Portfolio to USB adapter stack:
- Portfolio Serial Module
- Gender Changer
- Null Modem adapter
- RS232 to USB adapter
I can send and receive files on the Portfolio via xterm2, on my modern PC I use TeraTerm to communicate with xterm2 over serial using the XModem protocol.
I also wrote an image converter to convert jpg to pgf (portfolio graphics file). I haven't yet implemented the compression to write pgc (portfolio graphics compressed) files directly. I use pgcompress on the atari to convert pgf to pgc. Pgc files can be viewed on the Atari using pgshow.
I got all software for the portfolio from here: Portfolio Library
Damn that is some advanced Atari $#@%! You been busy going retro. I did not get much past pong with my first set and they are not even showing it here https://www.idealine.info/portfolio/library/pages/tx-games.html. Maybe the Chess is worth the battle.
Seems all setup to do 300 baud talking with CompuServe..think you can find it all there. And yes had RS232 memorized and could solder a 4k or 16k (going big here) on a motherboard for you without issue if you needed some hardware interventions on top of things.