The 74HC/HCT173 are high-speed Si-gate CMOS devices and are pin compatible with low power Schottky TTL (LSTTL). They are specified in compliance with JEDEC standard no. 7A. The 74HC/HCT173 are 4-bit parallel load registers with clock enable control, 3-state buffered outputs (Q0 to Q3) and master reset (MR). When the two data enable inputs are LOW, the data on the Dn inputs is loaded into the register synchronously with the LOW-to-HIGH clock (CP) transition. When one or both Enable inputs are HIGH one set-up time prior to the LOW-to-HIGH clock transition, the register will retain the previous data. Data inputs and clock enable inputs are fully edge-triggered and must be stable only one set-up time prior to the LOW-to-HIGH clock transition.