The designers made this calculating machine in 1973. The designers looked at a picture by Antonello da Messina from the 15th century. The picture shows a prayer desk. A prayer desk is a high table at which you can stand and pray. The prayer desk has a sloping surface at the top for a book. The calculating machine Logos 58 is shaped like the prayer desk in the picture. The shape is like a wedge or a triangle. The designers made it that way because it is better for the body.