MM54HC164/MM74HC164 8-Bit Serial-in/Parallel-out Shift Register General Description The MM54HC164/MM74HC164 utilizes advanced silicongate CMOS technology. It has the high noise immunity and low consumption of standard CMOS integrated circuits. It also offers speeds comparable to low power Schottky devices. This 8-Bit shift register has gated serial inputs and CLEAR. Each register bit is a D-type master/slave flip flop. Inputs A & B permit complete control over the incoming data. A low at either or both inputs inhibits entry of new data and resets the first flip flop to the low level at the next clock pulse. A high level on one input enables the other input which will then determine the state of the first flip flop. Data at the serial inputs may be changed while the clock is high or low, but only information meeting the setup and hold time requirements will be entered. Data is serially shifted in and out of the 8-Bit register during the positive going transition of the clock pulse. Clear is independent of the clock and accomplished by a low level at the CLEAR input. The 54HC/74HC logic family is functionally as well as pinout compatible with the standard 54LS/74LS logic family. All inputs are protected from damage due to static discharge by internal diode clamps to VCC and ground.