<s>
A	O
blitter	B-General_Concept
is	O
a	O
circuit	O
,	O
sometimes	O
as	O
a	O
coprocessor	B-General_Concept
or	O
a	O
logic	O
block	O
on	O
a	O
microprocessor	B-Architecture
,	O
dedicated	O
to	O
the	O
rapid	O
movement	O
and	O
modification	O
of	O
data	O
within	O
a	O
computer	O
's	O
memory	B-Architecture
.	O
</s>
<s>
A	O
blitter	B-General_Concept
can	O
copy	O
large	O
quantities	O
of	O
data	O
from	O
one	O
memory	B-Architecture
area	O
to	O
another	O
relatively	O
quickly	O
,	O
and	O
in	O
parallel	O
with	O
the	O
CPU	B-General_Concept
,	O
while	O
freeing	O
up	O
the	O
CPU	B-General_Concept
's	O
more	O
complex	O
capabilities	O
for	O
other	O
operations	O
.	O
</s>
<s>
A	O
typical	O
use	O
for	O
a	O
blitter	B-General_Concept
is	O
the	O
movement	O
of	O
a	O
bitmap	O
,	O
such	O
as	O
windows	O
and	O
fonts	O
in	O
a	O
graphical	B-Application
user	I-Application
interface	I-Application
or	O
images	O
and	O
backgrounds	O
in	O
a	O
2D	O
video	O
game	O
.	O
</s>
<s>
The	O
name	O
comes	O
from	O
the	O
bit	B-Algorithm
blit	I-Algorithm
operation	O
of	O
the	O
1973	O
Xerox	B-Device
Alto	I-Device
,	O
which	O
stands	O
for	O
bit-block	O
transfer	O
.	O
</s>
<s>
A	O
blit	B-Algorithm
operation	O
is	O
more	O
than	O
a	O
memory	B-Architecture
copy	O
,	O
because	O
it	O
can	O
involve	O
data	O
that	O
's	O
not	O
byte	O
aligned	O
(	O
hence	O
the	O
bit	O
in	O
bit	B-Algorithm
blit	I-Algorithm
)	O
,	O
handling	O
transparent	O
pixels	O
(	O
pixels	O
which	O
should	O
not	O
overwrite	O
the	O
destination	O
)	O
,	O
and	O
various	O
ways	O
of	O
combining	O
the	O
source	O
and	O
destination	O
data	O
.	O
</s>
<s>
Blitters	B-General_Concept
have	O
largely	O
been	O
superseded	O
by	O
programmable	O
graphics	B-Architecture
processing	I-Architecture
units	I-Architecture
.	O
</s>
<s>
In	O
computers	O
without	O
hardware	O
accelerated	O
raster	B-Algorithm
graphics	I-Algorithm
,	O
which	O
includes	O
most	O
1970s	O
and	O
1980s	O
home	O
computers	O
and	O
IBM	O
PC	O
compatibles	O
through	O
the	O
mid-1990s	O
,	O
the	O
frame	B-Algorithm
buffer	I-Algorithm
is	O
commonly	O
stored	O
in	O
CPU-accessible	O
memory	B-Architecture
.	O
</s>
<s>
Drawing	O
is	O
accomplished	O
by	O
updating	O
the	O
frame	B-Algorithm
buffer	I-Algorithm
via	O
software	O
.	O
</s>
<s>
For	O
basic	O
graphics	O
routines	O
,	O
like	O
compositing	O
a	O
smaller	O
image	O
into	O
a	O
larger	O
one	O
(	O
such	O
as	O
for	O
a	O
video	O
game	O
)	O
or	O
drawing	O
a	O
filled	O
rectangle	O
,	O
large	O
amounts	O
of	O
memory	B-Architecture
need	O
to	O
be	O
manipulated	O
,	O
and	O
many	O
cycles	O
are	O
spent	O
fetching	O
and	O
decoding	O
short	O
loops	O
of	O
load/store	O
instructions	O
.	O
</s>
<s>
To	O
reduce	O
the	O
size	O
of	O
