I do my 6502 programming in emacs. I found some code for a dasm-specific major mode, Per Olofsson's dasm-mode, but it was a bit limited. I've since extended it to make it more like a proper major mode.

It's a bit rough and ready, but I've found it quite satisfactory so far.


  1. Download 6502-mode.el and put it somewhere emacs can find it.
  2. Add the following to your .emacs, perhaps modifying it depending on the file extension you like to use:
    (require '6502-mode)
    (add-to-list 'auto-mode-alist '("\\.s65" . 6502-mode))