<s>
In	O
computer	B-General_Concept
science	I-General_Concept
,	O
a	O
single	B-Operating_System
address	I-Operating_System
space	I-Operating_System
operating	I-Operating_System
system	I-Operating_System
(	O
or	O
SASOS	B-Operating_System
)	O
is	O
an	O
operating	B-General_Concept
system	I-General_Concept
that	O
provides	O
only	O
one	O
globally	O
shared	O
address	B-General_Concept
space	I-General_Concept
for	O
all	O
processes	B-Operating_System
.	O
</s>
<s>
In	O
a	O
single	B-Operating_System
address	I-Operating_System
space	I-Operating_System
operating	I-Operating_System
system	I-Operating_System
,	O
numerically	O
identical	O
(	O
virtual	B-Architecture
memory	I-Architecture
)	O
logical	O
addresses	O
in	O
different	O
processes	B-Operating_System
all	O
refer	O
to	O
exactly	O
the	O
same	O
byte	O
of	O
data	O
.	O
</s>
<s>
Single	O
address-space	O
operating	B-General_Concept
systems	I-General_Concept
offer	O
certain	O
advantages	O
.	O
</s>
<s>
In	O
a	O
traditional	O
OS	O
with	O
private	O
per-process	O
address	B-General_Concept
space	I-General_Concept
,	O
memory	O
protection	O
is	O
based	O
on	O
address	B-General_Concept
space	I-General_Concept
boundaries	O
(	O
"	O
address	B-General_Concept
space	I-General_Concept
isolation	O
"	O
)	O
.	O
</s>
<s>
Single	O
address-space	O
operating	B-General_Concept
systems	I-General_Concept
use	O
a	O
different	O
approach	O
for	O
memory	O
protection	O
that	O
is	O
just	O
as	O
strong	O
.	O
</s>
<s>
One	O
advantage	O
is	O
that	O
the	O
same	O
virtual-to-physical	O
map	O
page	B-General_Concept
table	I-General_Concept
can	O
be	O
used	O
with	O
every	O
process	O
(	O
and	O
in	O
some	O
SASOS	B-Operating_System
,	O
the	O
kernel	B-Operating_System
as	O
well	O
)	O
.	O
</s>
<s>
This	O
makes	O
context	O
switches	O
on	O
a	O
SASOS	B-Operating_System
faster	O
than	O
on	O
operating	B-General_Concept
systems	I-General_Concept
that	O
must	O
change	O
the	O
page	B-General_Concept
table	I-General_Concept
and	O
flush	O
the	O
TLB	B-Architecture
caches	I-Architecture
on	O
every	O
context	O
switch	O
.	O
</s>
<s>
SASOS	B-Operating_System
projects	O
include	O
the	O
following	O
:	O
</s>
