<s>
The	O
Cray	B-Operating_System
Operating	I-Operating_System
System	I-Operating_System
(	O
COS	O
)	O
is	O
a	O
Cray	O
Research	O
operating	B-General_Concept
system	I-General_Concept
for	O
its	O
now-discontinued	O
Cray-1	B-Device
(	O
1976	O
)	O
and	O
Cray	B-Device
X-MP	I-Device
supercomputers	B-Architecture
.	O
</s>
<s>
It	O
succeeded	O
the	O
Chippewa	B-Operating_System
Operating	I-Operating_System
System	I-Operating_System
(	O
shipped	O
with	O
earlier	O
Control	O
Data	O
Corporation	O
CDC	B-Device
6000	I-Device
series	I-Device
and	O
7600	B-Device
computer	O
systems	O
)	O
,	O
and	O
was	O
the	O
Cray	O
main	O
OS	O
until	O
replaced	O
by	O
UNICOS	B-Operating_System
in	O
the	O
late	O
1980s	O
.	O
</s>
<s>
COS	O
was	O
delivered	O
with	O
Cray	O
Assembly	O
Language	O
(	O
CAL	O
)	O
,	O
Cray	O
FORTRAN	O
(	O
CFT	O
)	O
,	O
and	O
Pascal	B-Application
.	O
</s>
<s>
As	O
COS	O
was	O
written	O
by	O
ex-Control	O
Data	O
employees	O
,	O
its	O
command	O
language	O
and	O
internal	O
organization	O
bore	O
strong	O
resemblance	O
to	O
the	O
CDC	B-Operating_System
SCOPE	I-Operating_System
operating	B-General_Concept
system	I-General_Concept
on	O
the	O
CDC	B-Device
7600	I-Device
and	O
before	O
that	O
EXEC*8	O
from	O
CDC	O
's	O
earlier	O
ERA/Univac	O
pedigree	O
.	O
</s>
<s>
However	O
the	O
DEC	B-Device
VAX	I-Device
was	O
also	O
a	O
very	O
popular	O
front-end	O
.	O
</s>
<s>
Each	O
STP	O
task	O
was	O
similar	O
in	O
nature	O
to	O
the	O
peripheral	O
processor	O
programs	O
in	O
earlier	O
Control	O
Data	O
operating	B-General_Concept
systems	I-General_Concept
,	O
but	O
since	O
the	O
Cray	O
machines	O
did	O
not	O
have	O
peripheral	O
processors	O
,	O
the	O
main	O
central	O
processor	O
executed	O
the	O
operating	B-General_Concept
system	I-General_Concept
code	O
.	O
</s>
