Our journey begins as we seek Lord British's counsel and embark on the quest to master the eight Virtues, collecting four of the Runes in the process.
I'm playing with the Ultima IV Upgrade patch, downloadable here. This adds some improved graphics, MIDI music and corrects some bugs, as well as adding the ever-useful Reload and Quit hotkeys.
Be sure to run the game at least once and create your character first before you install the patch, as it will crash at the end of character creation.
You'll need two other files to get this patch running in DOSBOX:
Extract the CWSDPMI package (here) into your Ultima IV directory.
There's also a recompiled avpatch.exe that works under DOS here. Unzip it over the one included with the upgrade patch, then run setup.bat to get everything installed and ready to go.
Interestingly, Richard Garriott had wanted to produce a direct sequel to Ultima IV between it and Ultima V's release, appropriately titled Ultima IV Part 2. Judging from the lack of detailed information available about it, it's unlikely it got far into the planning stage.