The Commodore Plus/4, the C16 and the C116 from 1984 were members of the 6502-based “TED” series, named after the 7360 TED (“Text Editing Device”) video controller. The TED systems were basically the low-cost cousins of the C64: The overall system architecture and the video chip are very similar to the C64’s, but they lack certain features like hardware sprites. On the other hand, there are some added features like extra colors and more control over the internal timing of the video chip.
In the Commodore archive at zimmers.net, there is a collection of GIF images that are scans of the some very interesting technical documents on the TED series, originally provided by Tibor Biczo and published by William Levak and Marko Mäkelä. I sorted the pages and converted them into searchable PDFs that are much nicer to look at:
“TED System Hardware Manual”
(PDF, 48 pages, 7.6 MB)
“TED 7360R0 Preliminary Data Sheet” (Apr 1983)
(PDF, 23 pages, 5.8 MB)
“TED Extra Pages”
(PDF, 5 pages, 1.4 MB)
The “Extra Pages” contain a map of the circuit board, a Plus/4 memory map in German, a TED register map, and a German version of section 4.5.2 of the TED System Hardware Manual.
“Service Manual Model Plus 4 Computer.pdf” (Oct 1984, PN-314001-04)
(PDF, 25 pages, 4.9 MB)
The service manual is also taken from zimmers.net.