Hi.
I just found that there are flash memory on a cheap "coolboy" cartridges (about $3). So I can rewrite it! All you need is to unsolder /RD and /WR pins. So I can use my dumper with JTAG connector.
Attachment:
coolboy_rewrite.png [ 1.54 MiB | Viewed 6431 times ]
Video (russian language, sorry):
https://youtu.be/5_XZyVoEzE0?t=4m46sSo it's possible to create very large (32 megabytes) multirom cartridges for MMC3 games using ultra cheap $3 chinese cartridges.
It's just awesome.
How does the menu select which game to play? The MMC3 only supports 512 KiB (or maybe 2 MiB), and none of the documented multicart mappers go above 4MiB ... so how does it address 32 MiB of flash?
What is the exact name of the chip?
lidnariq wrote:
How does the menu select which game to play? The MMC3 only supports 512 KiB (or maybe 2 MiB), and none of the documented multicart mappers go above 4MiB ... so how does it address 32 MiB of flash?
It's "COOLBOY" MMC3-based mapper. It has additional registers. You can view it in fceux source code:
http://sourceforge.net/p/fceultra/code/ ... oolboy.cppFARID wrote:
What is the exact name of the chip?
"COOLBOY". It's UNIF mapper in fceux. You can find this cartridge as "coolboy 198 in 1" or "coolboy 400 in 1" on eBay or aliexpress.com.
That is a pretty cool multi-cart creation.
I watched the video with transliterated captions but it's difficult.
I've been tinkering with Coolboy carts for a while. but I'd never worked out how to rewrite them.
How do you change the game names, build the multiROM etc? Will you make tools available?
GameMachineJames wrote:
I watched the video with transliterated captions but it's difficult.
I've been tinkering with Coolboy carts for a while. but I'd never worked out how to rewrite them.
How do you change the game names, build the multiROM etc? Will you make tools available?
Hate to make a me-too reply, but yes, inquiring minds want to know!
Seriously, though, this is a great find. I've been wondering about the GBA games with the adapter daughterboards for a while, now. I have assumed that most of the pirate carts aren't Mask ROMs but since I don't have any FC/NES pirate carts, I can't try this just yet.
It'll be very like any other multicart. The registers are set by hardware to specific values on power-up (and maybe on reset), and the ordinary NES code there is responsible for everything needed to switch games.
It'd make a good "My First NES project", if it weren't flagrantly endorsing copyright infringement.
but how does it handle PRG and CHR? If there is only 1 chip for data (the other is some kind of mapper i'd assume), how can it run both busses?
getafixx wrote:
but how does it handle PRG and CHR? If there is only 1 chip for data (the other is some kind of mapper i'd assume), how can it run both busses?
There are 128KB/256KB (depends on revision) of CHR
RAM. Game loader loades all CHR data to RAM before game starts.
What disappoints me is "hardware tested logic, don't try to understand lol" in FCEUX's mapper source. That doesn't look very reassuring for someone planning to make and sell homebrew games.
The COOLBOY carts support four each different PRG and CHR banking modes. For a new game, you can safely just use the "obvious" (MMC3-like) one and ignore the weird modes.
Is there any reason why one couldn't use a clamp-on pin header over the PRG itself and reflash without desoldering?
There will be an address bus conflict between the chip-on-board mapper IC and the programming hardware. It might work anyway, but it's not good practice.
lidnariq wrote:
The COOLBOY carts support four each different PRG and CHR banking modes. For a new game, you can safely just use the "obvious" (MMC3-like) one and ignore the weird modes.
MMC3 with 128K CHR RAM would be wonderful as a start. But wouldn't that limit each game to 512K, the maximum size of an MMC3 PRG ROM image, wasting the other 31.5 MB of the flash? I imagine that there is an outer bank register controlling which 512K is visible to the running MMC3 program, but what explains how to set the outer bank? There appears to be nothing about this mapper on wiki.nesdev.com.
