I'm attempting an FPGA implementation for a basic GBA cart - have gotten as far as the Nintendo logo almost working but becoming garbled towards the end... does this look indicative of something in particular?
Wondering if it may have something to do with this (from http://problemkaputt.de/gbatek.htm#gbacartridges):
What are these pre-defined addresses? and what data is expected in return?
Thanks for any insights!
Wondering if it may have something to do with this (from http://problemkaputt.de/gbatek.htm#gbacartridges):
Quote:
"09Eh Bit 0,1 - Cartridge Key Number MSBs
This is part of the above Nintendo Logo area, and must be commonly set to F8h, however, Bit 0-1 may be set to other values.
During startup, the BIOS performs some dummy-reads from a stream of pre-defined addresses, even though these reads seem to be meaningless, they might be intended to unlock a read-protection inside of commercial cartridge. There are 16 pre-defined address streams - selected by a 4bit key number - of which the upper two bits are gained from 800009Eh Bit 0-1, and the lower two bits from a checksum across header bytes 09Dh..0B7h (bytewise XORed, divided by 40h)."
This is part of the above Nintendo Logo area, and must be commonly set to F8h, however, Bit 0-1 may be set to other values.
During startup, the BIOS performs some dummy-reads from a stream of pre-defined addresses, even though these reads seem to be meaningless, they might be intended to unlock a read-protection inside of commercial cartridge. There are 16 pre-defined address streams - selected by a 4bit key number - of which the upper two bits are gained from 800009Eh Bit 0-1, and the lower two bits from a checksum across header bytes 09Dh..0B7h (bytewise XORed, divided by 40h)."
What are these pre-defined addresses? and what data is expected in return?
Thanks for any insights!