The distinctive feature of SKETCHPAD was that it allowed the designer to interact with his computer graphically: the design can be fed into the computer by drawing on a CRT monitor with a light pen. was the development of the SKETCHPAD system at MIT in 1963 by Ivan Sutherland (who later created a graphics technology company). It is argued that the beginning of C.A.D.
CAD has fundamentally changed the way design is done.
If a change to one drawing affected other documents you were dependent upon having someone manually recognize the need to make the changes to the other drawings and to do so. Minor changes meant erasing and redrawing while major changes often meant recreating the drawing from the scratch. 25 years ago, nearly every drawing produced in the world was done with pencil or ink on paper.