原创 How it used to be: CAD, CAE, and EDA

Electronic components and circuits were handcrafted before the 1970s. Circuit diagrams (known as schematics) were drawn using pen, paper, and stencils. Similarly, the copper tracks on a circuit board were drawn using red and blue pencils to represent the top and bottom of the board. Any form of analysis (for example, "What frequency will this oscillator run at if I use this capacitor and this resistor?") was performed with pencil, paper, and a slide rule (or a mechanical calculator if you were lucky). Not surprisingly, this style of design was time-consuming, expensive, and prone to error.

Computer-Aided Design (CAD)
As electronic designs and devices grew more complex, it became necessary to develop automated techniques to aid in the design process.

In the early 1970s, companies like Calma, ComputerVision, and Applicon created special computer programs that helped personnel in the drafting department capture hand-drawn designs in digital form using large-scale digitizing tables.
Over time, these early computer-aided drafting tools evolved into interactive programs that performed integrated circuit layout; that is, they could be used to describe the locations of the transistors forming the integrated circuit and the connections between them.

Other companies like Racal-Redac, SCI-Cards, and Telesis created equivalent layout programs for printed circuit boards (PCBs). Collectively, these integrated circuit and circuit board layout programs became known as Computer-Aided Design (CAD) tools.

Computer-Aided Engineering (CAE)
Also in the late 1960s and early 1970s, a number of universities and commercial companies started to develop computer programs known as simulators. These programs allowed students and engineers to emulate the operation of an electronic circuit without actually having to build it first.

Perhaps the most famous of the early simulators was the simulation program with integrated circuit emphasis (SPICE). This was developed by the University of California in Berkeley and was made available for widespread use around the beginning of the 1970s. SPICE was designed to simulate the behavior of analog circuits – other programs called logic simulators were developed to simulate the behavior of digital circuits.

Around the beginning of the 1980s, companies like Daisy, Mentor, and Valid spawned computer programs that allowed engineers to capture schematic (circuit) diagrams on the computer screen. These tools could then be used to generate textual representations of the circuits called netlists that described the components to be used and the connections between them. In turn, these netlists could be used to drive analog and digital simulators (and eventually layout tools).

The companies promoting front-end tools for schematic capture and simulation classed them as Computer-Aided Engineering (CAE). This was based on the fact that these tools were targeted toward design engineers, and the CAE companies wished to distinguish their products from the CAD tools that were originally used by the drafting department. (With hindsight – the one exact science – it would have made much more sense to use CAD to refer to the front-end design tools and CAL to refer to the downstream layout tools ... but it was not to be... Oh well, that's the way the cookie crumbles...)

Designers vs Engineers
If you say things the wrong way when talking to someone in the industry, you immediately brand yourself as an outsiderÿ– one of "them" instead of one of "us" (and you certainly don't want to be "one of them" (grin).

For historical reasons that are based on the origins of the terms CAD and CAE, the term layout designer or simply designer is typically used to refer to someone who lays out a circuit board (determines the locations of the components and the routes of the tracks connecting them together).

By comparison, the term design engineer or simply engineer is typically used to refer to someone who conceives and describes the functionality of an integrated circuit, printed circuit board, or electronic system (what it does and how it does it).

Electronic Design Automation (EDA)
Sometime during the 1980s, all of the CAE and CAD tools used to help design electronic components and systems came to be referred to by the "umbrella" name of Electronic Design Automation (EDA), and everyone was happy (apart from the ones who weren't, but they don't count [grin]).