Magic is an interactive system for creating and modifying VLSI circuit layouts. With Magic, you
use a color graphics display and a mouse or graphics tablet to design basic cells and to combine
them hierarchically into large structures. Magic is different from other layout editors you may
have used. The most important difference is that Magic is more than just a color painting tool:
it understands quite a bit about the nature of circuits and uses this information to provide you
with additional operations. For example, Magic has built-in knowledge of layout rules; as you
are editing, it continuously checks for rule violations. Magic also knows about connectivity and
transistors, and contains a built-in hierarchical circuit extractor. Magic also has a plow operation
that you can use to stretch or compact cells. Lastly, Magic has routing tools that you can use to
make the global interconnections in your circuits.
Magic is based on the Mead-Conway style of design. This means that it uses simplified design
rules and circuit structures. The simplifications make it easier for you to design circuits and permit
Magic to provide powerful assistance that would not be possible otherwise. However, they result
in slightly less dense circuits than you could get with more complex rules and structures. For
example, Magic permits only Manhattan designs (those whose edges are vertical or horizontal).
Circuit designers tell us that our conservative design rules cost 5-10% in density.