<s>
The	O
Cray-2	B-Device
is	O
a	O
supercomputer	B-Architecture
with	O
four	O
vector	B-Operating_System
processors	I-Operating_System
made	O
by	O
Cray	O
Research	O
starting	O
in	O
1985	O
.	O
</s>
<s>
At	O
1.9	O
GFLOPS	O
peak	O
performance	O
,	O
it	O
was	O
the	O
fastest	O
machine	O
in	O
the	O
world	O
when	O
it	O
was	O
released	O
,	O
replacing	O
the	O
Cray	B-Device
X-MP	I-Device
in	O
that	O
spot	O
.	O
</s>
<s>
It	O
was	O
,	O
in	O
turn	O
,	O
replaced	O
in	O
that	O
spot	O
by	O
the	O
Cray	B-Device
Y-MP	I-Device
in	O
1988	O
.	O
</s>
<s>
The	O
Cray-2	B-Device
was	O
the	O
first	O
of	O
Seymour	O
Cray	O
's	O
designs	O
to	O
successfully	O
use	O
multiple	O
CPUs	O
.	O
</s>
<s>
This	O
had	O
been	O
attempted	O
in	O
the	O
CDC	B-Device
8600	I-Device
in	O
the	O
early	O
1970s	O
,	O
but	O
the	O
emitter-coupled	B-General_Concept
logic	I-General_Concept
(	O
ECL	O
)	O
transistors	B-Application
of	O
the	O
era	O
were	O
too	O
difficult	O
to	O
package	O
into	O
a	O
working	O
machine	O
.	O
</s>
<s>
The	O
Cray-2	B-Device
addressed	O
this	O
through	O
the	O
use	O
of	O
ECL	O
integrated	O
circuits	O
,	O
packing	O
them	O
in	O
a	O
novel	O
3D	O
wiring	O
that	O
greatly	O
increased	O
circuit	O
density	O
.	O
</s>
<s>
The	O
dense	O
packaging	O
and	O
resulting	O
heat	O
loads	O
were	O
a	O
major	O
problem	O
for	O
the	O
Cray-2	B-Device
.	O
</s>
<s>
The	O
unique	O
"	O
waterfall	O
"	O
cooler	O
system	O
came	O
to	O
represent	O
high-performance	B-Architecture
computing	I-Architecture
in	O
the	O
public	O
eye	O
and	O
was	O
found	O
in	O
many	O
informational	O
films	O
and	O
as	O
a	O
movie	O
prop	O
for	O
some	O
time	O
.	O
</s>
<s>
Unlike	O
the	O
original	O
Cray-1	B-Device
,	O
the	O
Cray-2	B-Device
had	O
difficulties	O
delivering	O
peak	O
performance	O
.	O
</s>
<s>
Other	O
machines	O
from	O
the	O
company	O
,	O
like	O
the	O
X-MP	O
and	O
Y-MP	O
,	O
outsold	O
the	O
Cray-2	B-Device
by	O
a	O
wide	O
margin	O
.	O
</s>
<s>
When	O
Cray	O
began	O
development	O
of	O
the	O
Cray-3	B-Device
,	O
the	O
company	O
chose	O
to	O
develop	O
the	O
Cray	B-Device
C90	I-Device
series	O
instead	O
.	O
</s>
<s>
With	O
the	O
successful	O
launch	O
of	O
his	O
famed	O
Cray-1	B-Device
,	O
Seymour	O
Cray	O
turned	O
to	O
the	O
design	O
of	O
its	O
successor	O
.	O
</s>
<s>
The	O
classic	O
example	O
of	O
this	O
design	O
is	O
the	O
CDC	B-Device
8600	I-Device
,	O
which	O
packed	O
four	O
CDC	O
7600-like	O
machines	O
based	O
on	O
ECL	B-General_Concept
logic	I-General_Concept
into	O
a	O
1	O
×	O
1	O
meter	O
cylinder	O
and	O
ran	O
them	O
at	O
an	O
8	O
ns	O
cycle	O
speed	O
(	O
125	O
MHz	O
)	O
.	O
</s>
<s>
The	O
circuit	O
boards	O
inside	O
were	O
densely	O
packed	O
,	O
