1. Introduction
2. Installation Instructions
3. Functions
4. Further Development

Screen is a full-screen window manager that multiplexes a physical terminal between several processes, typically interactive shells. Each process is given its own tty session, and the braille additions we have recently added to Screen allow the user to view these directly with the display without having to log in through a DOS machine. The newest version of the screen (3.8.6), which contains the braille accessibility program, is available from ftp://ftp.uni-erlangen.de/pub/utilities/screen/braille/screen-3.8.6.tar.gz .
It is also available along with explanatory notes and three braille tables from our site, screen-3.8.6.tar.gz .

While Screen allows access to tty terminal sessions, it does not access the X-Window; however, it will run in an xterm window. Currently, it works with the TSI Navigator 40, the TSI PowerBraille 40 and the TSI powerbraille 80 braille displays. We plan to support other displays, by request, and if sufficient information is made available from the braille display manufacturer. Screen runs under most UNIX variations, including the GNU Linux operating system available for PCs.

Installation Instructions

Please read the INSTALL file for full installation instructions. In addition to those instructions, note that you must create a .screenrc file and that file must contain the type of braille display that you are using and the serial device that the display is connected to. A minimal .screenrc file should contain something like the following four lines (these are only examples, please customize them for your configuration):

# example of .screenrc when using  braille display
bd_start_braille on
bd_type  powerbraille_40
bd_port  /dev/ttyS0
bd_braille_table /home/gardner/us-braille.tbl
# end of example

The basic operation of screen is described in the README file. The braille navigation commands are similar to commands usually found on DOS braille screenreaders. Also, because braille accessibility is integrated into screen, the user can switch back and forth easily between many applications that are running simultaneously. The braille commands can be changed any time after starting screen using the internal screen "C-a :" command line. All braille commands begin with "bd_"; The list of braille commands follows:

bd_start_braille on/off      # Starts/stops using braille features on screen
bd_link on/off               # links/unlinks braille cursor to/from screen
                             # cursor
bd_bell on/off               # turn on/off sending bell-signal to terminal
bd_scroll on/off             # enables/disables scrolling
bd_skip on/off               # skip/don't skip blank lines
bd_width      # number of braille cells that user wants to use,
                             # This number should always be less than or equal
                             # to the number of cells on the braille display
bd_ncrc      # number of cells displayed on the right side
                             # of physical cursor (default = 1)
bd_info       # displays braille/screen cursor position
                             # depending on its value, (no info: 0, only
                             # bc-info: 1, only sc-info: 2, bc- and sc-info: 3
bd_port       # serial port that braille display is connected to
bd_braille_table   # braille table to be used. German, US and GS
                             # braille tables are provided
bd_type 
                             # braille display type being used

bd_type:
 1. navigator_40
 2. powerbraille_40.
 3. powerbraille_80

bd_braille_table:
 1. gr-braille.tbl     German braille code
 2. us-braille.tbl     US computer braille code
 3. gs-braille.tbl     GS braille code

Further Development

Screen currently works with Telesensory braille displays, the PowerBraille and the Navigator because Telesensory has given us the information needed to program their displays. We are presently working to include the Blazie Braille-lite. We hope to add support for other braille displays if we get the requisite information from the braille display manufacturer. We also intend to add some features such as cursor routing from the braille display. If you find a feature missing that you think should be implemented, please contact us.

This software has been developed within the Science Access Project at Oregon State University under the direction of Prof. John Gardner. This research project is sponsored by grants from the US National Science Foundation.

Authors:

• Hadi Bargi Rangin
  URL: http://dots.physics.orst.edu/~bargi/
  E-mail: bargi@dots.physics.orst.edu
• Bill Barry
  E-mail: barryb@dots.physics.orst.edu