3 ms·
It's pretty hard to calculate that checksum if you're writing homebrew, since the checksum is written to the rom file, which changes the checksum again...
by nubinetwork 3y ago
It's pretty hard to calculate that checksum if you're writing homebrew, since the checksum is written to the rom file, which changes the checksum again...
- bdhcuidbebe 3y agoThat’s not how you do it, see https://snes.nesdev.org/wiki/ROM_header#Computing_the_Checksum https://snes.nesdev.org/wiki/ROM_header#Computing_the_Checks... specifically > Because the ROM header will be part of the computed checksum, before computing the checksum we should first fill the header's checksum and complement values with $0000 and $FFFF. Any value plus its complement will produce the same result, so this ensures the resulting checksum matches the ROM even after the computed checksum is replaced in the header.
- hakfoo 3y agoCould it be attacked as "the checksum is the value necessary to get the sum of the remaining bytes to (modulo) 00? I know that's how the option ROM checksums on PC BIOSes work.