<s>
Compute	B-Operating_System
Node	I-Operating_System
Kernel	I-Operating_System
(	O
CNK	O
)	O
is	O
the	O
node	B-Protocol
level	O
operating	B-General_Concept
system	I-General_Concept
for	O
the	O
IBM	B-Operating_System
Blue	I-Operating_System
Gene	I-Operating_System
series	O
of	O
supercomputers	B-Architecture
.	O
</s>
<s>
The	O
compute	O
nodes	B-Protocol
of	O
the	O
IBM	B-Operating_System
Blue	I-Operating_System
Gene	I-Operating_System
family	O
of	O
supercomputers	B-Architecture
run	O
CNK	O
,	O
a	O
lightweight	B-Device
kernel	I-Device
that	O
runs	O
on	O
each	O
node	B-Protocol
and	O
supports	O
one	O
application	O
running	O
for	O
one	O
user	O
on	O
that	O
node	B-Protocol
.	O
</s>
<s>
It	O
was	O
implemented	O
in	O
about	O
5,000	O
lines	O
of	O
C++	B-Language
code	I-Language
.	O
</s>
<s>
Physical	O
memory	O
is	O
statically	O
mapped	O
and	O
the	O
CNK	O
neither	O
needs	O
nor	O
provides	O
scheduling	O
or	O
context	B-Operating_System
switching	I-Operating_System
,	O
given	O
that	O
at	O
each	O
point	O
it	O
runs	O
one	O
application	O
for	O
one	O
user	O
.	O
</s>
<s>
By	O
not	O
allowing	O
virtual	B-Architecture
memory	I-Architecture
or	O
multi-tasking	B-Operating_System
,	O
the	O
design	O
of	O
CNK	O
aimed	O
to	O
devote	O
as	O
many	O
cycles	B-General_Concept
as	O
possible	O
to	O
application	O
processing	O
.	O
</s>
<s>
CNK	O
does	O
not	O
even	O
implement	O
file	O
input/output	B-General_Concept
(	O
I/O	B-General_Concept
)	O
on	O
the	O
compute	O
node	B-Protocol
,	O
but	O
delegates	O
that	O
to	O
dedicated	O
I/O	B-General_Concept
nodes	B-Protocol
.	O
</s>
<s>
The	O
I/O	B-General_Concept
nodes	B-Protocol
of	O
the	O
Blue	B-Operating_System
Gene	I-Operating_System
supercomputers	B-Architecture
run	O
a	O
different	O
operating	B-General_Concept
system	I-General_Concept
:	O
INK	B-Application
(	O
I/O	B-Application
Node	I-Application
Kernel	I-Application
)	O
.	O
</s>
<s>
INK	B-Application
is	O
based	O
on	O
a	O
modified	O
Linux	B-Operating_System
kernel	I-Operating_System
.	O
</s>