Or is it like "forging your own lightsaber", where it is considered normal and just that understanding FCEUX's code is part of the price of admission to the other 31.5 MB of the flash?
I just started translating the source code into wiki notes. Come back in an hour or two.
Edit: done.
Quote:
you MUST enable writes to the MMC3's PRG RAM to write to these registers
Actually it's not true. You can disable PRG RAM and write to $6000-$6003.
So you can keep you games saves safe while using loader.
Oh, I misread the conditional in FCEUX's source. → fixing
Cluster wrote:
So you can keep you games saves safe while using loader.
Saves, plural? Or will other games that use RAM overwrite your save? Is RAM even present on most carts? And won't writes to RAM trigger the lockout by accident?
tepples wrote:
Cluster wrote:
So you can keep you games saves safe while using loader.
Saves, plural? Or will other games that use RAM overwrite your save? Is RAM even present on most carts? And won't writes to RAM trigger the lockout by accident?
Other games will overwrite save, yes
I wrote "saves" bacause usually game using several save slots. My english is not so good, sorry
tepples wrote:
And won't writes to RAM trigger the lockout by accident?
That's clearly intentional: the mapper was designed for a multicart of games, so the menu "should" have already triggered the lockout as it starts the game.
Given that the control registers are present over the entire PRG RAM area, PRG RAM isn't really usable without having triggered the lockout anyway.
Hi all,
Sorry to reactivate this old thread, but I think it is very cool and interesting.
I have a question concerning the modification: If one uses a NES to SNES converter (e.g. RetroPort), is it then possible to install SNES roms on the chip and have a cheap SNES-game-compilation? I know one is 8bit the other one 16 bit ROMs, but for the Microprocessor this should make no difference, right?
From pin-point of view i think SNES has 62 pins instead of 72 pins on NES, so should also be fine, or?
Thanks in advance,
Best regards edizius
The RetroPort is a NOAC Famiclone, with its own CPU, PPU, and APU. It draws power and input from the Super NES Control Deck, interprets the instructions in the cartridge, outputs audio and video through a connector on the side, and can additionally send video to certain cart connector pins on certain Super Famiclone models (not an authentic Super NES). I'm guessing it outputs analog audio through the same cart connector pins that the Super Game Boy uses, but I'm not sure of that.
What I do know is that it is not a straight-through pin adapter. Even if there were a pin adapter, it couldn't work for games bigger than 32K because the connector doesn't provide enough CPU address lines.
Are you thinking of the way
Space Invaders for Game Boy can launch a full Super NES port of the game if used in Super Game Boy? That works by loading the ROM through the Game Boy's video output and running it from RAM. To accomplish this, the game is relinked to run from $7E0000 rather than the usual $C00000 (HiROM) or $808000 (LoROM), and the Game Boy game loads the Super NES game 4K at a time into video memory and then sends bulk transfer commands to the SGB over the link port.[1] Even if the RetroPort had a special mode for this, and I don't know if it does, it wouldn't be able to run commercial Super NES games, as games would be limited to just under 256K, the size of high WRAM (120K), VRAM (64K), and audio RAM (64K) combined, and relinked in high WRAM.
[1] "SGB VRAM Transfers" in
Pan Docs
Hi. Thanks for the fast reply. Unfortunately i read your post through several times, and i think i am either to stupid or not deep enough in the topic to understand everything, but as far as i understood, creating a custom snes rom is not feaseable with nes adapter nor with the official gameboy adapter. I hope other people coming across this thread understand more precisely what you wrote. Thanks again for your fast answer and your help.
So to create custom cartridges, best thing will be to order super everdrive or similar I guess
All the best wishes, edizius
Ok, googling "space invadors super gameboy snes" helped me to understand: this is pretty cool!!! And yes, something like that i was thinking about. Are there "snes gameboy cartridges" ? As far as I understood it, theoretically any snes game can be started via s modified space invaders cartridge, or?
Let's take the SGB discussion to
a separate topic.