I ran into (and solved) a problem today which has been bugging me for a while. I've found that some of the newer ProCurve switches will display output on the console when connected to a Linux box using minicom, but would not accept input. When booting the switch with the serial port set to 9600 8N1, it would display the boot ROM and OS load, and get to the message "Waiting for Speed Sense. Press <Enter> twice to continue.", and no input would be accepted.
I played around with some settings and found that minicom defaults to using hardware flow control, which does not seem to be supported on the E2810. I turned this off and it worked fine. Just thought i would document it here for search engine posterity.