idea for composite 80 columns

[adric22]

I was just thinking about something.  I did a little hack a few months ago where you take the video from a VGA card, run a special TSR in DOS which changes the clock on your VGA signal, and you can display your VGA on a TV or other composite monitor.   The way the cable is designed, the Red, Green, Blue, hsync, and vsync are all combined with different resistors.  Of course, the output on the TV is grayscale.  But it doesn't look bad.  I can't seem to find the link to the website I found this info on.

Well.. I know the 128 has a composite output already, but it sucks.  It shows black, white, and 1 gray.    I was thinking, maybe we could combine all those signals into a composite video signal and use different resistors on the red, green, and blue so that each color and combination of colors would have a different gray value.  That would make things a lot easier to see.

[Guest]

You're dealing with different technologies.  VGA is analog and CGA is digital.  Colors are actually rendered by the monitor based on the value on the CGA signal.  This is quite a bit different than VGA where the color data is part of the signal.

[adric22]

You're dealing with different technologies.  VGA is analog and CGA is digital.  Colors are actually rendered by the monitor based on the value on the CGA signal.  This is quite a bit different than VGA where the color data is part of the signal.

Yes, I am well aware of the differences between CGA and VGA.  Technically, VGA signals are rendered at the monitor as well.. so are composite and S-Video signals.   However, a composite signal can just as easily be digital.  Many PIC microcontroller projects output video data in NTSC but they are only outputting on or off signals to the TV.    So what I said still stands.. In fact, with proper placement of resistors, I'm fairly certain you could get close to creating 16 different gray shades.  The only part I am unsure of is if the CGA Hsync and Vsync are compatible to composite.  But I believe they are, though.  I think the 1084 monitor uses the same sync rate for NTSC, Y/C, RGBI, and analaog RGB.   So if I'm right, this could be done.