Earlier today, I received a CE-150, to go with my PC-1500A. When trying to use these two together though, the display shows two lines in the left half of the screen and when typing, it constantly acts as if <shift> was hit first.
I did run a quick test (in RUN mode, since I cannot access PRO mode in this setup) and found that a lprint command does get to the plotter and the plotter works correctly too,