What is it?
Computer-aided design has not completely replaced the drawing board and pen. Many creative professionals prefer to begin their work manually and, in many architects' offices, a couple of terminals sit alongside rows of drawing boards and plan chests. However, when it comes to archiving, manipulating, reproducing and transporting drawings, digitised designs have many advantages.
Where did it originate?
The first design package, Sketchpad, was developed in the early 1960s at about the same time IBM developed a Cad program for General Motors.
The first successful mass-market Cad package, Autodesk's Autocad, arrived in 1982, one year after the launch of the IBM PC.
Cad makes heavy demands on processors and memory and the first PCs had 8bit chips with a 64Kbyte Ram and an upper expansion limit of 640Kbytes.
Early PC Cad packages permitted "wireframe" drawings and "2.5D", rather than full 3D designs. More sophisticated drawings needed expensive graphics workstations. However, current PC Cad packages can handle most design and solid modelling requirements.
How does it work?
Designers specify the thickness, colour and other characteristics of lines drawn between points on a visible or invisible grid. Co-ordinates can be specified in three dimensions, and the Cad software stores them and displays them on screen.
The 3D objects can be rotated to present the required view. Once created, the drawings can be manipulated, copied or integrated into other drawings.
Because the drawings are in a virtual space, they are not restricted in scale as a hard copy would be. The drawings can be viewed at any level, from the most minute detail to the object in its entirety. Instead of using transparent overlays, layers can be added or removed from drawings automatically.
Cad can also be used in conjunction with computer-aided manufacturing and engineering systems, where digitised design can be used to drive machine tools.
What makes it special?
Cad eliminates much of the repetitive work of designing. It allows drawings to be re-used and modified. A UK office can provide modifications to a project in the Middle East as fast as a network connection allows.
How difficult is it to master?
You can use Cad even if you cannot draw, but you will still need to understand design principles. It is a tool, not a substitute for expertise.
Where is it used?
In engineering, manufacturing, architecture, facilities management and in craftwork such as jewellery design.
Not to be confused with...
Bounders, rotters, bad eggs and filthy upstarts.
What does it run on?
PCs, Macs, graphics workstations and supercomputers. Half of all companies using Cad in the UK use Autocad, but there are many other packages which meet different engineering and design needs.
What is coming up?
New facilities for sharing and managing drawings over the web.
Cad training is available from universities and colleges, suppliers and their partners and a host of small specialist companies offering courses for specific industries.
Rates of pay
Support jobs and public sector positions command about £15,000, but this rises to £40,000 plus for architects and mechanical engineers.
This was first published in July 2003