Re: Braille keyboard question. e

Richard Holloway

The problem is more complicated than it may seem at first. There is a problem (prat least a potential limit) referred to as "n-key rollover". When you exceed the key limit, which varies from one keyboard to the next, unpredictable things may happen. The computer may no longer see the first keys pressed, with only the last particular (keyboard specific number of) keys recognized. I have read the limit can be as low as three. (You don’t typically chord keys at the EXACT same time, there are tiny differences in when the contacts are made.)

The result is that only the last 3 (or 4, etc.) keys down will be seen. And there is a second problem called “ghosting” (nothing to do with ghosting braille on a Perkins). On some keyboards, extra “ghosted” keystrokes appear to the computer depending on the physical position of the keys you actually push— it has to do with the wiring matrix of the keyboard. These are extra keys you didn’t actually push.

As to why this is an issue? Partly cost, but also lack of planning for unusual applications of the hardware. It costs more to design keyboards that can handle more keys at once, and the need is rare for qwerty typists. You may see a need like ctrl + alt + delete often, but usually no more than three keys are needed at once. The common exceptions are Braille (obviously), musical applications (like playing a musical instrument, for example, without a conventional MIDI trigger instrument available), and certain types of computer gaming.

So the short answer is, even if you have software to solve your problem, your hardware setup may or may not accept the physical input from the keyboard. This will vary from one keyboard to the next, and so forth. Try-before-you-buy, if possible.

Read more about limitations here:

I did see a braille-style USB keyboard a while back— not like a Focus 40 (or such) with a built-in display. It was just a straight row of keys to use like on a braille notetaker but without a display. This setup had no n-key rollover issue, but I’ll be darned if I can find it now with a web search. If I run across it, I will post.

Good luck!

On Apr 11, 2014, at 7:50 PM, Sharon <mt281820@...> wrote:

Doesn't Duxbury allow that?
It's been a long long time since I've used it.

-----Original Message-----
From: Jfw [mailto:jfw-bounces@...] On Behalf Of Justin
Sent: Friday, April 11, 2014 3:47 PM
To: jfw@...
Subject: Braille keyboard question. e

Hello to all list members:

I am a long-time braille reader and a proficient braille writer since grade

As an alternative to the BrailleNote and the other note takers, which I
cannot afford to purchase right now, as a long-time braille writer, is there
a braille keyboard that I can purchase and connect to a laptop, using JAWS
and a braille translation program like Duxbury that I can use as an
alternative to the higher dollar braille note taking devices?

I know that I could buy a portable braille display which I believe has a
built-in keyboard, but again this would no doubt cost a couple of thousand

On the other hand, is there a program that can convert specific keys on a
regular keyboard to the configuration of a braille keyboard which I could
connect to a laptop, for note taking?

I would appreciate any and all input.

Best regards,


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