About F-1 race

Hi, everyone.
A strange situation occurred when my emulator run F-1 race.
Screen flashes once, then the lights change color.
This behavior was repeated four times(because 4 lights) before the car rush.
Did this behavior occured because of no APU implementation?

Certainly not.

Thank you.

Notice that each time the grid lights change (and plays a buzz sound), the screen glitches. It may be related with APU, yes.

Even if it is, the question to begin with is loaded with too many freaking variables.

The game writes $C0 to $4017, disabling frame IRQs, plus writes $00 to $4001/4005 (sweep off) and to $4011, plus $0F to $4015.
RAM at $01Cx are mirrors of the sound registers, like $01C0=$4000,$01C1=$4001,$01C2=$4002 etc.

Interesting, the game does a couple of timed writes to $4017 (always $C0).

When the APU is enabled/disabled on WedNESday there is no glitching. Therefore something is wrong with his emulator. Obviously it must be to do with sound then.

Why didn't you mention this right off the bat?

Sorry thefox. Just to clarify that WedNESday runs it just fine.

What I mean is no APU emulation means that it cannot be to do with the APU as I remember running this on WedNESday with NO APU emulation and it was error free. Obviously, its a timing issue where the NES updates the PPU address but outside of VBLANK. Or it could be a Sprite 0 problem.

Boolean how is the emulator on blargg's Sprite 0 tests?

blargg's sprite 0 hit tests(sprite_hit_tests_2005.10.05) and ppu tests(blargg_ppu_tests_2005.09.15b) almost pass. But there are some errors.
VirtuaNES has the same result.

Error code:
2) Should miss when entirely in left-edge clipping
2) Hit time shouldn't be based on pixels under left clip
6) Palette read should also read VRAM into read buffer