Surely it's easier to provide RGB inputs than
composite though - to do
RGB (and seperate sync inputs) isn't it almost as simple as feeding the
signals into the right point of the existing TV circuitry, whereas to
cope with composite you'd need circuitry to split the signals out at
extra cost?
Yes, but that circuity -- the colour decoder -- must exist in a TV
anyway. The signal you get from the video detector (at the output of the
video IF strip) is essentially a composite video signal.
RGB is slightly harder to provide (you have to switch 3 or 4 signals, not
just 1), but only slighty.
You could well be right though - I'm almost certain that my Domesday
setup (which only does video overlay on RGB outputs) wouldn't work with
my cheap 14" TV via the SCART connector when I tried it.
That could be a lot of things, including not enabling the RGB inputs on
the SCART connector. This is sometimes done by selecting a special
'channel' with the remote control, sometimes by applying 12V or so to the
right pin on the SCART connector. Do you have a service manual for the TV
(and if not, why the heck not?)
-tony