Subject: Re: [stella] FE Bankswitching From: Adam Wozniak <adam@xxxxxxxxxxxxxxxx> Date: Fri, 28 Feb 2003 16:51:47 -0800 (PST) |
On Fri, 28 Feb 2003, Eckhard Stolberg wrote: > So to handle FE bankswitching, you only need to wait > for two consecutive accesses to the stack area ($0100- > $01FF). During the next cycle the high byte of the > destination address will be read (from stack for RTS > and from ROM for JSR), so that you can take data bit > D5 from there and put it on A12 on your ROM chip. > You must invert D5, because the emulator ROM images > have the bank compiled for $F000-$FFFF before the > bank compiled for $D000-$DFFF. Almost, but not quite. Wait for two consecutive accesses to the stack ($0100-$01FF). IF the first access was at an EVEN address (A0 == 0) then use D5 of the second access. IF the first acces was at an ODD address (A0 == 1) then use D5 of the access AFTER the second access (i.e. the THIRD access). -- Will code for food. http://cuddlepuddle.org/~adam/resume.html Hey, and if you hire me to write a multi-protocol internet capable program before midnight tonight, you'll get the amazing toast-a-matic! Be the first on your block! adam@xxxxxxxxxxxxxxxx http://cuddlepuddle.org/~adam/pgp.html ---------------------------------------------------------------------------------------------- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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