Hello
From what I have read, the iNES format is actually an invention of the respective author. I assume then that the ROM ripper (if it can be called that) is responsible for detecting and writing the various values?
Thanks,
Richard Hughes
Whoever creates the ROM image is responsible for preparing a header wtih correct information. For homebrew games, the source code typically specifies the header. For games dumped from cartridges, the dumping software typically has to know what mapper is in use just to complete a dump because the mapper controls which of several overlays, or banks, is visible. Which mapper a cartridge uses can be autodetected (prod the mapper registers and see how they respond), or it can be looked up from the name of the cartridge's printed circuit board or the mapper chip. For example, the CNROM board are most often mapper 3, the UNROM board is mapper 2 except for one game, anything with an MMC3 chip is mapper 4 apart from about a half-dozen games, and anything with a RAMBO-1 chip is mapper 64.
tepples wrote:
For games dumped from cartridges, the dumping software typically has to know what mapper is in use just to complete a dump because the mapper controls which of several overlays, or banks, is visible.
The person might just dump the entire ROM chips and not deal with the mapper at all though...