1. A Braille display system comprising: A. a digital data processor for storing and processing alphanumeric text; B. a keyboard having a plurality of keys for generating input to said processor, said plurality of keys including a Braille display key; and C. a cursor control means, said processor responding to said cursor control means by identifying a location in said text and providing a Braille actuation signal corresponding to the character in the identified location in said text, and said Braille display key being arranged to provide a Braille indicator of the character in the identified location in said text in response to said Braille actuation signal, whereby, use of said cursor control means to sequentially identify locations within said text causes said text to appear at said Braille display key as sequential Braille indicators of said text so that said text can be read in Braille.
1. A Braille display system comprising: A. a digital data processor for storing and processing alphanumeric text; B. a keyboard having a plurality of keys for generating input to said processor, said plurality of keys including a Braille display key; and C. a cursor control means, said processor responding to said cursor control means by identifying a location in said text and providing a Braille actuation signal corresponding to the character in the identified location in said text, and said Braille display key being arranged to provide a Braille indicator of the character in the identified location in said text in response to said Braille actuation signal, whereby, use of said cursor control means to sequentially identify locations within said text causes said text to appear at said Braille display key as sequential Braille indicators of said text so that said text can be read in Braille. 3. A Braille display system as defined in claim 1 wherein: A. said keys cause the generation of said input when said keys are individually depressed, said input identifying the particular key which was depressed; and B. said Braille display key includes: 1. a holder having a plurality of first bearings and supporting a keycap which has a top surface, said top surface having a plurality of holes; 2. a keyguide on which said holder is slidably retained so that said holder can slide up and down on said keyguide; 3. a spring urging said holder upward on said guide; 4. a plurality of pins movably mounted on said holder, each of said pins being movable between a raised position in which said pin extends upwardly through one of said holes to project above said top surface and a lowered position in which the entire pin is below said top surface; 5. a plurality of double-crank rods having first crank arms and second crank arms separated by central shafts, said first crank arms being coupled to said pins, said center rods passing through and being supported by said first bearings so that rotation of said shafts moves said pins between said raised and lowered positions and said shafts move up and down with said holder without changing the vertical positions of said pins relative to said top surface; and 6. a plurality of solenoids responsive to said Braille actuation signal, said second crank arms being coupled to said solenoids so that said Braille actuation signal causes rotation of said shafts, thereby producing said Braille indicator.