Updated NES and FC EPROM conversion text file

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HVC-Man
Posts: 45
Joined: Wed Nov 25, 2015 7:54 pm

Updated NES and FC EPROM conversion text file

Post by HVC-Man » Sun Oct 04, 2020 10:32 am

I have this file from a long time ago, it has a lot more information in it than the usual text file hosted on nesdev.com:

http://nesdev.com/NES%20EPROM%20Conversions.txt

Hopefully this is useful to you guys here.

Contents of updated version:

Code: Select all

Using EPROMs in place of NES and Famicom Mask ROMS:

27CXXX series EPROMs,
27C64, 27C128, 27C256, 27C512, 27C010, 27C020, 27C040

You can use standard EPROMs/EEPROMs/FlashROMs on NROM, CNROM, MHROM, SAROM, SBROM, SEROM, AN1ROM, TBROM, TEROM, TVROM and most non-Nintendo made boards.
More specifically all chips below or equal to 64KB (or 512 kbits if you prefer) have standard pinout, while chips above or equal to 128KB (or 1MBit) have a swapped pinout, except for some non-Nintendo made boards.

Shortcut: 27C010 = highest address is A16. 27C020 = A17. 27C040 = A18. 

If using a 27C010 for CHR in a SL1ROM or TL1ROM, wire like UNROM and if need be lift and wire pin 24 to pin 22. If using 27C512 or less, just lift pin 1, pin 22 and wire it to pin 20. 

SROM (mapper 0, FC only)
PRG socket:
no modifications necessary
CHR socket:
Bend up pins 1, 2, 20, 23, 27, 28
solder pin 2 to hole 21 (A12)
solder pin 20 to GND (CE)
solder pin 23 to hole 18 (A11)
solder pin 28 to pin 27 to pin 26 to pin 1 (VCC)

NROM (mapper 0):
No modifications necessary

CNROM (mapper 3):
No modifications necessary

UNROM (32 pin EPROM in a 28 pin socket): 
Bend up pins 1, 2, 24, 31, 32
Solder pin 1 to pin 32 to pin 31 to pin 30 (VCC)
solder pin 2 to hole 24 (A16)
solder pin 24 to GND (OE)

UNROM -> UOROM conversion (Nintendo ver.):
Bend up pins 1, 2, 24, 30, 31, and 32
Bend up 74xx32 pins 9 and 10
Bend up 74xx161 pin 6
Solder pin 2 to hole 22 (A16)
Solder pin 24 to GND (/OE)
Solder pin 1 to pin 32 to pin 31 to hole 28 (VCC)
Solder 74xx32 pin 9 to 74xx32 pin 12 or 5 or 2
Solder 74xx32 pin 10 to 74xx161 pin 11
Solder 74xx32 pin 8 to pin 30 (A17)
Solder 74xx161 pin 6 to pin 17 (D3)
Adjust H / V mirroring


SNROM (mapper 1):
Bend up pins 1, 2, 24, 30 and 31 (or cut tracks 2, 24 and 30)
Solder pin 2 to hole 24 (A16)
Solder pin 24 to GND (OE)
Solder pin 30 to hole 1 (A17)

SNROM -> SUROM Conversion (mapper 1):
Bend up pins 1, 2, 24, 30, and 31 (or cut tracks 2, 24, 30 and 31)
Solder pin 2 to hole 24 (A16)
Solder pin 24 to GND (OE)
Solder pin 30 to hole 1 (A17)
Cut track from MMC1 pin 11 to WRAM pin 20
Solder pin 31 to pin 11 of MMC1 chip (A18)
Solder pin 20 of WRAM to Ground (CE or CHR /A13)

SNROM -> SJROM Conversion (mapper 1):
PRG ROM:
Bend up pins 1, 2, 24, 30 and 31
Solder pin 2 to hole 24 (A16)
Solder pin 24 to GND (OE)
Solder pin 30 to hole 1 (A17)
CHR ROM:
Remove 8K SRAM
Bend up pins 1, 26, 27
Solder pin 26 to MMC1 pin 8
Solder pin 27 to MMC1 pin 9
Solder pin 1 to MMC1 pin 10
(and so on and so forth)

