Abstract— Memristive crossbars have been shown to be excellent candidates for building an ultra-dense memory system because a per-cell access-transistor may no longer be necessary. However, the elimination of the access-transistor introduces several parasitic effects due to the existence of partially-selected devices during memory accesses, which could limit the scalability of access-transistor-free (ATF) memristive crossbars. In this paper we discuss these challenges in detail and describe some solutions addressing these challenges at multiple levels of design abstraction.