Posted By
Degauss
on 2007-04-15
06:29:44
|  Re: FLD on +4?
correct me if i'm wrong:
i noticed that $ff06 is triggering the DMA-cycle, while $ff1f is responsible for adding 40 to the read-cursor ($ff1a/1b aswell as the read-cursor for the DMA-cycle). to go safe, you have to modify both.
a "standard" +4-technique is to do this:
-modify $ff06 to circumvent the DMA-cycle
-modify $ff1f/1a/1b to display the line you want
this has more overhead but it's more powerful at the same time since you can flip a whole screen (which is not possible with *real* FLD)
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