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Author Topic: Trouble with Final Fantasy III and MMC5 mapper patch  (Read 1044 times)

Chaos Rush

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Trouble with Final Fantasy III and MMC5 mapper patch
« on: June 29, 2016, 04:31:47 am »
So I've applied Kea's FFIII MMC5 mapper patch onto a clean Japanese Final Fantasy III ROM and then expanded it up to 0x10000F, as per instructed by the MMC5 patch's readme file.

What I'm trying to do is have it load a copy of the vanilla game's text table, but from one of the expanded PRG banks. In the vanilla ROM, the text pointer tables start at 0x30010 (the actual text data starts at 0x30D70 and ends at 0x3E00E). I've copied the data from 0x30010-0x3E00E over to 0x80010-0x8E00E but I can't get the game to read the 'new' text table at 0x80010.

What I've found so far (with the help of FCEUX's debugger) is that the byte at 0x7EEAB controls what bank is loaded into $8000 every time a message box pops up. The default value is 0x18, which in turn loads the bank that starts at 0x30010 (which is where the text table is located in the vanilla ROM). According to my calculations, putting 0x40 at 0x7EEAB should load the bank that starts at 0x80010, but it instead loads the bank starting at 0x00010 (so rather than loading the first added PRG bank, it instead "rolls over" to bank 0 which is already in the ROM to begin with).

So, using Kea's FFIII MMC5 Mapper patch applied to a clean Japanese ROM, how would I get the game to recognize the added PRG banks?

Disch

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Re: Trouble with Final Fantasy III and MMC5 mapper patch
« Reply #1 on: June 29, 2016, 10:29:03 am »
Looks like Kea's instructions on how to expand the ROM are incomplete.  You also need to change the PRG size in the header to get emus to recognize that there's more PRG.

Offset 0x00004 is the PRG size.  Original value is '20'.  Double that to '40'

Chaos Rush

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Re: Trouble with Final Fantasy III and MMC5 mapper patch
« Reply #2 on: June 29, 2016, 11:45:53 am »
Looks like Kea's instructions on how to expand the ROM are incomplete.  You also need to change the PRG size in the header to get emus to recognize that there's more PRG.

Offset 0x00004 is the PRG size.  Original value is '20'.  Double that to '40'
Oh my God it works... Thank you! I can load data from added banks now. Now everything is all set up for me to start working on my Final Fantasy III translation!