[stella] heurustics for autodetecting bank switching type

Subject: [stella] heurustics for autodetecting bank switching type
From: Adam Wozniak <adam@xxxxxxxxxxxxxxxx>
Date: Sat, 15 Feb 2003 01:50:35 -0800 (PST)
Having lots of free time, I began pondering autodetection of bank
switching types (I'm bothered by the increasingly unweildy stella.pro
file size).

Here are some ideas.  Maybe they'll resonate with someone.

The Cartridge::autodetectType() routine in stella (1.2) is a good
start.

3F has been extended by many homebrew authors to do more than 16K carts.
These are not hard to spot.  Look for multiple occurances of the byte
string $85 $3F in images of 16K, 32K, etc...  I have a large corpus of
files and I did not find many false positives with this heurustic.

For 8K images, F8 can be spotted with multiple occurances of
{$8D | $AD | $2C} {$F8 | $F9} {$FF | $1F}
(thus $8D $F8 $1F would be a match, as would $2C $F9 $1F)
Not many false positives here.  This covers the bulk of the F8 images in
my corpus.

Similarly, for 16K images, F6 can be spotted with
{$8D | $AD | $2C} {$F6 | $F7 | $F8 | $F9} {$FF | $1F}

I've yet to come up with E7 or E0 heurustics, but they shouldn't be
hard, and would be similar to these.

-- 
Will code for food.       http://cuddlepuddle.org/~adam/resume.html

adam@xxxxxxxxxxxxxxxx        http://cuddlepuddle.org/~adam/pgp.html

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