1. Improved apparatus including computer equipment; program material including a plurality of instructions, part of which is a prescribed display instruction; said computer equipment being removably connectable to said program material; said computer equipment when connected to said program material operating to produce signals in accordance with said instructions; a display device responsive to said signals and producing displays in accordance therewith; said prescribed display instruction causing said computer equipment to produce signals which if received by said display device would cause it to produce a particular display; said computer equipment including means preventing said equipment from operating with program material not containing said prescribed display instruction, and wherein the improvement comprises a prescribed display instruction which produces a particular display including the phrase "This apparatus uses the invention of U.S. patent application entitled Protected Programmable Apparatus filed on Nov. 25, 1981 and any patent issuing thereon."