Subject: Re: [stella] PAL TIM64T values From: "Alex Herbert" <herbs64@xxxxxxxxxxx> Date: Sun, 15 Aug 2004 15:47:59 +0100 |
> 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
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