the	O
frame	B-Algorithm
buffer	I-Algorithm
,	O
a	O
single	O
byte	O
may	O
not	O
necessarily	O
correspond	O
to	O
a	O
pixel	O
,	O
but	O
contain	O
8	O
single-bit	O
pixels	O
,	O
4	O
two-bit	O
pixels	O
,	O
or	O
a	O
pair	O
of	O
4-bit	O
pixels	O
.	O
</s>
<s>
Manipulating	O
packed	O
pixels	O
requires	O
extra	O
shifting	O
and	O
masking	O
operations	O
on	O
the	O
CPU	B-General_Concept
.	O
</s>
<s>
Blitters	B-General_Concept
were	O
developed	O
to	O
offload	O
repetitive	O
tasks	O
of	O
copying	O
data	O
or	O
filling	O
blocks	O
of	O
memory	B-Architecture
faster	O
than	O
possible	O
by	O
the	O
CPU	B-General_Concept
.	O
</s>
<s>
This	O
can	O
be	O
done	O
in	O
parallel	O
with	O
the	O
CPU	B-General_Concept
and	O
also	O
handle	O
special	O
cases	O
which	O
would	O
be	O
significantly	O
slower	O
if	O
coded	O
by	O
hand	O
,	O
such	O
as	O
skipping	O
over	O
pixels	O
marked	O
as	O
transparent	O
or	O
handling	O
data	O
that	O
is	O
n't	O
byte-aligned	O
.	O
</s>
<s>
1973	O
:	O
The	O
Xerox	B-Device
Alto	I-Device
,	O
where	O
the	O
term	O
bit	B-Algorithm
blit	I-Algorithm
originated	O
,	O
has	O
a	O
bit	B-Algorithm
block	I-Algorithm
transfer	I-Algorithm
instruction	O
implemented	O
in	O
microcode	B-Device
,	O
making	O
it	O
much	O
faster	O
than	O
the	O
same	O
operation	O
written	O
on	O
the	O
CPU	B-General_Concept
.	O
</s>
<s>
The	O
microcode	B-Device
was	O
implemented	O
by	O
Dan	O
Ingalls	O
.	O
</s>
<s>
1982	O
:	O
In	O
addition	O
to	O
drawing	O
shape	O
primitives	O
,	O
the	O
NEC	B-Device
µPD7220	I-Device
video	B-Architecture
display	I-Architecture
processor	I-Architecture
can	O
transfer	O
rectangular	O
bitmaps	O
to	O
display	B-Algorithm
memory	I-Algorithm
via	O
direct	B-General_Concept
memory	I-General_Concept
access	I-General_Concept
and	O
fill	O
rectangular	O
portions	O
of	O
the	O
screen	O
.	O
</s>
<s>
1982	O
:	O
The	O
Robotron	B-Application
:	I-Application
2084	I-Application
arcade	O
video	O
game	O
from	O
Williams	O
Electronics	O
includes	O
two	O
blitter	B-General_Concept
chips	I-General_Concept
which	O
allow	O
the	O
game	O
to	O
have	O
up	O
to	O
80	O
simultaneously	O
moving	O
objects	O
.	O
</s>
<s>
The	O
blitter	B-General_Concept
operates	O
on	O
4-bit	O
(	O
16	O
color	O
)	O
pixels	O
where	O
color	O
0	O
is	O
transparent	O
,	O
allowing	O
for	O
non-rectangular	O
shapes	O
.	O
</s>
<s>
Williams	O
used	O
the	O
same	O
hardware	O
in	O
other	O
games	O
from	O
the	O
time	O
period	O
,	O
including	O
Sinistar	B-Application
and	O
Joust	B-Application
.	O
</s>
<s>
1984	O
:	O
The	O
MS-DOS	B-Application
compatible	O
Mindset	B-Device
personal	O
computer	O
contains	O
a	O
custom	O
VLSI	O
chip	O
to	O
move	O
rectangular	O
sections	O
of	O
a	O
bitmap	O
.	O
</s>
<s>
The	O
