This applies to the N64 Everdrive - I don't have any of the others, so I don't know if it's applicable, but I thought I'd post it here just in case.To use a background image (in the Everdrive 64, at least) you need to use a 640 x 480 bitmap file (.bmp) with 16 bit depth. The problem is, I couldn't find a program that would create or convert a .bmp file to 16 bit, but I finally got it to work using a freeware program called Easy Graphic Converter, from http://www.etrusoft.com/graphic-converter/index.htm
GIMP can do this easily. Save as a bmp file and you get a dialog box with an advanced options control. Expand it and you'll see you can set it to save as 16 bit, 24 bit, or 32 bit. Under 16 bit, you get a choice of R5 G6 B5, or X1 R5 G5 B5. Select one and click save for a 16 bit bmp file.
