<s>
KeyKOS	B-Operating_System
is	O
a	O
persistent	B-Application
,	O
pure	O
capability-based	O
operating	B-General_Concept
system	I-General_Concept
for	O
the	O
IBM	B-Device
S/370	I-Device
mainframe	B-Device
computers	O
.	O
</s>
<s>
It	O
allows	O
emulating	B-Application
the	O
environments	O
of	O
VM	B-Application
,	O
MVS	B-Application
,	O
and	O
Portable	O
Operating	B-General_Concept
System	I-General_Concept
Interface	O
(	O
POSIX	O
)	O
.	O
</s>
<s>
It	O
is	O
a	O
predecessor	O
of	O
the	O
Extremely	B-Operating_System
Reliable	I-Operating_System
Operating	I-Operating_System
System	I-Operating_System
(	O
EROS	B-Operating_System
)	O
,	O
and	O
its	O
successor	O
operating	B-General_Concept
systems	I-General_Concept
,	O
CapROS	B-Application
,	O
and	O
Coyotos	O
.	O
</s>
<s>
KeyKOS	B-Operating_System
is	O
a	O
nanokernel-based	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
In	O
the	O
mid-1970s	O
,	O
development	O
of	O
KeyKOS	B-Operating_System
began	O
at	O
Tymshare	O
,	O
Inc.	O
,	O
under	O
the	O
name	O
GNOSIS	B-Operating_System
.	O
</s>
<s>
A	O
year	O
later	O
MD	O
spun	O
off	O
Key	O
Logic	O
,	O
which	O
bought	O
GNOSIS	B-Operating_System
and	O
renamed	O
it	O
KeyKOS	B-Operating_System
.	O
</s>
