Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!decvax!decwrl!sun!jfarrell From: jfarrell@sun.UUCP (Jerry Farrell) Newsgroups: net.cog-eng Subject: Re: On Chord Keyboards Message-ID: <308@sun.UUCP> Date: Sun, 4-Sep-83 18:46:43 EDT Article-I.D.: sun.308 Posted: Sun Sep 4 18:46:43 1983 Date-Received: Sun, 4-Sep-83 23:45:55 EDT References: utcsrgv.2178 Lines: 33 Buxton's note was a welcome injection of facts & prior research into the discussion; thank you, Bill. I think two of his points about mice and chording deserve further discussion: It's true the dePraz (Swiss, ~hemispherical) mouse is well set up for chording its buttons. (The mouse is designed to be grasped with the whole hand in a grip which leaves the index, middle and ring fingers over the 3 buttons on its front edge.) Unfortunately, this aspect of its design conflicts with the mouse's use as a pointing device - the grip required is the "power grip"; it requires the large muscles of the upper arm to move the mouse, and loses the precision manipulation and pointing capabilities of the fingers. - the buttons are pushed in a plane parallel to the surface the mouse rests on; this makes it likely the mouse will be moved from its position by the act of pushing the button. His assertion that other mice (Hawley, Kirsh, etc.) are not suited to chording needs qualification. It's true that getting all 8 boolean combinations from 3 buttons is impractical if the mouse is only held in the fingers; the little finger is too weak to keep the mouse stable, and move it comfortably. But two-finger combinations can and have been used effectively. When NS-8000's with their 2-button mice replaced Altos in Xerox' development environment, it didn't take long before chording both buttons within n ms. was made an optional equivalent for pressing the missing middle button, even though that meant processing of >every< mouse button-push had to be delayed for those n ms. Similarly, Sun's window system uses two-finger chording as an expert-option for some common operations that are also available by a longer one-finger sequence. In both these contexts, the mouse is gripped between the thumb on the inside and the little & ring fingers on the outside; the other two fingers are free to range over the buttons. The heel of the palm rests on the table behind the mouse, which is moved almost entirely with the wrist and fingers -- canonical "precision grip."