Somewhere in my junk piles I still have dozens of hardware projects for the COCO 1,2 &3. This was a tinkerers dream machine. Kind of like Arduino of the time in a way. The bus was completely open on the side port and created many unique expansion options. It was based on a sensible CPU and architecture with ( in some cases) bank switching at 32K which was not hard to cope with. Coding for it was simple. I built ( or attempted) nearly everything that Dennis Kitz or Tony DiStefano published.
All that being said... there was a time when video processors were all the rage... like the TMS9900 family IC known as the TMS9918 video that was popularized by Tony as well as Steve Ciarcia of Byte Magazine.