<s>
Digital	O
computers	O
were	O
used	O
in	O
power	O
system	O
analysis	O
or	O
optimization	O
as	O
early	O
as	O
proto-	O
"	O
Whirlwind	B-Device
"	O
in	O
1949	O
.	O
</s>
<s>
Circuit	O
design	O
theory	O
or	O
power	O
network	O
methodology	O
was	O
algebraic	B-Language
,	O
symbolic	O
,	O
and	O
often	O
vector-based	O
.	O
</s>
<s>
Between	O
the	O
mid-1940s	O
and	O
1950s	O
,	O
various	O
developments	O
were	O
made	O
in	O
computer	B-Application
software	I-Application
.	O
</s>
<s>
In	O
1953	O
,	O
MIT	O
researcher	O
Douglas	O
T	O
.	O
Ross	O
saw	O
the	O
"	O
interactive	O
display	O
equipment	O
"	O
being	O
used	O
by	O
radar	O
operators	O
,	O
believing	O
it	O
would	O
be	O
exactly	O
what	O
his	O
SAGE-related	O
data	B-General_Concept
reduction	I-General_Concept
group	O
needed	O
.	O
</s>
<s>
Ross	O
and	O
the	O
other	O
researchers	O
from	O
the	O
Massachusetts	O
Institute	O
of	O
Technology	O
Lincoln	O
Laboratory	O
were	O
the	O
sole	O
users	O
of	O
the	O
complex	O
display	O
systems	O
installed	O
for	O
the	O
pre-SAGE	O
Cape	O
Cod	O
system	O
.	O
</s>
<s>
These	O
programs	O
also	O
enabled	O
objects	O
to	O
be	O
reproduced	O
at	O
will	O
;	O
it	O
also	O
was	O
possible	O
to	O
change	O
their	O
orientation	O
,	O
linkage	B-Language
(	O
flux	O
,	O
mechanical	O
,	O
lexical	B-Language
scoping	I-Language
)	O
,	O
or	O
scale	O
.	O
</s>
<s>
Ross	O
coined	O
the	O
term	O
computer-aided	B-Application
design	I-Application
(	O
CAD	B-Application
)	O
in	O
1959	O
.	O
</s>
<s>
The	O
invention	O
of	O
the	O
3D	O
CAD/CAM	O
is	O
attributed	O
to	O
French	O
engineer	O
Pierre	O
Bézier	O
(	O
Arts	O
et	O
Métiers	O
ParisTech	O
,	O
Renault	O
)	O
.	O
</s>
<s>
Between	O
1966	O
and	O
1968	O
,	O
after	O
his	O
mathematical	O
work	O
concerning	O
surfaces	O
,	O
he	O
developed	O
UNISURF	B-Algorithm
to	O
ease	O
the	O
design	O
of	O
parts	O
and	O
tools	O
for	O
the	O
automotive	O
industry	O
.	O
</s>
<s>
UNISURF	B-Algorithm
then	O
became	O
the	O
working	O
base	O
for	O
the	O
following	O
generations	O
of	O
CAD	B-Application
software	I-Application
.	O
</s>
<s>
In	O
parallel	O
,	O
French	O
carmaker	O
Citroen	O
had	O
developed	O
its	O
design	O
system	O
SPAC	O
(	O
system	O
de	O
programmatic	O
automatique	O
Citroen	O
)	O
as	O
part	O
of	O
its	O
CAD/CAM	O
solution	O
SADUSCA	O
(	O
aid	O
systems	O
for	O
the	O
defining	O
and	O
the	O
machining	O
of	O
bodywork	O
surfaces	O
)	O
,	O
both	O
based	O
on	O
the	O
1959	O
mathematical	O
works	O
of	O
Paul	O
de	O
Casteljau	O
.	O
</s>
<s>
In	O
1968	O
,	O
it	O
used	O
an	O
IBM	O
360-40	O
,	O
then	O
360-65	O
for	O
batch	O
jobs	O
,	O
but	O
already	O
had	O
a	O
graphical	B-Application
interface	I-Application
with	O
an	O
IBM	O
2250	O
prototype	O
.	O
</s>
<s>
The	O
development	O
of	O
the	O
SKETCHPAD	B-Application
system	O
at	O
MIT	O
by	O
Ivan	O
Sutherland	O
,	O
who	O
later	O
created	O
a	O
graphics	O
technology	O
company	O
with	O
David	O
Evans	O
,	O
was	O
a	O
turning	O
point	O
.	O
</s>
<s>
The	O
distinctive	O
feature	O
of	O
