Brian,
Good Ideal. I am starting a similar project my self. I need to over-
lay symbols to a video signal. This will be done with a video char-
acter generator and a video mux.(I hope.) Right now I'm looking in
to the Philip SAA5288 TV microcontroller with on screen display.
This device uses the 80c51 core. If This looks like a good route
for you or if you find another alternitive let me know.
My effort needs to place several symbols on an NTSC video frame
and change the color of the symbol based on other data. These
symbols will need to be multiplexed with another video signal.
This is very similar to text over-lay (on screen display) but with a
custom character ROM.
Good Luck,
Paul