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Reading Vietnamese on the Braille Display
1. Vietnamese in the computer
Vietnamese is a six tones monosyllabic language.
The alphabet consists of 33 letters (12 vowels and 21 consonants), with upper and lower case forms.Three accent symbols are used to represent different sounds of the same root vowel.
One additional symbol is used for a consonant sound.
In writing, the tone is attached to the vowel sound of the syllable.
A vowel sound might need three elements to represent it when a tone is applied to it.The Roman alphabet character, the graphic symbol specific to the sound and the tone marker of the syllable.
The computer tool used to represent the characters of all languages based on phonetic alphabets is a table of 256 cells called ASCII.
People refer to a cell in the table as an ASCII code. So ASCII code 65 is everywhere taken by the vowel "A". In this way the first 128 cells constitute the standard ASCII table used for characters and symbols common to many languages written by using the Roman alphabet.
Some of the first 128 and the others 128 (=extended ASCII) can be used to customize a particular alphabet or a "font" (=set of characters).
In Viet Nam the PC is used with two languages at the same time: English and Vietnamese. The first one for the operating system and for reading and writing in this language, the other for reading and writing in Vietnamese. The most common software is in English but data are entered in Vietnamese by using additional software that converts some keys to generate accents and tones symbols applied to the alphabet letter.
If characters in the ASCII table take 1 byte, we say that the table is a "8 bit ASCII table".
If characters in the ASCII table take 2 bytes, we say that the table is a "2 bytes ASCII table".In the history of computers in Viet Nam many solutions have been created to code Vietnamese letters using 8 bit ASCII tables. To show Vietnamese letters (with or without accent and/or tone), we must use the extended part of ASCII.
Two popular solutions are TCVN3 and VNI.
The TCVN3 solution maps one Vietnamese letter to one ASCII code.
The VNI solution combines 2 ASCII characters to show one (accented and/or toned) Vietnamese letter, one byte for the root letter and another for the accent and/or tone. Because of art requirement, VNI also uses one-to-one mapping for 12 letters.2. Vietnamese Braille
Vietnamese Braille Grade 1 uses 6 dots for each letter. The accented or toned letter is represented by 2 Braille characters, the first for the tone and the other for the alphabet letter. As a result, the 5 tones have their dot-combinations. The standard alphabet letters use the same dot-combinations of the International Braille.
Seven accented Vietnamese alphabet letters have also their own dot-combinations in one Braille cell.3. Braille Display
The Braille Display can only be used with a 8-bit code table.
It means one 8-bit character in the computer is mapped to one dotted character in the Braille Display cell.
Since we use Jaws as the screen reader, the mapping was defined in a JBT (JAWS Braille Table) file. Each JBT file contains 256 mappings for the 256 characters in a 8-bit code table. Each mapping defines a dot-combination for one 8-bit character. So for every 6 or 8-dot Braille character you can redefine the dot-combination output of an ASCII table.4. Solution for reading Vietnamese on the Braille Display
Because of the similarity between the VNI font and Vietnamese Braille in showing letters with tones (=2 cells, one for the root letter and the other for accent), we decided to use the VNI font to translate Vietnamese on the Braille Display and created a JBT file to show Vietnamese Braille on the Display, with a few necessary changes in the Braille code dot combinations.
The user can make copies of the available JBT files and change them to define new translation tables.
We made a copy of VISUADE.JBT and saved it as BUNGSANG.JBT, then we made the neccesary changes in BUNGSANG.JBT.
For reading Vietnamese on the Braille Display, it is necessary to set the user defined Braille Table (in our case bungsang) as the default braille table in the Configuration Manager of Jaws.
By simply changing the default table it is possible to read many languages on the Display, and the blind has a tool to study and read Vietnamese and other languages that may not be voice-supported by the screen reader.In customizing the JBT file and creating the Vietnamese Braille Code for the Braille Display, we had to make make some changes to the grade 1 Vietnamese Braille.
For example, in the Braille Display an upper case letter is shown by dot 7 and the dot combination for the tone comes after the vowel.
For the five marked tones, we used the same dot-combination of Vietnamese Braille grade 1.
5. Conclusion
With this solution, the Vietnamese blind can read a Braille code which is very similar to their grade 1, because only a few changes were made.
They can also define new dot-combinations for scientific signs and other symbols. This solution takes less than one hour of practice for learning the variations and then the blind will be able to read fluently any Vietnamese VNI source.
The limitation of this solution is that there are less Vietnamese web pages using VNI than TCVN3. However, there are many texts and documents written in VNI in southern Viet Nam.
For the Vietnamese blind it is therefore a simple and innovative solution (although expensive) for accessing information in digital format for many different purposes.(Adapted by Amedeo Pignatelli for reading without graphics, from a paper by Vu Huy Phuong, 2001. The original document is available in the version with graphics of this web site)