<s>
In	O
computer	B-General_Concept
architecture	I-General_Concept
,	O
shared	B-General_Concept
graphics	I-General_Concept
memory	I-General_Concept
refers	O
to	O
a	O
design	O
where	O
the	O
graphics	B-Device
chip	I-Device
does	O
not	O
have	O
its	O
own	O
dedicated	O
memory	O
,	O
and	O
instead	O
shares	O
the	O
main	O
system	O
RAM	B-Architecture
with	O
the	O
CPU	B-General_Concept
and	O
other	O
components	O
.	O
</s>
<s>
This	O
design	O
is	O
used	O
with	O
many	O
integrated	O
graphics	O
solutions	O
to	O
reduce	O
the	O
cost	O
and	O
complexity	O
of	O
the	O
motherboard	B-Device
design	O
,	O
as	O
no	O
additional	O
memory	O
chips	O
are	O
required	O
on	O
the	O
board	O
.	O
</s>
<s>
There	O
is	O
usually	O
some	O
mechanism	O
(	O
via	O
the	O
BIOS	B-Operating_System
or	O
a	O
jumper	B-Device
setting	O
)	O
to	O
select	O
the	O
amount	O
of	O
system	O
memory	O
to	O
use	O
for	O
graphics	O
,	O
which	O
means	O
that	O
the	O
graphics	O
system	O
can	O
be	O
tailored	O
to	O
only	O
use	O
as	O
much	O
RAM	B-Architecture
as	O
is	O
actually	O
required	O
,	O
leaving	O
the	O
rest	O
free	O
for	O
applications	O
.	O
</s>
<s>
A	O
side	O
effect	O
of	O
this	O
is	O
that	O
when	O
some	O
RAM	B-Architecture
is	O
allocated	O
for	O
graphics	O
,	O
it	O
becomes	O
effectively	O
unavailable	O
for	O
anything	O
else	O
,	O
so	O
an	O
example	O
computer	O
with	O
512MiB	O
RAM	B-Architecture
set	O
up	O
with	O
64MiB	O
graphics	O
RAM	B-Architecture
will	O
appear	O
to	O
the	O
operating	B-General_Concept
system	I-General_Concept
and	O
user	O
to	O
only	O
have	O
448	O
MiB	O
RAM	B-Architecture
installed	O
.	O
</s>
<s>
The	O
disadvantage	O
of	O
this	O
design	O
is	O
lower	O
performance	O
because	O
system	O
RAM	B-Architecture
usually	O
runs	O
slower	O
than	O
dedicated	O
graphics	O
RAM	B-Architecture
,	O
and	O
there	O
is	O
more	O
contention	O
as	O
the	O
memory	O
bus	O
has	O
to	O
be	O
shared	O
with	O
the	O
rest	O
of	O
the	O
system	O
.	O
</s>
<s>
It	O
may	O
also	O
cause	O
performance	O
issues	O
with	O
the	O
rest	O
of	O
the	O
system	O
if	O
it	O
is	O
not	O
designed	O
with	O
the	O
fact	O
in	O
mind	O
that	O
some	O
RAM	B-Architecture
will	O
be	O
'	O
taken	O
away	O
 '	O
by	O
graphics	O
.	O
</s>
<s>
A	O
similar	O
approach	O
that	O
gave	O
similar	O
results	O
is	O
the	O
boost	O
up	O
of	O
graphics	O
used	O
in	O
some	O
SGi	O
computers	O
,	O
most	O
notably	O
the	O
O2/O2	B-Device
+	I-Device
.	O
</s>
<s>
Most	O
early	O
personal	O
computers	O
used	O
a	O
shared	B-Operating_System
memory	I-Operating_System
design	O
with	O
graphics	O
hardware	O
sharing	O
memory	O
with	O
the	O
CPU	B-General_Concept
.	O
</s>
<s>
The	O
first	O
IBM	O
PC	O
to	O
use	O
the	O
SMA	O
was	O
the	O
IBM	B-Device
PCjr	I-Device
,	O
released	O
in	O
1984	O
.	O
</s>
<s>
Video	O
memory	O
was	O
shared	O
with	O
the	O
first	O
128KiB	O
of	O
RAM	B-Architecture
.	O
</s>
<s>
An	O
early	O
hybrid	O
system	O
was	O
the	O
Commodore	O
Amiga	O
which	O
could	O
run	O
as	O
a	O
shared	B-Operating_System
memory	I-Operating_System
system	O
,	O
but	O
would	O
load	O
executable	O
code	O
preferentially	O
into	O
non-shared	O
"	O
fast	B-Device
RAM	I-Device
"	O
if	O
it	O
was	O
available	O
.	O
</s>
