1. A method for inputting and editing an engineering drawing to a computer aided design system having a video monitor, said drawing being created on quadrille paper having criss-crossing lines, said criss-crossing lines having a first and second set of spaced apart parallel lines, said lines in the first and second set being perpendicular to each other, comprising the steps of: optically reading said drawing on said quadrille paper and producing an electrical output signal representative thereof, electrically connecting said electrical output signal as an input signal to the computer aided design system to form a video image representation so that said drawing is displayed on said video monitor, superimposing a grid pattern on the video monitor of the computer aided design system corresponding in scale to the quadrille paper, editing said displaying drawing by comparison of said displayed drawing and said superimposed grid pattern and thereafter altering said video image representation to conform to said drawing on said quadrille paper, whereby comparison of said superimposed grid pattern with said drawing on said video monitor facilitates editing of said drawing.