IIgs SVideo Mod Results

[MdntTrain <js@cimmeri.com>]

I finished modding my IIgs for SVideo and am posting some photos here
for review.  As it turns out, most all the components needed for SVid
are already on the IIgs mobo, the main part being the MC1377 encoder
chip.   To make SVid, only 7 additional, simple parts are needed, and
a few parts removed.   I used an SMD rework tool.   If you actually
remove all the composite video parts no longer needed, the total NTSC
video system parts count is much less for SVid.. meaning SVid would
have been a less costly method for Apple to implement... but of
course, lousy composite being as pervasive as it was, that wasn't
going to happen.   However, at little additional cost, a few jumpers
and parts could have allowed for BOTH on the IIgs.

As you'll see, SVid is a big improvement over composite.  I don't see
any difference between it and RGB for all but the 2 SHIRES modes.
320 mode isn't bad in SVid, but for 640 -- RGB outperforms by far.

Well, here we go with sucky photos + descriptions of what you're
seeing.


http://members.aol.com/mdnttrain/svid3.jpg
- HGR mode with 80 column white text and blue background.   I never
noticed this before but I see quite a number of colors other than the
normal few of HGR.   I guess this effect was used in certain games.

http://members.aol.com/mdnttrain/svid4.jpg
- 80 column text only, black background.   No color killer
implemented!

http://members.aol.com/mdnttrain/svid5.jpg
- Vertical HGR color test.   Note the visible scan lines in this mode
-- I'll mention again.

http://members.aol.com/mdnttrain/svid6.jpg
- Horiz HGR color test.   Note scan lines again.

http://members.aol.com/mdnttrain/svid7.jpg
- Marble Madness 320x200 mode.  Not too bad, but some detail
missing.   Look at vertical black lines in colored areas.

http://members.aol.com/mdnttrain/svid8.jpg
- Platinum Paint 320 mode.   Pic looks worse than reality.  But notice
SVid just now reaching its limits -- very, very faint "bar"-ing
visible on background.   Still, completely tolerable -- even to picky
eyes like mine.

http://members.aol.com/mdnttrain/svid9.jpg
- GSOS desktop 640 mode, color off.   Should be equivalent to
monochrome composite display, although due to my monitor's wider SVid
bandwidth, definitely looks better.   Very faint bars similar to 320
mode...

http://members.aol.com/mdnttrain/svid10.jpg
- GSOS desktop 640 mode, color on.  Now the bands are visible.  As
Mahon predicted, the SVid C bandwidth just doesn't provide the color
resolution needed.    Still perfectly useable, but not lush like RGB.


Now, you want to see lush?  Take a look at my IIgs RGB->VGA results.

http://members.aol.com/mdnttrain/rgbvga1.jpg
- same vertical HGR test as above.   Look, ma -- no scan lines.

http://hometown.aol.com/MdntTrain/rgbvga2.jpg
- same horiz HGR test as above.  No scan lines.  Why?   Because RGB-
>VGA system I use has a really good line doubler.. so you're really
looking at 456 x 480 resolution here (encompassing Apple's 280 dots
across x 192 lines)

http://members.aol.com/mdnttrain/rgbvga3.jpg
- Teenage Queen card game.  Rich coloration.

http://members.aol.com/mdnttrain/rgbvga4.jpg
- Marble Madness.   Note all details present that were missing above.

http://members.aol.com/mdnttrain/rgbvga5.jpg
- Platinum Paint 320 mode.   Perfect, solid, vibrant color.

http://members.aol.com/mdnttrain/rgbvga6.jpg
- GSOS desktop 640 mode.   As good as it gets.

Equipment used for RGB->VGA
1.  17" Dell (Sony Trinitron) monitor.
2.  Highway SCART RGB -> VGA converter.
                     OR
3.   Samsung 910MP LCD TV/Monitor w/ SCART connector.   Only one I've
        found sold normally in the USA.

3.  Roger Johnston's IIgs SCART cable.

If anyone is interested in actually doing the IIgs SVid mod, say
something and I'll get around to posting the how-to here.

JS