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PostPosted: Sun Nov 05, 2017 10:13 pm 
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Battery-backed wavetable sample ram? Now I've seen everything.

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PostPosted: Mon Nov 06, 2017 12:39 am 
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There are a significant number of 163-using games (edit:) that battery-backed the wavetable RAM and used it to store save data instead of using it for audio. List on nesdevwiki:iNES Mapper 210 ("internal").


Last edited by lidnariq on Tue Nov 07, 2017 3:03 pm, edited 1 time in total.

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PostPosted: Mon Nov 06, 2017 12:56 am 
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Should SRAM files be interchangeable between emulators? If so, then it needs to be specified whether internal or external NVRAM data comes first. For compatibility with existing emulators that do not save the N163's internal RAM at all, I suggest that external NVRAM comes first.


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PostPosted: Tue Aug 07, 2018 11:45 am 
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Not knowing about this thread, I unwittingly continued this discussion over here:
Namcot 163/MMC5/Konami VRC6 Audio Level test program

Though probably if you were looking for the continuation you'd want to fast forward to NewSunRising's restatement here (most of the stuff before that is about audio, and then a bunch of me being confused).
https://forums.nesdev.com/viewtopic.php?p=222934#p222934


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PostPosted: Fri Dec 21, 2018 9:46 am 
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Maybe I am asking the dumb question, but: should EEPROM-bearing games have the iNES "Battery" bit set (in addition to having the EEPROM size in the NES 2.0 PRG-NVRAM field)? The NES 2.0 wiki page seems somewhat ambiguous about this.


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PostPosted: Fri Dec 21, 2018 10:53 pm 
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Maybe the battery bit should be set for SRAM and not be set for EEPROM. There is a field for "battery backed" WRAM in the NES 2.0 header and a field for the non-battery backed WRAM. Right now we distinguish between EEPROM and SRAM by size, SRAM generally being 1K or larger and EEPROM being smaller than 1K. I only know of 128B and 256B varieties of EEPROM used in licensed Famicom games, perhaps some of the unlicensed or bootlegs may use more. I believe 2K was the smallest discrete SRAM chip used in licensed cartridges, I can't speak for the unlicensed stuff beyond what I put in my list. There could conceivably be some game out there that uses a 1K SRAM chip and another game that uses a 1K EEPROM, so the battery bit may be the key to distinguishing what type of chip to emulate.

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