Aw: Re: Aw: Re: [stella] Gunfight 2600: Final Release Version

Subject: Aw: Re: Aw: Re: [stella] Gunfight 2600: Final Release Version
From: cybergoth@xxxxxxxx
Date: Wed, 21 Nov 2001 10:33:24 +0100 (CET)
Hi Chad!

> >Do you know where and why the checksum differs?
> >Isn't that a 'bad sign' about the Cuttle Carts compatibility?

> It could be, but the fact that it also fails on the 7800 RAM cart makes me 
> think it's something in your code.  The 7800 RAM cart does not possess the 
> latch timing structure of the Cuttle Cart and so should run like an eprom 
> cart.  (Although taking a quick look at the 7800 RAM cart design it seems 
> that it relies on A14 and A15 being equal to A12 in 2600 mode.)
> After all, the 4K mode of the Cuttle Cart isn't that complicated.

After thinking some time about the checksum difference, I can 
suspect two things that possibly could result in a different 

- Any mechanism that'd alter the $FFFC entry vector of the BIN

- A different boot-up carry state betweeen the emulators and
  a real 6507

BTW: I wasn't trying to critisize the Cuttle Cart in any way. 
In fact I'm very happy that it can easily be rendered unusable 
by pure software manipulation.

You should be happy about that too, since I think you built
it for developers or for people wanting to play games that
aren't for sale anymore. But Homebrews are, so it's good
to be able to give our games a little protection against piracy.


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