MMC3 big CHR RAM test
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Author:  tepples [ Thu Feb 25, 2016 9:34 pm ]
Post subject:  MMC3 big CHR RAM test

FCEUX hasn't made an official release in years. The latest official release (2.2.2) doesn't even support NES 2.0. FCEUX SVN does, and builds for Windows are available from EmuCR, but instead of a smooth download experience, it links to a bunch of file upload sites that fill the screen with ads, including fake download buttons that are ads for malware installers.

Why NES 2.0? Because a project I'm working on needs MMC3 with 32K CHR RAM. The test ROM fails on the official FCEUX release but works on FCEUX SVN.

This test ROM distinguishes three situations:
  1. Writing 8K and reading back 8K fails. It assumes a dirty connector.
  2. Writing 8K and reading back 8K succeeds, but doing the same for 32K fails. It assumes lack of NES 2.0 support.
  3. Writing 32K and reading back 32K succeeds. Congratulations!

FCEUX release, my PowerPak, and someone's EverDrive all show 8K but not 32K.

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Author:  thefox [ Thu Feb 25, 2016 11:23 pm ]
Post subject:  Re: MMC3 big CHR RAM test

Have you tried with PowerMappers on PowerPak? It should work.

Author:  zxbdragon [ Fri Feb 26, 2016 12:16 am ]
Post subject:  Re: MMC3 big CHR RAM test


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Author:  tepples [ Fri Feb 26, 2016 9:42 am ]
Post subject:  Re: MMC3 big CHR RAM test

zxbdragon wrote:
15:11: The first 8 KiB of CHR RAM failed to verify
15:10: Title screen with scrambled CHR RAM
15:09: Congratulations!

Which version of Nestopia was this, and what steps did you take to make this happen?

A few hours later:

"Congratulations!" PowerMappers worked.

Author:  FHorse [ Sun Feb 28, 2016 3:15 am ]
Post subject:  Re: MMC3 big CHR RAM test

Fixed in puNES. Thanks for the rom.

Author:  tepples [ Mon Nov 21, 2016 8:34 pm ]
Post subject:  Re: MMC3 big CHR RAM test

Is this still broken on the EverDrive?

Author:  Quietust [ Mon Nov 21, 2016 9:19 pm ]
Post subject:  Re: MMC3 big CHR RAM test

For what it's worth, Nintendulator 0.975 appears to pass (which is good, because it means my NES 2.0 support is at least partially working). In theory, it should be able to handle up to 256KB of CHR RAM (since the PRG/CHR ROM/RAM buffers are all statically allocated in .bss), which is conveniently the maximum amount the MMC3 itself can handle.

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