Posted By
Mad
on 2017-01-14
17:49:26
|  Re: VB interrupt. How do you get it to trigger?
Stinaris it's always better to put as much lda and sta like gerliczer suggested into one loop. So you have the dex,bpl not taking too much time. A loop looking like this:
ldx #$00
.again
lda $4444,x
sta $4444,x
inx
bne .again
takes more cycles than a loop which processes several packets at once like gerliczers version (and it seems to copy the whole screen there ($400*2), you can do this in one frame (the version by gerlizcer is missing the second $400 though??). I really don't know why you only copy 160 characters per frame, there should be a lot more possible. If you do have tearing, than the selection of the start rasterline could also be crucial..
Turrican for instance (as far as I remember) just copies portions, so that the rasterbeam always doesn't intersect the copying.
However, if you have done your first plus/4 game I would be really curious about it  .. There aren't so many new prods like on the C64..
|
