A workstation for processing and producing a video signal comprises a video input system, a video graphics processor, and a video output system. The pressure adjusting knobs serve to adjust pressure for positioning in the upward-downward direction of a label sheet of the barcode printer. The imaging system includes a first refractive element configured to be optically coupled with the vehicle window. The bus control devices in the processor devices interchange signals through the crossover bus upon each data access operation by the processor units, and output an error signal if there is no correspondence.