1. Apparatus for electrically retrieving any selected one of a plurality of intelligence symbols from one of a pair of sets of intelligence symbols in accordance with a predetermined translation between the sets, comprising (a) input means for generating an electrical signal indicative of the selected intelligence symbol; (b) symbol storage means for storing a readable signal representative of each intelligence symbol in each said set at a separate address unique to each said intelligence symbol in each said set and for storing an address signal in association with each said readable signal in at least one said set for identifying the address of the corresponding intelligence symbol in the other set as required by the predetermined symbol translation; (c) comparison means connected with said input means and said symbol storage means for sequentially comparing said electrical signal generated by said input means with said readable signals with which address signals are associated and for reading out the address signal associated with the readable signal which corresponds to said electrical signal generated by said input means; and (d) symbol read out and display means connected with said symbol storage means and said comparison means for visually displaying the selected intelligence symbol and for reading out and displaying the intelligence symbol represented by the readable signal stored at the address read out by said comparison means.