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From: jones@pyrite.cs.uiowa.edu (Douglas W. Jones,201H MLH,3193350740,3193382879)
Newsgroups: comp.human-factors
Subject: Knob on a keyboard?
Message-ID: <6449@ns-mx.uiowa.edu>
Date: 12 Jun 91 17:08:18 GMT
References: <2909@sumax.seattleu.edu>
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The discussion of track balls leads me to remember the keyboard on my
old HP 9836 (RIP).  That machine had a knob on the keyboard, easily
reached by the left pinky without a great leap from the home row.
The knob was a circle about 3 cm in diameter with a raised edge, set
flush with the keyboard near the upper left corner.  It would spin freely
in either direction with only a slight amount of friction, and it gave
input to the computer with a rotary shaft encoder of some kind.

The knob moved the cursor in two dimensions, with the shift key selecting
the direction.  If I remember correctly, un-shifted knob rotation moved
the cursor horizontally, shift-knob was vertical.

Prior to the domination of HP by UNIX, HP had a screen editor that was
tightly integrated with the knob, and I still hold that that editor was
one of the best I've encountered from the point of view of ease of
learning without a manual.

From my experience using the knob, it was better than a mouse for text
editing because it was constrained to move in only one dimension at a
time.  You'd home in on the right line, then home in on a character,
without the awkward problems mice cause with slipping up or down a line
as you seek a character on a particular line.  In addition, the knob let
me switch between typing and cursor positioning much faster than a mouse
simply because I didn't have to move my hands as far from the home row.

For coarse graphics, I'd vote in favor of a mouse, but for fine graphics,
where you're trying to get precise alignment of items on the screen, I
think the knob was again a winning technology.

I conclude that I'd like something like HP's knob on my keyboard as well
as a mouse off to the side, and for most purposes, I'd like them to be
completely equivalent, so that motion of either would move the cursor.

					Doug Jones
					jones@cs.uiowa.edu