Super Gameboy ROM access

mic_ · Post by **mic_** » Mon Jan 31, 2011 5:18 am

Is the GB cart mapped into the SNES's memory space when using the SGB (either directly, or indirectly through some MMIO)? I.e. can the S-CPU access whatever is stored on the GB cart that is plugged into the SGB?

Near · Post by **Near** » Mon Jan 31, 2011 5:37 am

No, the SNES has no access to the Game Boy cartridge. Otherwise it'd be a neat way to dump Game Boy games.

The SGB boot ROM inside the Game Boy portion transmits the Nintendo copyright logo for bootup verification, but that is it. Basically the Game Boy side can send data over as it sees fit through either JOYP packet transfers or VRAM block transfers, but it has to initiate the action.

One could hypothetically design their own Game Boy program to act as a Z80-based SNES coprocessor, but there are better coprocessors for that sort of thing.

mic_ · Post by **mic_** » Mon Jan 31, 2011 5:58 am

Otherwise it'd be a neat way to dump Game Boy games.

It sure would

Oh well..

Post by **tepples** » Mon Jan 31, 2011 6:16 am

How well does the SGB tolerate pak swapping?

And how would one get the data out of the Super NES? The SGB2, the one with the link port, appears to be Japan-only. Nintendo Power never even mentioned it.

Has anyone managed to do anything with the N64 Transfer Pak?

mic_ · Post by **mic_** » Mon Jan 31, 2011 7:40 am

And how would one get the data out of the Super NES?

SNES flashcart with SD/CF interface.

Post by **tepples** » Mon Jan 31, 2011 8:26 am

But then you'd have to pak-swap the flashcart with the Super Game Boy.

mic_ · Post by **mic_** » Mon Jan 31, 2011 8:52 am

tepples wrote:But then you'd have to pak-swap the flashcart with the Super Game Boy.

Depends on which flashcart you're using, The neoflash cart has a connector on the back since it lacks a CIC of its own. I think the ToToTek carts had a similar solution, though the difference is that they had a hardware switch, while on the neoflash cart you can map the boot cart into ROM space through software.

Near · Post by **Near** » Mon Jan 31, 2011 9:54 am

tepples wrote:And how would one get the data out of the Super NES?

Through the controller port.
http://byuu.org/snes/serial/

marvelus10 · Post by **marvelus10** » Thu Feb 03, 2011 9:27 pm

When I saw this topic, I got to thinking. Would it be possible to make a ROM image of the Super Game Boy and then inject GB ROMS into that for play on the RetroZone SNES PowerPak.

mic_ · Post by **mic_** » Thu Feb 03, 2011 11:05 pm

marvelus10 wrote:When I saw this topic, I got to thinking. Would it be possible to make a ROM image of the Super Game Boy and then inject GB ROMS into that for play on the RetroZone SNES PowerPak.

The software wouldn't do much good without the hardware.. The SGB contains a near-complete Gameboy.

d4s · Post by **d4s** » Thu Feb 03, 2011 11:35 pm

byuu wrote:
The SGB boot ROM inside the Game Boy portion transmits the Nintendo copyright logo for bootup verification, but that is it.

Also most of the GB ROM "header" (or information sector or whatever), if I might add.
Thus, the SNES is able to determine name, mapper etc. of the inserted Gameboy game.

tepples wrote: How well does the SGB tolerate pak swapping?

Very.
Pulling the GB cartridge while it's running will of course crash the SGB, but after inserting another cartridge, all it takes for the SNES to reset the SGB is to strobe a register bit and presto.

Jeroen · Post by **Jeroen** » Fri Feb 04, 2011 8:53 pm

The supergameboy can be modified for link port acces rather easily btw. (depending on soldering skills) We know from space invaders that the game can in fact upload snes programs into ram. But I dont think the snes has any futher direct acces to the thing.

whicker · Post by **whicker** » Fri Feb 11, 2011 8:12 pm

d4s wrote:
byuu wrote:
The SGB boot ROM inside the Game Boy portion transmits the Nintendo copyright logo for bootup verification, but that is it.
Also most of the GB ROM "header" (or information sector or whatever), if I might add.
Thus, the SNES is able to determine name, mapper etc. of the inserted Gameboy game.

tepples wrote: How well does the SGB tolerate pak swapping?
Very.
Pulling the GB cartridge while it's running will of course crash the SGB, but after inserting another cartridge, all it takes for the SNES to reset the SGB is to strobe a register bit and presto.

In practice, I found that if one removes the GB game with the system power on, the saveram gets corrupted. Even worse, I did that with a 100%'d Kirby's Dream Land 2.

d4s · Post by **d4s** » Mon Feb 14, 2011 3:04 pm

whicker wrote: In practice, I found that if one removes the GB game with the system power on, the saveram gets corrupted. Even worse, I did that with a 100%'d Kirby's Dream Land 2.

I'd say that every game cartridge that doesn't implement some sort of write protection for its savegame memory(as opposed to the SA-1 or most types of flash memory) is prone to have its savegames corrupted if the system crashes or the cartridge is removed while the system is running.
This is not solely a SGB issue.