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Another MMC3 Clone: T1
Posted: Fri Mar 11, 2016 7:12 pm
by Fisher
Looks like I'm very lucky!!
Just found another MMC3 Clone, named T1:
So far, so good. It's Tom & Jerry.
But I would like to mod it, so... I removed the memories and the mapper.
So I could get a cool "naked" scan of the board:
But then I tested the ROMs on my testboard, no boot!!
Why? As I suspected, the ROMS are pin swapped!
I dumped the PRG and the CHR, generated the checksums, took a look at the checksums on Bootgod's site and tried some combinations with Farid's Rom pin swapper.
So far, so good. I could find the PRG pin sequence:
Code: Select all
.--\/--.
VCC |01 32| VCC
A11 |02 31| NC
A10 |03 30| NC
A12 |04 29| A14
A9 |05 28| A15
A8 |06 27| A16
A7 |07 26| A13
A6 |08 25| A1
A5 |09 24| /OE
A4 |10 23| A0
A3 |11 22| GND (/CE)
A2 |12 21| D7
D2 |13 20| D6
D1 |14 19| D5
D0 |15 18| D4
GND |16 17| D3
`------´
But could not find the CHR's
Maybe the CHR ROM's contents were edited, or I just couldn't find the right pin sequence.
I stopped at this:
Code: Select all
.--\/--.
VCC |01 32| VCC
? |02 31| NC
? |03 30| NC
A7 |04 29| ?
A8 |05 28| ?
A6 |06 27| A9
A5 |07 26| ?
A4 |08 25| ?
A3 |09 24| PPU /RD (/OE)
A2 |10 23| ?
A1 |11 22| A13 (/CE)
A0 |12 21| D7
D0 |13 20| D6
D1 |14 19| D5
D2 |15 18| D4
GND |16 17| D3
`------´
With this in mind, the mapper pins are more or less like this:
Code: Select all
.--\/--.
M2 |01 40| VCC
CPU R/W |02 39| PPU A10
/ROMSEL |03 38| PPU A11
? |04 37| ?
? |05 36| PRG A0
? |06 35| CPU A13
PRG /OE |07 34| CPU A14
CPU D0 |08 33| /IRQ
CPU D1 |09 32| ?
CPU D2 |10 31| CIRAM A10
CPU D3 |11 30| CHR ROM Pin 30
CPU D4 |12 29| CHR ROM Pin 23
CPU D5 |13 28| CHR ROM Pin 25
CPU D6 |14 27| CHR ROM Pin 26
CPU D7 |15 26| CHR ROM Pin 28
PRG A13 |16 25| CHR ROM Pin 29
PRG A14 |17 24| CHR ROM Pin 3
PRG A15 |18 23| CHR ROM Pin 2
PRG A16 |19 22| ?
GND |20 21| PRG A17 ?
`------´
Could someone please help me fill the "blanks"?
I'm attaching a link both ROMS. Split and with both md5sum and crc32 on a text file:
https://drive.google.com/file/d/0B0OtMD ... sp=sharing
if it's not OK, just tell me and I'll remove it right away!
Thanks in advance!
Re: Another MMC3 Clone: T1
Posted: Sat Mar 12, 2016 5:53 am
by Joe
How do these look? There might be mistakes, I can't get Farid's pin swapper to work (no VB6 runtime here).
PRG:
Code: Select all
___ ___
| V |
+5V--|01 32|--+5V
A11--|02 31|--A18
A10--|03 30|--A17
A12--|04 29|--A14
A9--|05 28|--A15
A8--|06 27|--A16
A7--|07 26|--A13
A6--|08 25|--A1
A5--|09 24|--/OE
A4--|10 23|--A0
A3--|11 22|--GND (/CE)
A2--|12 21|--D7
D2--|13 20|--D6
D1--|14 19|--D5
D0--|15 18|--D4
GND--|16 17|--D3
|_______|
CHR:
Code: Select all
___ ___
| V |
+5V--|01 32|--+5V
A16--|02 31|--
A10--|03 30|--A17
A7--|04 29|--A11
A8--|05 28|--A12
A6--|06 27|--A9
A5--|07 26|--A13
A4--|08 25|--A14
A3--|09 24|--PPU /RD (/OE)
A2--|10 23|--A15
A1--|11 22|--PPU A13 (/CE)
A0--|12 21|--D7
D0--|13 20|--D6
D1--|14 19|--D5
D2--|15 18|--D4
GND--|16 17|--D3
|_______|
"T1" MMC3 clone:
Code: Select all
___ ___
| V |
M2--|01 40|--+5V
CPU R/W--|02 39|--PPU A10
/ROMSEL--|03 38|--PPU A11
--|04 37|--PPU A12
--|05 36|--CPU A0
--|06 35|--CPU A13
PRG /OE--|07 34|--CPU A14
CPU D0--|08 33|--/IRQ
CPU D1--|09 32|--
CPU D2--|10 31|--CIRAM A10
CPU D3--|11 30|--CHR A17
CPU D4--|12 29|--CHR A15
CPU D5--|13 28|--CHR A14
CPU D6--|14 27|--CHR A13
CPU D7--|15 26|--CHR A12
PRG A13--|16 25|--CHR A11
PRG A14--|17 24|--CHR A10
PRG A15--|18 23|--CHR A16
PRG A16--|19 22|--
GND--|20 21|--PRG A17
|_______|
Unknown (not installed):
Code: Select all
___ ___ ___ ___
| V | | V |
--|01 16|--? PRG A18--|01 16|--GND
--|02 15|-- +5V--|02 15|--PRG A17
--|03 14|-- GND--|03 14|--
--|04 13|-- --|04 13|--
--|05 12|-- --|05 12|--
--|06 11|--GND --|06 11|--
PRG A17--|07 10|--+5V --|07 10|--
GND--|08 09|--PRG A18 ?--|08 09|--
|_______| |_______|
I wouldn't be surprised if the T1 has a PRG A18 pin, but for some reason the board routes it through whatever this is. If you want to put a bigger PRG ROM on this board, you'll have to find the T1 PRG A18 pin and connect it to the PRG ROM.
