27. A control circuit according to claim 26 wherein said means for storing a plurality of message signals includes a first modular language storage unit connected to said control circuit for storing first message signals and means for selectively disconnecting said first modular language storage unit from said control circuit, and a second modular language storage unit for storing second message signals and means for selectively connecting said second modular language storage unit to said control circuit in place of said first modular language storage unit, and wherein said display means is responsive to said first and second message signals for displaying messages in first and second languages respectively.
26. A control circuit according to claim 1 including means for storing a plurality of message signals and a display means responsive to said message signals for displaying messages associated with said predetermined grid pattern.