Exodus' Castle plays late in the game of Ultima III: Exodus, when you've finally breached the fortifications and entered Exodus' Castle.
The unofficial title Exodus' Castle was used for this song because it plays when the player is in Exodus' castle. Another popular title for this song is The Isle of Fire which is the location of Exodus' castle. Ken Arnold should be contacted for the official name of this song, failing that, game files should be checked for a proper title.
Ultima III: Exodus (A2)
Ultima III: Exodus (A8)
The Atari 8-bit port has comparable music that is used in the same place as the original Apple II release.
Ultima III: Exodus (C64)
When the game was ported to the Commodore 64, the music was arranged for the SID chip, probably by Ken Arnold, but it may have been done by the game's porter, Chuck Bueche. The music functions in the same manner as the Apple II release, but has a "buzzy" sound compared to the original.
The song is track 7 in the SID file and plays on the 6581.
Ultima III: Exodus (AMI)
The Amiga port features similar music and used in the same places as the original game.
Ultima III: Exodus (AST)
The Atari ST port features similar music and used in the same places as the original game.
Ultima III: Exodus (PC98)
In the PC-98 port Exodus' Castle is played at a faster tempo than the original. The song is also played not just in Exodus' Castle, but also in the dungeons and on Ambrosia. The original Dungeon song is absent in this port and the original Ambrosia song is played during the game's ending sequence instead.
The song is rendered on the YM2203 (OPN) and uses the file name M07.BIN.
Ultima III: Exodus (PC88)
Like the PC-98 port, the PC-88 renders the song on the YM2203, but at a lower quality.
Ultima III: Exodus (GBC)
A bootleg Game Boy Color part was made which includes this song rendered on the APU of the Game Boy's DMG-CPU B.