<s>
The	O
CDC	B-Device
STAR-100	I-Device
is	O
a	O
vector	B-Operating_System
supercomputer	B-Architecture
that	O
was	O
designed	O
,	O
manufactured	O
,	O
and	O
marketed	O
by	O
Control	O
Data	O
Corporation	O
(	O
CDC	O
)	O
.	O
</s>
<s>
It	O
was	O
one	O
of	O
the	O
first	O
machines	O
to	O
use	O
a	O
vector	B-Operating_System
processor	I-Operating_System
to	O
improve	O
performance	O
on	O
appropriate	O
scientific	O
applications	O
.	O
</s>
<s>
It	O
was	O
also	O
the	O
first	O
supercomputer	B-Architecture
to	O
use	O
integrated	O
circuits	O
and	O
the	O
first	O
to	O
be	O
equipped	O
with	O
one	O
million	O
words	O
of	O
computer	B-General_Concept
memory	I-General_Concept
.	O
</s>
<s>
The	O
100	O
alludes	O
to	O
the	O
nominal	O
peak	O
processing	O
speed	O
of	O
100	O
million	O
floating	O
point	O
operations	O
per	O
second	O
(	O
MFLOPS	O
)	O
;	O
the	O
earlier	O
CDC	B-Device
7600	I-Device
provided	O
peak	O
performance	O
of	O
36MFLOPS	O
but	O
more	O
typically	O
ran	O
at	O
around	O
10MFLOPS	O
.	O
</s>
<s>
A	O
number	O
of	O
basic	O
design	O
features	O
of	O
the	O
machine	O
meant	O
that	O
its	O
real-world	O
performance	O
was	O
much	O
lower	O
than	O
expected	O
when	O
first	O
used	O
commercially	O
in	O
1974	O
,	O
and	O
was	O
one	O
of	O
the	O
primary	O
reasons	O
CDC	O
was	O
pushed	O
from	O
its	O
former	O
dominance	O
in	O
the	O
supercomputer	B-Architecture
market	O
when	O
the	O
Cray-1	B-Device
was	O
announced	O
in	O
1975	O
.	O
</s>
<s>
The	O
STAR	O
had	O
a	O
64-bit	B-Device
architecture	I-Device
,	O
consisting	O
of	O
195	O
instructions	O
.	O
</s>
<s>
Its	O
main	O
innovation	O
was	O
the	O
inclusion	O
of	O
65	O
vector	B-Operating_System
instructions	O
for	O
vector	B-Operating_System
processing	I-Operating_System
.	O
</s>
<s>
The	O
operations	O
performed	O
by	O
these	O
instructions	O
were	O
strongly	O
influenced	O
by	O
concepts	O
and	O
operators	O
from	O
the	O
APL	B-Language
programming	I-Language
language	I-Language
;	O
in	O
particular	O
,	O
the	O
concept	O
of	O
"	O
control	O
vectors	O
"	O
(	O
vector	B-Operating_System
masks	O
in	O
modern	O
terminology	O
)	O
,	O
and	O
several	O
instructions	O
for	O
vector	B-Operating_System
permutation	O
with	O
control	O
vectors	O
,	O
were	O
carried	O
over	O
directly	O
from	O
APL	B-Language
.	O
</s>
<s>
The	O
vector	B-Operating_System
instructions	O
operated	O
on	O
vectors	O
that	O
were	O
stored	O
in	O
consecutive	O
locations	O
in	O
main	O
memory	O
;	O
memory	O
addressing	O
was	O
virtual	B-Architecture
.	O
</s>
<s>
The	O
vector	B-Operating_System
instructions	O
fed	O
an	O
arithmetic	O
pipeline	B-General_Concept
;	O
a	O
single	O
instruction	O
could	O
add	O
two	O
variable-length	O
vectors	O
of	O
up	O
to	O
65,535	O
elements	O
with	O
just	O
one	O
instruction	O
fetch	O
.	O
</s>
<s>
The	O
STAR	O
also	O
fetched	O
vector	B-Operating_System
operands	O
in	O
512-bit	O
units	O
(	O
superwords	O
)	O
,	O
reducing	O
average	O
memory	O
latency	O
.	O
</s>
<s>
As	O
with	O
instruction	B-General_Concept
pipelines	I-General_Concept
in	O
general	O
,	O
the	O
time	O
needed	O
to	O
complete	O
any	O
one	O
instruction	O
was	O
no	O
better	O
than	O
it	O
was	O
before	O
,	O
but	O
since	O
the	O
CPU	O
is	O
working	O
on	O
a	O
number	O
of	O
data	O
points	O
at	O
once	O
,	O
the	O
overall	O
performance	O
dramatically	O
improves	O
.	O
</s>
<s>
Many	O
of	O
the	O
STAR	O
's	O
instructions	O
were	O
complex	O
,	O
especially	O
the	O
vector	B-Operating_System
macro	O
instructions	O
,	O
which	O
performed	O
complex	O
operations	O
that	O
normally	O
would	O
have	O
required	O
