Oops, the section
-rs232_a null_modem
is missing in my invocation.
Instead, i see 4 lines in Rainbow.cpp saying
MCFG_DEVICE_MODIFY("rs232_a")
MCFG_SLOT_DEFAULT_OPTION("null_modem")
MCFG_DEVICE_MODIFY("rs232_b")
MCFG_SLOT_DEFAULT_OPTION("printer")
Putty connects directly to the bitbanger at 10000.
You may also have to specify "local echo" both in Putty and in Rainbow SETUP (on second screen after 1st Page Down).
This is also the place where the more obscure comms. features are hidden (Carrier Detect length, BREAK ...)
--- @Edstrom: if both machines are properly connected, you should be able to see what is typed on the other end.
(Putty requires an additional carriage return / line feed before it sends anything).
BUG: had to toggle "Handshake" On and Off in MESS' GUI (invoked by TAB) from time to time in my experiments (...).