https://msdn.microsoft.com/en-us/library/bb464139.aspx
Xbox 360 (2005): the GPU contains an embedded 10 MiB eDRAM; this is not sufficient to hold the raster for an entire 1280×720 image with 4× multisample anti-aliasing, so a tiling solution is superimposed when running in HD resolutions and 4× MSAA is enabled.
Xbox One (2013): the GPU contains an embedded 32 MiB eSRAM, which can be used to hold all or part of an image. It is not a tiled architecture, but is flexible enough that software developers can emulate tiled rendering.