waits until ly=3
sets lyc to 6
enables lyc int
enables mode2 int
waits for int

on int:
jumps to 0x1000
nops til next mode2
reads IF
outputs value of IF&3

DMG-08 / CGB:
m2irq_before_lycint_1.gb should output 1
m2irq_before_lycint_2.gb should output 3