Twin famicom ppu glitches

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zlakomanoff
Posts: 3
Joined: Wed Nov 09, 2016 1:19 pm

Twin famicom ppu glitches

Post by zlakomanoff » Thu Jul 11, 2019 9:16 am

Hello everyone.

I was made custom game cartrige, with micro mages game, based on original "F1 Race" famicom cartrige

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when i run this cart on dandy famiclone, game working fine

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but when i run on original hardware, i got this

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game and music work fine, all sprites shown as "nine" digit,
are anyone known whats can be wrong ?

lidnariq
Posts: 8704
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Re: Twin famicom ppu glitches

Post by lidnariq » Thu Jul 11, 2019 9:32 am

Check what CHR's /OE and /CE signals are connected to. I'd hunch you've accidentally left it enabled all the time, and that interferes with the real PPU's multiplexed address/data bus. (Many famiclones demultiplexed this bus)

zlakomanoff
Posts: 3
Joined: Wed Nov 09, 2016 1:19 pm

Re: Twin famicom ppu glitches

Post by zlakomanoff » Thu Jul 11, 2019 9:50 am

lidnariq wrote:Check what CHR's /OE and /CE signals are connected to. I'd hunch you've accidentally left it enabled all the time, and that interferes with the real PPU's multiplexed address/data bus. (Many famiclones demultiplexed this bus)
CE connected to the GND, OE connected to 17 pin (PPU /RD)

lidnariq
Posts: 8704
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Re: Twin famicom ppu glitches

Post by lidnariq » Thu Jul 11, 2019 10:14 am

CHR /CE should be connected to PPU A13. /OE is correct.

zlakomanoff
Posts: 3
Joined: Wed Nov 09, 2016 1:19 pm

Re: Twin famicom ppu glitches

Post by zlakomanoff » Thu Jul 11, 2019 11:57 am

lidnariq wrote:CHR /CE should be connected to PPU A13. /OE is correct.
Yes, /CE connect to the PPU A13, looks better but something wrong
also i connect CHR EEPROM A13 to GND - game run perfect!

Thank you "lidnariq" !

Where i can read about PPU A13 behaiour ?

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lidnariq
Posts: 8704
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Re: Twin famicom ppu glitches

Post by lidnariq » Thu Jul 11, 2019 12:26 pm

... mayyyybe nesdevwiki:Cartridge connector ?
Most boards tie [PPU A13] directly to the /CE of CHR ROM or CHR RAM to map it into pattern table space ($0000-$1FFF) without any extra logic.
Or maybe nesdevwiki:PPU memory map?

NewRisingSun
Posts: 1029
Joined: Thu May 19, 2005 11:30 am

Re: Twin famicom ppu glitches

Post by NewRisingSun » Thu Jul 11, 2019 12:29 pm

I did not know that even the Dendy Junior could already deglitch the PPU signals! I thought only later famiclones could do that, because I have only seen post-2000 cartridges that require such a thing.

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