From: utzoo!decvax!harpo!npois!ucbvax!C70:editor-people Newsgroups: fa.editor-p Title: Cursor motion in Emacs Article-I.D.: ucb.1270 Posted: Fri Jun 4 03:30:58 1982 Received: Sat Jun 5 01:28:30 1982 Reply-To: ople >From ZIMMER@DEC-MARLBORO Fri Jun 4 03:23:12 1982 Two points: 1) Cursor movement takes up a lot of the time that people spend using text editors. We have collected data with three diverse editors -- a word processing system, a production screen editor, and an experimental editor designed for rapid, consistent cursor movement using arrow keys. (None of these editors used multiple windows, or I/O devices like mice.) Each of these samples contained about half a million keystrokes. Typing took up 1/2 of the users' time. Cursor movement took up 1/4. Deletion took up 1/8. Everything else took up 1/8. 2) We performed an experiment involving a cursor positioning task and three editors (not the same ones as above). One had unpredictable cursor speed and lag when using the autorepeat key (30 cps, .5 second lag in the hardware). Another moved at a steady 30 cps with the .5 second lag. Yet another moved at a steady 60 cps with a .08 second lag. The effect of editor type was significant; those using the steady 30 cps/.5 second lag editor did best, followed by the steady 60 cps/.08 second lag. The unpredictable cursor speed and lag did worst. Conclusion: I used Twenex Emacs regularly for two years and have used VMS Emacs regularly for the past year. I like these editors better than any other editor available to me on either system. But I don't like the slow speed of the cursor movement keys. One ^N or ^P is fine, but the problem is in binding these functions to keys on the VT100 alternate keypad so that you can autorepeat them. This is slow and unpredictable in Twenex Emacs. VMS Emacs is better, but the screen manager will often delay some of the cursor motion feedback in order to avoid unnecessary redisplay. I wish we could do better without changing other aspects of the Emacs interface. Since cursor movement takes a lot of the users' time and unpredictable autorepeat/lag hampers cursor movement, there is some data to go beyond the personal preference. --------