<s>
SX-Window	B-Application
is	O
a	O
graphic	O
user	O
interface	O
(	O
GUI	O
)	O
operating	B-General_Concept
system	I-General_Concept
for	O
the	O
Sharp	B-Device
X68000	I-Device
series	O
of	O
computers	O
,	O
which	O
were	O
popular	O
in	O
Japan	O
.	O
</s>
<s>
It	O
runs	O
on	O
top	O
of	O
the	O
Human68k	O
disk	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
,	O
similarly	O
to	O
how	O
Windows	B-Application
3.1	I-Application
runs	O
on	O
top	O
of	O
MS-DOS	B-Application
.	O
</s>
<s>
SX-Window	B-Application
was	O
introduced	O
for	O
X68000	B-Device
in	O
1989	O
,	O
and	O
came	O
preinstalled	O
on	O
the	O
X68000	B-Device
EXPERT	I-Device
model	O
.	O
</s>
<s>
In	O
2000	O
,	O
Sharp	O
released	O
the	O
system	O
software	O
for	O
the	O
X68000	B-Device
free-of-charge	O
,	O
including	O
SX-Window	B-Application
.	O
</s>
<s>
The	O
look	B-Application
and	I-Application
feel	I-Application
of	O
the	O
GUI	O
is	O
like	O
that	O
of	O
the	O
NeXTSTEP	B-Application
operating	B-General_Concept
system	I-General_Concept
,	O
and	O
its	O
API	B-Application
is	O
similar	O
to	O
the	O
Macintosh	B-Device
Toolbox	I-Device
.	O
</s>
<s>
It	O
uses	O
non-preemptive	B-Operating_System
multitasking	I-Operating_System
with	O
the	O
event-driven	B-Application
paradigm	O
.	O
</s>
<s>
It	O
has	O
a	O
garbage	O
collection	O
system	O
without	O
MMU	B-General_Concept
of	O
MPU	O
,	O
but	O
it	O
was	O
difficult	O
to	O
program	O
because	O
all	O
pointers	O
derived	O
from	O
handles	O
become	O
invalid	O
once	O
any	O
API	B-Application
is	O
called	O
.	O
</s>
<s>
The	O
X68000	B-Device
was	O
very	O
powerful	O
for	O
game	O
software	O
,	O
but	O
this	O
GUI	O
could	O
be	O
slow	O
,	O
as	O
no	O
hardware	O
acceleration	O
card	O
was	O
supported	O
.	O
</s>
