This circuit is designed to convert a standard TTL level CGA/RGBI
signal to analog RGB voltages. I have tested it with the output from
my Commodore 128. It does *not* do any scan doubling or conversion to
VGA frequences. The output will still be at the CGA/RGBI frequencies
which works with old Apple or arcade monitors. I'm using a GBS-8200
clone to convert the SeaGeelog output to a VGA signal.