GIF decoder in Microsoft QBasic. Based on my Python GIF decoder/encoder.
Limitations:
- size: 320×200 pixels or less
- only the first image in the file will be decoded
- the image must use the Global Color Table (not a Local Color Table)
- there must be no extra fields before the first image
Some of the included GIF files are from Commander Keen 4: Secret of the Oracle, Doom and Wolfenstein 3D by id Software.