Re: 6561 (PAL VIC-I) interlace mode bit

From: Richard Atkinson <>
Date: 26 Aug 2011 16:03:10 +0100
Message-ID: <>
>I think Anders was saying that in interlace mode, the VIC displays the
>same picture on both even and odd field (but one of them shifted a half
>line down).  You of course trick it into displaying a different picture
>every field :-)
>Btw, the 6560 datasheets say it is 262.5 lines per field for interlace
>mode (like NTSC should be), and 262 for non-interlace mode; your docs
>(and everything else I googled) say it is 261.  Which is wrong?
>(PAL should be 312.5, your doc says 312; that's also what the VIC-II

By my recollection the 6567R8 puts out 65 cycles * 263 lines and the 
6560-101 is the same in non-interlace mode. I would expect the number of 
lines to alternate between 262 and 263 in interlace mode. Since the raster 
line register starts at zero, on one frame it would count to 261 and on the 
next 262. Marko's program must have some means of detecting which frame it 
is in; this would be one method.

I've never seen a 6567R7 nor a 6569R2. I'm reliably informed the 6567R5 
exists though I've never seen one either. The 6567R56A seems to be 
equivalent to the 6569R1 and the 6567R8 to the 6569R3. Where that leaves 
the 6567R9, the 6569R4 and the 6569R5 I'm not entirely sure. Was there a 

6569R5 chips were found in the 12V 65xx equipped 64C. I'd expect the NTSC 
versions of these to contain the latest 6567 revisions, though I haven't 
got any.


       Message was sent through the cbm-hackers mailing list
Received on 2011-08-26 16:00:03

Archive generated by hypermail 2.2.0.