数控机床的产生 TAPE D- MATIC (b) FIGURE 1-16(a)A pre-CNC electromechanical tape reader and Nc tape (b)The finger-like contact pass through tape holes, touching electrical contacts in the drum as the tapes passes over the drum The first commercial "N/c machines were shown at the 1955 National Machine tool show数控机床的产生 The first "commercial" N/C machines were shown at the 1955 National Machine Tool Show