I just got my VCS back from Chris Wilkson. Although he forgot to send my
power supply back (doh!) I had a spare handy and was able to see what he
hath wrought.
Jerry Jessop was wrestling with my six switcher trying to eliminate this
weird hardware noise pattern that was showing up in the video. According
to Jerry, problems like these have plagued Atari itself when they were
showing the VCS at trade shows and wanted to avoid RF and go composite.
I do believe that Chris has designed the ultimate 2600 modification because
Chris decided to make two snips to the TIA chip itself and this eliminated
the problem entirely!
When I saw the display in Y/C, I have got to imagine that it is the
cleanest display ever generated by a 2600 in history. Now, it isn't
perfect. There is a vertical gridding pattern when you view it in Y/C
which has something to do with the way the VCS times its video. As I
recall, many Atari 8-bits also exhibit this phenomenon while in Y/C mode,
especially the 130XE, so it's normal. There is also a twinge of ghosting
in the sprites even in Y/C, but aside from my sub-standard Y/C cable, it's
probably the theoretical highest quality output you are ever going to see.
Being able to hear the 2600 in "stereo" for the first time was also a
thrill. In Space Invaders, the marching is on one side, and the firing is
on the other. In Pitfall II, the percussion is on one side, and the three
melodies are on the other. For Decathalon, you have a nice effect of the
melody on one side, and the harmony on the other. Chris set the audio
levels so that they zero out perfectly through my mixing board.
--
For games that do not use flicker, the 2600 will record well into my
nonlinear system. However, most games which use flicker wind up with
certain sprites totally dropping out of the picture based on which field
they are flickered in. It looks as if the time base corrector throws away
one or two fields per image, replacing them with duplicate fields. If I do
a traditional framegrab, the missing sprite will show up and I can step
through the fields (useful for demonstrating how flicker works, by the way).
I'm going to have to try recording the VCS footage to tape and see if the
deck can do a better job of preserving the flicker, otherwise I won't be
able to show the games totally faithfully.
--
If you want to see a sample screengrab, go here:
http://home.earthlink.net/~cybpunks/index.html
Chris says he'll be submitting an article for 2600 Connection. I wholly
endorse the modfication!
--Glenn
--
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