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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 SupportFor up to date information, see our web page athttp://www.cam.org/~nico/brltty.

BRLTTY represents the work of a team, which includes

Comments, suggestions, criticisms and contributions 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 both active developers.

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 BRLTTY on installation/rescue rootdisks

From version 1.0.1, BRLTTY can run as a stand-alone executable, without any configuration files. In this case the compiled-in defaults will be used. If the directory /etc/brltty (used to store the configuration file, the online help file and the table files) is not present, BRLTTY looks in /etc for the help file brlttydev.hlp and the configuration file brlttyconf.dat. Even if these are not present, BRLTTY will still work!

If, for some reason, you ever create the /etc/brltty directory by hand, it is important to set the permissions so that only root can create files in that directory.

Note: The /dev/vcsa0 device is also required. It should already be present unless your Linux distribution is quite old. You can create it with:

mknod /dev/vcsa0 c 7 128
chown root.tty /dev/vcsa0
chmod 660 /dev/vcsa0

When constructing floppy rootdisks for installation or rescue purposes, space is often of the essence. This new resiliance allows BRLTTY to be installed as a single executable on such disks, reducing the space requirement.

Note: The script install-brltty assumes a complete installation of BRLTTY is to be copied.

One problem often encountered when trying to use BRLTTY in an uncertain environment like a bootdisk or an incomplete system is that BRLTTY might not find the shared libraries it requires. Bootdisks often use smaller but outdated versions of the libraries which may not work. The solution is to compile BRLTTY with the -static flag (see Makefile). This removes any dependency on shared libraries, but unfortunately produces a larger executable.

The executable is stripped during the make install. If you take the executable straight from the compilation directory, don't forget to strip it.

4.4 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.

See the TODO file for a more complete list.

4.5 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 (March 1999), 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 situations, e.g. over a slow serial link to a remote host.

Operation in DOSEmu

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.

There is a bug in the Linux kernel 2.0.35 which causes console beeps to never stop once started. We have found a way to avoid this problem in the current version of BRLTTY.


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