Re: Aw: My ColourPET Project

Martin,
 
Thanks for the spreadsheet! Yes, it was the one I referred to in my status section. It was very handy when figuring out the values I needed. I think most computer monitors have a tolerance to slightly varying frequencies so I'm not so concerned about getting exact timing. As long as it works on a 1902 or 1084 I'm happy. Of course I can make an edit rom with values for PAL timing but it would be nice to have them verified with real hardware. I also wouldn't mind expanding my user base ;-)
 
What if any other side effects would there be in changing the main crystal to 16.128? Would the pet run at 18 MHz (like the CBM-II machines)?
 
Steve


>________________________________
> From: Martin Hoffmann-Vetter <martinHV@arcor.de>
>To: cbm-hackers@musoftware.de 
>Sent: Friday, April 12, 2013 11:39:42 AM
>Subject: RE: Aw: My ColourPET Project
>  
>
>Hello Steve,
>
>> Actually, it would be nice if someone in PAL country could help me
>> with the PAL timing values. I will make the software you see in the
>> screenshots available to download.
>
>Look at my spreadsheet http://mhv.bplaced.de/cbmroms/Commodore%20CRTC%20Einstellungen%2040xx,%2080xx,%208x96,%206x0%20und%207x0.xls. There is an rom called 901474-04a, this must have the PAL values (15.625 kHz horizontal and 50 Hz vertical). But i don't know the source from this rom. In text mode it display only one extra scanline between two character lines. So with PAL you can use totaly 312.5 rasterlines (in 901474-04a are 313 used). (With interleave it's 625, only 576 lines are visable.) in NTSC it's 262.5 rasterlines (or 525 with interleave, only 480 are visable). I think, you can't display an extra scanline with NTSC or you aspect ratio is wrong. So the right NTSC frequencies are 15.750 kHz horizontal and 60 Hz vertical. If you want the correct video timing for NTSC you need a new crystal with 16.128 MHz.
>
>If i remember correctly, some versions of 6545/6845 can interleave.
>
>Martin
>
>
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