Re: LYNX-DEV Lynx and braille

[Lloyd G. Rasmussen]

On Tue, 13 May 1997 07:51:49 -0400, 
Larry W. Virden, x2487  <address@hidden > wrote:

>For the benefit of enlightening those of us who are multi-sense deprived
>(otherwise known as sighted), could someone describe for us how one uses
>lynx and braille?  Is there somehow a Braille 'screen' that one can use
>with cursor positioning, etc.?

For all you people with light dependence:

There are two ways in which Braille and computers connect.  For the 
past 30 years we have had various kinds of embossers which could act 
as printers for braille documents.  They have gradually improved and 
become less expensive, but they are still in the above-$1700 range.  
Usually, if you are going to read a document in hard-copy braille, you 
want to run the source file through a braille translation program 
which adds contractions (standardized abbreviations) and reformats the 
document to fit the standard braille page size, usually 25 lines per 
page, 40 braille characters per line.  Because braille copies, even 
when embossed on both sides of a page, take up a lot of space (a 
World Book Encyclopedia took up 32 linear feet of shelf space in 145 
volumes), a serious effort is expended in reducing the amount of blank 
lines and hard page breaks.  This all means that you need a formatter 
for the translated braille.  People have been working on this problem, 
and both of the major American braille translation programs, Duxbury
and MegaDots, can accept HTML 2 and do something nice with it.

But I didn't answer your question.  How do we get interactive 
braille and use it with Lynx?  How was the output of Lynx adapted for 
this medium?

Over the last 20 years, various companies have developed "refreshable" 
braille displays.  Due to the high cost and mechanical constraints, 
they consist of one line of braille cells.  Models are available that 
can display a single line of 18, 20, 40, 65 or 80 characters.  Because 
braille is produced at one standard size, the "pitch" is usually 4 
characters per inch, so an 80-cell braille display will be 20 inches 
wide.  This is a rather wide sweep for one hand or two.  Each of the 6 
or 8 dots that form a braille character must be pushed up and 
retracted by a piezoelectric actuator that is driven by a source of a 
couple hundred volts at a minute current. A one-line 80-cell display 
costs about $15,000; 20 cells will cost about $4,000.  But if you are 
deaf-blind, or do programming, or want to accurately see the format of 
documents you type, you will find a way to get one of these 
refreshable displays.  There should be more descriptions at 
www.telesensory.com and 
www.humanware.com

The braille display is driven by a screen reading program designed for 
the purpose, running under DOS or a DOS box.  The screen reader keeps 
the user informed of changes throughout the 25 by 80 screen, and 
must do some kind of mapping onto the number of characters 
available.  It will follow the system cursor.  It can be programmed to 
follow a highlight bar of a color if such a color is consistently 
used.  Bookmarks can be set so you can go to the top and bottom of 
screen, or some other user-defined spot like line 4 as we discussed 
last week.  The whole line won't be displayed if it isn't an 80-cell 
display; I would guess that 40 cells is the most common.  There are 
keys for advancing the display through the screen, skipping over blank 
areas if desired.  The user can determine whether or not to display 
screen color attributes, how to indicate the position of the cursor, 
whether to translate the text into contracted braille "on the fly", 
etc.  The screen reading software is monitoring the screen for 
changes, and these changes are being caused by a communications 
program, a telnet program, or Lynx or Bobcat running on the PC 
itself.  The screen reader may generate tones through the PC speaker 
to help keep users who can hear informed of activity that is too fast 
for braille display.  The user can control whether to slave the 
display "window" to the cursor position or roam around the screen and 
not "snap to" the cursor if the cursor moves.  It's a different way of 
grokking the fullness of a 2000-character screen, a little bit like 
viewing it with screen magnification software, but with that software 
restricted to a fixed number of characters of one line.

I could probably go on about why different kinds of error messages 
should be displayed for different lengths of time, but I don't 
actually use a braille display nowadays.  I used them a lot in the 
past, and should probably get back into it.  I use speech output, 
which is another way of grokking the screen.  I don't number the links 
and don't use show_cursor, and have things set up so that I hear very 
little speech unless I ask for it.

I know it's a long answer, but you asked for it!  
[link]  [link] [link]
Click *here* for more information ...

-- Lloyd Rasmussen
Senior Staff Engineer, Engineering Section
National Library Service for the  Blind and Physically Handicapped
Library of Congress          202-707-0535
(work)       address@hidden    www.loc.gov/nls/
(home) address@hidden

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