<s>
TUTSIM	B-Application
was	O
the	O
first	O
commercial	O
simulation	O
software	O
ever	O
to	O
run	O
on	O
an	O
IBM-PC	B-Device
.	O
</s>
<s>
The	O
package	O
was	O
used	O
for	O
the	O
modeling	O
and	O
simulation	O
of	O
multi-domain	O
systems	O
using	O
differential	O
equations	O
and	O
bond	B-Application
graphs	I-Application
.	O
</s>
<s>
TUTSIM	B-Application
(	O
Twente	O
University	O
of	O
Technology	O
SIMulator	O
)	O
was	O
developed	O
at	O
the	O
Control	O
Laboratory	O
of	O
the	O
University	O
of	O
Twente	O
in	O
the	O
early-1970s	O
.	O
</s>
<s>
The	O
program	O
was	O
initially	O
created	O
for	O
the	O
PDP-11	B-Device
and	O
LSI-11	O
series	O
of	O
DEC	O
.	O
At	O
the	O
end	O
of	O
the	O
1970s	O
it	O
was	O
ported	O
to	O
run	O
on	O
microprocessors	O
like	O
the	O
MOS	B-General_Concept
Technology	I-General_Concept
6502	I-General_Concept
of	O
the	O
Apple	B-Device
II	I-Device
and	O
the	O
Intel	B-General_Concept
8086	I-General_Concept
of	O
the	O
IBM	B-Device
Personal	I-Device
Computer	I-Device
.	O
</s>
<s>
The	O
rise	O
of	O
the	O
IBM	B-Device
PC	I-Device
gave	O
TUTSIM	B-Application
its	O
world	O
fame	O
,	O
making	O
scientific	O
simulation	O
software	O
available	O
for	O
researchers	O
all	O
over	O
the	O
world	O
.	O
</s>
<s>
Failing	O
to	O
meet	O
the	O
demands	O
of	O
a	O
graphical	O
user	O
interface	O
with	O
the	O
rise	O
of	O
Microsoft	B-Application
Windows	I-Application
in	O
the	O
late-1980s	O
the	O
popularity	O
of	O
TUTSIM	B-Application
slowly	O
faded	O
away	O
.	O
</s>
<s>
Multiple	O
requests	O
from	O
bond	B-Application
graph	I-Application
researchers	O
caused	O
the	O
University	O
of	O
Twente	O
to	O
begin	O
development	O
of	O
a	O
successor	O
to	O
TUTSIM	B-Application
.	O
</s>
<s>
This	O
resulted	O
in	O
the	O
software	O
20-sim	B-Application
,	O
released	O
by	O
Controllab	O
,	O
which	O
contained	O
many	O
of	O
the	O
features	O
that	O
made	O
TUTSIM	B-Application
popular	O
.	O
</s>
<s>
TUTSIM	B-Application
was	O
an	O
interactive	O
simulation	O
language	O
for	O
continuous	O
dynamical	O
systems	O
.	O
</s>
<s>
Input	O
had	O
to	O
be	O
given	O
in	O
block	O
diagram	O
form	O
or	O
in	O
bond	B-Application
graph	I-Application
form	O
.	O
</s>
