INES Mapper 020: Difference between revisions

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(may as well make this page for completionism.)
 
(link to the format that is used for game disk images)
 
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[[Category:Bad iNES Mappers|020]][[Category:iNES Mappers|020]]
[[Category:iNES Mappers|020]][[Category:Bad iNES Mappers|020]]
Mapper 20 is defined as reserved for the Famicom Disk System ([[FDS]]) in official [[iNES]] specs.
The mapper number is mostly intended for being internally used by emulators (to indicate to themselves that they are emulating the FDS hardware).


[http://nocash.emubase.de/everynes.htm#mapper20disksystemprgrambiosdiskirqsound According to Nocash], [[iNES Mapper 020]] at least used to be used for holding [[FDS]] games inside the [[iNES]] format. At some point it was realized that that's a terrible idea (.NES holds a ROM image, FDS images aren't read-only), so don't do it.
Actual FDS game disk images normally use the [[FDS disk format]].
 
The mapper number could be theoretically used for the FDS BIOS ROM-image, but this isn't done in practice. The FDS BIOS is typically stored as [[NROM]] if it is dumped in [[iNES]] format, or it's stored as raw BIOS dump (without iNES header and thus without mapper number).

Latest revision as of 03:44, 17 May 2020

Mapper 20 is defined as reserved for the Famicom Disk System (FDS) in official iNES specs. The mapper number is mostly intended for being internally used by emulators (to indicate to themselves that they are emulating the FDS hardware).

Actual FDS game disk images normally use the FDS disk format.

The mapper number could be theoretically used for the FDS BIOS ROM-image, but this isn't done in practice. The FDS BIOS is typically stored as NROM if it is dumped in iNES format, or it's stored as raw BIOS dump (without iNES header and thus without mapper number).

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