Chorded keyboard (a writing system for the blind) uses either 6 or 8 tactile 'points' from which all letters and numbers are formed. When Louis Braille invented it, it was produced with a needle holing successively all needed points in a cardboard sheet. In 1892, Frank Haven Hall, superintendent of the Illinois Institute for the Education of the Blind, created the Hall Braille Writer, which was like a typewriter with 6 keys, one for each dot in a braille cell. The Perkins Brailler, first manufactured in 1951, uses a 6-key chord keyboard (plus a spacebar) to produce braille output, and has been
Braille Braille has adopted eight-dot cells for general use; for example, it adds a dot below each letter to derive its capital variant. Braille was the first writing system with binary encoding. The system as devised by Braille consists of two parts: Within an individual cell, the dot positions are arranged in two columns of three positions. A raised dot can appear in any of the six positions, producing sixty-four (2) possible patterns, including one in which there are no raised dots. For reference purposes, a pattern is commonly described by listing the positions where dots are raised, the positions being