Subject: Re: [stella] some questions about the a2600 From: emooney@xxxxxxxxxxxxxxxx (Erik Mooney) Date: Wed, 26 May 1999 02:14:54 GMT |
>> > There are no interrupts on the 2600. > >but dont games usually have interrupt vectors stored at the end of the roms? They have vectors, yes, but they're not really for interrupts. The word at address $FFFC is the address where the CPU will transfer control at powerup, and the word at address $FFFA is the address where the CPU will transfer control after hitting a BRK instruction. >> You can do whatever you want at the beginning.. whenever you start >> generating VSYNCs, the TV will pick up on it and start displaying. > >ah, so the hardware and television don't even begin displaying until VSYNCs >are >used...kewl They'll start displaying right at powerup (actually, the TV even before powerup - static, or whatever happens to be on channel 3). But it doesn't matter if it displays garbage or blankness for a few sixtieths of a second before you get your VSYNCs rolling. >> Yes. I believe there was an 8K bankswitched version of the text adventure >> Dark Mage, by.... <blanking>... Greg Troutman? There's also been at least >> a couple 6k bankswitched Supercharger games. > >well, i thought maybe i could use the f8 method of bankswitching by >essentially >creating two 4K files with code that could in essence be seperate roms, append >one >on top of the other, and then access locations $FFF9 and $FFF8 (since $1000 >and $F000 are the same to the 6507) to switch back and forth between 4K >sections... >thats the way i see it...you think that would work? Sounds about like the standard method of writing bankswitched games. -- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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