	O
8-bit	O
(	O
256-colors	O
)	O
color	O
depths	O
.	O
</s>
<s>
The	O
solution	O
to	O
this	O
problem	O
was	O
indexed	B-Data_Structure
color	I-Data_Structure
which	O
adds	O
a	O
lookup	B-Data_Structure
table	I-Data_Structure
to	O
the	O
framebuffer	B-Algorithm
.	O
</s>
<s>
Each	O
color	O
stored	O
in	O
framebuffer	B-Algorithm
memory	B-General_Concept
acts	O
as	O
a	O
color	O
index	O
.	O
</s>
<s>
The	O
lookup	B-Data_Structure
table	I-Data_Structure
serves	O
as	O
a	O
palette	B-Data_Structure
with	O
a	O
limited	O
number	O
of	O
different	O
colors	O
meanwhile	O
the	O
rest	O
is	O
used	O
as	O
an	O
index	O
table	O
.	O
</s>
<s>
In	O
some	O
designs	O
it	O
was	O
also	O
possible	O
to	O
write	O
data	O
to	O
the	O
lookup	B-Data_Structure
table	I-Data_Structure
(	O
or	O
switch	O
between	O
existing	O
palettes	B-Data_Structure
)	O
on	O
the	O
run	O
,	O
allowing	O
dividing	O
the	O
picture	O
into	O
horizontal	O
bars	O
with	O
their	O
own	O
palette	B-Data_Structure
and	O
thus	O
render	O
an	O
image	O
that	O
had	O
a	O
far	O
wider	O
palette	B-Data_Structure
.	O
</s>
<s>
This	O
required	O
each	O
palette	B-Data_Structure
to	O
have	O
overlapping	O
colors	O
,	O
but	O
carefully	O
done	O
,	O
allowed	O
great	O
flexibility	O
.	O
</s>
<s>
While	O
framebuffers	B-Algorithm
are	O
commonly	O
accessed	O
via	O
a	O
memory	B-Architecture
mapping	I-Architecture
directly	O
to	O
the	O
CPU	B-Device
memory	B-General_Concept
space	O
,	O
this	O
is	O
not	O
the	O
only	O
method	O
by	O
which	O
they	O
may	O
be	O
accessed	O
.	O
</s>
<s>
Framebuffers	B-Algorithm
have	O
varied	O
widely	O
in	O
the	O
methods	O
used	O
to	O
access	O
memory	B-General_Concept
.	O
</s>
<s>
Mapping	O
the	O
entire	O
framebuffer	B-Algorithm
to	O
a	O
given	O
memory	B-General_Concept
range	O
.	O
</s>
<s>
Port	O
commands	O
to	O
set	O
each	O
pixel	B-Algorithm
,	O
range	O
of	O
pixels	B-Algorithm
or	O
palette	B-Data_Structure
entry	I-Data_Structure
.	O
</s>
<s>
Mapping	O
a	O
memory	B-General_Concept
range	O
smaller	O
than	O
the	O
framebuffer	B-Algorithm
memory	B-General_Concept
,	O
then	O
bank	B-General_Concept
switching	I-General_Concept
as	O
necessary	O
.	O
</s>
<s>
The	O
framebuffer	B-Algorithm
organization	O
may	O
be	O
packed	B-General_Concept
pixel	I-General_Concept
or	O
planar	B-Device
.	O
</s>
<s>
The	O
framebuffer	B-Algorithm
may	O
be	O
all	O
points	O
addressable	O
or	O
have	O
restrictions	O
on	O
how	O
it	O
can	O
be	O
updated	O
.	O
</s>
<s>
Video	B-Device
cards	I-Device
always	O
have	O
a	O
certain	O
amount	O
of	O
RAM	B-Architecture
.	O
</s>
<s>
A	O
small	O
portion	O
of	O
this	O
RAM	B-Architecture
is	O
where	O
the	O
bitmap	O
of	O
image	O
data	O
is	O
"	O
buffered	O
"	O
for	O
display	O
.	O
</s>
<s>
The	O
term	O
frame	B-Algorithm
buffer	I-Algorithm
is	O
thus	O
often	O
used	O
interchangeably	O
when	O
referring	O
to	O
this	O
RAM	B-Architecture
.	O
</s>
<s>
The	O
CPU	B-Device
sends	O
image	O
updates	O
to	O
the	O
video	B-Device
card	I-Device
.	O
</s>
<s>
The	O
video	O
processor	O
on	O
the	O
card	O
forms	O
a	O
picture	O
of	O
the	O
screen	O
image	O
and	O
stores	O
it	O
in	O
the	O
frame	B-Algorithm
buffer	I-Algorithm
as	O
a	O
large	O
bitmap	O
in	O
RAM	B-Architecture
.	O
</s>
<s>
The	O
bitmap	O
in	O
RAM	B-Architecture
is	O
used	O
by	O
the	O
