[Coco] RGB-to-VGA converter

[Aaron Wolfe]

I spent some time this weekend playing with my new RGB-to-VGA
Converter from Roy Justus.
It really makes using the CoCo more enjoyable.  I never owned a proper
monitor even back when the coco was my only computer, so finally using
80 column text is truly a dream come true :)   Highly recommended to
anyone that doesn't have a decent display.  Maybe now I'll make some
progress on my goal of using the drivewire as a serial port under os9.
-Aaron