RE: Aw: My ColourPET Project

From: Martin Hoffmann-Vetter <>
Date: Fri, 12 Apr 2013 17:39:42 +0200
Message-ID: <003b01ce3793$f41dffd0$>
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,%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.


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Received on 2013-04-12 16:00:04

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