<s>
The	O
CDC	B-Device
8600	I-Device
was	O
the	O
last	O
of	O
Seymour	O
Cray	O
's	O
supercomputer	B-Architecture
designs	O
while	O
he	O
worked	O
for	O
Control	O
Data	O
Corporation	O
.	O
</s>
<s>
As	O
the	O
natural	O
successor	O
to	O
the	O
CDC	B-Device
6600	I-Device
and	O
CDC	B-Device
7600	I-Device
,	O
the	O
8600	O
was	O
intended	O
to	O
be	O
about	O
10	O
times	O
as	O
fast	O
as	O
the	O
7600	O
,	O
already	O
the	O
fastest	O
computer	O
on	O
the	O
market	O
.	O
</s>
<s>
The	O
8600	O
design	O
effort	O
was	O
eventually	O
canceled	O
in	O
1974	O
,	O
and	O
Control	O
Data	O
moved	O
on	O
to	O
the	O
CDC	B-Device
STAR-100	I-Device
series	O
instead	O
.	O
</s>
<s>
Cray	O
revisited	O
the	O
8600	O
's	O
basic	O
design	O
in	O
his	O
Cray-2	B-Device
of	O
the	O
early	O
1980s	O
.	O
</s>
<s>
The	O
Cray-2	B-Device
is	O
very	O
similar	O
to	O
the	O
8600	O
both	O
physically	O
and	O
conceptually	O
.	O
</s>
<s>
In	O
the	O
1960s	O
,	O
computer	O
design	O
was	O
based	O
on	O
mounting	O
electronic	O
components	O
(	O
transistors	B-Application
,	O
resistors	O
,	O
etc	O
.	O
)	O
</s>
<s>
The	O
proposed	O
design	O
bears	O
a	O
strong	O
resemblance	O
to	O
the	O
later	O
Cray-2	B-Device
,	O
but	O
even	O
shorter	O
and	O
smaller	O
in	O
diameter	O
.	O
</s>
<s>
The	O
main	O
CPU	B-General_Concept
circuits	O
moved	O
to	O
ECL-based	O
logic	O
,	O
enabling	O
a	O
clock	O
speed	O
increase	O
to	O
125MHz	O
(	O
8ns	O
cycle	O
time	O
)	O
from	O
the	O
7600	O
's	O
36.4MHz	O
(	O
27.5ns	O
cycle	O
time	O
)	O
an	O
increase	O
of	O
about	O
four	O
times	O
.	O
</s>
<s>
Main	O
memory	O
was	O
also	O
moved	O
to	O
an	O
ECL	B-General_Concept
implementation	O
and	O
the	O
machine	O
was	O
equipped	O
with	O
a	O
whopping-for-the-times	O
256k-words	O
(	O
2megabytes	O
)	O
standard	O
.	O
</s>
<s>
A	O
high-speed	O
core	B-General_Concept
memory	I-General_Concept
with	O
a	O
20ns	O
access	O
(	O
overall	O
)	O
was	O
also	O
designed	O
as	O
a	O
backup	O
to	O
the	O
semiconductor	O
memory	O
.	O
</s>
<s>
This	O
technique	O
,	O
today	O
known	O
as	O
SIMD	B-Device
,	O
reduced	O
the	O
total	O
number	O
of	O
memory	O
accesses	O
because	O
the	O
instruction	O
was	O
only	O
read	O
once	O
,	O
instead	O
of	O
four	O
times	O
.	O
</s>
<s>
The	O
government	O
made	O
it	O
clear	O
that	O
all	O
future	O
computer	O
purchases	O
would	O
require	O
ASCII	B-Protocol
processing	O
.	O
</s>
<s>
To	O
meet	O
this	O
requirement	O
,	O
the	O
8600	O
used	O
a	O
64-bit	B-Device
word	O
(	O
eight	O
eight-bit	O
characters	O
)	O
instead	O
of	O
the	O
earlier	O
60-bit	O
word	O
(	O
ten	O
six-bit	O
characters	O
)	O
used	O
in	O
the	O
6600	O
and	O
7600	O
.	O
</s>
<s>
A	O
6600/7600	O
Peripheral	O
Processor	O
system	O
was	O
used	O
for	O
I/O	B-General_Concept
,	O
largely	O
unchanged	O
.	O
</s>
<s>
Instead	O
,	O
floating	B-Algorithm
point	I-Algorithm
formats	I-Algorithm
were	O
retained	O
,	O
allowing	O
Fortran	B-Application
code	O
to	O
port	O
directly	O
.	O
</s>
<s>
He	O
may	O
have	O
come	O
to	O
this	O
conclusion	O
after	O
the	O
ILLIAC	B-Device
IV	I-Device
finally	O
entered	O
operation	O
at	O
about	O
the	O
same	O
time	O
,	O
and	O
proved	O
to	O
have	O
disappointing	O
performance	O
.	O
</s>
<s>
Jim	O
Thornton	O
's	O
competing	O
STAR	B-Device
design	O
had	O
reached	O
production	O
quality	O
at	O
this	O
point	O
,	O
and	O
the	O
8600	O
project	O
was	O
then	O
cancelled	O
.	O
</s>
<s>
In	O
service	O
STAR	B-Device
proved	O
to	O
have	O
poor	O
real-world	O
performance	O
,	O
and	O
when	O
the	O
Cray-1	B-Device
entered	O
the	O
market	O
in	O
1976	O
,	O
CDC	O
was	O
quickly	O
pushed	O
from	O
the	O
supercomputer	B-Architecture
market	O
.	O
</s>
<s>
An	O
effort	O
was	O
made	O
to	O
re-enter	O
the	O
market	O
in	O
the	O
1980s	O
with	O
the	O
ETA-10	B-Operating_System
,	O
but	O
this	O
ended	O
poorly	O
.	O
</s>
