Collection of test roms to check and verify the behavior of the Gameboy Color during the development of my emulator - MagenBoy
Well during the development of MagenBoy (My gameboy emulator) I found plenty of test roms and information about the original Gameboy (DMG).
Unfortuntly, now when adding support for the Gameboy Color (CGB) I had a hard time finding all the information online so I decided to try and test it myself
The gameboy color has 3 different places where the priority between the Background layer and the OAM a layer can be declared.
This test verifies the reltions between those flags and the behavior when they colide.
Checkout the PanDocs for background on the CGB behavior.
You should see 5 green squares and 3 half grren and half blue squares with no red lines
Screnshoot from Orignal CGB hardware
Special thanks to ISSOtm for running this test rom on original hardware, verifying it actually works and screenshoting the result.
The gameboy color changes the way the PPU manages its internal OAM objects priority.
For more info checks the PanDocs.
You should see 2 pairs of rectangles connected or touching each other.