Mindset	B-Device
was	O
claimed	O
to	O
have	O
graphics	O
up	O
to	O
50x	O
faster	O
than	O
IBM	O
PC	O
compatibles	O
of	O
the	O
time	O
,	O
but	O
the	O
system	O
was	O
not	O
successful	O
.	O
</s>
<s>
1985	O
:	O
One	O
of	O
the	O
coprocessors	B-General_Concept
in	O
the	O
Amiga	B-Device
personal	O
computer	O
is	O
a	O
blitter	B-General_Concept
.	O
</s>
<s>
The	O
first	O
US	O
patent	O
filing	O
to	O
use	O
the	O
term	O
blitter	B-General_Concept
was	O
"	O
Personal	O
computer	O
apparatus	O
for	O
block	O
transfer	O
of	O
bit-mapped	O
image	O
data	O
,	O
"	O
assigned	O
to	O
Commodore-Amiga	O
,	O
Inc	O
.	O
</s>
<s>
The	O
blitter	B-General_Concept
performs	O
an	O
arbitrary	O
boolean	O
operation	O
on	O
three	O
bit	O
vectors	O
of	O
size	O
16	O
:	O
</s>
<s>
1986	O
:	O
The	O
TMS34010	B-General_Concept
is	O
a	O
general	O
purpose	O
32-bit	O
processor	O
with	O
additional	O
blitter-like	O
instructions	O
for	O
manipulating	O
bitmap	O
data	O
.	O
</s>
<s>
It	O
is	O
optimized	O
for	O
cases	O
that	O
take	O
extra	O
processing	O
on	O
the	O
CPU	B-General_Concept
,	O
such	O
as	O
handling	O
transparent	O
pixels	O
,	O
working	O
with	O
non-byte	O
aligned	O
data	O
,	O
and	O
converting	O
between	O
bit	O
depths	O
.	O
</s>
<s>
The	O
TMS34010	B-General_Concept
served	O
as	O
both	O
CPU	B-General_Concept
and	O
GPU	B-Architecture
for	O
a	O
number	O
of	O
arcade	O
games	O
starting	O
in	O
1988	O
with	O
Narc	B-Application
and	O
including	O
Hard	B-Application
Drivin	I-Application
 '	I-Application
,	O
Smash	B-Application
TV	I-Application
,	O
Mortal	B-Application
Kombat	I-Application
,	O
and	O
NBA	B-Application
Jam	I-Application
,	O
It	O
was	O
also	O
used	O
in	O
professional-level	O
graphics	B-Architecture
accelerator	I-Architecture
boards	O
in	O
the	O
1990s	O
.	O
</s>
<s>
1986	O
:	O
The	O
Intel	O
82786	O
is	O
a	O
programmable	O
graphics	B-Architecture
processor	I-Architecture
with	O
a	O
BIT_BLT	O
instruction	O
to	O
move	O
rectangular	O
sections	O
of	O
bitmaps	O
.	O
</s>
<s>
1987	O
:	O
The	O
IBM	B-Device
8514/A	I-Device
display	O
adapter	O
,	O
introduced	O
with	O
the	O
IBM	B-Device
Personal	I-Device
System/2	I-Device
computers	O
in	O
April	O
1987	O
,	O
includes	O
bit	B-Algorithm
block	I-Algorithm
transfer	I-Algorithm
hardware	O
.	O
</s>
<s>
1987	O
:	O
The	O
Atari	B-Device
Mega	I-Device
ST	I-Device
2	I-Device
ships	O
with	O
a	O
blitter	B-General_Concept
chip	I-General_Concept
.	O
</s>
<s>
Officially	O
called	O
the	O
"	O
Atari	B-Device
ST	I-Device
Bit-Block	O
Transfer	O
Processor	O
"	O
,	O
stylized	O
as	O
BLiTTER	B-General_Concept
,	O
it	O
provides	O
16	O
options	O
for	O
merging	O
source	O
and	O
destination	O
data	O
.	O
</s>
<s>
The	O
blitter	B-General_Concept
is	O
