The DEC UNIX CDE Desktop. Click image for larger view.
I was able to change the DEC UNIX 4 root password as follows:
>>> b dka0 [enter]
# mount -u /
# mount /usr
(enter new password 2X. )
HINT: Use a complex password with Upper/Lower/special chars/numbers in the event the system requires complex passwords. Even if you can change the password X Windows might not let you in. I found that in this systems' case the OK button is be greyed out when the password stored in the passwd file does not conform to the rules.
Restart your system.
In this particular Multia running DEC UNIX 4 here is what I have to do to get into the DEC GUI known as the Common Desktop Environment (CDE), EXACTLY, from a cold boot (assume you hit enter after each line):
>>> b dka0
# init 3
This initiates the startup script for single user CDE session. Because I am not connected to anything and the system has not been configured the system freezes trying to connect to the network for an update (watch for when the line "Update: started" prints on the screen). To bypass I hit CTRL+C.
Once the startup script finishes the system asks me to log in. Upon successful login I am greeted with a # prompt again.
To enter the CDE I enter these commands:
# ./xlogin stop
# ./xlogin start
(why I can't use restart I don't know)
Finally, I get to the CDE GUI login screen prompts.
NOTE: If you have issues check /etc/securettys for lines that contain references to :0 in them (meaning root display ":0" can login locally).