Re: NTSC VIC-II timing

Date: Wed, 21 Jun 2017 17:01:04 +0200
Message-ID: <2830771.djjMl5YRDn@rakete>
On Wednesday 21 June 2017, 16:40:03 wrote:
> According to the famous document by Chris Bauer, there are three timing
> variants of the VIC-II. While PAL is always 63 cycles per  line, with NTSC
> there can be either 64 or 65 cycles per line and I am in fact able to
> reproduce the difference with -model ntsc and -model oldntsc in the current
> The question (before I spend weekend on trial'n error counting cycles and
> possibly reinventing the hammer ;-) is: do we have ane established,
> reliable software method for detecting which NTSC VIC-II is installed in
> the machine? I guess it must have been done multiple times by now and used
> in some NTSC games/demos..

most demos or games probably dont care about detecting the difference - as the 
64 cycle VIC is extremely rare.

however, iirc on codebase there are some detection routines. basically just 
count the cycles for a line (or a frame) using a CIA timer.


The weirder you are going to behave, the more normal you should look... When I 
see a kid with three or four rings in his nose, I know there is absolutely 
nothing extraordinary about that person. 
<P.J. O'Rourke>

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Received on 2017-06-21 15:03:42

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