Post by zontar on Feb 5, 2011 23:01:41 GMT -5
I've consulted the guide at both devster.monkeeh.com/sega/yavdp.html and emudocs.org/Genesis/Graphics/genvdp.txt however, something does not quite add up with the code I'm using.
I am *very* new to programming the megadrive and know just some 68k assembly as a starting point. I've used drx's template as a sort of starting-point and my goal is to get at least a palette and small 8x8 tile loaded onto the screen. However, nothing I do seems to show up on the screen, not even a simple BG color change, and I don't seem to understand what exactly is going on in the initialization.
This is the line I've looked at in particular:
dc.w $8134 ;Genesis display = 1, DMA = 1, VBlank = 1, display = 0
I'm assuming I have to convert the "34" from hex to binary, so windows calc gives me 110100.
According to the "YaVDP" document, this would mean it's in SMS mode, display enabled, no vertical interrupt, with DMA, in NTSC mode, and SMS mode to "do nothing."
But the comment says it's in genesis mode.
Am I doing this wrong? How do I make sure this ROM write is doing what it should be doing?
I am *very* new to programming the megadrive and know just some 68k assembly as a starting point. I've used drx's template as a sort of starting-point and my goal is to get at least a palette and small 8x8 tile loaded onto the screen. However, nothing I do seems to show up on the screen, not even a simple BG color change, and I don't seem to understand what exactly is going on in the initialization.
This is the line I've looked at in particular:
dc.w $8134 ;Genesis display = 1, DMA = 1, VBlank = 1, display = 0
I'm assuming I have to convert the "34" from hex to binary, so windows calc gives me 110100.
According to the "YaVDP" document, this would mean it's in SMS mode, display enabled, no vertical interrupt, with DMA, in NTSC mode, and SMS mode to "do nothing."
But the comment says it's in genesis mode.
Am I doing this wrong? How do I make sure this ROM write is doing what it should be doing?
