<s>
Valencia	O
's	O
Simple	O
Tasker	O
(	O
VSTa	O
)	O
is	O
an	O
operating	B-General_Concept
system	I-General_Concept
with	O
a	O
microkernel	B-Operating_System
architecture	O
,	O
with	O
all	O
device	B-Application
drivers	I-Application
and	O
file	B-Application
systems	I-Application
residing	O
in	O
userspace	B-Operating_System
mode	O
.	O
</s>
<s>
It	O
mostly	O
complies	O
with	O
the	O
Portable	O
Operating	B-General_Concept
System	I-General_Concept
Interface	O
(	O
POSIX	O
)	O
,	O
except	O
where	O
such	O
compliance	O
interferes	O
with	O
extensibility	O
and	O
modularity	O
.	O
</s>
<s>
It	O
is	O
conceptually	O
inspired	O
by	O
QNX	B-Operating_System
and	O
Plan	B-Operating_System
9	I-Operating_System
from	I-Operating_System
Bell	I-Operating_System
Labs	I-Operating_System
.	O
</s>
<s>
Written	O
by	O
Andy	O
Valencia	O
,	O
and	O
released	O
under	O
a	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
(	O
GPL	B-License
)	O
.	O
</s>
<s>
As	O
of	O
2020	O
,	O
the	O
licensing	O
for	O
VSTa	O
is	O
Copyleft	B-License
.	O
</s>
<s>
It	O
was	O
originally	O
written	O
to	O
run	O
on	O
Intel	B-General_Concept
80386	I-General_Concept
hardware	O
,	O
and	O
then	O
was	O
ported	O
to	O
several	O
different	O
platforms	O
,	O
e.g.	O
,	O
Motorola	B-Device
68030	I-Device
based	O
Amigas	B-Device
.	O
</s>
<s>
A	O
fork	O
,	O
named	O
Flexible	O
Microkernel	B-Operating_System
Infrastructure/Operating	O
System	O
(	O
FMI/OS	O
)	O
,	O
did	O
not	O
make	O
a	O
release	O
.	O
</s>
<s>
The	O
default	O
graphical	B-Application
user	I-Application
interface	I-Application
provided	O
as	O
a	O
tar-ball	O
with	O
the	O
system	O
was	O
ManaGeR	O
(	O
MGR	O
)	O
.	O
</s>
