What is a floorplan?

This paper surveys the more important oorplan models and their u s e in the backend of chip design.Floorplans are here considered as data structures that capture the relative p ositions o f o b je c t s i n a p lane.This is in correspondance with how they were introduced in design automation in the early eighties: as a generalization of placement, that is t h e m anipulation of geometrically xed objects in order to get an overlap-free arrangement of these objects in a plane region.The introduction of the oorplanning concept n o t o n ly liberated back-end design from its (manual) puzzle character and its intractable and sometimes even undecidable problems, but a l s o enabled hierarchical design, even taking a functional hierarchy a n d transforming it by stepwise re nement into a oorplan with a compatible representation.The elegance of that procedure was so overpowering that many identi ed oorplanning with hierarchical back-end design.That oorplanning proves to be a powerful notion by itself becomes once more apparent, since almost all modern effective \placement" procedures are in essence oorplanning followed by packing or some other \legalization" stage.