A pneumatic spanner structure includes a head body, a link bevel gear unit, a hit unit and a driving handle. The invention is characterized in that there is provided a control device for shifting on-state respectively one semiconductor switch or simultaneously several semiconductor switches according to a predetermined programme and for determining whether the respective voltages at the outputs are respectively within a predetermined tolerance range for the corresponding switching state. An array of image texels are stored in a plurality of cache memories to reduce the area occupied by cache memories of the computer graphic processing system.