Very late reply, just for posterity: I was mistaken about the GBC not having a Joypad interrupt. Turns out I just had a bug, and apparently misread or misunders

Very late reply, just for posterity: I was mistaken about the GBC not having a Joypad interrupt. Turns out I just had a bug, and apparently misread or misunderstood something somewhere along the line that made me think that was the cause.