Early Experimental Prototype

Steve designed and built this Keyboard/control for early 1980s wearable computer system. Unit is built into the handle of an electronic flash lamp housing to allow for simultaneous one-handed control of computer, camera, and flash lamp. The original design had one microswitch for each finger and 3 possible microswitches for thumb. With the advent of the Twiddler this keyboard has become obsolete, though it still hangs in Steve's closet, and still works. (Now the Twiddler has replaced it in the current version of the WearCam system).

The original version ran a 6820 Peripheral Interface Adapter (PIA) on an Apple ][ (6502) architecture, but you can easily build one to work on a PC architecture. The simplest interface is via the parallel port of a PC, where the eight (4+3 = 7) switches can be wired right to the parallel port. By far this is still the lowest cost form of keyboard, as a set of microswitches can easily be found from surplus equipment.


alternate top view showing thumb key (58k gif) is available.
HandyKey Corp.  
(516) 474-4405
141 Mt. Sinai Avenue
Mt. Sinai, NY 11766  Handykey's web site

Thad prefers the Twiddler and has reached speeds of 50 wpm on it. It includes a tilt sensitive mouse and retails for around $200, which is quite reasonable for a keyboard/mouse combo. Learning the alphabet takes 5 min. (it's sequential), touch typing in an hour, and 10+ wpm over a weekend. Thad says it was uncomfortable to use at first, but over a week of use you learn how to hold it properly for your size and shape of hand. The default key layout is more optimized for speed than is first expected. The user defineable macro package pushes word rates significantly higher over letter typing (supposedly > 4000 button combinations are possible). Macro packages can be reloadable depending on the application.

Linux X and console driver

X and console Linux driver for Twiddler 1.0 (by Jeff Levine-tarred and gzipped-with thanks to Mark Eichin) This Linux driver should be relatively efficient with regard to memory/cpu. It can run in both X and console mode. The mouse works and has various speeds/resolutions. Comments to

ETAOIN SHRDLU alternate Twiddler keymapping (by Brad Rhodes): tarred and gzipped or PKZIPed. This key mapping makes the most commonly typed letters the easiest to reach.

Macintosh (680x0) interface to the Twiddler (courtesy Philippe Riviere,

We tried this; it works. The original is here . To decode binhex, use the stuffit-expander which can be found here You may want the pin-out schematic below.

General technical info on Twiddler

The BAT by Infogrip

Their web site. You may also be able to get these (or a variant) from:
Select Tech
(215) 277 4264
1657 The Fairway
Suite 151
Jenkintown, PA 19046

Both the Chord Keypad and the DataEgg represent good solutions to one-handed keyboarding. The advantage they have over the Twiddler is instant access to the typing hand (the Twiddler requires the strap to type comfortably). Thus, these keyboards are good for providing wearable computer support for emergency crews. The 7 button typing standards have also been around for a longer period of time.


Preliminary Image (34k gif)
Gary Friedman
(916) 983-2249


Forearm computer (350k gif)
One-handed Keyboard Software

Touch type with one hand using a standard keyboard!
Minimal training required for skilled typists.


This remarkable new software utility allows users to touch 
type with one hand, using a standard QWERTY keyboard.  As such, 
it is a cost-effective way to make one-handed touch typing 
accessible to people with special needs.  What really sets 
this product apart from the rest, however, is its potential 
for skill transfer.  Half-QWERTY is designed in such a way 
that people already trained in standard two-handed typing 
techniques can use those skills to type with one hand, with 
minimal retraining!

The design builds on a user's ability to touch type on a 
standard QWERTY keyboard, and the fact that human hands are 
symmetrical - one hand is a mirror image of the other.  A Half-
QWERTY keyboard is comprised of all the keys typed by one hand, 
with the keys of the other hand unused.  When the space bar is 
depressed, the missing characters are mapped onto the remaining 
keys in a mirror image, such that the typing hand makes movements 
analogous to those previously performed by the other hand.

Normal QWERTY typing is performed (with both hands on the keyboard 
in home row) by alternating between the left and right hand, as 
necessary for the given character.  Half-QWERTY typing is performed 
(with one hand on the keyboard in the home row) by alternating 
between the left and right half of the layout, using the space bar.

Notice that you have the choice of using either your left or your 
right hand to type.  The software actually creates two virtual 
Half-QWERTY keyboards - one under each hand!  Both sides are 
remapped in a mirror image when the space bar is depressed.  This 
means that you can change typing hands on the fly, without having 
to alert Half-QWERTY of your intentions - an added bonus for those 
with repetitive strain injuries.

Sticky keys (also called "key latching") allows for one-fingered 
use of modifier keys - the shift and control keys, for example.  
Depressing and releasing one of these keys once makes it active for 
the next key.  Depressing it twice locks that key until it is 
unlocked by depressing it again.  It is this feature that allows you 
to type capital letters with one hand.  Sticky Keys is built into 
the MS-DOS version of Half-QWERTY, while on the Macintosh this 
feature is provided by the operating system.

Note that you still use the space bar to type a space.  Merely 
depress and release the space bar, within an interval of 1/4 second, 
and a space will appear on the  screen.  If you take longer than a 
quarter second, nothing will appear on the screen.  This feature is 
called the "space bar timeout".  An example of the usefulness of 
this feature is as follows:

Sometimes, you'll run into a character for which you are not sure 
whether you need to hold down the space bar.  You may hold down the 
space bar for a while, but then change your mind and release it.  
If there were no timeout, you would have an unwanted space on the 
screen, which you would then have to erase before continuing.  The 
timeout helps alleviate this problem.  A quarter second timeout is 
just long enough to allow you to generate a space, when you really 
want one.

Half-QWERTY is very unobtrusive software.  Its hardware requirements 
are few and modest.  Its effects on normal keyboard operations are 
barely noticeable to all but those who benefit from its presence.  
This is a definite advantage.  It means that abled and disabled users 
can share the same computers without the expense of customized hardware.  
Half-QWERTY brings computers one step closer to being universally 

Half-QWERTY has a wide scope of potential users, ranging from people 
with hand-related physical disabilities to those with visual 
impairments.  Used in conjunction with a Braille screen, blind and 
visually impaired persons can read what they type as they are typing 
it, much as a seeing person does.

This utility also has an audience among the general public.  Writers, 
secretaries, and other frequent keyboard users will benefit from being 
able to operate the keyboard and mouse concurrently.  For example, 
when editing text, a user can now scroll through a document with the 
mouse in one hand, while correcting errors using the keyboard with the 
other hand.  Similar gains can be achieved by accountants, who no longer 
have to remove their hand from the number pad to type words.

The package includes a set of keyboard labels.  Half-QWERTY is available 
for MS-DOS and Macintosh computers.  Call or write for a FREE software 
demo!  Please specify Macintosh or MS-DOS; 3 1/2 or 5 1/4 inch diskette.

Edgar Matias

The Matias Corporation
178 Thistledown Boulevard
Rexdale, Ontario, Canada
M9V 1K1
(416) 749-3124
Gary Friedman

A good source for more keyboard information

Visit the keyboards web page.

Last modified: Mon Nov 27 15:41:45 EST 1995