Vinyl siding installed over cement board (might be asbestos).  This vinyl siding is a low end brand (Cedar Creek) with a .04″ thickness and a thinner butt (1/2″).  At a cost of $45 per 100 square feet, it is affordable and covers nicely over the somewhat uneven surface of the cement board.  This house is one I’ve worked on before (installed siding on the back and aluminum fascia/soffit all around).