Hello - I'm a newbie to these forums. Please excuse me if I am posting in the wrong area. My dilemma. The HD on our ancient Xenix system apparently is full. I receive the "no space on dev 1/40" prompt. This occurred after I attempted to purge some unwanted files. This system runs our small rental business. Without it we're in trouble. How can I free up space? Thanks in advance!

There are several threads about this going back to June 2007.
Delete all the files in /tmp
Check the size of the following log files and truncate them using:
#cat >file
<ctrl>d
#
/usr/spool/lp/logs/*
/usr/adm/messages
/etc/wtmp
/etc/utmp

When you have enough free space to get the machine running again, run the following:
#du -a |sort -r -n >/tmp/filelist

filelist will contain a list of all the files on the system in descending order by size, including directories.

PS. A couple of years ago SCO had a contest for the longest running system.