some questions about SNES repros

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shion arita
Posts: 1
Joined: Fri Jul 13, 2018 9:28 am

some questions about SNES repros

Post by shion arita » Fri Jul 13, 2018 1:09 pm

I've successfully made some NES reproductions/translations in the past, and would like to get into doing it for SNES. I've found some unclear/conflicting information about the compatibility of donor boards, so I'd like to see if I can clear that up.

One game that I would like to make is an English Fire Emblem: Monshou no Nazo, and the first question is in realtion to that:

There would be some difficulties in using the orignal board, since upon opening it I find that it has the somewhat unusual SHVC-BA3M-01 board. The It's a 24 megabit lorom split
into what I'm guessing is a 16M mask rom and an 8m. I'd prefer not to have to use 2 chips in mine, plus the translation expands the rom to 32m.

So, I've been looking into using other donor boards. The one I have right now is SHVC-1A3B-13, which uses the 74LS139 decoder chip. Here is where the unclear information starts. The decoder switches between the Sram and the rom, and I've heard that the MAD1 decodor chip is necessary for switching between 3 chips (2 rom and ram, like in the original) But I've

and the question I have is whether I can put one 32m chip on the SHVC-1A3B-13, which has the 74LS139 and have it work, or will I have to get a different lorom 64kSram board that has a MAD1, such as SHVC-1A3M-10? Or could I also use an additional different decoder chip (I do have a few 74LS139P)?

The second question pertains to making games over 32mbit. One game I want to make is Fire Emblem: Seisen no Keifu (32m Hirom SHVC-1J3M-20. The translation of this game doubles the rom size to 64m, so I would theoretically need 2 32m chips and a memory decoder. However, the only instructions I've found are for games like Tales of Phantasia and Star Ocean, which seem to have some kind of special layout(?) So how would I make a 'regular' 64m game? Can it be done on a 'regular' donor, like SHVC-1J3M-20?

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