SOROM -> SNROM Conversion (mapper 1):
Bend up pins 1, 2, 24, 30 and 31
Solder pin 2 to hole 24 (A16)
Solder pin 24 to GND (OE)
Solder pin 30 to hole 1 (A17)
Cut track from MMC1 pin 10 to WRAM /CE control
Solder WRAM /CE control to VCC
Solder MMC1 pin 11 to WRAM 1 pin 20 (/CE)
(WRAM 0 goes unused)

SLROM (mapper 1):
PRG socket:
Bend up pins 1, 2, 24, 30 and 31 (or cut tracks)
Solder pin 2 to hole 24 (A16)
Solder pin 24 to GND (OE)
Solder pin 30 to hole 1 (A17)
CHR socket:
Bend up pins 1, 2, 22, 24, 30 and 31 (or cut tracks)
Solder pin 2 to hole 24 (A16)
Solder pin 22 to hole 31 (CE or CHR /A13)
Solder pin 24 to hole 2 (OE or CHR /RD)

TKROM & TSROM (mapper 4):
PRG socket:
Bend up pins 1, 2, 24, 30 and 31 (or cut tracks 2, 24, 30 and 31)
Solder pin 2 to hole 24 (A16)
Solder pin 24 to GND (OE)
Solder pin 30 to hole 1 (A17) (only for 27C020)
Solder pin 31 to hole 2 (A18) (only for 27C040)
CHR socket:
Bend up pins 1, 2, 22, 24, 30, 31 (or cut tracks 2, 22, 24 and 30)
Solder pin 2 to hole 24 (A16)
Solder pin 22 to hole 31 (CE or CHR /A13)
Solder pin 24 to hole 2 (OE or CHR /RD)
Solder pin 30 to hole 1 (A17) (only for 27C020)

TKROM -> TNROM conversion (mapper 4):
PRG socket:
Bend up pins 1, 2, 24, 30 and 31 (or cut tracks 2, 24, 30 and 31)
Solder pin 2 to hole 24 (A16)
Solder pin 24 to GND (OE)
Solder pin 30 to hole 1 (A17)
Solder pin 31 to hole 2 (A18)
CHR RAM conversion:
Seat the RAM chip 2 pins back (pin 1 of RAM is pin 3 of socket)
cut track to hole 3, 22, 24, 28 and 29
Solder pin 1 to hole 30 (+5V)
Solder pin 20 to hole 31 (CE or CHR /A13)
Solder pin 22 to hole 2 (OE or CHR /RD)
Solder pin 26 to hole 28 (+5V or RESET)
Solder pin 27 to NES pin 56 (CHR /WR), you will probably need to glue in the missing tab on the PC board that goes into the NES, I used a thin piece of metal and super glued it, then sanded it with fine sand paper

FKROM (mapper 10, FC only):
Same as TKROM & TSROM

FJROM (mapper 10, FC only):
PRG socket:
Bend up pins 1, 2, 24, 30 and 31 (or cut tracks 2, 24 and 30)
Solder pin 2 to hole 24 (A16)
Solder pin 24 to GND (OE)
Solder pin 30 to hole 1 (A17)
CHR socket:
no modifications necessary.

AMROM -> AOROM conversion (mapper 7):
Bend up pins 1, 2, 24, 30, 31, 32
Solder pin 1 to pin 32 to pin 31 to hole 28 (VCC)
solder pin 2 to hole 22 (A16)
solder pin 24 to GND (OE)
solder pin 30 to pin 12 of '161 (A17)

UNROM -> AOROM conversion (mapper 7):
Bend up pins 1, 2, 24, 30 and 31
remove '32 chip
Bend up pin 6 of '161 or cut track
Solder pin 2 to pin 13 of '161 (or hole 1 of '32 socket)
Solder pin 18 to pin 6 of '161
Solder pin 24 to GND (OE)
Solder pin 30 to pin 12 or '161 (or hole 13 of '32 socket)
Bridge gap between pins 3 and 4 where '32 was
Bridge gap between pins 5 and 6 where '32 was
remove solder gap from either V or H
solder middle tab of V/H pads to pin 11 of '161
Solder pins 31 and 32 to hole 28

