I looked into it, but it would cost me more than just buying a Pokemon cart and burning the chip.
Again, you can't just
Nobody has called you stupid once before you pulled out the numbnuts on us. There were no bullshit responses either - I wanted to establish whether the cartridge even had those features in the first place and they were removed or if you wanted to add them. We wanted to know what you're trying to do to best assist you.
What you're trying to do is physically impossible - you cannot rewrite the ROM, you have to swap the chip for a rewrittable one and you will require a compatible MBC revision if you count on any compatibility whatsoever. You will not reach full compatibility due to various Bank setups the Game Boy used, but with the schematics I posted you'll get the best compatibility there is. If you are really dedicated, get one of the listed games, one of the listed chips and start soldering.
Pokemon Gold is said to have MBC3: http://jra.so/proyectos/Game-Boy-Cart-Flasher/game-boy-cartridges.html
The cart I have has MBC5.
what would happen if you address non-existing physical area (burned on the MBC?) and/or the game issues MBC commands that are not available on MBC5?
Well, the obvious difference between MBC3 and MBC5 is MBC5 is missing clock/timer. I could just ditch it, since it's not really necessary. I mean, my mod will include everything at a certain daytime. I could just route the data elsewhere.
I believe Pokemon Gold has a way to say "well the clock is missing, so you can't use the full potential of this game", but it's still playable.
However, the bank sizes are different too.
PIC burners are used to write instructions into PIC microcontrollers which have the capability to be written into, you cannot flash a chip which does not have this capability. Once a ROM chip has been filled with data, that's it, done. I apologize if you felt offended at any point, I'm not here to argue with you, I'm here to explain things to you.
If you want to achieve what you are trying to achieve, you will need a cartridge with a compatible MBC setup (5 is the most compatible of all), SRAM, a battery and a compatible ROM chip that you can replace the original with. No other method will work, otherwise people wouldn't bother with soldering 20-odd wires to their boards.
Alright.
I read up that an EPROM was used on a GBC cart, a 1:1 match.
That's probably the flash chip you mentioned, which has the matching pinouts.
*Glances at the photo, doesn't see a window, sincerely doubts that you have a flippin' mercury-vapor light source*
...good luck?
...and then send it onto the surface of the sun instead of, y'know, replacing it with rewrittable flash like everybody else. ;O;
...or he could build a mercury-vapor lamp... and get mercury poisoning in the process. ;O;
...I also have a feeling that he might damage the actual chip if he's never used a dremel to de-surface a chip before. Just a hunch.
EDIT: Anticipating the "but I can write to it, why would I want to erase from it anyways? I don't want it empty" argument, I shall explain how EPROM works.
In a natural, empty state all cells in EPROM are set to the value "1", once current passes through them from a programmer, they are set to the value "0" where desired.
Erasing from EPROM is a necessary part of the writing process and has to be performed. This is because you can effectively write a "0" onto a position where a "1" is stored but not the other way around. Whether you like it or not, the second write without an erase will end up with false writes, "0's" where you don't want them which are left-overs from the previous write.
In other words, to change the ROM/ROM's on your cartridge you would have to put the chip under a strong UV light each and every time to erase the data stored on it... provided you wouldn't kill it with a dremel beforehand. This wouldn't be the case if the cartridge was equipped with an EEPROM module, but you said it's EPROM. You can make sure by looking up the serial number from the chip online.
This will quickly cause much wear and tear to the aged chip and will eventually break it, which is why you want to replace it with a chip that isn't a pain to write to.
More on the subject here: EPROM Tutorial
tl;dr you can write to EPROM except it's a pain in the butt and you really don't want to do that.
...and then send it onto the surface of the sun instead of, y'know, replacing it with rewrittable flash like everybody else. ;O;
...or he could build a mercury-vapor lamp... and get mercury poisoning in the process. ;O;
...I also have a feeling that he might damage the actual chip if he's never used a dremel to de-surface a chip before. Just a hunch.
You might want to go to a chiropractor if you have a hunch... poor posture is no joke.
(Also I have no idea if desurfacing the IC with a dremel/sander/anything like that would be a good/feasible idea or even possible period. I sure as hell am not trying XD)
It's possible if you're extremely gentle and precise - it has been done with more delicate circuitry, it can be done with this. I just don't know if the OP realizes that UV erasing is something he will have to perform every single time he changes the ROM image... or that it causes wear and tear... or that keeping the chip under the light for too long will damage it... or that keeping it under the light not long enough will cause false writes... Or that erasing itself will gradually lower access times regardless of whether he does it right or wrong...
And I've been considering making a custom cart, seeing as the wires go.... differently. I will be looking into getting a custom cart, maybe. The wires from the ROM remain the same, but the MBC5 baffles me compared to other carts. I might research it later, I dunno.
I think this was an educational $6 piece.
To be 100% fair, you can mod this cartridge to work with other games, but you will not be able to save or use a clock simply because the cartridge does not support that. Leave the MBC alone and focus on the chip (CGB-AOXE-0) on the side, that's what you're interested in.
The reason I was looking at the MBC was how it looks like it connects to the SRAM in this picture:
I mean, it looks like it shares some paths. Just a hunch, but I haven't dug into the depths of Google to find a good back-front scan of the chip board.
I mean, what if I used an SD card as an SRAM? (I know I'm probably stretching that one)
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