[rescue] 420R serial ports are different?

[Patrick Giagnocavo]

looks like the 420R serial ports are different from many other Sun  
boxen.

http://www.sunhelp.org/unix-serial-port-resources/serial-pinouts/ 
#420r.link

Does anyone know the proper incantation to get them working?  I have at  
my disposal an Ultra 5, and a PC with DB9 serial ports.  I also have a  
pile of different connectors; so far nothing seems to be working, on  
the PC at least (running Solaris 10 and just used to netboot the AX1105  
box, so I know that tip will work right if I can get it set properly).

Like,

do I need a null modem in the middle ?
can I connect the DB25 on the 420R to the U5 DB25 (with/without null  
modem) and get a connection?

or any other hints that can be provided.

--Patrick