STEM: An IC Design Environment Based on the Smalltalk Model-View-Controller Construct

STEM (SmallTalk Environment of Module design) is an IC design environment written in Smalltalk aimed at integrating design automation tools with manual design. STEM is based on the Smalltalk model-view-controller concept. Each cell in the database is represented by a single Smalltalk class. This serves as the "model" and encapsulates all (permanent) information about the cell. Different design representations of the single model are achieved by calculating views which are strictly temporary. All views of an object are linked to the model. This allows views to be updated whenever a change in the model\´s state is detected, and prevents permanent aliases of data. Design changes are entered using a Smalltalk controller attached to the model.