> I'm trying to use TIM64T for easy T.V format conversions
> Here are the values I'm trying to use. The NTSC values
> work perfectly but the Kernel value for PAL is too high
>
>
> NTSC
> VERTICAL_BLANK = 46
> KERNEL = 228
> OVERSCAN = 35
> TOTAL 262 lines
>
> PAL
> VERTICAL_BLANK = 57
> KERNEL = 270
> OVERSCAN = 42
> TOTAL 312 lines
>
> Has anyone succesfully used this method?
Hi,
Yes, but I used T1024T instead of TIM64T to time the kernel period. Over 13
scanlines pass in each tick of the timer with divide by 1024, so it means
setting the timer a few scalines early to get it to time-out on the correct
scanline. (I seem to remember it was 4 scanlines for NTSC, 2 for PAL.).
Something like this:
lda #PAL_FLAG
beq set_ktime_ntsc
set_ktime_pal
lda #KTIME_PAL
sta T1024
bne set_ktime_done
set_ktime_ntsc
lda #KTIME_NTSC
sta T1024
sta WSYNC
sta WSYNC
set_ktime_done
sta WSYNC
sta WSYNC
; kernel starts here
I actually ditched this in the end becuase I decided to display the same
number of lines for both PAL and NTSC modes.
Alex Herbert
www.herbs64.com
