[For Chris Pile]
I see chars 128-255 are printed like chars 0-127; it seems bit 7 is
reset before printing on the screen.
AFAIK CP/M used 7-bit ASCII, and only certain versions of CP/M 3 (e.g.
the one by Amstrad) used a kind of CP/M standard 8-bit charset.
Is there any way to configure or hack Pro-DOS in order to use an 8-bit
charset (and define the chars above 127)? This would let to write
programs in other languages than English, with a modern encoding.