The latest version of des.el is 1.14a. Download: des.el

Copy des.el to your home directory, and add to your .emacs:
      (load "~/des")
      ; adapt the following path as necessary:
      (setq des-prolog-file "~/des/systems/swi/")
      (add-to-list 'auto-mode-alist '("\\.dl$" . des-mode))
Restart Emacs, open a *.dl-file, and press F1 to load it into a DES process (this currently only works with SWI-Prolog). If the region is active, F1 consults the text in the region. You then interact with DES as on a terminal.

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