and	O
since	O
even	O
a	O
single	O
malfunctioning	O
transistor	B-Application
would	O
cause	O
an	O
entire	O
module	O
to	O
fail	O
,	O
packing	O
more	O
of	O
them	O
onto	O
the	O
cards	O
greatly	O
increased	O
the	O
chance	O
of	O
failure	O
.	O
</s>
<s>
At	O
the	O
time	O
the	O
8600	O
was	O
being	O
designed	O
the	O
simple	O
MOSFET-based	O
technology	O
did	O
not	O
offer	O
the	O
speed	O
Cray	O
needed	O
.	O
</s>
<s>
Relentless	O
improvements	O
changed	O
things	O
by	O
the	O
mid-1970s	O
,	O
however	O
,	O
and	O
the	O
Cray-1	B-Device
had	O
been	O
able	O
to	O
use	O
newer	O
ICs	O
and	O
still	O
run	O
at	O
a	O
respectable	O
12.5	O
ns	O
(	O
80MHz	O
)	O
.	O
</s>
<s>
In	O
fact	O
,	O
the	O
Cray-1	B-Device
was	O
actually	O
somewhat	O
faster	O
than	O
the	O
8600	O
because	O
it	O
packed	O
considerably	O
more	O
logic	O
into	O
the	O
system	O
due	O
to	O
the	O
ICs	O
 '	O
small	O
size	O
.	O
</s>
<s>
Dramatic	O
improvements	O
in	O
density	O
were	O
possible	O
,	O
as	O
the	O
rapid	O
improvement	O
in	O
microprocessor	B-Architecture
design	O
was	O
showing	O
,	O
but	O
for	O
the	O
type	O
of	O
ICs	O
used	O
by	O
Cray	O
,	O
ones	O
representing	O
a	O
very	O
small	O
part	O
of	O
a	O
complete	O
circuit	O
,	O
the	O
design	O
had	O
plateaued	O
.	O
</s>
<s>
In	O
order	O
to	O
gain	O
another	O
10-fold	O
increase	O
in	O
performance	O
over	O
the	O
Cray-1	B-Device
,	O
the	O
goal	O
Cray	O
aimed	O
for	O
,	O
the	O
machine	O
would	O
have	O
to	O
grow	O
more	O
complex	O
.	O
</s>
<s>
In	O
the	O
era	O
of	O
the	O
CDC	B-Device
6600	I-Device
memory	O
ran	O
at	O
the	O
same	O
speed	O
as	O
the	O
processor	O
,	O
and	O
the	O
main	O
problem	O
was	O
feeding	O
data	O
into	O
it	O
.	O
</s>
<s>
As	O
the	O
Cray	B-Device
2	I-Device
had	O
a	O
much	O
larger	O
memory	O
than	O
Cray	B-Device
1s	I-Device
or	O
X-MPs	O
,	O
this	O
problem	O
was	O
easily	O
rectified	O
by	O
adding	O
an	O
extra	O
unused	O
element	O
to	O
an	O
array	O
to	O
spread	O
the	O
work	O
out	O
.	O
</s>
<s>
Early	O
Cray-2	B-Device
models	O
soon	O
settled	O
on	O
a	O
design	O
using	O
large	O
circuit	O
boards	O
packed	O
with	O
ICs	O
.	O
</s>
<s>
While	O
this	O
was	O
going	O
on	O
the	O
Cray	B-Device
X-MP	I-Device
was	O
being	O
developed	O
under	O
the	O
direction	O
of	O
Steve	O
Chen	O
at	O
Cray	O
headquarters	O
,	O
and	O
looked	O
like	O
it	O
would	O
give	O
the	O
Cray-2	B-Device
a	O
serious	O
run	O
for	O
its	O
money	O
.	O
</s>
<s>
In	O
order	O
to	O
address	O
this	O
internal	O
threat	O
,	O
as	O
well	O
as	O
a	O
series	O
of	O
newer	O
Japanese	O
Cray-1-like	O
machines	O
,	O
the	O
Cray-2	B-Device
memory	O
system	O
was	O
dramatically	O
improved	O
,	O
both	O
in	O
size	O
as	O
well	O
as	O
the	O
number	O
of	O
