Braille display terminal for personal computers

A fully functional Braille display terminal developed for visually handicapped people to access and work with IBM personal computers is described. The hardware and software design required for the fabrication of control circuitry, the Braille character conversion modules, and the Braille display terminal are described. The Braille display system consists of a control unit, a display terminal and a keypad. To minimize the number of devices to be accessed, the special keypad required to issue commands to the display control unit is integrated with the normal PC keypad. The electromechanical components of the BDT comprise (a) a 40-Braille cell unit which displays 40 characters at a time and (b) two separate cells to display the two-digit cursor line number. An 80-character computer screen line is displayed by dividing it into two 40-character lines. The first 40 characters and the line number are displayed first. The subsequent characters are displayed on the user request. The line break is identified by means of a special character. The computer Braille codes as specified by the Singapore Society for the Blind are adopted in the design of the Braille cells