Posted By
bubis
on 2018-09-26
06:27:14
|  Re: Multicolor DFLI with different background colors per scanline plus x-shift
"This should work."  You better test it properly first.
So, as Sandor already figured it out, the INC $FF14 trick works because TED sets the unused bits to one and the lowest 3 bits are unused in $FF14. So, for example if you write $08 there you read $0F, thus INC $FF14 will write $10 but it will read $17. When you INC again, the result will be $18, etc. So, INC $FF14 will increment by 8 every time and not just one. :) Also INC will steal 2 cycles before the DMA, so in that rasterline we will use 24 CPU cycles.
The other trick is that you trigger the badline by reseting $FF1D to 2 every second line. If mem[0xFF06]&7 = 3 it will trigger a badline when mem[0xFF1D]&7 changes to 3.
I will leave it to Sandor now to integrate this into his converter and demonstrate it working with some pretty DFLI pics. :)
BTW, is this really new or IstvanV's converter can do this as well?
|
