bunnyboy wrote:
Of course getting the new mapper info out there is the harder part. Otherwise its an extra incentive for people to buy the physical game!
Hum... I'd rather have it be easy to run... don't ask me why! =)
bunnyboy wrote:
The only USA games that used SUROM are Dragon Warrior 3 and Dragon Warrior 4.
Bootgods awesome site is much more complete (and correct) than the boardtable.txt. You should be able to take the SNROM board, reroute the unused CHR A16 to the PRG A18. A18 is likely tied to gnd on the pcb so you can bend that pin up or cut the trace. Battery isn't required so cut it off or just leave it there.
I just found my Hatris cart. I'll do the conversion now and see what happens. I'll probably just leave the battery... Although I don't need it, it's presence does not bother me, and I might break the cart while trying to remove it. When you say "cut it off", what do you mean exactly? What would be the correct procedure for removing the battery?
bunnyboy wrote:
Also make sure in your code to set the CHR A16 of BOTH banks to the correct value, or the PRG could be switched while rendering.
I understand the reason for that, but I recently read this from the wiki:
wiki wrote:
In 4KB CHR bank mode, the P bits in both CHR bank registers must be set to the same value, or the PRG ROM will be bankswitched as the PPU renders, causing disastrous results. As there is not much of a reason to use 4 KB bankswitching with CHR RAM, it is wise for programs to just set 8 KB bankswitching mode in the Control register.
So I though I was safe by using 8KB CHR bankswitching. Man, I already find the way registers are written a pain in the ass, if I had to do it
twice to switch between the 256KB parts that would really suck.
Bregalad wrote:
- You said you hate the MMC1, but it's just a slightly enhanced UNROM like mapper if you look it that way.
What I hate is the way the registers are written to, one bit at a time. Each swap will require at least 30 CPU cycles worth of code. That's just too much when you need a lot of bankswitching. I have however been able to think of a way to cut down on the ammount of bankswitching during the processing of the frame by rearranging some of the data in the ROM and by copying some data to WRAM. I'm not a big fan of the 4KB CHR bankswitching either, but that will not matter as long as I use CHR-RAM.
Bregalad wrote:
- While only DW3 and DW4 uses SUROM in the United States (and a couple of more games in japan), any SNROM board can be converted to SUROM by changing ONE wire, wich is less than the number of wires you should change to make a SNROM board accept regular EPROMs. Just tie A18 to CHR A16 (the pin is originally on PRG R/W for some reason, SNROM have 2 pins connected to it).
I'll do this to my Hatris cart. I'm a bit confused about what you said about the pin being connect to PRG R/W. Could you explain it a bit better?
Bregalad wrote:
- I don't know if you will be able to sell repros if your game is labelled Sonic, so I don't think you will want to avoid MMC3 just for that. I may be wrong tough.
I know. That's one of the reasons I don't plan on selling it. But I don't want to make it hard to reproduce either. I'm all for breaking loose from the need of Nintendo-made boards... so that should be incentive enough, no?
Bregalad wrote:
- If you already made complex routines with CHRRAM, think again before to switch to (usually more limited) CHRROM. That doesn't mean you should avoid this, if you feel like doing this, do it but be sure of what you're doing.
If I use the MMC1 I'll sure stick to CHR-RAM. I have almost made my mind. The final product will be closer to the original design if I do it like this.