Currently I am playing around Atari Portfolio
( I even bought a used one on ebay which will arrive in a few days including parallel port interface)
and while I was googl'ing aroundf I stumbled over this gem of a prototype.
On first thought it looks to me to use the same basic hardware as the original from 1989, just with a bigger screen size.Portfolio 2 Prototype
the page here even got a link to the rom dumped by the
person who found this gem.
I currently don't feel like I am the correct person to play around the drivers and recompile the mame portfolio driver to try and get this to run.
Anybody else who gets interested in this one?