"	O
pipes	O
"	O
into	O
the	O
processors	O
.	O
</s>
<s>
The	O
first	O
Cray-2	B-Device
delivered	O
possessed	O
more	O
physical	O
memory	O
(	O
256	O
MWord	O
)	O
than	O
all	O
previously	O
delivered	O
Cray	O
machines	O
combined	O
.	O
</s>
<s>
The	O
Cray-2	B-Device
was	O
predominantly	O
developed	O
for	O
the	O
United	O
States	O
Departments	O
of	O
Defense	O
and	O
Energy	O
.	O
</s>
<s>
Uses	O
tended	O
to	O
be	O
for	O
nuclear	O
weapons	O
research	O
or	O
oceanographic	O
(	O
sonar	B-Application
)	O
development	O
.	O
</s>
<s>
However	O
,	O
the	O
first	O
Cray-2	B-Device
(	O
serial	O
number	O
1	O
)	O
was	O
used	O
at	O
the	O
National	O
Magnetic	O
Fusion	O
Energy	O
Computer	O
Center	O
at	O
Lawrence	O
Livermore	O
National	O
Laboratory	O
for	O
unclassified	O
energy	O
research	O
.	O
</s>
<s>
For	O
example	O
,	O
Ford	O
and	O
General	O
Motors	O
both	O
used	O
the	O
Cray-2	B-Device
for	O
processing	O
complex	O
Finite	B-Application
Element	I-Application
Analysis	I-Application
models	O
of	O
car	O
bodyshells	O
,	O
and	O
for	O
performing	O
virtual	O
crash	O
testing	O
of	O
bodyshell	O
components	O
prior	O
to	O
production	O
.	O
</s>
<s>
The	O
Cray-2	B-Device
would	O
have	O
been	O
superseded	O
by	O
the	O
Cray-3	B-Device
,	O
but	O
due	O
to	O
development	O
problems	O
only	O
a	O
single	O
Cray-3	B-Device
was	O
built	O
and	O
it	O
was	O
never	O
paid	O
for	O
.	O
</s>
<s>
The	O
spiritual	O
descendant	O
of	O
the	O
Cray-2	B-Device
is	O
the	O
Cray	B-Device
X1	I-Device
,	O
offered	O
by	O
Cray	O
.	O
</s>
<s>
In	O
2012	O
,	O
Piotr	O
Luszczek	O
(	O
a	O
former	O
doctoral	O
student	O
of	O
Jack	O
Dongarra	O
)	O
,	O
presented	O
results	O
showing	O
that	O
an	O
iPad	B-Operating_System
2	I-Operating_System
matched	O
the	O
historical	O
performance	O
of	O
the	O
Cray-2	B-Device
on	O
an	O
embedded	O
LINPACK	B-Application
benchmark	O
.	O
</s>
<s>
Due	O
to	O
the	O
use	O
of	O
liquid	O
cooling	O
,	O
the	O
Cray-2	B-Device
was	O
given	O
the	O
nickname	O
"	O
Bubbles	O
"	O
,	O
and	O
common	O
jokes	O
around	O
the	O
computer	O
made	O
reference	O
to	O
this	O
unique	O
system	O
.	O
</s>
<s>
The	O
power	O
consumption	O
of	O
the	O
Cray-2	B-Device
was	O
150	O
–	O
200kW	O
.	O
</s>
<s>
Research	O
conducted	O
at	O
the	O
Lawrence	O
Livermore	O
National	O
Laboratory	O
in	O
the	O
early	O
1990s	O
indicated	O
that	O
to	O
a	O
limited	O
extent	O
the	O
perfluorinated	O
polyether	O
used	O
to	O
cool	O
Cray-2	B-Device
circuits	O
would	O
break	O
down	O
to	O
form	O
the	O
extremely	O
toxic	O
gas	O
perfluoroisobutylene	O
.	O
</s>
<s>
The	O
Cray-2	B-Device
was	O
powered	O
by	O
two	O
motor-generators	O
,	O
which	O
took	O
in	O
480	O
V	O
three-phase	O
.	O
</s>
