This is a list of resources that you use to create the reference. They are not limited to the C128 but could also deal with other computers, in particular the C64 with which a good part of the architecture is shared.
Bart’s place Tons of informations, projects and resources for C128
Sven’s Techsite Interesting information about C64 chips timings
The memory accesses of the MOS 6569 VIC-II and MOS 8566 VIC-IIe An article from Marko Mäkelä about Vic2 (and Vic2e) memory access
The MOS 6567/6569 video controller (VIC-II) and its application in the Commodore 64 An article from Christian Bauer about Vic2