Re: [stella] Supercharger Bank Switching

Subject: Re: [stella] Supercharger Bank Switching
From: Eckhard_Stolberg@xxxxxxxxxxxxxxxxxxxxx (Eckhard Stolberg)
Date: Sun, 22 Jun 1997 14:15:13 +0200
>What I don't get is which addresses trigger a which 
>bank switch?  And which bank switches does the modification
>disable.  For example, I understand that I don't want to switch 
>the ROM back in once my program is loaded.  However,
>I might want to swap one 2K RAM for another from 
>my program, to use a total of 6K.  Can this be done, 
>or am I stuck with the 4K that was selected when the 
>audio finished?

Bob's hardware modification disables all bankswitches. It is meant to be
used only with ROM dumps of actual carts. Some of those accidently access the
address which triggers the bankswitching and therefore crash. It is limited
to 2k and 4k games.

For your own games you don't need the modification. Your program can switch
banks and enable and disable the Supercharger ROM or writes to SC RAM everytime
you want.

Which RAM banks are currently accessable or if writing is enabled etc. is
controled by the bits in the control byte at address $FFF8. You can't read it,
but you can change it's content for example by

LDX ControlByteValue
CMP $F000,X
CMP $FFF8

There is a very good text about the Supercharger by Christopher Salomon on
http://www.primenet.com/~nickb/sctech.txt , where you can find more info on
this.


Ciao, Eckhard Stolberg



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