[Coco] CoCo 2 vs CoCo 3 changes

[Kevin Becker]

So I finally broke down and bought a CoCo 3 on eBay.  It arrived today but
I haven't had a chance to try it out yet since I'm at work.  It suddenly
occurred to me though that I don't actually know that much about the CoCo
3.  I had a CoCo 2 back in the 80s and I bought a CoCo 2 last winter that
I've been having fun with.

I know it has more RAM, different keyboard layout, composite and RGB
video.  I know the GIME provides better graphics.  Anything else I should
know?  I'm especially curious about the MicroWare additions to BASIC to
support the improved graphics.  Should I just RTFM or is there any sort of
quickstart list of things to know for someone upgrading from CoCo 2 to a
CoCo 3?