Luma discussions

i have changed the subject as it did not relate to my initial thread and
got bored of reading things that i was not interested in

2017-02-20 10:00 GMT+01:00 <groepaz@gmx.net>:

> On Monday 20 February 2017, 09:55:11 HÁRSFALVI Levente
> <publicmailbox@harsfalvi.net> wrote:
> > On 2017-02-20 08:26, groepaz@gmx.net wrote:
> > > On Monday 20 February 2017, 08:19:57 Gerrit Heitsch
> > >
> > > <gerrit@laosinh.s.bawue.de> wrote:
> > >> On 02/19/2017 11:47 PM, HÁRSFALVI Levente wrote:
> > >>> Another addendum: Marko once measured the luma levels of different
> > >>> VIC-II chips in the same C64 motherboard,
> > >>> http://www.zimmers.net/anonftp/pub/cbm/documents/
> chipdata/656x-luminance
> > >>> s.
> > >>> txt>
> > >>>
> > >>>  . I don't know how well the data practically holds, since the
> > >>>
> > >>> measurements have been done without using a standard 75 ohm load;
> yet,
> > >>> one thing seems to be sure: there are slight differences between
> > >>> different VIC-II chip revisions in the luma levels they produce.
> Maybe
> > >>> part of what I've seen has been a result of that. I can't speak of
> the
> > >>> other symptoms, I didn't make measurements myself.
> > >>
> > >> We have to remember that VIC is a bit of a mixed signal chip, it is
> > >> mostly digital, but also produces analog signals. I take it as a given
> > >> that there will be slight differences between VICs of the same
> revision,
> > >> even if they come from the same wafer, let alone from different
> > >> production runs where the process was tweaked over time.
> > >>
> > >> So measuring luma levels only counts if you have multiple VICs of each
> > >> revision you can compare against each other.
> > >
> > > indeed, some other ppl checked the luma levels in the past decades, and
> > > its
> > > always slightly different :)
> >
> > The question here would be IMHO whether there is a correlation between
> > VIC-II revision numbers and the luma maps the respective chips produce.
> > The rest (general phenomenon of output level variances of mixed signal
> > chips, general statements about measurement variances due to people
> > measuring video signals with different / generally inadequate equipment
> > etc. etc. etc.) is obvious.
>
> unfortunately, to find that out... you'd have to check quite a few chips. i
> dont think the existing data is even remotely close to draw this kind of
> conclusions.
>
> --
>
> http://www.hitmen-console.org    http://magicdisk.untergrund.net
> http://www.pokefinder.org        http://ar.pokefinder.org
>
> C makes it easy to shoot yourself in the foot; C++ makes it harder, but
> when
> you do it blows your whole leg off.
> <Bjarne Stroustrup>
>
>
>
>        Message was sent through the cbm-hackers mailing list
>


       Message was sent through the cbm-hackers mailing list