long	O
sequences	O
of	O
instructions	O
.	O
</s>
<s>
These	O
instructions	O
,	O
along	O
with	O
the	O
STAR	O
's	O
generally	O
complex	O
architecture	B-General_Concept
,	O
was	O
implemented	O
with	O
microcode	B-Device
.	O
</s>
<s>
Main	O
memory	O
was	O
32-way	O
interleaved	B-General_Concept
to	O
pipeline	B-General_Concept
memory	O
accesses	O
.	O
</s>
<s>
It	O
was	O
constructed	O
from	O
core	B-General_Concept
memory	I-General_Concept
with	O
an	O
access	B-General_Concept
time	I-General_Concept
of	O
1.28μs	O
.	O
</s>
<s>
There	O
is	O
also	O
a	O
128-bit	O
data	O
bus	O
for	O
instruction	O
fetch	O
,	O
I/O	O
,	O
and	O
control	O
vector	B-Operating_System
access	O
.	O
</s>
<s>
Both	O
pipelines	O
are	O
64-bit	B-Device
for	O
floating	O
point	O
operations	O
and	O
are	O
controlled	O
by	O
microcode	B-Device
.	O
</s>
<s>
Each	O
I/O	O
processor	O
is	O
a	O
16-bit	O
minicomputer	B-Architecture
with	O
its	O
own	O
main	O
memory	O
of	O
65,536	O
words	O
of	O
16	O
bits	O
each	O
,	O
which	O
is	O
implemented	O
with	O
core	B-General_Concept
memory	I-General_Concept
.	O
</s>
<s>
Firstly	O
,	O
the	O
vector	B-Operating_System
instructions	O
,	O
being	O
"	O
memory-to-memory	O
,	O
"	O
had	O
a	O
relatively	O
long	O
startup	O
time	O
,	O
since	O
the	O
pipeline	B-General_Concept
from	O
the	O
memory	O
to	O
the	O
functional	O
units	O
was	O
very	O
long	O
.	O
</s>
<s>
So	O
the	O
vector	B-Operating_System
length	O
needed	O
for	O
the	O
STAR	O
to	O
run	O
faster	O
than	O
the	O
7600	O
occurred	O
at	O
about	O
50	O
elements	O
;	O
if	O
the	O
loops	O
were	O
working	O
on	O
data	O
sets	O
with	O
fewer	O
elements	O
,	O
the	O
time	O
cost	O
of	O
setting	O
up	O
the	O
vector	B-Operating_System
pipeline	B-General_Concept
was	O
higher	O
than	O
the	O
time	O
savings	O
provided	O
by	O
the	O
vector	B-Operating_System
instruction(s )	O
.	O
</s>
<s>
This	O
forced	O
most	O
programs	O
to	O
pay	O
the	O
high	O
setup	O
cost	O
of	O
the	O
vector	B-Operating_System
units	O
,	O
and	O
generally	O
the	O
ones	O
that	O
did	O
"	O
work	O
"	O
were	O
extreme	O
examples	O
.	O
</s>
<s>
Worse	O
,	O
basic	O
scalar	O
performance	O
was	O
sacrificed	O
to	O
improve	O
vector	B-Operating_System
performance	O
.	O
</s>
<s>
(	O
See	O
Amdahl	B-Operating_System
's	I-Operating_System
Law	I-Operating_System
.	O
)	O
</s>
<s>
In	O
preparation	O
for	O
the	O
STAR	O
deliveries	O
,	O
LLNL	O
programmers	O
developed	O
a	O
library	B-Library
of	O
subroutines	O
,	O
called	O
STACKLIB	O
,	O
on	O
the	O
7600	O
to	O
emulate	B-Application
the	O
vector	B-Operating_System
operations	O
of	O
the	O
STAR	O
.	O
</s>
<s>
Jim	O
Thornton	O
,	O
formerly	O
Seymour	O
Cray	O
's	O
close	O
assistant	O
on	O
the	O
CDC	B-Device
1604	I-Device
and	O
6600	B-Device
projects	O
and	O
the	O
chief	O
designer	O
of	O
STAR	O
,	O
left	O
CDC	O
to	O
form	O
Network	O
Systems	O
Corporation	O
.	O
</s>
<s>
An	O
updated	O
version	O
of	O
the	O
basic	O
architecture	B-General_Concept
was	O
later	O
released	O
in	O
1979	O
as	O
the	O
Cyber	O
203	O
,	O
followed	O
by	O
the	O
Cyber	O
205	O
in	O
1980	O
,	O
but	O
by	O
this	O
point	O
systems	O
from	O
Cray	O
Research	O
with	O
considerably	O
higher	O
performance	O
were	O
on	O
the	O
market	O
.	O
</s>
<s>
The	O
failure	O
of	O
the	O
STAR	O
led	O
to	O
CDC	O
being	O
pushed	O
from	O
its	O
former	O
dominance	O
in	O
the	O
supercomputer	B-Architecture
market	O
,	O
something	O
they	O
tried	O
to	O
address	O
with	O
the	O
formation	O
of	O
ETA	O
Systems	O
in	O
September	O
1983	O
.	O
</s>
<s>
Five	O
CDC	B-Device
STAR-100s	I-Device
were	O
built	O
.	O
</s>
