8 bit 74HC595 Shift Register
The 74HC595 contains an 8-bit serial input, parallel output shift register that provides data to an 8-bit D-type memory register. The 74HC595's storage registers have a tri-state output. The shift register and the memory register have separate clocks. The 74HC595 shift register has the highest priority direct clear (SRCLR), serial input (SER), and serial output for cascading. When the output enable (OE) is high, the output of the 74HC595 will be in a high-impedance state.
Whether it is a shift register clock (SRCLK) or a storage register clock (RCLK), both rising edge triggers. If the two clocks are tied together, the shift register will always store a clock pulse in the register.