card	O
to	O
continually	O
refresh	O
the	O
screen	O
image	O
.	O
</s>
<s>
Many	O
systems	O
attempt	O
to	O
emulate	O
the	O
function	O
of	O
a	O
framebuffer	B-Algorithm
device	O
,	O
often	O
for	O
reasons	O
of	O
compatibility	O
.	O
</s>
<s>
The	O
two	O
most	O
common	O
virtual	B-General_Concept
framebuffers	B-Algorithm
are	O
the	O
Linux	B-Language
framebuffer	I-Language
device	O
(	O
fbdev	B-Language
)	O
and	O
the	O
X	B-Operating_System
Virtual	B-General_Concept
Framebuffer	B-Algorithm
(	O
Xvfb	B-Device
)	O
.	O
</s>
<s>
Xvfb	B-Device
was	O
added	O
to	O
the	O
X	B-Operating_System
Window	I-Operating_System
System	I-Operating_System
distribution	O
to	O
provide	O
a	O
method	O
for	O
running	O
X	B-Operating_System
without	O
a	O
graphical	O
framebuffer	B-Algorithm
.	O
</s>
<s>
The	O
Linux	B-Language
framebuffer	I-Language
device	O
was	O
developed	O
to	O
abstract	O
the	O
physical	O
method	O
for	O
accessing	O
the	O
underlying	O
framebuffer	B-Algorithm
into	O
a	O
guaranteed	O
memory	B-General_Concept
map	O
that	O
is	O
easy	O
for	O
programs	O
to	O
access	O
.	O
</s>
<s>
This	O
increases	O
portability	O
,	O
as	O
programs	O
are	O
not	O
required	O
to	O
deal	O
with	O
systems	O
that	O
have	O
disjointed	O
memory	B-General_Concept
maps	O
or	O
require	O
bank	B-General_Concept
switching	I-General_Concept
.	O
</s>
<s>
A	O
frame	B-Algorithm
buffer	I-Algorithm
may	O
be	O
designed	O
with	O
enough	O
memory	B-General_Concept
to	O
store	O
two	O
frames	O
worth	O
of	O
video	O
data	O
.	O
</s>
<s>
In	O
a	O
technique	O
known	O
generally	O
as	O
double	O
buffering	O
or	O
more	O
specifically	O
as	O
page	O
flipping	O
,	O
the	O
framebuffer	B-Algorithm
uses	O
half	O
of	O
its	O
memory	B-General_Concept
to	O
display	O
the	O
current	O
frame	O
.	O
</s>
<s>
While	O
that	O
memory	B-General_Concept
is	O
being	O
displayed	O
,	O
the	O
other	O
half	O
of	O
memory	B-General_Concept
is	O
filled	O
with	O
data	O
for	O
the	O
next	O
frame	O
.	O
</s>
<s>
Once	O
the	O
secondary	O
buffer	B-General_Concept
is	O
filled	O
,	O
the	O
framebuffer	B-Algorithm
is	O
instructed	O
to	O
display	O
the	O
secondary	O
buffer	B-General_Concept
instead	O
.	O
</s>
<s>
The	O
primary	O
buffer	B-General_Concept
becomes	O
the	O
secondary	O
buffer	B-General_Concept
,	O
and	O
the	O
secondary	O
buffer	B-General_Concept
becomes	O
the	O
primary	O
.	O
</s>
<s>
As	O
the	O
demand	O
for	O
better	O
graphics	O
increased	O
,	O
hardware	O
manufacturers	O
created	O
a	O
way	O
to	O
decrease	O
the	O
amount	O
of	O
CPU	B-Device
time	O
required	O
to	O
fill	O
the	O
framebuffer	B-Algorithm
.	O
</s>
<s>
This	O
is	O
commonly	O
called	O
graphics	B-Architecture
acceleration	I-Architecture
.	O
</s>
<s>
Common	O
graphics	O
drawing	O
commands	O
(	O
many	O
of	O
them	O
geometric	O
)	O
are	O
sent	O
to	O
the	O
graphics	B-Architecture
accelerator	I-Architecture
in	O
their	O
raw	O
form	O
.	O
</s>
<s>
The	O
accelerator	O
then	O
rasterizes	O
the	O
results	O
of	O
the	O
command	O
to	O
the	O
framebuffer	B-Algorithm
.	O
</s>
<s>
This	O
method	O
frees	O
the	O
CPU	B-Device
to	O
do	O
other	O
work	O
.	O
</s>
<s>
Early	O
accelerators	O
focused	O
on	O
improving	O
the	O
performance	O
of	O
2D	O
GUI	B-Application
systems	O
.	O
</s>
<s>
A	O
common	O
design	O
uses	O
a	O
graphics	B-Library