Re: Another MMC3 Clone: T1
Posted: Sat Mar 12, 2016 9:52 am
by Fisher
Cool!
It's correct!!
I swapped the ROM and looked the checksum, it matches!
I'm a little afraid to play more with this chip, since I fried a "9112" some weeks ago.
Thanks for the help!
With this, we already know of 4 MMC3's clones with different pinouts.
Re: Another MMC3 Clone: T1
Posted: Sun Mar 13, 2016 1:37 pm
by mikejmoffitt
Very naughty, there are no bypass caps on that board! You can see a spot for one above the empty DIP spot.
Re: Another MMC3 Clone: T1
Posted: Sun Mar 13, 2016 2:20 pm
by Joe
I don't think that's for a bypass capacitor. One end goes to +5V GND and the other end goes to the missing chip (either pin 8 or pin 16 depending on how it would be installed).
edit: oops
Re: Another MMC3 Clone: T1
Posted: Sun Mar 13, 2016 11:29 pm
by mikejmoffitt
The pin on the missing chip it goes to is ground - pin 8 in this case.
Re: Another MMC3 Clone: T1
Posted: Mon Mar 14, 2016 12:15 am
by Joe
Are you sure about that? All the chips I saw with GND on pin 8 had VCC on pin 16, but pin 16 is connected to GND.
Re: Another MMC3 Clone: T1
Posted: Mon Mar 14, 2016 2:13 pm
by mikejmoffitt
My mistake - the chip is rotated 180 degrees off of what I expect. Still, that has the cap going between GND and VCC.
Re: Another MMC3 Clone: T1
Posted: Mon Mar 14, 2016 8:27 pm
by Joe
But the capacitor doesn't go between GND and VCC, it only connects GND and one pin of the not present chip.
...Maybe it's a mistake in the board layout?
Re: Another MMC3 Clone: T1
Posted: Fri Mar 18, 2016 7:07 am
by Fisher
A weird thing is happening: the new, byteswapped game don't boots.
I have checked the byteswapped original ROM's crc again and the pinout seems fine.
The new game just b links the screen, while flashes some horizontal lines and locks on a gray screen.
I tried another flash chip with similar results.
Tried with the original swapped ROMs and confirmed that the mapper isn't friend.
What could be wrong? Maybe the board "dislikes" flash chips?
Re: Another MMC3 Clone: T1
Posted: Fri Mar 18, 2016 12:49 pm
by Joe
Have you tried flashing the chips with the original ROMs?
What flash chips are you using?
Re: Another MMC3 Clone: T1
Posted: Fri Mar 18, 2016 1:45 pm
by Fisher
Another very weird thing!!
I tried again, turned on the console and got a little time out of the room.
When I came back, I saw the scrambled title screen with the sound playing.
I went to test and see if the game was fine, but after the intro... locked out again!!
This time I waited and no deal. Dead on a gray screen.
I think this mean the mapper is buggy, and some games may not work.
The game I'm trying to mod it to is Double Dragon 2.
Re: Another MMC3 Clone: T1
Posted: Fri Mar 18, 2016 1:53 pm
by Fisher
Sorry Joe, I didn't read your post...
Looks like I have not refreshed the window for a while..
I'm using a 28F1000, from Macronix.
It reads:
MX J9734
28F1000PPC-12C4
M30887R
TAIWAN
edit: flashed the original ROMs and worked fine.
Just can't understand!!
Maybe this chip is really buggy!!
Re: Another MMC3 Clone: T1
Posted: Sat Mar 19, 2016 3:18 am
by Joe
Have you tried connecting pin 31 to +5V?
What settings are you using to pin-remap the PRG and CHR?
Re: Another MMC3 Clone: T1
Posted: Sat Mar 19, 2016 4:30 am
by Fisher
I connected pin 31 to pin 32 and pin 1.
To remap the pins I'm using Farid's eprom pin swapper with the pinouts that are in this topic.
The weirdest thing is that the md5 of the original ROMs matchs the swapped.
Do you know another way to bitswap?
Maybe dd?