Using the command SHOW VERSION you will see the model number of the line card: WS-X5xxx = SupI (1st generation) WS-X55xx = SupII (2nd generation) WS-X553x = SupIII (3rd generation) Viewed from outside the physical: 1st generation engine – only reset key, no PCMCIA slot. 2nd generation engine – reset key, active status light, no PCMCIA. 3rd generation engine – has PCMCIA slot and port to upper level.