Posted By
gerliczer
on 2016-12-27
05:58:01
|  Re: Porting to Commodore Plus 4 of my game Genius, memory/bitmap mode questions..
You should really read all the TED registers' descriptions.
$FF0B/$FF0A is the raster interrupt input register. To read the actual raster line value, you should access $FF1D/$FF1C. If you keep the KERNAL interrupt handler running than probably you shouldn't be surprised that you raster interrupt is "denied". The TED machines have graphic screen modes accessible in BASIC with dedicated commands. And there are graphic modes that create split screen where there are graphics in the upper part (~20 rows) and text in the bottom (~5 rows). That requires support in the KERNAL interrupt handler which is what, I guess, interferes with your actions. No, you don't have to sync to the raster for flipping pages, but it could result in ugly tearing.
You are free to use any available memory. System area is below $0800, so it is advised to keep it intact if you want stay compatible with the KERNAL, all others can be used as it fits your needs. Although I'll say just in case caveat emptor.
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