Gameboy Development Forum

Hi all,
Fairly new to development on the Gameboy and I'm looking at ways to create a simple dungeon or FPS. It wouldn't be a proper first person shooter, more of a dungeon scroller. I guess I'm looking for advice on how best to achieve this. I'm using prerendered images, resized in Photoshop with a limited colour scheme (4 colour gameboy palette).

At present my idea is to create a sort of slideshow with limited options, trouble is I believe I'm filling the bank quite quickly by this method and have to employ bank switching for this to work. I have found that I can fit three images on screen(one after the other) before GBDK complains about an overwrite i.e. WARNING: Multiple write of  1649 bytes at 0x4000 -> 0x4670 (4000 -> 47af, 4000 -> 4670)

I am mainly using draw_image(); with a small delay between each image. Can anyone provide me with a practical example of bank switching? If not - is there an alternative way around my problem?

Thanks in advance...