Re: [stella] heurustics for autodetecting bank switching type

Subject: Re: [stella] heurustics for autodetecting bank switching type
From: "Andrew Davie" <atari2600@xxxxxxxxxxxxx>
Date: Sat, 15 Feb 2003 21:33:18 +1100
Just load and run the thing for a few frames.  Check the scanline count.  if
it's 262ish or 312ish, then you've probably got the correct banking scheme.
If you have the wrong banking scheme it's highly unlikely a cart will
generate a valid frame :)   Then cycle thru the available schemes -  most
likely first - until you get a valid frame.  Yeah, I know ....
Cheers
A

----- Original Message -----
From: "Adam Wozniak" <adam@xxxxxxxxxxxxxxxx>
To: <stella@xxxxxxxxxxx>
Sent: Saturday, February 15, 2003 8:50 PM
Subject: [stella] heurustics for autodetecting bank switching type


> 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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