We first heard about Toshiba's plan to increase NAND flash capacities by building "3D" memory chips with "pillars" of stacked cells in January of 2007, but it looks like the effort is getting revived -- Tosh and SanDisk have entered into an agreement to jointly develop and cross-license 3D memory tech. SanDisk was once rumored to be developing write-once 3D flash chips, so both companies have experience building the stuff, but it sounds like it'll take another three or four years for the partnership to produce actual products, as high-yield production is still difficult.

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