SKETCHPAD	B-Application
was	O
that	O
it	O
allowed	O
the	O
designer	O
to	O
interact	O
with	O
their	O
computer	O
graphically	O
;	O
the	O
design	O
can	O
be	O
fed	O
into	O
the	O
computer	O
by	O
drawing	O
on	O
a	O
CRT	B-Device
monitor	I-Device
with	O
a	O
light	B-Device
pen	I-Device
.	O
</s>
<s>
In	O
effect	O
,	O
this	O
feature	O
of	O
SKETCHPAD	B-Application
was	O
a	O
prototype	O
for	O
a	O
graphical	B-Application
user	I-Application
interface	I-Application
,	O
an	O
indispensable	O
feature	O
of	O
modern	O
CAD	B-Application
.	O
</s>
<s>
In	O
1963	O
,	O
under	O
doctoral	O
adviser	O
Claude	O
Shannon	O
,	O
Sutherland	O
presented	O
his	O
PhD	O
thesis	O
paper	O
,	O
Sketchpad	B-Application
:	O
A	O
Man-Machine	O
Graphical	O
Communication	O
System	O
,	O
at	O
a	O
Joint	O
Computer	O
Conference	O
.	O
</s>
<s>
Over	O
time	O
,	O
efforts	O
would	O
be	O
directed	O
toward	O
the	O
goal	O
of	O
having	O
the	O
designers	B-Algorithm
 '	I-Algorithm
drawings	I-Algorithm
communicate	I-Algorithm
not	O
just	O
with	O
shops	O
,	O
but	O
also	O
with	O
the	O
shop	O
tool	O
itself	O
;	O
however	O
,	O
it	O
was	O
a	O
long	O
time	O
before	O
this	O
goal	O
was	O
achieved	O
.	O
</s>
<s>
The	O
first	O
commercial	O
applications	O
of	O
CAD	B-Application
were	O
in	O
large	O
companies	O
within	O
the	O
automotive	O
and	O
aerospace	O
industries	O
,	O
as	O
well	O
as	O
in	O
electronics	O
.	O
</s>
<s>
Notable	O
company	O
projects	O
included	O
a	O
joint	O
project	O
between	O
Patrick	O
J	O
.	O
Hanratty	O
from	O
GM	O
and	O
Sam	O
Matsa	O
,	O
Doug	O
Ross	O
's	O
MIT	O
APT	O
research	O
assistant	O
from	O
IBM	O
,	O
to	O
develop	O
a	O
prototype	O
system	O
for	O
design	O
engineers	O
,	O
DAC-1	B-Algorithm
(	O
Design	O
Augmented	O
by	O
Computer	O
)	O
1964	O
,	O
Lockheed	O
projects	O
,	O
Bell	O
GRAPHIC	O
1	O
,	O
and	O
Renault	O
.	O
</s>
<s>
One	O
of	O
the	O
most	O
influential	O
events	O
in	O
the	O
development	O
of	O
CAD	B-Application
was	O
the	O
founding	O
of	O
Manufacturing	O
and	O
Consulting	O
Services	O
Inc	O
.	O
(	O
MCS	O
)	O
in	O
1971	O
by	O
Patrick	O
J	O
.	O
Hanratty	O
,	O
who	O
wrote	O
the	O
system	O
Automated	O
Drafting	O
And	O
Machining	O
(	O
ADAM	O
)	O
,	O
but	O
more	O
importantly	O
supplied	O
code	O
to	O
companies	O
such	O
as	O
McDonnell	O
Douglas	O
(	O
Unigraphics	B-Algorithm
)	O
,	O
Computervision	O
(	O
CADDS	B-Application
)	O
,	O
Calma	O
,	O
Gerber	O
,	O
Autotrol	O
,	O
and	O
Control	O
Data	O
.	O
</s>
<s>
As	O
computers	O
became	O
more	O
affordable	O
,	O
the	O
application	O
of	O
CAD	B-Application
gradually	O
expanded	O
into	O
new	O
areas	O
.	O
</s>
<s>
The	O
development	O
of	O
CAD	B-Application
software	I-Application
for	O
personal	O
desktop	O
computers	O
was	O
the	O
impetus	O
for	O
almost	O
universal	O
application	O
in	O
all	O
areas	O
of	O
construction	O
.	O
</s>
<s>
Other	O
notable	O
events	O
in	O
the	O
1960s	O
and	O
1970s	O
include	O
the	O
foundation	O
of	O
CAD	B-Application
systems	O
United	O
Computing	O
,	O
Intergraph	O
,	O
IBM	O
,	O
