KARL is the acronym of KAiserslautern Register transfer Language a pioneering early hardware description language also comping along with a graphic companion language ABL ("A Blockdiagram Language") and its hierarchical graphic editor ABLED. Both, KARL and ABL have been initiated in the 1970 by Reiner Hartenstein. KARL has been the first hardware description language supporting both, functional and structural description, so that also the structured design of VLSI floor plan layout is supported.