<s>
In	O
computer	B-General_Concept
science	I-General_Concept
,	O
Actor	B-Application
model	I-Application
implementation	I-Application
concerns	O
implementation	O
issues	O
for	O
the	O
Actor	B-Application
model	I-Application
.	O
</s>
<s>
The	O
Caltech	B-Operating_System
Cosmic	I-Operating_System
Cube	I-Operating_System
was	O
developed	O
by	O
Chuck	O
Seitz	O
et	O
al	O
.	O
</s>
<s>
at	O
Caltech	O
providing	O
architectural	O
support	O
for	O
Actor	B-Application
systems	I-Application
.	O
</s>
<s>
A	O
direct	O
network	O
like	O
the	O
hypercube	B-Operating_System
satisfies	O
this	O
requirement	O
,	O
with	O
respect	O
to	O
both	O
the	O
aggregate	O
bandwidth	O
achieved	O
across	O
the	O
many	O
concurrent	O
communication	O
channels	O
and	O
the	O
feasibility	O
of	O
the	O
implementation	O
.	O
</s>
<s>
The	O
hypercube	B-Operating_System
is	O
actually	O
a	O
distributed	O
variant	O
of	O
an	O
indirect	O
logarithmic	O
switching	O
network	O
like	O
the	O
Omega	O
or	O
banyan	O
networks	O
:	O
the	O
kind	O
that	O
might	O
be	O
used	O
in	O
shared-storage	O
organizations	O
.	O
</s>
<s>
With	O
the	O
hypercube	B-Operating_System
,	O
however	O
,	O
communication	O
paths	O
traverse	O
different	O
numbers	O
of	O
channels	O
and	O
so	O
exhibit	O
different	O
latencies	O
.	O
</s>
<s>
The	O
J	B-Device
–	I-Device
Machine	I-Device
was	O
developed	O
by	O
Bill	O
Dally	O
et	O
al	O
.	O
</s>
<s>
at	O
MIT	O
providing	O
architectural	O
support	O
suitable	O
for	O
Actors	B-Application
.	O
</s>
<s>
Concurrent	O
Smalltalk	O
(	O
which	O
can	O
be	O
modeled	O
using	O
Actors	B-Application
)	O
was	O
developed	O
to	O
program	O
the	O
J	O
Machine	O
.	O
</s>
<s>
Hewitt	O
 [ 2006 ] 	O
presented	O
a	O
prototype	O
Actor	O
programming	O
language	O
in	O
the	O
sense	O
that	O
it	O
directly	O
expresses	O
important	O
aspects	O
of	O
the	O
behavior	O
of	O
Actors	B-Application
.	O
</s>
<s>
Environment	O
Actors	B-Application
are	O
immutable	O
,	O
i.e.	O
,	O
they	O
do	O
not	O
change	O
.	O
</s>
