1. A method for fabricating an analog memristor crossbar array, comprising: providing an insulating layer on part of a substrate; providing a trench within the insulating layer to expose a portion of a substrate surface; providing a first electrode layer on said insulating layer and in said trench, said first electrode layer connecting with said portion of said substrate surface to provide a self-aligning first electrode layer; planarizing the first electrode layer and the insulating layer to isolate said first electrode layer from all adjacent electrode layers with the insulating layer; providing a memristive layer on said planarized first electrode layer; and forming a second electrode on said memristive layer; wherein said first electrode layer forms a continuous first electrode bar extending along the length of the memristor crossbar array; wherein said providing a memristive layer on said planarized first electrode layer comprises: providing a memristive layer bar along the length of said first electrode bar; and wherein said forming a second electrode on said memristive layer comprises forming a second electrode on said memristive layer bar wherein the memristive layer bar is arranged to self-align the second electrode on the memristive layer bar anywhere along the length of the first electrode bar.