<s>
NuttX	B-Operating_System
is	O
a	O
free	B-License
and	I-License
open-source	I-License
Real-Time	B-Operating_System
Operating	I-Operating_System
System	I-Operating_System
(	O
RTOS	B-Operating_System
)	O
with	O
an	O
emphasis	O
on	O
technical	O
standards	O
compliance	O
and	O
on	O
having	O
a	O
small	O
footprint	O
.	O
</s>
<s>
Scalable	O
from	O
8-bit	O
to	O
64-bit	B-Device
microcontroller	B-Architecture
environments	O
,	O
the	O
main	O
governing	O
standards	O
in	O
NuttX	B-Operating_System
are	O
from	O
the	O
Portable	O
Operating	O
System	O
Interface	O
(	O
POSIX	O
)	O
and	O
the	O
American	O
National	O
Standards	O
Institute	O
(	O
ANSI	O
)	O
.	O
</s>
<s>
Further	O
standard	O
application	B-Application
programming	I-Application
interfaces	I-Application
(	O
APIs	B-Application
)	O
from	O
Unix	B-Application
and	O
other	O
common	O
RTOSes	O
(	O
such	O
as	O
VxWorks	B-Operating_System
)	O
are	O
adopted	O
for	O
functions	O
unavailable	O
under	O
these	O
standards	O
,	O
or	O
inappropriate	O
for	O
deeply	O
embedded	O
environments	O
,	O
such	O
as	O
the	O
fork( )	O
system	O
call	O
.	O
</s>
<s>
NuttX	B-Operating_System
was	O
first	O
released	O
in	O
2007	O
under	O
the	O
permissive	O
BSD	B-Operating_System
license	I-Operating_System
.	O
</s>
<s>
NuttX	B-Operating_System
RTOS	I-Operating_System
is	O
used	O
in	O
a	O
variety	O
of	O
applications	O
,	O
including	O
the	O
Sony	O
CXD5602/Spresense	O
microcontroller	B-Architecture
as	O
well	O
as	O
an	O
audio	O
recorder	O
from	O
Sony	O
.	O
</s>
<s>
The	O
firmware	O
for	O
some	O
of	O
Motorola	O
's	O
MotoMod	O
accessories	O
for	O
the	O
Moto	O
Z	O
used	O
NuttX	B-Operating_System
RTOS	I-Operating_System
,	O
and	O
NuttX	B-Operating_System
is	O
also	O
used	O
in	O
the	O
PX4	B-Application
autopilot	I-Application
drones	O
,	O
which	O
use	O
NuttX	B-Operating_System
to	O
control	O
a	O
variety	O
of	O
autonomous	O
platforms	O
.	O
</s>
