Subject: Re: [stella] Supercharger strangeness From: "Frank Palazzolo" <palazzol@xxxxxxxx> Date: Sat, 5 Aug 2000 11:41:52 -0400 |
> >It seems to be related to the placement of instructions in the bank > >switch code. ??? > > Like putting that code in the $F0xx area? ;-) > > When SC writing is enabled, an access to an address in the $F0xx page > might trigger a write to an address a couple of address changes later. > If you execute the bankswitching code in the $F0xx page, accesses to > $FFF8 will take the value to be written from the last address that was > accessed in $F0xx. So depending on which address you put the STA $FFF8 at, > the last fetch when the processor reads that instuction might be on > an address which has the bits set for a working bankswitching/write-enable > value or not. In general it's best not to execute any code at $F0xx while > SC writing is enabled. Looks like you nailed it - thank you! Although...even if I never turn RAM writing on, it still seems to be a problem. So, I guess the resetting of the bank can happen on an instruction fetch from the $F0xx area, even if supercharger RAM is disabled. This seems like an important safety tip...after all, that's 1/16th of your ROM space where the bankswitch code is forbidden ;-) -Frank -- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
Current Thread |
---|
|
<- Previous | Index | Next -> |
---|---|---|
Re: [stella] Supercharger strangene, Eckhard Stolberg | Thread | Re: [stella] Supercharger strangene, Glenn Saunders |
Re: [stella] Supercharger strangene, Eckhard Stolberg | Date | Re: [stella] Supercharger strangene, Glenn Saunders |
Month |