Dragon Quest III Translation Repro

Hi,

Another repro question!

I am trying to make a DQIII repro using an original Jap copy of the game, which is a SHVC-1J3M-20 board with only 1 Mask ROM. The translated DQIII ROM is 48Mb in size, meaning I have to use 2x'033 chips in parallel, one soldered in front and one on the back. I am struggling with the wiring scheme for the onboard Mad-1 chip in order to get this working. I have had a look around forums but I can't find any definitive info.

I imagine that I need to wire the /OE lines of the 2 new chips to pins 1 and 16 of the MAD-1, but is there anything else I need to do?

 

Update, I found this on the nintendoage forum, where someone suggests using an LS139 decoder:

Does this work in my case?

 

Update 2, I also found this on a RackeyBoy forum, seems easier since no decoder?

 

Keep us posted on how you get along on this. I have a DQ3 cart and I'm curious about doing this myself as well.

 

OK managed to get it working, using this tutorial.

All the pictures and circuit diagram had gone dead, so I asked the OP to reupload them and he did. Works great.