Monday, June 28, 2010

BrailleNote: how does blind people type and read text?

Last time we looked at what the BrailleNote looks and basic features that it offers. This time, let us find out how blind people type and read information on a BN.

Blind people throughout the world uses braille, a special character set that uses tactile dots to represent alphabets, numerals and punctuation. This involves a set of six dots on a paper's surface - two columns by three rows. From the top, these dots are called DOT 1, DOT 2, DOT 3 (left side), DOT 4, DOT 5 and DOT 6 (right side). These six dots provide 63 different combinations - enough to cover majority of the keys on a QWERTY keyboard. Thus, braille characters are entered and read using one or a combination of these dots. A list of basic alphanumeric characters and their braille equivalence are as follows:

CharacterBraille dot patterns/symbol
DDOTS 1-4-5
FDOTS 1-2-4
GDOTS 1-2-4-5
HDOTS 1-2-5
JDOTS 2-4-5
LDOTS 1-2-3
MDOTS 1-3-4
NDOTS 1-3-4-5
ODOTS 1-3-5
PDOTS 1-2-3-4
QDOTS 1-2-3-4-5
RDOTS 1-2-3-5
SDOTS 2-3-4
TDOTS 2-3-4-5
UDOTS 1-3-6
VDOTS 1-2-3-6
WDOTS 2-4-5-6
XDOTS 1-3-4-6
YDOTS 1-3-4-5-6
ZDOTS 1-3-5-6

For numbers, one uses number sign (DOTS 3-4-5-6) followed by letters A through J e.g. number 1 would be number sign, DOT 1, number 5 would be number sign, DOTS 1-5 and so forth. Punctuations are entered using special dot combinations e.g. DOTS 2-5-6 for a period, dots 2-3-6 for a question mark and so forth.

It would be hard to list all 63 different dot combinations and what they correspond to in print, but the above table gives you a general overview of how braille characters are entered.

using the method above, blind people use these characters when typing text, such as documents, email messages and forms on the web. Also, people use braille displays (see the below post for more information) to read braille symbols, which are arranged in groups of two-by-four pins (for a total of eight). The top six pins correspond to braille characters, while the two pins below them - DOT 7 and DOT 8 on the left and right, respectively - provides information about the cursor. Thus, in terms of electronic devices, if all eight dots are used, then a total of 256 different combinations are achievable - using the six dots, adding dot 7 and/or 8 - enough to cover ASCII characters and more.

So how does blind people use a device like this using a limited number of keys? This is achieved by typing the dot combination with SPACE, BACKSPACE A.K.A. DOT 7 and/or ENTER A.K.A. DOT 8 keys. Using this method, a total of 512 different combinations are possible - 64 for regular characters (including space character) , 448 for executing commands; thus the braille display can display up to 256 different combinations of eight dot braille (64 for six dot braille).

Up next: An overview of basic KeySoft operations (from windows Mobile perspective).
Note: ASCII stands for American Standard Code for Information Interchange.

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