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?
IMG_20190205_1824026.jpg [ 2.79 MiB | Viewed 4629 times ]
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!
Attachment:
IMG_20190205_1824026.jpg [ 2.79 MiB | Viewed 4629 times ]
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!
