<s>
The	O
Mac	B-Operating_System
OS	I-Operating_System
nanokernel	I-Operating_System
is	O
an	O
operating	B-Operating_System
system	I-Operating_System
kernel	I-Operating_System
serving	O
as	O
the	O
basis	O
of	O
most	O
PowerPC	B-Architecture
based	O
system	B-Application
software	I-Application
versions	O
7	O
through	O
9	O
of	O
the	O
classic	B-Application
Mac	I-Application
OS	I-Application
,	O
predating	O
Mac	B-Application
OS	I-Application
X	I-Application
.	O
</s>
<s>
The	O
initial	O
revision	O
of	O
this	O
software	O
is	O
a	O
single	O
tasking	O
system	O
which	O
delegates	O
most	O
tasks	O
to	O
an	O
emulator	B-Application
running	O
the	O
Motorola	B-Device
68000	I-Device
series	I-Device
(	O
68K	B-Device
)	O
version	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
The	O
second	O
major	O
revision	O
supports	O
multitasking	B-Operating_System
,	O
multiprocessing	B-Operating_System
,	O
and	O
message	B-Architecture
passing	I-Architecture
,	O
and	O
would	O
be	O
more	O
properly	O
called	O
a	O
microkernel	B-Operating_System
.	O
</s>
<s>
Unlike	O
the	O
68K-derived	O
Mac	B-Application
OS	I-Application
kernel	B-Operating_System
running	O
within	O
it	O
,	O
the	O
PowerPC	B-Architecture
kernel	B-Operating_System
exists	O
in	O
a	O
protected	B-General_Concept
memory	I-General_Concept
space	O
and	O
executes	O
device	B-Application
drivers	I-Application
in	O
user	B-Operating_System
mode	I-Operating_System
.	O
</s>
<s>
The	O
nanokernel	O
is	O
very	O
different	O
from	O
the	O
Copland	B-Application
OS	I-Application
microkernel	B-Operating_System
,	O
although	O
they	O
were	O
created	O
in	O
succession	O
with	O
similar	O
goals	O
.	O
</s>
<s>
The	O
original	O
nanokernel	O
,	O
and	O
the	O
tightly	O
integrated	O
Mac	B-Device
68k	I-Device
emulator	I-Device
,	O
were	O
written	O
by	O
emulation	B-Application
consultant	O
Gary	O
Davidian	O
.	O
</s>
<s>
Its	O
main	O
purpose	O
is	O
to	O
allow	O
the	O
existing	O
Motorola	B-Device
68K	I-Device
version	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
to	O
run	O
on	O
new	O
hardware	O
.	O
</s>
<s>
As	O
such	O
,	O
the	O
normal	O
state	O
of	O
the	O
system	O
is	O
to	O
be	O
running	O
68K	B-Device
code	O
.	O
</s>
<s>
The	O
operating	B-General_Concept
system	I-General_Concept
does	O
little	O
until	O
activated	O
by	O
an	O
interrupt	B-Application
,	O
which	O
is	O
quickly	O
mapped	O
to	O
its	O
68K	B-Device
equivalent	O
within	O
the	O
virtual	O
machine	O
.	O
</s>
<s>
Other	O
tasks	O
may	O
include	O
switching	O
back	O
to	O
PowerPC	B-Architecture
mode	O
,	O
if	O
necessary	O
,	O
upon	O
completion	O
of	O
the	O
interrupt	B-Application
handler	O
,	O
and	O
mapping	O
the	O
Macintosh	O
virtual	B-Architecture
memory	I-Architecture
system	O
to	O
the	O
PowerPC	B-Architecture
hardware	O
.	O
</s>
<s>
However	O
,	O
as	O
the	O
software	O
is	O
little	O
documented	O
,	O
these	O
might	O
instead	O
be	O
handled	O
by	O
the	O
emulator	B-Application
running	O
in	O
user	B-Operating_System
mode	I-Operating_System
.	O
</s>
<s>
This	O
nanokernel	O
is	O
stored	O
on	O
the	O
Mac	B-Application
OS	I-Application
ROM	B-Device
chip	I-Device
integrated	O
into	O
Old	B-Device
World	I-Device
ROM	I-Device
computers	O
,	O
or	O
inside	O
the	O
Mac	B-Application
OS	I-Application
ROM	B-Device
file	O
on	O
disk	O
on	O
the	O
New	B-Device
World	I-Device
ROM	I-Device
computers	O
,	O
rather	O
than	O
being	O
installed	O
in	O
the	O
familiar	O
sense	O
.	O
</s>
<s>
A	O
forward-looking	O
architecture	O
was	O
introduced	O
for	O
PCI	B-Protocol
card	I-Protocol
drivers	O
in	O
anticipation	O
of	O
the	O
Copland	B-Application
microkernel	B-Operating_System
called	O
NuKernel	O
,	O
which	O
supports	O
memory	B-General_Concept
protection	I-General_Concept
.	O
</s>
<s>
The	O
Open	B-Protocol
Transport	I-Protocol
networking	O
architecture	O
introduced	O
standardized	O
PowerPC	B-Architecture
synchronization	O
primitives	O
.	O
</s>
<s>
The	O
DayStar	O
Digital	O
Genesis	O
MP	O
Macintosh	B-Device
clone	I-Device
requires	O
kernel	B-Operating_System
extensions	O
to	O
support	O
multiprocessing	B-Operating_System
.	O
</s>
<s>
This	O
evolution	O
would	O
later	O
affect	O
the	O
overhaul	O
to	O
the	O
nanokernel	O
in	O
Mac	B-Application
OS	I-Application
8.6	O
.	O
</s>
<s>
Mac	B-Application
OS	I-Application
8.6	O
'	O
s	O
nanokernel	O
was	O
rewritten	O
by	O
René	O
A	O
.	O
Vega	O
to	O
add	O
Multiprocessing	B-Operating_System
Services	I-Operating_System
2.0	O
support	O
.	O
</s>
<s>
PowerMacInfo	O
,	O
distributed	O
in	O
the	O
Multiprocessing	B-Operating_System
SDK	O
,	O
is	O
an	O
application	O
that	O
displays	O
statistics	O
about	O
the	O
nanokernel	O
's	O
operation	O
.	O
</s>
