<s>
Atom	B-Language
is	O
a	O
domain-specific	B-Language
language	I-Language
(	O
DSL	O
)	O
in	O
Haskell	B-Language
,	O
for	O
designing	O
real-time	B-General_Concept
embedded	B-Architecture
software	I-Architecture
.	O
</s>
<s>
Originally	O
intended	O
as	O
a	O
high-level	B-Language
hardware	O
description	O
language	O
(	O
HDL	O
)	O
,	O
Atom	B-Language
was	O
created	O
in	O
early	O
2007	O
and	O
released	O
as	O
free	B-License
and	I-License
open-source	I-License
software	I-License
(	O
FOSS	B-License
)	O
of	O
April	O
of	O
that	O
year	O
.	O
</s>
<s>
Inspired	O
by	O
TRS	O
and	O
Bluespec	O
,	O
Atom	B-Language
compiled	B-Language
circuit	O
descriptions	O
,	O
that	O
were	O
based	O
on	O
guarded	O
atomic	B-General_Concept
operations	I-General_Concept
,	O
or	O
conditional	O
term	O
rewriting	O
,	O
into	O
Verilog	B-Language
netlists	O
for	O
simulation	O
and	O
logic	O
synthesis	O
.	O
</s>
<s>
As	O
a	O
hardware	O
compiler	B-Language
,	O
Atom	B-Language
's	O
main	O
objective	O
is	O
to	O
maximize	O
the	O
number	O
of	O
operations	O
,	O
or	O
rules	O
,	O
that	O
can	O
execute	O
in	O
a	O
given	O
clock	O
cycle	O
without	O
violating	O
the	O
semantics	O
of	O
atomic	B-General_Concept
operation	I-General_Concept
.	O
</s>
<s>
By	O
employing	O
the	O
properties	O
of	O
conflict-free	O
and	O
sequentially	O
composable	O
rules	O
,	O
Atom	B-Language
reduced	O
maximizing	O
execution	O
concurrency	B-Operating_System
to	O
a	O
feedback	O
arc	O
set	O
optimization	O
of	O
a	O
rule-data	O
dependency	O
graph	O
.	O
</s>
<s>
When	O
Atom	B-Language
's	O
author	O
switched	O
careers	O
in	O
late	O
2007	O
,	O
from	O
logic	O
design	O
to	O
embedded	B-Architecture
software	I-Architecture
engineering	O
,	O
Atom	B-Language
was	O
redesigned	O
from	O
an	O
HDL	O
to	O
a	O
domain-specific	B-Language
language	I-Language
targeting	O
hard	B-General_Concept
realtime	I-General_Concept
embedded	O
applications	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
Atom	B-Language
's	O
compiler	B-Language
's	O
main	O
objective	O
changed	O
from	O
maximizing	O
rule	O
concurrency	B-Operating_System
to	O
balancing	O
processing	O
load	O
and	O
minimizing	O
worst	B-General_Concept
case	I-General_Concept
timing	I-General_Concept
latency	I-General_Concept
.	O
</s>
<s>
In	O
September	O
2008	O
,	O
Atom	B-Language
was	O
presented	O
at	O
the	O
Commercial	O
Users	O
of	O
Functional	B-Language
Programming	I-Language
(	O
CUFP	O
)	O
conference	O
.	O
</s>
<s>
In	O
April	O
2009	O
,	O
in	O
its	O
new	O
form	O
,	O
it	O
was	O
released	O
as	O
FOSS	B-License
.	O
</s>
<s>
Atom	B-Language
is	O
a	O
concurrent	O
programming	O
language	O
intended	O
for	O
embedded	O
applications	O
.	O
</s>
<s>
Atom	B-Language
features	O
compile	B-Application
time	I-Application
task	O
scheduling	O
and	O
generates	O
code	O
with	O
deterministic	O
execution	B-Library
time	I-Library
and	O
memory	O
use	O
,	O
simplifying	O
worst	B-General_Concept
case	I-General_Concept
execution	I-General_Concept
time	I-General_Concept
analysis	O
for	O
applications	O
that	O
need	O
hard	B-General_Concept
realtime	I-General_Concept
performance	O
.	O
</s>
<s>
Atom	B-Language
's	O
concurrency	B-Operating_System
model	O
is	O
that	O
of	O
guarded	O
atomic	B-General_Concept
actions	I-General_Concept
,	O
which	O
eliminates	O
the	O
need	O
for	O
,	O
and	O
the	O
problems	O
of	O
using	O
,	O
mutex	B-Operating_System
locks	I-Operating_System
.	O
</s>
<s>
By	O
removing	O
runtime	B-Library
task	O
scheduling	O
and	O
mutex	B-Operating_System
locking	B-Operating_System
,	O
two	O
services	O
traditionally	O
served	O
by	O
a	O
real-time	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
(	O
RTOS	B-Operating_System
)	O
,	O
Atom	B-Language
can	O
eliminate	O
the	O
need	O
and	O
overhead	O
of	O
an	O
RTOS	B-Operating_System
in	O
embedded	O
applications	O
.	O
</s>
<s>
To	O
provide	O
guarantees	O
of	O
deterministic	O
execution	B-Library
time	I-Library
and	O
memory	O
consumption	O
,	O
Atom	B-Language
places	O
several	O
restrictions	O
on	O
computing	O
.	O
</s>
<s>
First	O
,	O
Atom	B-Language
designs	O
are	O
always	O
finite	B-Architecture
state	I-Architecture
:	O
all	O
variables	O
are	O
global	O
and	O
declared	O
at	O
compile	B-Application
time	I-Application
and	O
dynamic	O
memory	O
allocation	O
is	O
disallowed	O
.	O
</s>
<s>
Second	O
,	O
Atom	B-Language
provides	O
no	O
function	O
or	O
looping	O
constructs	O
.	O
</s>