and	O
Intergraph	O
IGDS	O
in	O
1974	O
(	O
which	O
led	O
to	O
Bentley	O
Systems	O
MicroStation	B-Algorithm
in	O
1984	O
)	O
,	O
as	O
well	O
as	O
the	O
Applicon	O
in	O
1969	O
and	O
commercial	O
CAD	B-Application
systems	O
from	O
Japanese	O
manufacturers	O
Seiko	O
and	O
Zuken	O
during	O
the	O
1970s	O
.	O
</s>
<s>
CAD	B-Application
implementations	O
have	O
evolved	O
dramatically	O
since	O
this	O
early	O
development	O
.	O
</s>
<s>
Initially	O
,	O
with	O
3D	O
in	O
the	O
1970s	O
,	O
CAD	B-Application
was	O
typically	O
limited	O
to	O
producing	O
drawings	O
similar	O
to	O
hand-drafted	O
drawings	O
.	O
</s>
<s>
In	O
1981	O
,	O
the	O
key	O
products	O
were	O
the	O
solid	O
modeling	O
packages	O
—	O
Romulus	B-Application
(	O
ShapeData	O
)	O
and	O
Uni-Solid	O
(	O
Unigraphics	B-Algorithm
)	O
based	O
on	O
PADL-2	O
—	O
and	O
the	O
surface	O
modeler	O
CATIA	B-Algorithm
(	O
Dassault	O
Systemes	O
)	O
.	O
</s>
<s>
Autodesk	O
was	O
founded	O
in	O
1982	O
by	O
John	O
Walker	O
,	O
which	O
led	O
to	O
the	O
two-dimensional	O
system	O
AutoCAD	B-Algorithm
.	O
</s>
<s>
The	O
next	O
milestone	O
was	O
the	O
release	O
of	O
Pro/ENGINEER	B-Algorithm
in	O
1987	O
,	O
which	O
heralded	O
greater	O
usage	O
of	O
feature-based	O
modeling	O
methods	O
and	O
parametric	O
linking	O
of	O
the	O
parameters	O
of	O
features	O
;	O
this	O
marked	O
the	O
introduction	O
of	O
parametric	O
modeling	O
.	O
</s>
<s>
Also	O
important	O
to	O
the	O
development	O
of	O
CAD	B-Application
was	O
the	O
development	O
in	O
the	O
late	O
1980s	O
and	O
early	O
1990s	O
of	O
B-rep	B-Algorithm
solid	B-Algorithm
modeling	I-Algorithm
kernels	I-Algorithm
(	O
engines	O
for	O
manipulating	O
geometrically	O
and	O
topologically	O
consistent	O
3D	O
objects	O
)	O
,	O
Parasolid	B-Application
(	O
ShapeData	O
)	O
,	O
and	O
ACIS	O
(	O
Spatial	O
Technology	O
Inc	O
.	O
)	O
.	O
</s>
<s>
This	O
subsequently	O
led	O
to	O
the	O
release	O
of	O
mid-range	O
packages	O
such	O
as	O
SolidWorks	B-Application
and	O
TriSpective	O
(	O
later	O
known	O
as	O
IRONCAD	B-Algorithm
)	O
in	O
1995	O
,	O
Solid	B-Algorithm
Edge	I-Algorithm
(	O
then	O
Intergraph	O
)	O
in	O
1996	O
,	O
and	O
Autodesk	B-Device
Inventor	I-Device
in	O
1999	O
.	O
</s>
<s>
An	O
independent	O
geometric	B-Algorithm
modeling	I-Algorithm
kernel	I-Algorithm
has	O
been	O
evolving	O
in	O
Russia	O
since	O
the	O
1990s	O
.	O
</s>
<s>
Availability	O
of	O
free	B-License
and	I-License
open-source	I-License
CAD	B-Application
software	I-Application
and	O
high	O
costs	O
of	O
advanced	O
and	O
3D	O
CAD	B-Application
software	I-Application
may	O
restrain	O
the	O
growth	O
of	O
the	O
CAD	B-Application
software	I-Application
market	O
.	O
</s>
<s>
Free	B-License
and	I-License
open-source	I-License
CAD	B-Application
software	I-Application
packages	O
include	O
BRL-CAD	B-Language
developed	O
for	O
the	O
US	O
Army	O
,	O
LibreCAD	B-Language
,	O
FreeCAD	B-Language
,	O
and	O
others	O
.	O
</s>
<s>
CAD	B-Application
software	I-Application
:	O
</s>
