A rollover cable (also known as a Yost cable, Cisco cable, or console cable) is a type of null-modem cable that is used to connect a computer terminal to a network appliance's console port. This cable is typically flat and light blue in color, to distinguish it from other types of network cable. The name rollover alludes to how the pinouts on one end are reversed with respect to the other, as if the flat cable had been rolled over.
This cabling system was invented to eliminate the differences in RS-232 wiring systems. Any two RS-232 systems can be directly connected by a standard rollover cable and a standard connector. For legacy equipment, an adapter is permanently attached to the legacy port.