Re: NTSC VIC-II timing

From: Segher Boessenkool <>
Date: Thu, 22 Jun 2017 10:51:12 -0500
Message-ID: <>
On Thu, Jun 22, 2017 at 08:25:03AM +0200, Gerrit Heitsch wrote:
> On 06/21/2017 09:02 PM, Segher Boessenkool wrote:
> >On Wed, Jun 21, 2017 at 08:51:34PM +0200, Gerrit Heitsch wrote:
> >>>>>What about HMOS and NTSC? 8565 is only PAL, right? What's been used on
> >>>>>narrow NTSC boards? Or weren't there actually any?
> >>>>
> >>>>That would have been the 8562 for the C64 and the 8564 for the C128.
> >>>
> >>>Admittedly never seen any of the two. Can those also be distinguished 
> >>>from
> >>>their NMOS counterparts with the collision based detection?
> >>
> >>No idea, the code I found spoke about PAL... But I would assume that
> >>those parts of the circuit would be the same between PAL and NTSC.
> >
> >The only difference between PAL and NTSC should be the contents of the
> >X and Y comparator arrays.  I've never seen a die pic of any NTSC VIC-II,
> >so no idea if that is actually true...  But I cannot think of any other
> >difference currently.
> Well, the color generator should be a bit different since PAL and NTSC 
> differ in that respect. The overall differences are small enough that 
> you can make a chip that is switchable between PAL and NTSC as the 8360 
> TED proves.

Right, the PAL version switches colour phase on odd/even lines.  There
are metal contacts for that (exactly like in the big timing arrays; also
for changing a chip from 8-bit addressed dram to 7-bit).

Same silicon, except for the metal contacts mask.


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Received on 2017-06-22 16:00:01

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