Re: Luma discussions

From: Bo Herrmannsen <bo.herrmannsen_at_gmail.com>
Date: Mon, 20 Feb 2017 11:46:18 +0100
Message-ID: <CAFqpYu65HTViTDjZFz9LLMAMYJ=i5Bf8PppEeObx10yyvggymQ@mail.gmail.com>
nope i know that :-D

but i know that thread hijacking is not a nice thing either :-D

that is the reason why i tried to change the subject so i can just delete
the mails that has a subject i dont care for

but oh well, if it does not work i can live with it

2017-02-20 11:10 GMT+01:00 HÁRSFALVI Levente <publicmailbox@harsfalvi.net>:

> Of course you're free to do so, but (FYI) this is not an Internet forum.
>
>
> On 2017-02-20 10:42, Bo Herrmannsen wrote:
>
>> 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 <mailto:groepaz@gmx.net>>:
>>
>>     On Monday 20 February 2017, 09:55:11 HÁRSFALVI Levente
>>     <publicmailbox@harsfalvi.net <mailto:publicmailbox@harsfalvi.net>>
>>     wrote:
>>     > On 2017-02-20 08:26, groepaz@gmx.net <mailto:groepaz@gmx.net>
>> wrote:
>>     > > On Monday 20 February 2017, 08:19:57 Gerrit Heitsch
>>     > >
>>     > > <gerrit@laosinh.s.bawue.de <mailto: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
>>     <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://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
>


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Received on 2017-02-20 11:02:35

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