<s>
The	O
Cray	B-Device
Superserver	I-Device
6400	I-Device
,	O
or	O
CS6400	B-Device
,	O
is	O
a	O
discontinued	O
multiprocessor	B-Operating_System
server	B-Application
computer	I-Application
system	O
produced	O
by	O
Cray	O
Research	O
Superservers	O
,	O
Inc.	O
,	O
a	O
subsidiary	O
of	O
Cray	O
Research	O
,	O
and	O
launched	O
in	O
1993	O
.	O
</s>
<s>
The	O
CS6400	B-Device
was	O
also	O
sold	O
as	O
the	O
Amdahl	O
SPARCsummit	O
6400E	O
.	O
</s>
<s>
The	O
CS6400	B-Device
(	O
codenamed	O
SuperDragon	O
during	O
development	O
)	O
superseded	O
the	O
earlier	O
SPARC-based	O
Cray	B-Device
S-MP	I-Device
system	O
,	O
which	O
was	O
designed	O
by	O
Floating	O
Point	O
Systems	O
.	O
</s>
<s>
However	O
,	O
the	O
CS6400	B-Device
adopted	O
the	O
XDBus	O
packet-switched	O
inter-processor	O
bus	O
also	O
used	O
in	O
Sun	O
Microsystems	O
 '	O
SPARCcenter	B-Device
2000	O
(	O
Dragon	O
)	O
and	O
SPARCserver	B-Device
1000	O
(	O
Baby	O
Dragon	O
or	O
Scorpion	O
)	O
Sun4d	B-Device
systems	O
.	O
</s>
<s>
This	O
bus	O
originated	O
in	O
the	O
Xerox	B-Device
Dragon	I-Device
multiprocessor	B-Operating_System
workstation	O
designed	O
at	O
Xerox	O
PARC	O
.	O
</s>
<s>
The	O
CS6400	B-Device
was	O
available	O
with	O
either	O
60MHz	O
SuperSPARC-I	O
or	O
85MHz	O
SuperSPARC-II	O
processors	O
,	O
maximum	O
RAM	O
capacity	O
was	O
16GB	O
.	O
</s>
<s>
Other	O
features	O
shared	O
with	O
the	O
Sun	O
servers	O
included	O
use	O
of	O
the	O
same	O
SuperSPARC	B-Architecture
microprocessor	B-Architecture
and	O
Solaris	B-Application
operating	I-Application
system	I-Application
.	O
</s>
<s>
However	O
,	O
the	O
CS6400	B-Device
could	O
be	O
configured	O
with	O
four	O
to	O
64	O
processors	O
on	O
quad	O
XDBusses	O
at	O
55MHz	O
,	O
compared	O
with	O
the	O
SPARCcenter	B-Device
2000	O
's	O
maximum	O
of	O
20	O
on	O
dual	O
XDBusses	O
at	O
40	O
or	O
50MHz	O
and	O
the	O
SPARCserver	B-Device
1000	O
's	O
maximum	O
of	O
8	O
on	O
a	O
single	O
XDBus	O
.	O
</s>
<s>
Unlike	O
the	O
Sun	O
SPARCcenter	B-Device
2000	O
and	O
SPARCserver	B-Device
1000	O
,	O
each	O
CS6400	B-Device
is	O
equipped	O
with	O
an	O
external	O
System	B-Architecture
Service	I-Architecture
Processor	I-Architecture
(	O
SSP	O
)	O
,	O
a	O
SPARCstation	B-Device
fitted	O
with	O
a	O
JTAG	O
interface	O
to	O
communicate	O
with	O
the	O
CS6400	B-Device
to	O
configure	O
its	O
internal	O
bus	O
control	O
card	O
.	O
</s>
<s>
While	O
the	O
CS6400	B-Device
only	O
requires	O
the	O
SSP	O
to	O
be	O
used	O
for	O
configuration	O
changes	O
(	O
e.g.	O
</s>
<s>
a	O
CPU	O
card	O
is	O
pulled	O
for	O
maintenance	O
)	O
,	O
some	O
derivative	O
designs	O
,	O
in	O
particular	O
the	O
Sun	B-Device
Enterprise	I-Device
10000	I-Device
,	O
are	O
useless	O
without	O
their	O
SSP	O
.	O
</s>
<s>
This	O
included	O
Starfire	O
,	O
the	O
CS6400	B-Device
's	O
successor	O
then	O
under	O
development	O
,	O
which	O
became	O
the	O
Sun	B-Device
Enterprise	I-Device
10000	I-Device
.	O
</s>
