Re: PET / cbm2 timing questions...

From: André Fachat <afachat_at_gmx.de>
Date: Mon, 20 Dec 2010 22:16:38 +0100
Message-ID: <20101220211638.23710@gmx.net>
> No (I hope not), the CRTC timing is programmed to get this value. 
> PAL defines 313 rasterlines for one half-image (actually 625 per full 
> image) with 64us (i.e. 64 cycles) per rasterline. That results in 20032 
> cycles per screen - 49.920Hz. The second half-image is defined as 312
> raster lines, which makes 19968 cycles - 50.080 Hz. Both together 
> are 40000 cycles for two screens. So small derivations are ok. 

Just a clarification. PAL standard is given as _example_ only, the PET
 - in general - is _not_ according to PAL. Especially the PET displays
a full image for what PAL defines as half-image, and the number of lines
does not change from image to image as with the PAL half-images.

André


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Received on 2010-12-20 22:00:36

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