Help needed Tales Of Phantasia with 3 x 27c160

(also posted on nesdev, maybe it will helps other members...)

Hi guys !

I'm trying to make a translated TOP with 3 x 27c160 (3 x 2mo).
I've already make some mods with 2 x 27c160 (much easier than this one ^^), but this time I don't know how to proceed..

Eproms seems to be soldered/connected correctly as its not my first time and I've verified every connections few times (just in case).

I've already make a thing on the board : lift MAD-1 pin 13 and connect it to A22 (which is connected to pin 48 ) like on TOP board.

How to connect eproms correctly with the mad-1, with a 74ls139 or a 74ls138 I suppose ?, maybe not...


Donor board : Romancing Saga 3 : 32 mbit hirom + 64kb sram


Some pictures of the original Romancing Saga 3 board

Front


rom removed



Back



Thanks for your lights far better than mine

 

ToP is an odd game.

1st half (16MB) is wired like a LOROM (mode 20) game and the second half is wired like an HIROM (Mode 21) game with 32MB of ROM.

What that means ? Means that the last two eproms are wired straight to every single pin of the cartridge connector while the first eprom skips A15.

So if you piggy back them, the 1st EPROM has to be with it's A15 pin and up connected one addres line ahead on the bus.