Improved teleprinter keyboard technique

The problem of double case operation with the retention of a five-unit code is solved by arranging for the automatic insertion of a shift signal whenever the sending of a figure or punctuation mark is required. In order to transmit this additional signal without slowing down the operation, a storage device is provided which holds the permutations corresponding to the key last depressed until the appropriate shift signal has been automatically transmitted. A keyboard is thus provided conforming strictly to the commerical typewriter layout in which both figures and symbols are accommodated on the fourth row of keys, the symbols being selected by holding down a shift key.