Turn on EDT emulation with M-x edt-emulation-on. M-x edt-emulation-off restores normal Emacs command bindings.

Most of the EDT emulation commands are keypad keys, and most standard Emacs key bindings are still available. The EDT emulation rebindings are done in the global keymap, so there is no problem switching buffers or major modes while in EDT emulation.

Viper is the newest emulator for vi. It implements several levels of emulation; level 1 is closest to vi itself, while level 5 departs somewhat from strict emulation to take advantage of the capabilities of Emacs. To invoke Viper, type M-x viper-mode; it will guide you the rest of the way and ask for the emulation level. See Viper.

M-x vi-mode enters a major mode that replaces the previously established major mode. All of the vi commands that, in real vi, enter ``input'' mode are programmed instead to return to the previous major mode. Thus, ordinary Emacs serves as vi's ``input'' mode.

Because vi emulation works through major modes, it does not work to switch buffers during emulation. Return to normal Emacs first.

If you plan to use vi emulation much, you probably want to bind a key to the vi-mode command.

M-x vip-mode invokes another vi emulator, said to resemble real vi more thoroughly than M-x vi-mode. ``Input'' mode in this emulator is changed from ordinary Emacs so you can use ESC to go back to emulated vi command mode. To get from emulated vi command mode back to ordinary Emacs, type C-z.

This emulation does not work through major modes, and it is possible to switch buffers in various ways within the emulator. It is not so necessary to assign a key to the command vip-mode as it is with vi-mode because terminating insert mode does not use it.

See VIP, for full information.