The MC74HC164B is identical in pinout to the LS164. The deviceinputs are compatible with standard CMOS outputs; with pullupresistors, they are compatible with LSTTL outputs.The MC74HC164B is an 8−bit, serial−input to parallel−output shiftregister. Two serial data inputs, A1 and A2, are provided so that oneinput may be used as a data enable. Data is entered on each rising edgeof the clock. The active−low asynchronous Reset overrides the Clockand Serial Data inputs. Schmitt−trigger action at the Clock inputenhances the device’s tolerance to slower rise and fall times andimmunity to noise of the input clock signal.