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4. Appendices

4.1 Disclaimer and License

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

(A copy of the GNU General Public License can be found in the file COPYING in the top-level directory.)

4.2 Support

This software is being maintained by the original author, Nikhil Nair <nn201@cus.cam.ac.uk>. However, it now represents the work of a team, which also includes

The maintainer can also be contacted at: Nikhil Nair, Trinity College, CAMBRIDGE, CB2 1TQ, England; tel.: +44 1223 368353.

Comments and criticisms are welcome. We will try to respond promptly to all (sensible) mail, but give no guarantee. In general, we suggest you send email messages to all three active developers, rather than just one; if you don't hear anything, please be patient---make sure you copied the relevant addresses accurately, though.

If you have a query about a particular display type supported by BRLTTY, you may want to contact the author of that particular driver. See the README file in the relevant subdirectory for contact details.

4.3 Future Enhancements

Apart from fixing bugs and supporting more types of Braille display, we hope, time permitting, to work on some or all of the following:

Better attribute handling

Attribute tracking, mixed text and attribute mode etc.

Revision of cut & paste

Linear (as opposed to rectangular) cut mode.

Revision of beeps

A greater variety of beeps.

Scroll tracking

Locking the Braille window on one line as it scrolls on the screen.

Elementary speech support

Mixed Braille and speech for faster reading of text.

On-the-fly grade II translation

This would also allow faster reading of text.

First, however, we plan to restructure BRLTTY, separating the low-level Braille display handling from the high-level, device-independent part; this would allow BRLTTY to coexist with other programs which access the Braille display, e.g. any future X access software.

4.4 Known Bugs

This software has been tested on

It has proved stable so far, but if it isn't on your system, or if you find a bug not mentioned here, please let us know so that we can try to sort out the problem.

At the time of writing (26 July 1996), the following problems are known:

Cursor routing performance

Routing is implemented by a looping sub-process which runs at lowered priority to avoid using too much cpu time. Different system loads require different settings of the parameters here. The defaults work excellently in a standard Unix editor on a fairly lightly loaded system, but very badly in other applications, e.g. some applications working under DOSEmu (the MS-DOS emulator for Linux).

Operation in DOSEmu

As well as the cursor routing problems outlined above, keystroke simulation of any kind does not work correctly in DOSEmu's raw keyboard mode. This is because keystroke simulation must be done differently in this case, possibly by using scan codes. This affects the cursor routing and cut & paste functions.

Pasting non-ASCII characters

Unfortunately, due to the way the Linux kernel handles some operations, the character number stored in video memory for an accent mark etc. may not correspond to the character value in the keyboard buffer for the same symbol---they are represented in different character sets. As a result, pasting of non-ASCII characters may give strange results. BRLTTY should probably do some internal character set translation---this needs further investigation.


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