supported	O
on	O
most	O
subsequent	O
ST	O
machines	O
.	O
</s>
<s>
1989	O
:	O
The	O
short-lived	O
Atari	B-Device
Transputer	I-Device
Workstation	I-Device
contains	O
blitter	B-General_Concept
hardware	O
as	O
part	O
of	O
its	O
(	O
Mega	O
ST-based	O
)	O
"	O
Blossom	O
"	O
video	O
system	O
.	O
</s>
<s>
1993	O
:	O
The	O
last	O
game	O
console	O
produced	O
by	O
Atari	O
Corporation	O
,	O
the	O
Jaguar	B-Device
,	O
ships	O
with	O
blitter	B-General_Concept
hardware	O
as	O
part	O
of	O
the	O
custom	O
"	O
Tom	O
"	O
chip	O
.	O
</s>
<s>
1996	O
:	O
The	O
VESA	O
Group	O
introduced	O
a	O
common	O
standardized	O
way	O
to	O
access	O
features	O
like	O
hardware	O
Bit	B-Algorithm
Block	I-Algorithm
transfers	I-Algorithm
(	O
Bit	O
Blt	O
)	O
with	O
VBE/accelerator	O
functions	O
(	O
VBE/AF	O
)	O
on	O
PCs	O
.	O
</s>
<s>
Typically	O
,	O
a	O
computer	O
program	O
puts	O
information	O
into	O
certain	O
hardware	O
registers	O
describing	O
what	O
memory	B-Architecture
transfer	O
needs	O
to	O
be	O
completed	O
and	O
the	O
logical	O
operations	O
to	O
perform	O
on	O
the	O
data	O
.	O
</s>
<s>
The	O
CPU	B-General_Concept
then	O
triggers	O
the	O
blitter	B-General_Concept
to	O
begin	O
operating	O
.	O
</s>
<s>
The	O
CPU	B-General_Concept
is	O
free	O
for	O
other	O
processing	O
while	O
the	O
blitter	B-General_Concept
is	O
working	O
,	O
though	O
the	O
blit	B-Algorithm
running	O
in	O
parallel	O
uses	O
memory	B-Architecture
bandwidth	O
.	O
</s>
<s>
To	O
copy	O
data	O
with	O
fully	O
transparent	O
pixels	O
—	O
such	O
sprites	O
—	O
some	O
hardware	O
allows	O
a	O
specific	O
pixel	O
value	O
to	O
be	O
ignored	O
,	O
such	O
as	O
color	O
0	O
,	O
during	O
the	O
blit	B-Algorithm
.	O
</s>
<s>
The	O
mask	O
operates	O
like	O
a	O
stencil	B-Algorithm
.	O
</s>
<s>
Hardware	O
sprites	O
are	O
small	O
bitmaps	O
that	O
can	O
be	O
positioned	O
independently	O
,	O
composited	O
together	O
with	O
the	O
background	O
on-the-fly	O
by	O
the	O
video	O
chip	O
,	O
so	O
no	O
actual	O
modification	O
of	O
the	O
frame	B-Algorithm
buffer	I-Algorithm
occurs	O
.	O
</s>
<s>
The	O
downside	O
of	O
sprites	O
is	O
a	O
limit	O
of	O
moving	O
graphics	O
per	O
scanline	O
,	O
which	O
can	O
range	O
from	O
three	O
(	O
Atari	B-General_Concept
2600	I-General_Concept
)	O
to	O
eight	O
(	O
Commodore	O
64	O
and	O
Atari	B-Device
8-bit	I-Device
family	I-Device
)	O
to	O
significantly	O
higher	O
for	O
16-bit	O
consoles	O
and	O
arcade	O
hardware	O
(	O
the	O
Neo	B-Operating_System
Geo	I-Operating_System
can	O
display	O
96	O
sprites	O
per	O
line	O
)	O
,	O
and	O
the	O
inability	O
to	O
update	O
a	O
permanent	O
bitmap	O
(	O
making	O
them	O
unsuitable	O
for	O
general	O
desktop	O
GUI	B-Application
acceleration	O
)	O
.	O
</s>
