Hi,
> The antiques collection ROM format is a type of compressed file, when rom
> is loaded in PSX memory, is exectly the same to original rom.
It turns out there are two different versions of Antartic Adventure. The one
called AntarcticAdventure.rom on komkon is the one used in the Antiques
collection.
I have a guess about the compression format. The base unit is one byte.
Repeated patterns are encoded by storing a length and offset into the already
unpacked data.
The meanings of the various bytes are:
11111111: special/unknown
11nnnnnn: uncoded, length=n+8
10nndddd: length=n+2, offset=d+1
0nnnnnnn dddddddd: length=n+3, offset=d
So far the #FF byte seems to have no meaning, but I doubt Konami doubt have
put it there if it was useless (it's compression after all).
I found the table above by manually examining the first #60 bytes
(approximately). To verify this theory, a program must be written that
attempts to unpack the file using the codes in the table, then the unpacked
file must be compared to the Antarctic Adventure ROM. I'm sleepy so I won't
write that program now, feel free to write it yourself and post the results.
If no-one writes it tomorrow I might have a go at it on Sunday.
Bye,
Maarten
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