Castlevania: Castlevania UNROM to MMC3 Hack

Here is a patch that converts Castlevania's mapper from UNROM to MMC3. Documentation is included.

5/26/12
UPDATE 7/16/13
infidelity

Castlevania UNROM to MMC3

MMC3 Bankswap Routine To Insert Into ROM = 0A48A9068D0080688D0180090148A9078D0080688D018060

$1C1A6 loads bank id from $1C010-$1C017
$1C1A9-$1C1AE performs a double STA,Y to $C000

So, find a free location in the rom to place the bankswap routine, then, at $1C1A9, put...
20####EAEAEA, and thats it.

Done!

UPDATE 7-16-13

Now works on an actual NES!

I've placed the Bankswap routine and the CHR register setup within the DPCM of when Simon gets hit. It's barely noticeable to me, but if someone is willing to do a thorough runthrough of this game, to find a good amount of unused space within the HW bank, i'll be more than happy to relocate my work out of Simon's DPCM sample.

$1C039 = 2058FF EA
$1C1A9 = 2040FF EAEAEA
$1FF43 (chr values) = 000204050607

Following Is Witin Simon's DPCM Sample
$1FF50-$1FF67 (Bankswap) = 0A48A9068D0080688D0180090148A9078D0080688D018060
$1FF68 (CHR Routine JSR'd From Reset Vector) = A2058E0080BD33FF8D0180CA10F4A906852460
END

UPDATE 7/20/13

ISSUE REGARDING MIRRORING

Need to add Mirroring Mode within Reset Vector. For Castlevania it starts as Vertical

$1FF76 = A900 8D00A0 A906 8524 60
END

Castlevania (USA).nes - NOINTRO
CRC32: 39C879BB
MD5: 00D93C9F6B8AEFB8B6C02B20147DF4EC
SHA-1: A31B8BD5B370A9103343C866F3C2B2998E889341
SHA-256: 55BCAB0D9EFC33A9D9EFC90F2C3C4AB12F3221A44B1F357E6C6202A456399AA8