Re: IIgs Analog Video Circuitry

[Kevin Dady <kevin@hackaday.com>]

On Sep 30, 7:46 pm, Daniel Kruszyna <d...@krue.net> wrote:
> Kevin Dady <ke...@hackaday.com> wrote:
> > I have never even seen a IIGS in person (I know I know) so I am just stabbing
> > in the dark, do you have any idea what of what timing that monitor is
> > expecting? I would guess its much faster than what the GS is putting out
> > (somewhere close to VGA?) and that starts to get pretty tricky (though if you
> > feel the need to blow a small pile of money there are scan converters
> > available)
>
> The monitor is expecting exactly what the IIgs is outputting, since it is the
> standard IIgs monitor :) Timing is ~15kHz lines and 60Hz frames.
>
> It looks like this module shifts the rgb components to the correct voltage
> range, and adds in the sync. Why would it need the sync if there is already a
> composite sync signal on the monitor port?
>
> -- Daniel
You need the sync cause if there is stuff on the lines while the
monitor should be syncing it wont sync properly, this is usually
handled by whatever is creating the signal and its just simpler to
send it though a chip (or just a passive dac)  rather than to lock two
signals together.

What I am confused about is what are you hooking up to this screen? I
get that your doing something to output a RGB signal but from where
and how?