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DS Flash Equipment > GBAMP M3 Questions, Paging, Clarification and Memory Map?

#78669 - Dwedit - Sat Apr 08, 2006 7:46 pm

So far, I can see that the GBAMP M3 locks itself on boot, and has boot code almost identical to the original GBAMP. Only the first 512 bytes are visible every 0x4000 bytes, the rest is "an increasing memory pattern" (open bus?). Is the BIOS unlocked the same way the original GBAMP is unlocked? Does it still have that funky mirroring?

How do you switch between the BIOS, CF registers, and 32MB of RAM? How do you enable or disable writing to RAM? Is the bios combined with the CF registers, like the original GBAMP?

It says here [http://www.bottledlight.com/ds/index.php/Hardware/FlashCartridges] that the M3 has an "unlocking sequence", then RAM can be made writable by writing somewhere.

What does "unlocking sequence" mean? Does that mean it switches from the RAM back to the BIOS+CF registers? Then it says that the RAM is made writable by writing 0xAA55 to 0x09FFEFFE, but does that mean that it maps the RAM back in at that point?

I wonder if there are also similar answers for the Supercard CF, or the SD versions of the M3/Supercard.
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#78671 - pepsiman - Sat Apr 08, 2006 7:57 pm

Dwedit wrote:
What does "unlocking sequence" mean? Does that mean it switches from the RAM back to the BIOS+CF registers?
Yes. (Not sure about the BIOS).
Quote:
Then it says that the RAM is made writable by writing 0xAA55 to 0x09FFEFFE, but does that mean that it maps the RAM back in at that point?
No. At present nobody knows how to map the RAM back in.
Quote:
I wonder if there are also similar answers for the Supercard CF, or the SD versions of the M3/Supercard.
The same sequences work on the M3SD.

Supercard sequences are on the page you linked to.
Some of the supercard RAM remains mapped when accessing the CF.

#78723 - Dwedit - Sun Apr 09, 2006 6:02 am

So, would I need to dump the M3's firmware to find out how to switch between RAM and CF mode?
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"We are merely sprites that dance at the beck and call of our button pressing overlord."

#78784 - tepples - Sun Apr 09, 2006 7:52 pm

GBAMP products tend to lock themselves if the initial reads don't come in the right order. You'd probably need to dump it in an "in circuit emulator" fashion, reading 16-bit words from ROM in the same order that the GBA would when running the code.
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-- I think he moved to Tilwick.

#78795 - pepsiman - Sun Apr 09, 2006 9:02 pm

Dwedit wrote:
So, would I need to dump the M3's firmware to find out how to switch between RAM and CF mode?

I have a dump of the M3CF firmware (by Darkfader).
I can email it to you.
PM me your email.

#79041 - Dwedit - Tue Apr 11, 2006 5:47 am

If you do this:
0x09FFFFFE=0xA55A
0x09FFFFFE=0xA55A
0x09FFFFFE=0x0005
0x09FFFFFE=0x0005
0x09FFEFFE=0xAA55

Will it enable the SDRAM on both the Supercard and M3?
_________________
"We are merely sprites that dance at the beck and call of our button pressing overlord."

#79068 - pepsiman - Tue Apr 11, 2006 10:50 am

Dwedit wrote:
If you do this:
0x09FFFFFE=0xA55A
0x09FFFFFE=0xA55A
0x09FFFFFE=0x0005
0x09FFFFFE=0x0005
0x09FFEFFE=0xAA55

Will it enable the SDRAM on both the Supercard and M3?

Should do.
Add 0x09FFFFFE=0xAA55 to get the G6 too.