Commodore 128 VDC Reference

 

The VDC8563 and VDC8568 were used in Commodore 128 and Commodore 128D computers for the secondary 80-column text screen.  There were other modes available to developers not exposed to BASIC end users (graphics, interlaced modes for higher resolutions including graphics and text, and lower resolution modes too).

I gathered this information from multiple sources including example data from VICE (sorry, didn't power on the DCR) while implementing support for my own emulator.

Hope you find this useful!

Link: PDF