Rare Prototype of Commodore C65 Classroom was revealed in December 2018 by Fred Bowen on Facebook who published details on facebook ‘Commodore International Historical Society’. From technical specs it has RGB output, printer port an expansion port but no floppy drive. As you can see on board there is place for only one SID in U4 and extra headers for internal connections.
Overall it seems like C65 cost reduction model,more pictures in galery.
news source:Commodore International Historical Society group
news source: 6502.org