It's not as easy as it should be. I have never figured out how to connect to the console through the ASCII console port using Windows HyperTerminal, but would be interested in how it works. I do have a cable with the correct pinout to go from the DB9 COM1 port on the PC to the DB25 console port on the Sun box, but don't know what the actual pinout is. I am sure you can find it on
http://docs.sun.com/ .Most Sun boxes use the same pinout, the new Netra T1's use a Cisco pinout. Anyway, once you have the correct cable, I know that ProComm will connect with the setting at 9600 baud and 8,n,1. Once you can connect to the host (press enter for a prompt), you can change the input and output device to ttya. From the ok prompt, enter:
setenv input-device ttya
setenv output-device ttya
or from the shell as root:
eeprom input-device=ttya
eeprom output-device=ttya
On a side note, though I didn't spend much time on it, I was unable to get an Ultra 10 to talk on the serial port, it would not boot without a keyboard/monitor
We have an Ultra 5 at work that has no video card and the serial port works fine.
Sorry I can't help more.