Hi,
I've built a disassembler for the NES roms to test the 6502 cpu of my nes emulator. However the disassembler showed many FF opcodes (mostly chained in long groups of FF op's). I used other NES disassemblers to compare the output so to rule out errors and I also looked at the binary data directly. So I would like to know why there are so many FF opcodes in Nes roms (e.g. zelda, SMB2, Ninja Gaiden)?

Thanks