Hey guys,
I know what some will say but I really want to have a X3 cart to play on real hardware. I live in Australia and Mega Man X3 is fetching some ridiculous prices.
Anyway I managed to grab a X2 donor from Japan and want to do a basic 2 x 27C801 eprom exchange to it for X3.
I used the same pinout I have used for Star Fox 2 repro. I wired up all 64 pads with wires and split the PAL X3 rom in 2 and wrote have to each eprom. I just get a blank screen.
I have checked all wiring and it is all correct.
Does X2 carts have a different pinout to the regular SNES mask roms? Do I need to patch the rom first before I can make it work?
I read another thread about doing this the other way using a X3 PCB to make a X2 and it mentioned patching the rom.
If someone can help that would be great. This is purely for my personal use and collection.
The Japanese cartridge would have a NTSC CIC. Maybe that is the issue?
Markfrizb wrote:
The Japanese cartridge would have a NTSC CIC. Maybe that is the issue?
I am running the game on a SuperCIC modded console so I don't think that is the issue.
So is the mask rom the same pinout as a regular SNES game and with the X3 rom do I just split it down the middle and write first half to rom 1 and second have to rom 2?
mamejay wrote:
Markfrizb wrote:
The Japanese cartridge would have a NTSC CIC. Maybe that is the issue?
I am running the game on a SuperCIC modded console so I don't think that is the issue.
So is the mask rom the same pinout as a regular SNES game and with the X3 rom do I just split it down the middle and write first half to rom 1 and second have to rom 2?
The SMT mask roms have the same pinout as the dip mask roms. There's no difference. I doubt this could be the issue, but there have been some reports that sometimes the OE and CE lines are switched. It's might be worth investigating.
As far as splitting the rom, it should be split at the highest address point (someone correct me here if I'm wrong )-- at the $1FFFF. I'm going off memory here as I am away from the computer.
I am not family with the hex code. I use Wasabi to split the file into 2 pieces which does run correctly in an emulator.
I just read somewhere that when trying to put X2 onto a X3 cart the rom needed to be patched. I removed all the hookup leads and soldered the original mask roms back in and the cart works with X2 I know that the cart is working.
I might try soldering all the cables on again. Might have missed one.
If you have a cart dumper, I would dump the cart and check that both ROMs are mapped correctly.
As far as I know, by default the second ROM chip is disabled. Mega man X2 enables the second ROM, Mega man X3 doesn't?
You may have to patch the ROM or rewire the board.
There is a register in the Cx4 that determines whether the upper ROM bank is mapped to a single ROM (like in MMX3), or whether it's mapped to a second ROM (like in MMX2). You'd need to patch MMX3 to set that register properly in order to use MMX2 as a donor board. I don't remember exactly which register it is, sorry. There's a couple of ways you could get around this in hardware, but the easiest would be to use a single 16Mbit ROM wired up to the ROM1 pads, then manually wire the high address line to pin 34 on the Cx4 chip.
qwertymodo wrote:
There is a register in the Cx4 that determines whether the upper ROM bank is mapped to a single ROM (like in MMX3), or whether it's mapped to a second ROM (like in MMX2). You'd need to patch MMX3 to set that register properly in order to use MMX2 as a donor board. I don't remember exactly which register it is, sorry. There's a couple of ways you could get around this in hardware, but the easiest would be to use a single 16Mbit ROM wired up to the ROM1 pads, then manually wire the high address line to pin 34 on the Cx4 chip.
Interesting. I have made a few repros where they are a single 2mb rom game and I have split them onto a 2 rom board using 1mb eproms.
I will look into it . I think I have a few 27C160 chips floating around somewhere.
Yeah, that works for most simple mappers, but since the Cx4 sits fully between the cart bus and the ROM chips, it handles the 2-ROM situation a bit differently.
If you search this forum, I think the patch information was posted here before. Not necessarily this sub-forum, but nesdev in general.
I know the info was posted, but I don't know if an actual patch was ever completed. Probably just easier to wire it up like I described.
Edit: Here you go.
byuu wrote:
And by the way, if you do attempt to flash in RMX2, it will need one tiny code patch. Somewhere in the game it writes #$01 to $7f52. That needs to be commented out or set to #$00. (I may have the bit flipped in my head again.) The register toggles whether banks 20-3f go to the second ROM chip or not.
qwertymodo wrote:
I know the info was posted, but I don't know if an actual patch was ever completed. Probably just easier to wire it up like I described.
Edit: Here you go.
byuu wrote:
And by the way, if you do attempt to flash in RMX2, it will need one tiny code patch. Somewhere in the game it writes #$01 to $7f52. That needs to be commented out or set to #$00. (I may have the bit flipped in my head again.) The register toggles whether banks 20-3f go to the second ROM chip or not.
So inversely, to play x3 using the x2 board will you have to change #$00 in the x3 ROM to #$01?
It depends on the default/power up state of the register and if it is consistent or not. To be safe you might want to be sure that the register is set to the proper value for how many rom chips are being used.
MottZilla wrote:
It depends on the default/power up state of the register and if it is consistent or not. To be safe you might want to be sure that the register is set to the proper value for how many rom chips are being used.
How would I go as to doing this.