On Sat, 28 Feb 2004, Glenn Saunders wrote:
> At 01:15 PM 2/28/2004, you wrote:
> >Did you ever open up the 2600 I sent you and take a look at the CyberTech
>
> Yeah, but not being an electronics expert it's hard to understand exactly
> what's going on or whether that's "a lot" of stuff for what it's being
> asked to do.
Heh...I feel the same way about the Windows source code that recently
went public.
> But I can tell there is a better signal path and more cleaning up of
> signals going on than the simple mods out there. I think the mods were all
> created by people through trial and error, whereas you have a more thorough
> understanding of video signals so that the end result is more exacting.
Yeah, my first attempts were trial and error hacks for my own machines.
I think your Stella at 20 machine was the first one that I really tried to
design to produce NTSC. It mostly got the luma right at least. :P
I think the CyberTech Video Card is the 5th generation in that line.
The color circuitry is about the 80th generation. NTSC color is a bitch
to put it mildly. (...I can hear all the PAL guys laughing out loud...)
Especially if you want to mess around with the saturation. Ow it hurts.
For the CyberTech board, I paid a lot of attention to power delivery, signal
routing, and generating precise voltages and impedances. There are actually
2 power supplies on the board. I also tried to match the signal path delays
between the luma and chroma sections. And I isolated them as much as possible.
(...comedy to follow...)
This is the first board that I actually put real thought into designing
the audio section. I kept putting it off until the next revision because
"eh, audio is the easy stuff...I'll do that later." But when the video
circuits were finished last fall, and I was finishing the PCB layout and
testing RF emissions and such, I realized that the board was video only...
the audio was missing entirely!
So I started the layout again. That'll teach me to procrastinate.
-Chris
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