07-25-2000, 08:26 AM
I just came across this (hidden in plain sight I guess)
On this page: http://www.hpcalc.org/docs/misc/
You'll find a link to an article about adding an RS232 port to the HP28: http://www.hpcalc.org/docs/misc/hp28io.txt
It's not complete, but it does show you what you can do if you're prepared to take to your HP28 with a saw! (gasp)