[Coco] Last video I promise... :)

[Luis Antoniosi (CoCoDemus)]

Yeah I can try making a new version without framebuffer since I matched the
GIME cock now.

Just one line is enough, in fact I need two lines: one being doubled and
other being scanned.




Luis Felipe Antoniosi



On Wed, Nov 12, 2014 at 7:23 AM, Mark McDougall <msmcdoug at iinet.net.au>
wrote:

> On 12/11/2014 11:02 PM, Luis Antoniosi (CoCoDemus) wrote:
>
>  I needed a framebuffer because I couldn't make it to work without it. The
>> GIME clock gets out of the sync with the VGA timing and I ended up having
>> a
>> rolling screen.
>>
>> The pixel clocks are not mutiple. While the GIME pixel clock is 14.318Mhz,
>> the VGA pixel clock is 25.175Mhz
>>
>
> You can clock the VGA off 2x your GIME pixel clock, you don't have to be
> absolutely perfect on the 'standard' VGA timing, and even less so on CRT's.
> The monitor should be able to handle it; I've certainly not had any
> problems simply doubling the 'composite' clock.
>
>  My converter needs a pixel perfect representation of the screen in order
>> to
>> reconstruct the artifact modes.
>>
>
> Surely you just need a line buffer to do that? Or do adjacent lines affect
> one-another for the artifact mode?
>
>  Having a framebuffer in the middle gives me freedom to each component to
>> work at their own speeds. Also, this solves the problem to convert from
>> 50Hz to VGA 60Hz. I have a french coco2 peritel that does RGB SCART in
>> 50Hz
>> and a MSX computer that can operate in 50Hz NTSC.
>>
>
> OK, this I concur. I didn't factor in PAL video modes, despite being
> Australian! Doh! ;)
>
> Regards,
>
> --
> |              Mark McDougall                | "Electrical Engineers do it
> |  <http://members.iinet.net.au/~msmcdoug>   |   with less resistance!"
>
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