Different behaviour between real NES and Emulators in Battle City

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Ben Boldt
Posts: 1149
Joined: Tue Mar 22, 2016 8:27 pm
Location: Minnesota, USA

Re: Different behaviour between real NES and Emulators in Battle City

Post by Ben Boldt »

Wow, what a strange failure. Since the normal writes work, that sort of proves that the addressing and /DBE between CPU and PPU works. I think reading must work in order to read the PPU status. So that means CPU R/W must also work. So I am not seeing any way that something external to the PPU has a problem, indicating a PPU broken in a very strange way.

I believe that you can cheaply replace the PPU with UA6528 (NTSC) or UA6528P (PAL) from AliExpress.

https://www.nesdev.org/wiki/PPU_variants
MastErAldo
Posts: 14
Joined: Wed Jun 29, 2022 6:07 am

Re: Different behaviour between real NES and Emulators in Battle City

Post by MastErAldo »

Ben Boldt wrote: Sat Jul 02, 2022 6:53 pm I believe that you can cheaply replace the PPU with UA6528 (NTSC) or UA6528P (PAL) from AliExpress.

https://www.nesdev.org/wiki/PPU_variants
Ah, good to know, thanks!

Anyway if anyone is wondering, the main screen of SMB now appears like this:
Image
The "constant" parts (title, 1 player, 2 players) are invisible, while the high score is garbage. Can't really see from the photo, but the high score is like random pixels. The mushroom seems fine, but I guess it's because it is displayed in a different way, more like the other overlayed texts.
Attachments
smb glitch.jpg
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