The Cartographer is a dungeon editor for both Dungeon Master and Chaos Strikes Back. Version 1.0 was released in 1990, the last version released was 2.5E, in late 1991. The Cartographer is copyright © 1991 DreamPark Development.
It is available for Atari ST and for Amiga.
Note that the Amiga version cannot edit Dungeon Master v3.6 saved games. But unlike DMute, it can edit the Chaos Strikes Back Prison (the two levels dungeon where you choose your champions).
Here is a Review of The Cartographer at www.textfiles.com.
You can also visit The Cartographer web page.