3.1 (An Introduction to Methods Historically Used to Help the Blind Read)

Samuel Morse wasn’t the first to:

• translate the letters of written language into an interpretable code

• be remembered more as the name of his code than as himself

Louis Braille was born in France in the early 1800’s.

Early Attempts to Help the Blind Read

Valentin Haüy (who was not blind) invented a system of raised letters on paper that could be read by touch, but it was difficult to use and was used infrequently.

• he was stuck in a paradigm where an ‘A’ was an ‘A’ was an ‘A’

• In the Flashlight Problem example, he would have tried drawing the ‘A’ with a flashlight – ineffectively

Charles Barbier devised écriture nocturne (a.k.a. night writing)

• this system used a pattern of raised dot and dashes on heavy paper

• intended for sue by soldiers in passing notes to each other in the dark when noise couldn’t be made

• but rather than using patterns of dot and dashes corresponding to letters of the alphabet, his system used patterns that corresponded to sounds, often requiring many codes for a single word

Louis Braille improved the system within three years (from the age of 12 to 15)

3.2 (Dissecting Braille Code)

In Braille, every symbol used in normal written language is encoded as one or more raised dots within a two by three cell.

• The dots of the cell are commonly numbered 1 though 6

1 ° ° 4

2 ° ° 5

3 ° ° 6

Example of braille character in non-raised notation:

1 • ° 4

2 ° • 5

3 • ° 6

Dots 1, 3 and 5 are raised. Dots 2, 4, and 6 are not raised.

The dots are binary! Because a particular dot can be either flat or raised

• so we can combine what we know about Morse code and combinatorial analysis to Braille.

  • We know we have 6 dots which can be either flat or raised

  • So we know the total number of combinations of 6 flat and raised dots is:

    • 22222*2

    • 2^6

    • 64

  • So the Braille system is capable of representing 64 unique codes:

The first step in dissecting the code is looking at the basic lowercase alphabet.

^ These three rows show a pattern

1. Letters ‘a’ through ‘j’ use only the top four spots in the cell – dots 1, 2, 4, and 5

2. Letters ‘k’ through ’t’ exhibit the same pattern as row 1, except dot 3 is also raised

3. Letters ‘u’ through ‘z’ follow the same pattern as row 1, but ‘3’ and ‘6’ are also raised

Grade 2 Braille

-> A variation meant to speed reading and reduce space

In this variant, if letter codes appear by themselves, they stand for common words:

All of this still only described 31 out of a possible 64 codes.

A variant where dot 6 is raised for the lowercase row ‘a’ through ‘j’ is used for contractions, e.g.
‘ch’ =
• °
° º
º •

A variant where dot 6 is raised for the lowercase row ‘a’ through ‘j’, but which excludes the use of dots ‘1’ and ‘4’ is used for additional contractions and punctuation marks, e.g.
‘was’ and a closing quotation mark =
° °
° •
• •

These variants give us 51 codes so far.

The remaining variants help denote numbers, accents, capital letters, decimal points or emphasis depending on context.

3.3 (Summary)

Six binary elements (the dots) yield 64 possible codes, many of which perform ‘double duty’ depending on context.

Precedence / Shift Codes

Two especially interesting elements are the number indicator and the letter indicator which undoes the number indicator.

• they alter the meaning of the codes that follow them

  • from letters to numbers

  • from numbers back to letters

Precedence / Shift Code: Alters the meaning of all subsequent codes until the shift is done.

Escape Codes

-> The capital indicator means only the following letter should be changed

Escape Code: Lets you ‘escape’ from the routine interpretation of a sequence of codes and move to a new interpretation.

Both shift codes and escape codes are common when written languages are represented as binary codes.