Hi Chris, >> That's basically all necessary to know from the user perspective... > > Fine. But I'm not a user in this respect, I think ... :-) Certainly. I just wanted to point out that there *is* documentation available. >> "While running main() the Language Card bank 2 is enabled for read >> access." > > Ok. This probably means, the OS is switched out and RAM is present > at its location. I'm no Apple guy, so I overlooked this. Exactly. 'Language Card' is the name of the RAM area that can be enabled in favour of the ROM. In early Apple II machines it was optional - therefore 'Card'. It was originally used to provide alternatives the the ROM BASIC - therefore 'Language'. > How do you handle interrupts? Is the complete ROM switched out, or only a > part? Only a part is switched. But that isn't relevant for the interrupt topic as $FFFE/$FFFF *are* switched. When running ProDOS then the DOS uses most of the Language Card (incl. $FFFE/$FFFF) itself and it takes care itself to handle interrupts correctly when they occure while the Language Card is active (incl. restoring the state found before the interrupt occured). http://www.cc65.org/doc/apple2-4.html#ss4.1 : "A plain vanilla ProDOS 8 doesn't actually use the Language Card bank 2 memory from $D400 to $DFFF." When running DOS 3.3 interrupts are simply supposed to not occur. http://www.cc65.org/doc/apple2-4.html#ss4.2 : "A plain vanilla DOS 3.3 doesn't make use of the Language Card at all." > Can one call ROM routines from code placed in HIGHCODE? No. ROM calls are supposed to be made solely by the C library - which isn't placed in HIGHCODE. > So many questions... :-) No problem. Just ask :-) Regards, Oliver ---------------------------------------------------------------------- To unsubscribe from the list send mail to majordomo@musoftware.de with the string "unsubscribe cc65" in the body(!) of the mail.Received on Sat Nov 13 18:29:13 2010
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