A feature not available in the RXTX_BITSLICE but available in the RX_BITSLICE is called cascade. This feature allows unused output delay lines in TX_BITSLICE cascaded to input delay lines in RX_BITSLICEs. The result is a delay line of double length passing data to the RX_BITSLICE deserializer registers. A single delay line is 512 taps. Cascading both input and output delay lines can double the length of the available delay. This feature is discussed in detail in the RX_BITSLICE Extended Delay Control Signals.