<s>
In	O
computation	O
,	O
a	O
finite-state	B-Architecture
machine	I-Architecture
(	O
FSM	O
)	O
is	O
event	O
driven	O
if	O
the	O
transition	O
from	O
one	O
state	O
to	O
another	O
is	O
triggered	O
by	O
an	O
event	O
or	O
a	O
message	O
.	O
</s>
<s>
This	O
is	O
in	O
contrast	O
to	O
the	O
parsing-theory	O
origins	O
of	O
the	O
term	O
finite-state	B-Architecture
machine	I-Architecture
where	O
the	O
machine	O
is	O
described	O
as	O
consuming	O
characters	O
or	O
tokens	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
telecommunication	O
protocol	O
is	O
most	O
of	O
the	O
time	O
implemented	O
as	O
an	O
event-driven	B-Application
finite-state	I-Application
machine	I-Application
.	O
</s>
<s>
This	O
code	O
describes	O
the	O
state	B-Architecture
machine	I-Architecture
for	O
a	O
very	O
basic	O
car	O
radio	O
system	O
.	O
</s>
<s>
The	O
state	B-Architecture
machine	I-Architecture
is	O
only	O
2	O
states	O
:	O
radio	O
mode	O
,	O
or	O
CD	O
mode	O
.	O
</s>
<s>
is	O
an	O
industrial-strength	O
compiler	O
producing	O
multitape	O
finite	B-Architecture
state	I-Architecture
automata	I-Architecture
from	O
rational	O
patterns	O
,	O
functions	O
and	O
relations	O
expressed	O
in	O
semiring	O
algebraic	O
terms	O
.	O
</s>
