How computer software works


Computer aided design

Computer-aided design (CAD) is the usecoined by Doug Ross at MIT in 1959.[6]
of a wide range of computer-based toolsIt is argued that a turning point was
that assist engineers, architects andthe development of SKETCHPAD system in
other design professionals in theirMIT in 1963 by Ivan Sutherland (who
design activities. It is the mainlater created a graphics technology
geometry authoring tool within thecompany with Dr. David Evans). The
Product Lifecycle Management process anddistinctive feature of SKETCHPAD was
involves both software and sometimesthat it allowed the designer to interact
special-purpose hardware. Currentwith his computer graphically: the
packages range from 2D vector baseddesign can be fed into the computer by
drafting systems to 3D solid and surfacedrawing on a CRT monitor with a light
modellers.pen. Effectively, it was a prototype of
CAD is sometimes translated asgraphical user interface, an
"computer-assisted", "computer-aidedindispensable feature of modern CAD.
drafting", or a similar phrase. RelatedFirst commercial applications of CAD
acronyms are CADD, which stands forwere in large companies in the
"computer-aided design and drafting",automotive and aerospace industries, as
CAID for Computer-aided Industrialwell as in electronics. Only large
Design and CAAD, for "computer-aidedcorporations could afford the computers
architectural design". All these termscapable of performing the calculations.
are essentially synonymous, but thereNotable company projects were at GM (Dr.
are some subtle differences in meaningPatrick J.Hanratty) with DAC-1 (Design
and application.Augmented by Computer) 1964; Lockhead
CAD was originally the three letterprojects; Bell GRAPHIC 1 and at Renault
acronym for "Computer Aided Draughting"(Bezier) – UNISURF 1971 car body
as in the early days CAD was really adesign and tooling.
replacement for the tradition draughtingOne of the most influential events in
board. But now is the term is oftenthe development of CAD was the founding
interchanged with "Computer Aidedof MCS (Manufacturing and Consulting
Design" to reflect the fact that modernServices Inc.) in 1971 by Dr. P. J.
CAD tools do much more than justHanratty[7], who wrote the system ADAM
draughting.(Automated Drafting And Machining) but
Introductionmore importantly supplied code to
CAD is used to design, develop andcompanies such as McDonnell Douglas
optimize products, which can be goods(Unigraphics), Computervision (CADDS),
used by end consumers or intermediateCalma, Gerber, Autotrol and Control
goods used in other products. CAD isData.
also extensively used in the design ofAs computers became more affordable, the
tools and machinery used in theapplication areas have gradually
manufacture of components, and in theexpanded. The development of CAD
drafting and design of all types ofsoftware for personal desk-top computers
buildings, from small residential typeswas the impetus for almost universal
(houses) to the largest commercial andapplication in all areas of
industrial structures (hospitals andconstruction.
factories).Other key points in the 1960s and 1970s
CAD is mainly used for detailedwould be the foundation of CAD systems
engineering of 3D models and/or 2DUnited Computing, Intergraph, IBM,
drawings of physical components, but itIntergraph IGDS in 1974 (which led to
is also used throughout the engineeringBentley MicroStation in 1984)
process from conceptual design andCAD implementations have evolved
layout of products, through strength anddramatically since then. Initially, with
dynamic analysis of assemblies to2D in the 1970s, it was typically
definition of manufacturing methods oflimited to producing drawings similar to
components.hand-drafted drawings. Advances in
CAD has become an especially importantprogramming and computer hardware,
technology with benefits, such as lowernotably solid modeling in the 1980s,
product development costs and a greatlyhave allowed more versatile applications
shortened design cycle, because CADof computers in design activities.
enables designers to lay out and developKey products for 1981 were the solid
their work on screen, print it out andmodelling packages -Romulus (ShapeData)
save it for future editing, saving a lotand Uni-Solid (Unigraphics) based on
of time on their drawings.PADL-2 and the release of the surface
Designers have long used computers formodeler CATIA (Dassault Systemes).
their calculations. Initial developmentsAutodesk was founded 1982 by John
were carried out in the 1960s within theWalker, which led to the 2D system
aircraft and automotive industries inAutoCAD. The next milestone was the
the area of 3D surface construction andrelease of Pro/ENGINEER in 1988, which
NC programming, most of it independentheralded greater usage of feature-based
of one another and often not publiclymodeling methods and parametric linking
published until much later. Some of theof the parameters of features. Also of
mathematical description work on curvesimportance to the development of CAD was
was developed in the early 1940s bythe development of the B-rep solid
Isaac Jacob Schoenberg, Apalatequimodeling kernels (engines for
(Douglas Aircraft) and Roy Liming (Northmanipulating geometrically and
American Aircraft), however probably thetopologically consistent 3D objects)
most important work on polynomial curvesParasolid (ShapeData) and ACIS (Spatial
and sculptured surface was done byTechnology Inc.) at the end of the 1980s
Pierre Bezier (Renault), Paul deand beginning of the 1990s, both
Casteljau (Citroen), Steven Anson Coonsinspired by the work of Ian Braid. This
(MIT, Ford), James Ferguson (Boeing),led to the release of mid-range packages
Carl de Boor (GM), Birkhoff (GM) andsuch as SolidWorks in 1995, SolidEdge
Garabedian (GM) in the 1960s and W.(Intergraph) in 1996, and IronCAD in
Gordon (GM) and R. Riesenfeld in the1998. Today CAD is one of the main tools
1970s.used in designing products.
The term "computer-aided design" was



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