[Coco] CoCoVGA 64-column mode

[Brendan Donahe]

(This time around I'm cross-posting for folks not on Facebook.)

I have a 64-column text mode working on CoCoVGA.  This is a 64k CoCo 2 with
the FPGA board Ed Snider, Steve Spiller, and I have been working on for a
few years.

https://youtu.be/F6yw1nHYpTc

For folks who haven't seen the other CoCoVGA videos before or seen the mode
demo in person at CoCoFEST, videos of that are also posted on that YouTube
channel.

Thanks to Allen Huffman for posting clear and concise info for putting the
CoCo in all-RAM mode and copying ROM to RAM so that I could use the
Unravelled books to patch BASIC for this.

Brendan