The ’HC166 and ’HCT166 8-bit shift register is fabricated with silicon gate CMOS technology. It possesses the low power consumption of standard CMOS integrated circuits, and can operate at speeds comparable to the equivalent low power Schottky device.

The ’HCT166 is functionally and pin compatible with the standard ’LS166.

The 166 is an 8-bit shift register that has fully synchronous serial or parallel data entry selected by an active LOW Parallel Enable (PE\) input. When the PE\ is LOW one setup time before the LOW-to-HIGH clock transition, parallel data is entered into the register. When PE\ is HIGH, data is entered into the internal bit position Q0 from Serial Data Input (DS), and the remaining bits are shifted one place to the right (Q0 → Q1 → Q2, etc.