Re: [stella] Supercharger Bankswitches and RAM access!

Subject: Re: [stella] Supercharger Bankswitches and RAM access!
From: Nick S Bensema <nickb@xxxxxxxxxxxx>
Date: Fri, 14 Mar 1997 07:20:00 -0700 (MST)
>
>Hi!
>
>I posted a message a few days ago.
>I'll try to be more specific.
>
>I think the only thing I'm doing not right yet are the RAM access routines.
>
>Poking is a two step process, something like (write enable assumed):
>
>         <0xf100
>            -----
>           /      \    
>1.lda    $f000,x     (x=0xf0 for example) 
>2.cmp  $f72b 
>
>
>This will poke 0xf0 to to location $f72b.
,snip,
>How is the value determined using indirect-x and indirect-y?
>How is the address determined using indirect-x and indirect-y?

With indirect addressing, you might have a problem if pokes to real RAM
send rogue signals to the address lines that either the TIA doesn't use,
or the SC doesn't check for.

However, both addressing modes index from the zero page.  Therefore there
shouldn't be any problems.  But this is a strange hack, and the way I see
it, if a program reads the wrong two bytes sequentially at $f0 it'll screw
up the code and the programmer will have a hard time figuring out why.


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