MMC5 (mapper 5):
PRG socket: 
Bend up pins 1, 2, 24, 30 and 31
Solder Pin 1 to Hole 30 (A19)
Solder pin 2 to hole 24 (A16)
Solder pin 24 to hole 31 (/CE)
Solder pin 30 to hole 1 (A17)
Solder pin 31 to hole 2 (A18)
CHR socket:
bend up pins 1, 2, 22, 24, 30 and 31
Solder Pin 1 to Hole 30 (A19)
Solder pin 2 to hole 24 (A16)
Solder pin 22 to hole 31 (/CE)
Solder pin 24 to hole 22 (A13)
Solder pin 30 to hole 1 (A17)
Solder pin 31 to hole 2 (A18)

MMC5 + CHR-RAM (mapper 5):
PRG socket: 
Bend up pins 1, 2, 24, 30 and 31
Solder Pin 1 to Hole 30 (A19)
Solder pin 2 to hole 24 (A16)
Solder pin 24 to hole 31 (/CE)
Solder pin 30 to hole 1 (A17)
Solder pin 31 to hole 2 (A18)
CHR socket:
Bend up pins 22, 26, 27, 28
set pin 1 in hole 3
Solder Pin 22 to Hole 31
Solder pin 26 and Pin 28 to Hole 32
Solder pin 27 to cart edge pin 56 (NES) or pin 47 (FC)

MMC5 PRG RAM (mapper 5):
64Kbit SRAM
Bend up pins 1, 20, 22, 26, 27, 28
Solder pin 2 to PRG pin 4 etc (skip pin 1)
Solder pin 20 to MMC5 71
Solder pin 22 to GND
Solder pin 26 to NES pin 56 or FC pin 47
Solder pin 27 to MMC5 76
Solder pin 28 to MMC5 56
Battery
Lift MMC5 pin 57
Solder + side to 1k resistor to MMC5 pin 57
Solder - side to GND

Konami 2Mbit up (FC only): 
No modifications necessary.

Bandai (Mapper 16, FC only)
32 pin EPROMs in 28 pin sockets
PRG socket: 
Bend up pins 1, 2, 24, 30, 31, 32
Solder pin 1 to pin 32 to hole 28
Solder pin 2 to hole 22
Solder pin 24 to pin 16
Solder pin 30 to FCG-1 pin 40
CHR socket: 
Bend up pins 1, 2, 24, 31, 32
Solder pin 1 to pin 32 to pin 31 to pin 30/hole 28
Solder pin 2 to hole 22
Solder pin 24 to pin 16


Bandai (Mapper 159, FC only) (should work for most Bandai published games, except 32KB or less games):
PRG and CHR:
Bend up pins 1, 2, 24, 30
Solder pin 1 to pin 32
Solder pin 2 to hole 24
Solder pin 24 to pin 16
Solder pin 30 to hole 1

Sunsoft-5A Gremlins 2 -> Gimmick (Mapper 69): 
PRG:
Bend up pins 1, 2, 24, 30, 31, 32
Solder pin 1 to pin 32 to pin 31 to hole 28 (VCC)
solder pin 2 to hole 22 (A16)
solder pin 24 to GND (OE)
solder pin 30 to mapper pin 32 (A17)
CHR:
No modifications necessary.

CNROM-256K (Mapper 185) -> CNROM (Mapper 3):
Remove D1 and D2
CHR ROM:
Solder pin 27 (PGM) to pin 28 (VCC)

TLSROM (mapper 118) -> TLROM (mapper 4):
Bend up MMC3 pin 12 (A17)
Bend up CHR pin 30 (A17)
Solder CHR pin 30 to MMC3 pin 12 (A17)
Solder NES pin 22 or FC pin 18 or MMC3 pad 12 (CIRAM A10) to MMC3 pin 10 (CIRAM A10)

PRG RAM 32KB (256Kbit) -> PRG RAM 8KB (64Kbit):
Solder pin 26 to pin 28

drk421@yahoo.com
Attachments
NES-FC EPROM Conversions.txt
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