Re: Let's pay a developer to make a VGA output card

["js@cimmeri.com" <js@cimmeri.com>]

Scott Alfter wrote:
> S-video should produce clean 80-column text and monochrome graphics, as long
> as you're just connecting the composite output from the II into the S-video
> jack's Y input and leave the C input disconnected.

But the C is quite important.  :-)



> As a quick experiment, I tried plugging a IIGS into my HD LCD TV.  Instead
> of running a cable from the composite output on the computer to a composite
> input on the TV, I ran it from the composite output to the Y input on one of
> the TV's component inputs.  The image wasn't 100% stable (there was some
> flickering), but 80-column text was easily readable.  I suspect that a
> CRT-based TV (SD or HD) with component input would work better.

Interesting idea, however, these TVs / LCDs that are natively 480p or
higher, with 480i component inputs, are upconverting 480i to 480p
(31.5khz).  They are not displaying native 480i at 15.734khz.  Thus, I
would think you would encounter the same conversion artifacts as you do
with the RGB->VGA scan doublers.

I've not seen any TVs with native 480i component inputs (no
progressive).  Has anyone?



>  A higher-resolution LCD and/or one intended for computer use (which will have
> a button to make graphics more stable for the currently-active mode) might
> also work better.

I checked my HD LCD monitor, and did not find stability / dot phase
function on anything but the VGA input.


> It should be possible to make an adapter to convert the IIGS's RGB output to
> component video that would be usable on a growing number of TVs.  Since no
> scan doubling would be necessary, the design should be simpler and cheaper:
> a handful of op-amps to convert from RGB to YPbPr, and something to mix the
> composite sync provided on the GS's RGB port with the Y signal.

I've seen relatively inexpensive devices on the market that do convert
from RGBS to YPbPr... thus converting the IIgs to 480i.   But again, my
concern is that 480i with an upconverting 480i monitor won't look very
good.

~ J