FDS header

Discuss technical or other issues relating to programming the Nintendo Entertainment System, Famicom, or compatible systems.

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oRBIT2002
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Location: Gothenburg/Sweden

FDS header

Post by oRBIT2002 » Mon Oct 26, 2020 1:29 pm

I am a little bit obsessed with the cool Famicom Disk System (perhaps because it never was released here in Sweden). After checking out the FDS-header in the wiki at(https://wiki.nesdev.com/w/index.php/FDS_disk_format, there's still many "unknown"-fields here. Is the wiki updated properly, are these still considered unknown? I've googled a bit but haven't found anything..

NewRisingSun
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Joined: Thu May 19, 2005 11:30 am

Re: FDS header

Post by NewRisingSun » Mon Oct 26, 2020 2:18 pm

I don't know if the meaning of any unknowns has been discovered, but the "Price" field at offset $37 seems to indicate the "Disk Version" (which is separate from the "Game Version" at $14) rather than the "Price", per No-Intro and the FDS files/spreadsheet in one of the "gigaleaks".

Pokun
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Location: Hokkaido, Japan

Re: FDS header

Post by Pokun » Wed Oct 28, 2020 3:11 am

What does "Disk Version" mean then? I guess if it's about package and Disk Writer versions, it would affect the price as well, which is probably why it was thought to be price.


I have also in the past googled around about this a lot in both English and Japanese in hope to find more info about the header, but I can only find the same information as on the wiki and on Enri's homepage.
Some of the unknown field seems to have fixed bytes (like field $33 has $07), but if you look at various games they don't always match. I'm not sure I had good dumps though.

The leaked FDS images seems to come from master disks that Nintendo stored their FDS games on until the Wii Virtual Console service. Zelda's master disk was apparently not healthy, so they took it from some EPROM instead. I guess the same ROMs used to store games in the Disk Writer kiosks (on yellow NES-style 72-pin ROM cartridges)? Either way they should probably contain the default values of everything like disk rewrite count and rewrite date.

NewRisingSun
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Joined: Thu May 19, 2005 11:30 am

Re: FDS header

Post by NewRisingSun » Wed Oct 28, 2020 4:16 am

Pokun wrote:What does "Disk Version" mean then?
Nobody knows exactly, but I think it counts up sequentially the master that Nintendo received. Some publishers, including Nintendo themselves on some games, do not increase the Game Version number even though they should, so the Disk Version is the only indication which version is newer in the case of different disk content. For example, SMB2J exists with DV 0 and DV 2. Nintendo's master archive only contains the latest DVs, indicating that a higher DV indeed denotes a newer version. "Nakayama Miho no Tokimeki High School" goes up to DV 13. I assume that not all fourteen versions were actually sold to the public.

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