<s>
The	O
general	B-Device
purpose	I-Device
analog	I-Device
computer	I-Device
(	O
GPAC	O
)	O
is	O
a	O
mathematical	O
model	O
of	O
analog	O
computers	O
first	O
introduced	O
in	O
1941	O
by	O
Claude	O
Shannon	O
.	O
</s>
<s>
The	O
GPAC	O
can	O
be	O
implemented	O
in	O
practice	O
through	O
the	O
use	O
of	O
mechanical	B-Device
devices	I-Device
or	O
analog	O
electronics	O
.	O
</s>
<s>
In	O
particular	O
it	O
was	O
shown	O
in	O
2007	O
that	O
(	O
a	O
deterministic	O
variant	O
of	O
)	O
the	O
GPAC	O
is	O
equivalent	O
,	O
in	O
computability	O
terms	O
,	O
to	O
Turing	B-Architecture
machines	I-Architecture
,	O
thereby	O
proving	O
the	O
physical	O
Church	O
–	O
Turing	O
thesis	O
for	O
the	O
class	O
of	O
systems	O
modelled	O
by	O
the	O
GPAC	O
.	O
</s>
<s>
The	O
General	B-Device
Purpose	I-Device
Analog	I-Device
Computer	I-Device
was	O
originally	O
introduced	O
by	O
Claude	O
Shannon	O
.	O
</s>
<s>
This	O
model	O
came	O
as	O
a	O
result	O
of	O
his	O
work	O
on	O
Vannevar	O
Bush	O
's	O
differential	B-Device
analyzer	I-Device
,	O
an	O
early	O
analog	O
computer	O
.	O
</s>
