Pixel explorer

Drop a memory dump, a screen saved by a DOS game, or any file that may hold a picture, and try its bytes as pixels. A wrong width shows as slanted stripes. Change it by one until the picture stands straight, then move the offset to the start of the picture. A 64,000-byte block that shows a screen at 320 by 200 is a raw 256-colour screen. Drop a palette as well (768 bytes of RGB, or a file that holds one) to see the real colours.

The modes are those of the PC's video hardware (2D graphics). In a project, tools/formats/rawimage.py writes the same picture as a PNG, for comparing with the port's frames.