Some gba cartridges use flash chips produced by a few different
manufacturers for backup memory. A game rom may then try to read the
device id for its flash chip and break if it's the wrong one. There's
no way for us to know which chip is supposed to be there, save for
looking it up in some database. These chips are either 64k or 128k
big. gba(1) hardcodes the id for the SST 64k chip, but games like the
Pokémon ones use a 128k Macronix chip and expect a different id,
completely breaking them.
This patch sets a different default for 128k flash backups, and gives
the ability to set the exact type when creating the save file if it's
really necessary. This new default fixes the Pokémons. The type is
saved in the save file, but this will *not* break existing ones. It
may be that we don't need to worry about the type and just have an id
that corresponds to the right chip size, which is why these defaults
make sense, but I haven't tested more than a dozen roms, mostly since
I don't really know which games use 128k flash.
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