Quote Originally Posted by wal666 View Post
Hello there.. Thanks for all the info, it has been very useful. Can I buy a Japanese phantasy star IV cartridge and put the English version on it ? Are the PCB the same? I understand there is 2 mask ROMs so how do I go about splitting the ROM to put it on 2 EPROMS? Any help would be much appreciated
You could do that if you wanted to. It is likely that you could use most any cartridge that you could find for much cheaper. Lets have a look at the game in question. According to uCON64:

uCON64 2.0.0 Win32 (MinGW) 1999-2005
Uses code from various people. See 'developers.html' for more!
This may be freely redistributed under the terms of the GNU Public License

C:\Users\Jordan\Desktop\Phantasy Star IV (USA).md

Magicom/BIN/RAW

00000100 53 45 47 41 20 47 45 4e 45 53 49 53 20 20 20 20 SEGA GENESIS
00000110 28 43 29 53 45 47 41 20 31 39 39 34 2e 4e 4f 56 (C)SEGA 1994.NOV
00000120 50 48 41 4e 54 41 53 59 20 53 54 41 52 20 54 68 PHANTASY STAR Th
00000130 65 20 65 6e 64 20 6f 66 20 74 68 65 20 6d 69 6c e end of the mil
00000140 6c 65 6e 6e 69 75 6d 20 20 20 20 20 20 20 20 20 lennium
00000150 50 48 41 4e 54 41 53 59 20 53 54 41 52 20 54 68 PHANTASY STAR Th
00000160 65 20 65 6e 64 20 6f 66 20 74 68 65 20 6d 69 6c e end of the mil
00000170 6c 65 6e 6e 69 75 6d 20 20 20 20 20 20 20 20 20 lennium
00000180 47 4d 20 4d 4b 2d 31 33 30 37 20 2d 30 30 05 cb GM MK-1307 -00..
00000190 4a 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 J
000001a0 00 00 00 00 00 2f ff ff 00 ff 00 00 00 ff ff ff ...../..........
000001b0 52 41 f8 20 00 20 00 01 00 20 3f ff 20 20 20 20 RA. . ... ?.
000001c0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
000001d0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
000001e0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
000001f0 34 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 4

Genesis/Sega Mega Drive/Sega CD/32X/Nomad
PHANTASY STAR The end of the millennium
Sega
Brazil
3145728 Bytes (24.0000 Mb)

Padded: Maybe, 46572 Bytes (0.3553 Mb)
Interleaved/Swapped: No
Backup unit/emulator header: No
Japanese game name: PHANTASY STAR The end of the millennium
Date: 1994.NOV
Internal size: 24.0000 Mb
ROM start: 00000000
ROM end: 002fffff
Cartridge RAM: Yes, 15 kBytes (backup)
RAM start: 00200001
RAM end: 00203fff
Product type: Game
I/O device(s): 3 Button Pad
Modem data:
Memo:
Product code: MK-1307
Version: 1.00
Checksum: Ok, 0x05cb (calculated) == 0x05cb (internal)
Checksum (CRC32): 0xfe236442
The information above shows that the game seems pretty typical. 24MegaBits, or 3MBytes starting at address 0x00000000 to 0x002fffff and has SRAM. However, SRAM is located at 0x00200001 to 0x00203FFF. You'll notice that SRAM overlaps with the ROM, so you'll need a slightly different cart. One such cart is descirbed in detail here:
http://forums.nesdev.com/viewtopic.p...11615&start=15
So the Japanese copy would probably be easiest to mod. I don't see many carts like that one. In fact I don't have any as far as I know. if you come across another cartridge with two ROMs, one SRAM a 74ls74 and 74ls139, let me know. We can rewire it if need be.