library	I-Library
such	O
as	O
OpenGL	B-Application
or	O
Direct3D	B-Application
which	O
interfaces	O
with	O
the	O
graphics	O
driver	O
to	O
translate	O
received	O
commands	O
to	O
instructions	O
for	O
the	O
accelerator	O
's	O
graphics	B-Architecture
processing	I-Architecture
unit	I-Architecture
(	O
GPU	B-Architecture
)	O
.	O
</s>
<s>
The	O
GPU	B-Architecture
uses	O
those	O
instructions	O
to	O
compute	O
the	O
rasterized	O
results	O
and	O
the	O
results	O
are	O
bit	O
blitted	O
to	O
the	O
framebuffer	B-Algorithm
.	O
</s>
<s>
The	O
framebuffer	B-Algorithm
's	O
signal	O
is	O
then	O
produced	O
in	O
combination	O
with	O
built-in	O
video	O
overlay	O
devices	O
(	O
usually	O
used	O
to	O
produce	O
the	O
mouse	O
cursor	O
without	O
modifying	O
the	O
framebuffer	B-Algorithm
's	O
data	O
)	O
and	O
any	O
final	O
special	O
effects	O
that	O
are	O
produced	O
by	O
modifying	O
the	O
output	O
signal	O
.	O
</s>
<s>
An	O
example	O
of	O
such	O
final	O
special	O
effects	O
was	O
the	O
spatial	B-Algorithm
anti-aliasing	I-Algorithm
technique	O
used	O
by	O
the	O
3dfx	O
Voodoo	O
cards	O
.	O
</s>
<s>
At	O
one	O
time	O
there	O
were	O
many	O
manufacturers	O
of	O
graphics	B-Architecture
accelerators	I-Architecture
,	O
including	O
:	O
3dfx	O
Interactive	O
;	O
ATI	O
;	O
Hercules	O
;	O
Trident	O
;	O
Nvidia	O
;	O
Radius	O
;	O
S3	O
Graphics	O
;	O
SiS	O
and	O
Silicon	O
Graphics	O
.	O
</s>
<s>
the	O
market	O
for	O
graphics	B-Architecture
accelerators	I-Architecture
for	O
x86-based	O
systems	O
is	O
dominated	O
by	O
Nvidia	O
(	O
acquired	O
3dfx	O
in	O
2002	O
)	O
,	O
AMD	O
(	O
who	O
acquired	O
ATI	O
in	O
2006	O
)	O
,	O
and	O
Intel	O
.	O
</s>
<s>
With	O
a	O
framebuffer	B-Algorithm
,	O
the	O
electron	O
beam	O
(	O
if	O
the	O
display	B-Device
technology	I-Device
uses	O
one	O
)	O
is	O
commanded	O
to	O
perform	O
a	O
raster	O
scan	O
,	O
the	O
way	O
a	O
television	O
renders	O
a	O
broadcast	O
signal	O
.	O
</s>
<s>
The	O
color	O
information	O
for	O
each	O
point	O
thus	O
displayed	O
on	O
the	O
screen	O
is	O
pulled	O
directly	O
from	O
the	O
framebuffer	B-Algorithm
during	O
the	O
scan	O
,	O
creating	O
a	O
set	O
of	O
discrete	O
picture	B-Algorithm
elements	I-Algorithm
,	O
i.e.	O
</s>
<s>
pixels	B-Algorithm
.	O
</s>
<s>
Framebuffers	B-Algorithm
differ	O
significantly	O
from	O
the	O
vector	B-General_Concept
displays	I-General_Concept
that	O
were	O
common	O
prior	O
to	O
the	O
advent	O
of	O
raster	O
graphics	O
(	O
and	O
,	O
consequently	O
,	O
to	O
the	O
concept	O
of	O
a	O
framebuffer	B-Algorithm
)	O
.	O
</s>
<s>
With	O
a	O
vector	B-General_Concept
display	I-General_Concept
,	O
only	O
the	O
vertices	O
of	O
the	O
graphics	O
primitives	O
are	O
stored	O
.	O
</s>
<s>
Likewise	O
,	O
framebuffers	B-Algorithm
differ	O
from	O
the	O
technology	O
used	O
in	O
early	O
text	B-Application
mode	I-Application
displays	O
,	O
where	O
a	O
buffer	B-General_Concept
holds	O
codes	O
for	O
characters	O
,	O
not	O
individual	O
pixels	B-Algorithm
.	O
</s>
<s>
The	O
video	O
display	B-Device
device	I-Device
performs	O
the	O
same	O
raster	O
scan	O
as	O
with	O
a	O
framebuffer	B-Algorithm
,	O
but	O
generates	O
the	O
pixels	B-Algorithm
of	O
each	O
character	O
in	O
the	O
buffer	B-General_Concept
as	O
it	O
directs	O
the	O
beam	O
.	O
</s>
